Solids

THE HANDBOOK ON

SOLIDS CONTROL &WASTE MANAGEMENT

4th EDITIONPublished by Brandt / EPI ™

1st Edition © 19822nd Edition © 19853rd Edition © 19954th Edition © 1996

All rights reserved. No part of this book may be reproduced inany form without permission in writing from the publisher.

Printed in the U.S.A.

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PREFACE

This Handbook was written by the Technical Services staff of Brandt/EPIto provide a basic understanding of effective mechanical removal of drilledsolids and management of drilling wastes. Based on sound theoretical con-cepts, this Handbook is a practical working tool. It is designed for use byanyone needing to optimize drilling efficiency: drilling engineers, supervi-sors, tool pushers, mud engineers, derrick hands, service personnel andothers.

This 4th edition of the Handbook provides updated sections on equip-ment and techniques, and includes new information on waste processingsystems, including downhole injection, solidification/ stabilization, waterclarification, and other site remediation techniques. We would appreciateany suggestions for improving future editions of the Handbook. Pleaseaddress your comments to:

Brandt/EPI Technical GroupP.O. Box 2327Conroe, TX 77305

TEL: (713) 756-4800FAX: (713) 756-8102

Thanks,

Mike MontgomeryManager, Technical GroupBrandt/EPI

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TABLE OF CONTENTS

PAGE1.0 DRILLING MUD AND MUD SOLIDS .....................................................1.1

1.1 Functions of Drilling Mud ............................................................................1.11.2 The Nature of Drilled Solids ........................................................................1.21.3 Properties of Drilling Mud ...........................................................................1.41.4 Types of Drilling Muds.................................................................................1.8

2.0 BENEFITS OF SOLIDS REMOVAL BY MECHANICAL SEPARATION.....2.12.1 Reduced Total Solids ....................................................................................2.12.2 Reduced Dilution Requirements ..................................................................2.2

3.0 MECHANICAL SOLIDS CONTROL AND RELATED EQUIPMENT .........3.13.1 Particle Classification and Cut Point ............................................................3.33.2 Separation by Vibratory Screening ..............................................................3.63.3 Shale Shakers ..............................................................................................3.143.4 Mud Cleaners/Conditioners........................................................................3.213.5 Separation by Settling and Centrifugal Force............................................3.283.6 Sand Trap ....................................................................................................3.293.7 Hydrocyclones ............................................................................................3.303.8 Desanders....................................................................................................3.333.9 Desilters.......................................................................................................3.353.10 Decanting Centrifuge..................................................................................3.383.11 Auxiliary Equipment...................................................................................3.433.12 Unitized Systems.........................................................................................3.483.13 Rig Enhanced Systems................................................................................3.493.14 High Efficiency Solids Removal Systems...................................................3.503.15 Basic Arrangement Guidelines...................................................................3.51

4.0 BRANDT/EPI™ PRODUCTS AND SERVICES ........................................4.1Company Profile..........................................................................................................4.14.1 Scope of Services..........................................................................................4.14.2 Business Relationship...................................................................................4.14.3 Certification...................................................................................................4.14.4 Personnel Resources.....................................................................................4.2Products and Services .................................................................................................4.24.5 Linear Motion Shakers..................................................................................4.3

ATL-1000 .......................................................................................................4.3ATL-1200 .......................................................................................................4.3LCM-2D .........................................................................................................4.4ATL-CS...........................................................................................................4.4LCM-2D/CM2 ................................................................................................4.5ATL Drying Shaker........................................................................................4.5SDW-25 Drying Shaker.................................................................................4.6ATL-16/2 Mud Conditioner...........................................................................4.6ATL-2800 Mud Conditioner ..........................................................................4.7LCM-2D Mud Conditioner ............................................................................4.7

4.6 Orbital Motion Screen Separators ................................................................4.7Tandem Screen Separator ............................................................................4.7Standard Screen Separator ...........................................................................4.8Mud Cleaners ................................................................................................4.8

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4.7 Screen Panels ................................................................................................4.9BlueHexSM 3HX Screen Panels .....................................................................4.9Pinnacle™ Screen Panels .............................................................................4.9PT Screen Panels ........................................................................................4.10Hook-Strip Screen Panels...........................................................................4.10

4.8 Hydrocyclone Units ....................................................................................4.10Desanders....................................................................................................4.10Desilters.......................................................................................................4.11

4.9 Centrifuges ..................................................................................................4.11SC-1 Decanting Centrifuge .........................................................................4.11SC-4 Decanting Centrifuge .........................................................................4.12HS 3400 High Speed Decanting Centrifuge ..............................................4.12SC 35HS High Speed Decanting Centrifuge..............................................4.12HS 5200 High Speed Decanting Centrifuge ..............................................4.13Roto-Sep Perforated Rotor Centrifuge .......................................................4.13

4.10 Dewatering Units ........................................................................................4.144.11 Filtration Units ............................................................................................4.144.12 Vacuum Degassers......................................................................................4.154.13 Mud Agitators..............................................................................................4.154.14 Portable Rig Blowers ..................................................................................4.154.15 Integrated Systems......................................................................................4.16

Closed Loop Processing Systems ...............................................................4.16Coiled Tubing (CT) Processing Systems....................................................4.17Trenchless Technology Processing Systems..............................................4.17Live Oil Systems..........................................................................................4.17

4.16 Remediation Management Services ...........................................................4.174.17 Technical & Engineering Services..............................................................4.18

APPENDICESGlossary .....................................................................................................................A.2Mud Solids CalculationsStandard Calculations..................................................................................................B.1Field Calculations to Determine Total Solids Discharge...........................................B.4Field Calculations to Determine High and Low Gravity Solids Discharge ..............B.5Solids Control Performance Evaluation .....................................................................B.6Method for Comparison of Cyclone Efficiency .......................................................B.10Mud Engineering DataConversion Constants and Formulas..........................................................................C.1Density of Common Materials ....................................................................................C.2Hole Capacities ...........................................................................................................C.3Pounds per Hour Drilled Solids — Fast Rates ..........................................................C.4Pounds per Hour Drilled Solids — Slow Rates .........................................................C.5Solids Content Chart ...................................................................................................C.6Equipment SelectionPre-well Project Checklist...........................................................................................D.1Screen Cloth Comparisons .........................................................................................D.2Brandt/EPI Equipment Specifications........................................................................D.3Selecting Size and Number of Agitators ....................................................................D.7Brandt/EPI™ Sales & Service Locations ....................................................................D.8

1.1

1.0 DRILLING MUD AND MUD SOLIDS

Mud is the common name fordrilling fluid. While it is outside thescope of this handbook to offer adetailed discussion of drilling fluids,a brief outline of the general char-acteristics of drilling mud isincluded to establish the basic rela-tionships between drilling mud andsolids control.

Similarly, any discussion of solidscontrol would be incomplete with-out establishing an understandingof the nature of mud solids — theirsize, shape and composition.

1.1 FUNCTIONS OF DRILLING FLUID

The mud system in a drillingoperation performs many importantfunctions. Among these are: 1. Carry the drilled solids from

the bottom of the hole to thesurface.

2. Support the wall of the hole. 3. Control pressure within the for-

mation being drilled.4. Cool the bit and lubricate the

drill string.5. Clean beneath the bit.6. Suspend cuttings while circula-

tion is interrupted (e.g., duringtrips).

7. Secure accurate informationfrom the well (cuttings sam-ples, electric logs, etc.).

8. Help support the weight of thedrill string.

9. Transmit hydraulic horse-power to the bit.

10. Allow removal of cuttings bythe surface system.

Of the ten functions listed, the fol-lowing are generally consideredmost important:1. Drilling mud moves the forma-

tions’ solids cut by the drill bitfrom the bottom of the hole tothe surface. Removal of cut-tings from the wellbore isessential in order to continuedrilling.

2. Drilling mud must withstandthe pressure exerted by theformations exposed in thehole. The pressure exerted bythe mud against the formationshelps the driller control thepressure created by the gas, oiland water that are exposedwhile drilling, thus reducingthe potential for costlyblowouts.

3. Drilling mud protects and sup-ports the walls of the wellbore.The mud has a plastering effecton the walls of the hole andhelps prevent the walls fromcaving in, causing an enlargedhole or leading to stuck pipe.

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These problems significantlyincrease drilling expense andtime.

4. Drilling mud cools the bit andlubricates the drill string. Thisfunction is important in drillingbecause it increases the usefullife of bits and the drill string.

Drilling mud is obviously a majorfactor in the success of any drillingprogram, and the key to any effec-tive mud system is good solidscontrol.

1.2 THE NATURE OF DRILLED SOLIDS

Mud solids include particles thatare drilled from the formation,material from the inside surface ofthe hole and materials that areadded to control the chemical andphysical properties of the mud,such as weight material. Drilledsolids’ particles are created by thecrushing and chipping action ofrotary drill bits. Additional solidsenter the well bore by sloughingfrom the sides of the open hole.

The unit of measurement general-ly used to describe particle size isthe micron (µ). A micron is onethousandth (0.001) of a millimeter,or approximately 0.00003973 of aninch. To relate this unit of measure-ment in more familiar terms, Figure1-1 provides a list of common itemsand their size in microns.

Although individual mud solidscan range in size from less thanone micron to larger than a humanfist, the average particle size is lessthan 35–40 microns, too small to beseen with the human eye.

Note: The various sizes of solidsparticles in a particular drillingmud are referred to as the mud’scuttings, sand, silt or clay content.This content is important to remem-ber because solids control practiceswill affect the average particle sizeand the concentration of solids inspecific size ranges which maygreatly affect mud properties anddrilling operations.

Mud solids may be convenientlygrouped according to micron sizerange, but unfortunately not with-out introducing some element ofconfusion. The API Committee onStandardization of Drilling FluidMaterials, in API Bulletin 13C pub-lished in 1974, recommendedcertain terminology for mud solidsparticle size in an attempt to mini-mize this confusion. This newterminology has not yet, however,gained universal acceptance.

Figure 1-1 Micron Size Range of Common Materials

ITEM DIAMETER IN MICRONS

Cement Dust (Portland) 3-100 µTalcum Powder 5-50 µRed Blood Corpuscles 7.5 µFinger Tip Sensitivity 20 µHuman Sight 35-40 µHuman Hair 30-200 µCigarette (diameter) 7520 µOne inch 25,400 µ

1.3

The more commonly used classifi-cations shown in Figure 1-2,cuttings, sand, silt and clay (or col-loidal size) will be used throughoutthis handbook, as they are the mostreadily recognized in the field.These terms will refer to size classi-fication only, not to materialcomposition.

Note: Drilled solids can originatefrom sand, limestone, shale or otherformations, but their classificationin regard to solids control usuallydepends on particle size since theirspecific gravity is assumed to beapproximately 2.6.

It is important to note that com-mercial solids (such as barite orbentonite added for weight and vis-cosity) are also affected by solidscontrol equipment, according tosize. Most barite particles are in thesame size group as silt (2–74microns); bentonite particles aregrouped with clay (smaller than 2microns).

From the time they enter the welluntil they reach the surface, drilledsolids particles are continuouslyreduced in size by abrasion withother particles and by the grindingaction of the drill pipe.

Abrasiveness of mud solids isdetermined by particle shape andhardness. Drilled solids come invarious shapes such as round, nee-dle shaped, platelets, cubic, etc. Tobe destructive, particles must besharper and harder than the materi-al they are to abrade. Figure 1-3illustrates the degradation of drilledsolids in a mud system. The mainbody of the particle becomes lessabrasive with wear as the mostabrasive corners continue todegrade down through the silt sizeto approximately 15–20 microns.

Particles smaller than 15–20microns have much less abrasiveeffect on drilling equipment. Bariteparticles, which are not as hard asmost drilled solids, are generallyless abrasive than similarly-sizeddrilled solids. Other weightingmaterials, such as hematite, aregenerally harder and more abrasivethan barite.

Specific surface area, as it relates

Figure 1-2 Common Field Terminology of Particle Size

CLASSIFICATION PARTICLE SIZE(Diameter in Microns)

Cuttings Larger than 500 µ

Sand 74-500 µ

Silt 2-74 µ

Clay Smaller than 2 µ

Figure 1-3 Mechanical Degradation of Drilled Solids

1.4

to various shapes and sizes ofsolids, is another important con-cept. Specific surface area refers tothe surface area per unit of weightor volume. Figure 1-4 lists examplesthat show surface area greatlyincreases per unit of mass: 1) asparticle size decreases, and 2) asparticles become less spherical inshape.

Surface area adsorbs or “ties-up”water. The more surface area, themore water adsorbed. As the parti-cle size decreases toward thecolloidal size, the relative effect ofthe water coating increases. Thespecific surface area has a pro-nounced effect on viscosity, asFigure 1-5 illustrates. The higher therelative specific surface area, thegreater is the viscosity. Formations

composed of clays that easily dis-perses into the mud producerelatively more viscosity increase andwill have “wetter” separations inremoval by equipment than forma-tions that produce larger sized solids.Bentonite disperses easily into col-loidal solids and also absorbs muchmore water than most solids types.Hence bentonite builds viscosity atrelatively low concentrations.Viscosity and other mud propertiesare discussed in Section 1.3 of thisHandbook.

1.3 PROPERTIES OF DRILLING MUD

The ability of a drilling fluid toperform its functions depends onvarious properties of the mud, mostof which are measurable and areaffected by solids control.

DENSITY (MUD WEIGHT)

Density is a measure of the weightof the mud in a given volume, andis frequently referred to as mudweight. The instrument used tomeasure density is the mud balance(see Figure 1-6). The instrumentconsists of a constant volume cupwith a lever arm and rider calibrat-ed to read directly the density ofthe fluid in lbs/gal (water = 8.33lbs/gal) and pressure gradient inpsi/1000 ft (water = 433 psi/1000 ft)or pounds per cubic foot (water =62.4 lbs/ft).

Figure 1-4Effect of Particle Size and Shape on Surface Area

Figure 1-5Effect of Specific Surface Area on Viscosity

EQUIVALENT SPHERICALPARTICLE DIAMETER TYPE SQUARE FEET

(Microns) PARTICLES PER POUND

5.0 µ Glass Spheres 2,345

5.0 µ Crushed Quartz 3,435


1.0 µ Crushed Quartz 17, 160


0.1 µ Crushed Quartz 171,500

1.5

The density of the mud is relatedto the specific gravity of the fluid.Specific gravity is the ratio of amaterials density to the density ofwater. Pure water has a specificgravity of 1.0. A material twice asdense as water would have a spe-cific gravity of 2.0. A material halfas dense as water would have aspecific gravity of 0.5. Low gravitysolids have an average specificgravity of 2.6. The solids are 2.6times the weight of the same vol-ume of water.

VISCOSITY

Viscosity measures the mud’sresistance to flow as a liquid and isone of the key physical propertiesof mud. Increasing the amount ofsolids or exposed surface area in amud increases its resistance to flowas a liquid and therefore increases

its viscosity. Viscosity is routinelymeasured with a Marsh Funnel andMud Cup at the drilling site (seeFigure 1-7). The person measuringthe viscosity fills the funnel with asample of mud and allows it to

Figure 1-6 Mud Balance

Figure 1-7 Marsh Funnel and Cup

1.6

flow through the tip of the funnelcontainer while measuring the timein seconds that it takes to fill themud cup to the one quart level.The funnel viscosity recorded is inseconds per quart. Internationally,funnel viscosity is recorded in sec-onds per thousand ccs or secondsper liter.

PLASTIC VISCOSITY

A mud’s Plastic Viscosity is the por-tion of a mud’s flow resistancecaused by the mechanical frictionbetween the suspended particlesand by the viscosity of the continu-ous liquid phase. In practical terms,plastic viscosity depends on thesize, shape, and number of parti-cles. For example, as the amount ofdrilled solids in a mud increases,the plastic viscosity also increases.

Plastic viscosity is measured with a

rotational viscometer (Figure 1-8)and is expressed in centipoise(grams per centimeter-second).

YIELD POINT

Yield point is the part of flow resis-tance that measures the positiveand negative inter-particle, orattractive, forces within a mud.Yield point is measured with aviscometer and expressed inlbs/100 ft2. Internationally, yieldpoint is sometimes measured indynes/cm2.

GEL STRENGTH

Gel Strength is a function of amud’s inter particle forces and givesan indication of the amount of gela-tion that will occur after circulationceases and the mud remains staticfor a period of time. Typically, gelstrengths are reported for initial and10-second gel strength. A largedeviation of these two figures mayindicate progressive gels, that is,gelation structures that gainstrength over time. Gel strength isalso measured with a viscometerand expressed in lbs/100 ft2.Internationally, gel strength issometimes measured in dynes/cm2.

SOLIDS CONTENT

The solids content is the volumepercentage of the total solids in the

Figure 1-8 Rotational Viscometer (VG Meter)

1.7

mud. To determine the solids con-tent of a mud containing weightmaterial, a mud container in theretort is filled with a measured vol-ume of mud (see Figure 1-9). Themud is then heated to boil off theliquid. The percentage of the liquiddistilled off is measured in a glasscylinder and subtracted from 100%.The difference is the percentage ofsolids by volume contained in thedrilling mud and is recorded as per-centage solids. The total solids fromthe retort and mud weight are usedto calculate the low and high gravi-ty solids content.

If the mud does not contain oil orweight material, such as barite orhematite, the low gravity solids canbe determined without a retort byweighing the mud and referring toa solids content chart.

SAND

Sand is any particle larger than 74

microns when referring to solidscontrol separation. Therefore, thesand content of a mud is simply theamount of solids too large to passthrough a US Test Sieve 200-meshscreen. This is determined with asand content set (see Figure 1-10)by washing a mea-sured amount ofmud through the200-mesh screen inthe kit. Theamount of solidsthat does not passthrough the screenis measured aspercentage by vol-ume and isrecorded as per-cent sand.

FILTRATION

Filtration and wall-cake buildingare actions that the drilling mudcarries out through and on thewalls of the hole. Some formationsallow the liquid in the mud to seepinto them, leaving a layer of mudsolids on the wall of the hole. Thislayer of mud solids is called filtercake or wall-cake. The filter cakebuilds up a barrier and reduces theamount of the liquid that enters theformation and is lost from the mud.This process is referred to as filtra-tion, or fluid loss. The instrumentused to measure the fluid loss dueto filtration is a filter press (seeFigure 1-11).

Figure 1-9 Retort (Mud Still)

Figure 1-10Sand Content Set

1.8

The person using the filter pressplaces a mud sample in the instru-ment on top of a piece of filterpaper and brings the pressure up to100 pounds per square inch. Theamount of fluid flowing from thesample in 30 minutes is measuredin milliliters. The mud filtrationproperty is recorded in units ofcubic centimeters (ccs) or milliliters(ml) per 30 minutes. Examination ofthe filter paper will indicate howthe solids will plaster the wall ofthe hole and affect fluid loss. Thecake thickness is recorded in unitsof 1/32s of an inch.

CHEMICAL PROPERTIES

Chemical Properties is a broadcategory, including measurementsof pH, alkalinity, chlorides, calcium

content, salt content, and otherproperties that affect drilling mudperformance. Some of these chemi-cal properties can be controlledthrough various mud additives thatthicken, thin, precipitate, disperse,emulsify, lubricate or otherwiseadjust the mud depending on spe-cific drilling needs. For example,caustic soda can be added to somesaltwater mud in order to maintaina high pH level; it makes disper-sants more effective and reducescorrosion. Chemical changes suchas these are used to fine tunedrilling muds.

1.4 TYPES OF DRILLING MUDS

Drilling fluids are generally cate-gorized as “water-base” or “oil-base”, and as “weighted” or“unweighted” muds.

Water-base Muds contain water asthe liquid phase and are used todrill most of the wells in the worldbecause they are relatively simple,expense is usually reasonable, andwater is commonly available inmost places.

Oil-base Mud contains either nat-ural oil or synthetic oil as thecontinuous liquid phase and is usedfor maximum hole protection. Oil-base mud and synthetic oil mud areusually much more expensive thanwater-base mud and therefore areonly used when there is a specific

Figure 1-11 Filter Press

1.9

need, such as to keep the holefrom swelling or caving in, or toreduce friction and prevent stuckpipe in very crooked or high angleholes. Either water-base or oil-basemud can be used as “weighted”mud.

Weighted Mud refers to any mudwhich has barite or barite substi-tutes added to increase density.These muds normally have a densi-ty greater than 10.0 lbs/gal. Thesolids in weighted mud consist ofdrilled solids from the hole, plusbarite, plus commercial clays addedto control fluid loss and viscosity.

Unweighted Mud refers to anymud which has not had bariteadded. This mud type normally hasa density of less than 10.0 lbs/gal.The solids in unweighted mud con-sist of drilled solids from the hole,plus commercial clays.

Solids control techniques will varyconsiderably depending on the typeof mud being used. For example,with many unweighted water-basemuds, the loss of fluids along withthe drilled solids may be economi-cally insignificant, allowing simplesolids control techniques. In thecase of mud that contains expen-sive chemical additives and/orbarite, especially oil-base mud,sophisticated solids control tech-niques must be utilized to minimizeoverall costs. In addition, environ-mental costs of haul-off and

disposal may require sophisticatedsolids control techniques. Systemrecommendations for specific appli-cations are covered in detail inChapter 4.

Here is a list of the most commonmud types, followed by a briefdescription of each type:I. Water-Base Mud (WBM)

A. Spud MudB. Natural mudC. Chemically-Treated Mud

1. Lightly Treated ChemicalMud

2. Highly Treated ChemicalMud

3. Low Solids Mud4. Polymer Mud5. Calcium Treated Mud

D. Saltwater Mud1. Sea Water Mud2. Saturated Salt Mud

II. Oil-Base Mud (OBM)A. “True” Oil BaseB. Invert Emulsion C. Synthetic (SBM)

SPUD MUD

Spud Mud is used to start thedrilling of a well and continues tobe used while drilling the first fewhundred feet of hole. Spud mud isusually an unweighted water-basemud, made up of water and naturalsolids from the formation beingdrilled. It may contain some com-mercial clay, added to increaseviscosity and improve wall-cakebuilding properties.

1.10

NATURAL MUD

Natural Mud (sometimes called“native” mud) is usually unweight-ed water-base mud which containsmostly drilled solids. Some ben-tonite and small amounts ofchemicals may be used to improvefilter cake quality and help preventhole problems. This mud is oftenthe next mud type used after spudmud. Often, natural mud is used todrill the first few thousand feet ofhole, where only minor hole prob-lems are expected.

CHEMICALLY TREATED MUD

Chemically Treated Mud is water-base mud which contains chemicalsto control physical and chemicalproperties. Bentonite is usuallyadded to help control viscosity andfluid loss. Barite (weight material)may be added to increase density.

This mud is used where moresevere hole problems are expected,in order to prevent these problems.

Lightly Treated Chemical Mud isusually unweighted water-basemud. It is used where minor holeproblems are expected, such assloughing or caving of the walls ofthe hole.

Highly Treated Chemical Mud isusually weighted, water-base mudthat contains larger amounts ofchemicals, bentonite, additives, andbarite to maintain strict control ofviscosity, fluid loss, chemical prop-

erties, and density. Chemical mudsare often treated with lignosul-fonates or lignite and are thereforecommonly called “lignosulfonatemud” or “lignite” mud.

These muds are used where mod-erate to severe hole problems areexpected or high down-hole pres-sures occur. Of all the water-basemud types, these are the mostexpensive to maintain. As mud den-sity is increased and potential holeproblems (such as stuck drill pipe)become more of a risk, the removalof drilled solids by mechanicalsolids control equipment becomesincreasingly important.

Low Solids Muds are water-basemud containing less than ten per-cent (10%) drilled solids; 1–5% is anormal range. Generally speaking,the lower the solids content in themud, the faster the bit will drill.

Low solids muds are usuallyexpensive to maintain because thesolids, chemical, and fluid lossproperties have to be kept veryclose to prescribed levels. It isabsolutely essential that all solidsremoval equipment operate at max-imum effectiveness in order tomaintain the desired low level ofsolids at a reasonable cost.

Polymer Muds are special types oflow solids mud which contain syn-thetic materials, polymers, designedto control viscosity and fluid loss.Polymers are very expensive and

1.11

often difficult to screen when ahigh viscosity fluid is used.

Calcium Treated Muds are specialwater-base muds, usually weighted,which have lime or gypsum added.Calcium Treated Muds are normallyused to prevent shale type forma-tions from swelling or sloughing –problems which could lead to stuckpipe or a ruined hole.

SALTWATER MUD

Saltwater Muds contain a highconcentration of salt. They may beweighted or unweighted.

Sea Water Muds contain sea wateras the continuous phase and, usual-ly, only sea water is used fordilution. They may be weighted orunweighted. These muds are usedoffshore and in bay areas wherefresh water is not readily available.

When sea water mud is beingused, only sea water should beused to rinse or wash the screens insolids control equipment.

Saturated Salt Muds (sometimescalled brine fluids) contain as muchsalt as can be dissolved in the waterphase. This mud type is often usedto drill through salt formations sothe fluid will not dissolve the saltformation. If fresh water mud isused, greatly enlarged holes wouldresult, usually leading to hole trou-ble.

It is important to be aware of theuse of salt mud because screen

blinding can occur when salt driesand cakes on the solids controlequipment. Fresh water may beused to clean the screens, but itmust be used very carefullybecause too much fresh water canupset the chemical balance of thismud.

“TRUE” OIL-BASE MUD

“True” Oil-base Mud contains aliquid phase with ninety to ninety-five percent (90–95%) diesel oil andfive to ten percent (5–10%) wateremulsified within the oil. Thesemuds often use asphaltic type mate-rials suspended in the liquid forcontrolling viscosity and fluid loss.“True” oil-base muds provide goodhole protection, especially in shaletype formations, and also increasedrill string lubrication.

INVERT EMULSION MUD

Invert Emulsion Mud is oil-basemud in which the liquid phase issixty to ninety percent (60–90%)diesel oil with ten to forty percent(10–40%) water emulsified withinthe oil. An invert mud can be for-mulated with mineral oil or otherlow environmental risk oil substi-tutes when needed. In this mud,water and chemicals are used to-gether to control viscosity and fluidloss. Invert emulsion muds providegood hole protection and are themost commonly used oil mud.

1.12

SYNTHETIC OIL MUDS

The term “Synthetic-Based Mud”,or SBM, describes any oil-base mudthat has a synthesized liquid base.Some common synthetic base fluidsinclude linear alphaolefins (LAO),straight internal olefins (IO), polyal-phaolefins (PAO), vegetable oils,esters, and ethers. This base fluid isthen combined with viscosifiers,weighting material, and other addi-tives to produce a stable, usefuldrilling fluid.

SBMs share several advantageswith traditional oil-base muds,including excellent wellbore stabili-ty, improved drilling rates, goodhole cleaning, excellent cuttingsintegrity, and reduced torque.SBMs also provide additional healthand safety benefits — higher flashpoints, lower vapor production, and

reduced eye and respiratory irrita-tion. The major benefit of SBMsover traditional OBMs is thereduced environmental impact ofcuttings and liquid mud. Currently,SBMs and cuttings meet U.S. off-shore environmental requirementsand may be discharged underWBM protocols.

SBMs are expensive, $200–400/bbl., depending on the oil/waterratio. Proper solids removal and liq-uid recovery techniques must beused to maintain desired fluid prop-erties and drilling rate, and tocontrol mud maintenance costs.The alternatives to mechanicalsolids control — dilution and wholeSBM additions — are prohibitivelyexpensive when compared to thecost of proper solids control equip-ment.

2.1

INTRODUCTION

Of all the problems that couldconceivably occur during thedrilling of a well, mud contamina-tion from drilled solids is acertainty. The volume and type ofsolids present in drilling mud exerta considerable influence over mudtreating costs, drilling rates,hydraulics, and the possibility ofdifferential sticking, kicks, and lostreturns. Solids control is one of themost important phases of mud con-trol — it is a constant issue, everyday, on every well. If drilled solidscan be removed mechanically, it isalmost always less expensive thantrying to combat them with chemi-cals and dilution.

The primary reason for usingmechanical solids control equip-ment is to remove unwanted drilledsolids particles from the mud inorder to prevent drilling problemsand reduce mud and waste costs,thereby reducing overall drillingcosts. The benefits of solidsremoval by mechanical separationcan best be seen in terms of twooutcomes: 1) reduced total mudsolids and 2) reduced dilutionrequirements.

2.1 REDUCED TOTAL SOLIDS

The presence of large amounts ofdrilled solids in a drilling mud usu-ally spells trouble for the drillingoperation. These solids adverselyaffect the performance characteris-tics of the mud and can lead to amultitude of costly hole problems.

Drilled solids decrease the life ofa mud pump’s parts and thus, candecrease drilling efficiency due tolost time for pump repairs.Continued recirculation of drilledsolids produces serious mud prob-lems because recirculated solidswill gradually be reduced in size.The smaller the solids become, themore they negatively influence mudproperties and hydraulic perfor-mance. The greatest impact of thesolids is seen in reduced ROP. Thehigher the drilled solids content,the lower the penetration rate.

If mud solids are not properlycontrolled, the mud’s density canincrease above its desired weightand the mud can get so thick that itbecomes extremely difficult or evenimpossible to pump.

Since the earliest days of the oil-field, drillers have been trying tocombat high solids content throughthe use of settling pits. However,

2.0 BENEFITS OF SOLIDS REMOVAL BY MECHANICAL SEPARATION

2.2

some drilled solids are so finelyground that they tend to remain insuspension. This results inincreased mud viscosity and gelstrength which, in turn results inlarger particles also remaining insuspension. Thus, the approach ofremoving cuttings through settlingalone is of limited practical value.

Solids control equipment wasdeveloped in order to more effec-tively remove unwanted solids fromdrilling mud. A variety of devices(which will be discussed in detail inChapter 3 of this handbook) areavailable which mechanically sepa-rate the solids particles from theliquid phase of the mud. Thus thedriller, depending on the particularsituation and equipment used, canregulate to a fine degree theamount and size of solids particlesthat are removed or maintained inany given drilling mud.

Such control of mud solids throughmechanical separation allows themud to perform its drilling-relatedfunctions and avoids the downholeproblems caused by excessive solidscontamination. Effective solids con-trol permits viscosity and density to bekept within desired levels, dramati-cally increases the life of pump partsand drill bits, and promotes fasterpenetration — all of which decreasethe time and expense of drilling.

2.2 REDUCED DILUTION REQUIREMENTS

A common method of trying tooffset the build-up of drilled solidsis the addition of more liquid. Thisis known as dilution and does notremove cuttings but reduces (ordilutes) their concentration in adrilling mud, thereby reducing thepercent of total solids in the mud.

However, it is important to notethat dilution is expensive. Everybarrel of dilution water (or oil)added requires an additionalamount of chemicals, barite orother materials in order to maintaindesired mud properties. The lowerthe drilled solids content to bemaintained, the greater the dilutionrequired. In the case of an oil-basemud, oil must be used for dilution— which can become extremelyexpensive.

It should be noted that chemicaltreatment alone will ultimatelyresult in high solids content anduncontrollable mud properties. Themost effective approach is to usemechanical solids control equip-ment to remove as much of thedrilled solids as possible beforethey are incorporated into the mudsystem and then treat what is leftwith appropriate amounts of chemi-cals and dilution.

Effective solids removal bymechanical separation can maintaina minimum solids level in drilling

2.3

mud and greatly reduce the needfor dilution. Reducing the need todilute the mud can drasticallydecrease the cost of having to pur-chase mud products such as weightmaterial (barite) and chemicals.These materials are expensive —mud costs can be 10% of the totalcost of drilling a well.

The Dilution Ratio Chart (Figure2-1) can be used indirectly toapproximate the amount of dilutionthat can be eliminated by use ofsolids removal equipment. Forexample, suppose a drilling engi-neer required that no more than 5%solids were to be maintained in anunweighted mud. The chart showsthat at 5%, each barrel of mudwould contain about 45 pounds ofdrilled solids. If solids controlequipment were removing 1 ton(2000 lbs) of solids per hour, thenthe equipment would save 2000 ÷

45 = 44 barrels of dilution per hour.If the chemicals and additives wereworth only $10 per barrel, the mudtreating costs would be reduced byapproximately $440 per hour! Overthe life of a drilling operation, $440per hour adds up to a very signifi-cant cost savings.

The same procedure can be usedto show reduced dilution require-ment in weighted mud. Whenheavily — weighted muds (16–18lbs/gal) are being used, drillingusually proceeds more slowly andless drilled solids are removed perhour. However, if approximately 5%drilled solids are allowed in themud, then each barrel of mud stillcontains roughly 44 pounds ofdrilled solids.

Therefore, if the solids controlequipment were removing even apencil-sized stream of solids whichwould amount to 44 pounds per

MUD WEIGHT(LBS/GAL)

TO BE MAINTAINED

8.58.68.78.88.99.09.19.29.39.49.59.69.79.89.9

10.0

DRILLED SOLIDS

PERCENT BYVOLUME

1.22.02.73.54.25.05.76.47.28.08.79.4

10.211.011.712.4

POUNDS OF2.6 SPECIFIC GRAVITY

SOLIDS PER BARREL OF MUD

11182532384552596673798693

100107114

BBLS OF WATERREQUIRED TO DILUTE

1 TON SOLIDS ANDMAINTAIN MUD WEIGHT

1821118063534438343027252322201918

Figure 2-1 Dilution Ratio Chart

2.4

hour, then 44 ÷ 44 = 1 barrel ofdilution saved per hour. With thehigh cost weighted mud (usually aminimum of $30 per barrel), thesolids removal equipment would besaving at least $30 per hour. Overan average operation of 20 hoursper day, this represents a savings ofapproximately $600 per day. If themaximum amount of drilled solidswere reduced to 3%, the cost savingswould double to approximately$1200 per day.

The expense of the dilution liquidis a major factor in considering theadvantages of reduced dilutionrequirements. Oil is obviouslymuch more costly than water, butwater also can be expensive if ithas to be trucked into a remotedrilling location.

The disposal of “waste” mud canalso be a significant factor in overalldilution costs. Heavy reliance ondilution to control solids contentcan result in the addition of somuch extra liquid that the volumeof mud exceeds the capaci-ty of the active mud pits.When this happens, wholemud (including all of theexpensive additives) mustbe discarded into waste orreserve pits.

Appropriate use of solidscontrol equipment in placeof dilution lessens the vol-ume of the mud system andcan usually eliminate the

discarding of excess mud. The sizeof the active and waste pits them-selves can be reduced due tosmaller capacity requirements.Instead of throwing away valuablemud additives, these can be sal-vaged and returned to the activemud system.

If properly used, solids controlequipment can virtually eliminatewaste liquid mud through a “closedmud system”. In such a system theliquid phase can be recycled —which can be critical in specialapplications such as when usingoil-base or polymer muds, especial-ly offshore, or where environmentalconcerns prohibit disposal of liquidwaste materials. In these cases thecost of hauling the liquid wasteaway for disposal is also avoided.

Solids removal by mechanical sep-aration can achieve the benefits oflow solids content and at the sametime significantly reduce the manycosts associated with dilution.

DRILLED SOLIDS

3.1

INTRODUCTION

The goal of modern solids controlsystems is to reduce overall wellcosts by prompt, efficient removalof drilled solids while minimizingthe loss of liquids. Since the size ofdrilled solids varies greatly — fromcuttings larger than one inch indiameter to sub-micron size — sev-eral types of equipment may beused depending upon the specificsituation. The fundamental purposefor solids removal equipment is justthat — remove drilled solids. Theend result is reduced mud andwaste disposal costs.

To reach this goal, each piece ofequipment will remove a portion ofthe solids, either by screening orcentrifugal force. Each type ofequipment is designed to economi-cally separate particles of aparticular size range from the liq-uid. Also to operate effectively,each type of equipment must besized, installed, operated, and main-tained properly.

The efficiency of the solids con-trol system can be evaluated bycomparing the final volume of mudaccumulated while using the equip-ment to the volume of mud thatwould result if drilled solids werecontrolled only by dilution. The

overall results of solids removal canbe monitored by the use of flowmeters to determine the actual mudvolume built.

The efficiency of solids removalequipment and/or systems used canbe evaluated in two ways: 1) Efficiency of drilled solids

removal, 2) Efficiency of liquid conservation.

The greater percentage of drilledsolids removed, the higher theremoval efficiency. The higher thesolids fraction of the waste stream,the better. Both aspects should beconsidered.

For example, a desilter usuallydoes well at removing solids but atthe cost of significant losses of liq-uid; sometimes 80% of the volumeof the waste stream will be liquid.By contrast, a properly operatingshale shaker or centrifuge typicallyremoves 1 barrel or less of mudwith each barrel of solids. Mostremaining equipment delivers alesser degree of dryness than dothe shakers or centrifuges.

Most solids control systemsinclude several pieces of equipmentconnected in series. Each stage ofprocessing is partly dependentupon the previous equipment func-tioning correctly so as to allow thenext stage to perform its role.

3.0 MECHANICAL SOLIDS CONTROL AND RELATED EQUIPMENT

3.2

Should one piece of equipment fail,the equipment downstream willsoon lose efficiency or fail com-pletely.

The first piece of equipment usedto separate the solids from the mudis usually a vibrating screen orseries of screens. The cuttings thatare larger than the mesh openingsare removed by the screen butcarry an adhered film of mud. Thescreen mesh should be sized toprevent excessive losses of wholemud over the end screen.

The second step is to remove thesand-sized, silt sized and larger clayparticles that were not removed inthe shakers by using hydrocy-clones. Hydrocyclones with a conediameter of 6 to 12 inches arecalled desanders, and hydrocy-clones with a cone diameter of lessthan 6 inches are called desilters.These units should normally besized to process 125% of the maxi-mum flow rate used to drill.

Sometimes a screen is used belowa hydrocyclone to “dry-out” the

cone’s discharge to minimize theloss of fluid. The hydrocyclone andvibrating screen device is called amud cleaner or mud conditioner. Ifa location must be “pitless”, thenthe screens are essential to mini-mize the liquid waste volume.

The final step may be to removethe ultrafine silt and clay-sizedsolids with the use of a decantingcentrifuge. On a weighted mud,two centrifuges may be used inseries: the first to salvage barite, thesecond to remove fine solids andreclaim the valuable liquid phase.

3.1 PARTICLE SIZEAND CUT POINT

Modern drilling rigs may beequipped with many different typesof mechanical solids removaldevices depending on the applica-tion and requirements of a particularproject. Each device has a specificfunction in the solids controlprocess. Equipment commonly uti-lized and the effective removal rangefor each are listed in Figure 3-1.

3.3

CUT POINT

Notice the removal range, or CutPoint, is given as a range of theparticle size removed. Mechanicalsolids control equipment classifiesparticles based on size, shape, anddensity. It is typical to refer to parti-cles as being either larger than thecut point of a device (oversize) or

smaller than the cut point (under-size).

Figure 3-2 shows a typical cutpoint curve. The cut point curverepresents the amount of solids of agiven size that will be classified aseither oversize or undersize.Particles to the right of the cut pointcurve, in the area labeled “A”, rep-

Figure 3-1 Particle Diameter and Ideal Equipment Placement

3.4

resent the removed, oversize solids.Particles to the left of the curve, inthe area labeled “B”, represent theundersize solids returned with thewhole mud.

Particular interest is given to threepoints along the cut point curve,the D50, the D16, and the D84. Giventhese three points, the removalcharacteristics of screens, hydrocy-clones, or other devices can becompared.

The D50, or median cut point, isthe point where 50% of a certainsize of solids in the feed stream willbe classified as oversize and 50% asundersize. The D16 and D84 are the

points where 16% and 84%, respec-tively, of the solids in the feedstream will be classified as oversize.These two points are statisticallysignificant because they are onestandard deviation from the D50 in anormal distribution. An “ideal” clas-sifier (the dashed line) would showvery little difference between theD50, D16 and D84.

Separation Efficiency is a measureof the D50 size relative to the num-ber of undersize particles that areremoved or oversize particles thatare not removed. The higher theseparation efficiency, the lower the

Figure 3-2 Typical Cut Point Curve

3.5

false classification. An example willassist in understanding this concept.

Figure 3-3 shows the cut pointcurves for two screens, each withthe same D50. Curve No.1 is almostvertical with a small tail at eachend. This results in a very sharp,distinct cut point. Almost all parti-cles larger than the cut point arerejected, with very few undersizesolids. Almost all particles smallerthan the cut point are recovered,with very few oversize particlesincluded.

Curve No. 2 is an S-shaped curvewith a large tail at each end. Eventhough the D50 is the same as forCurve No.1, the D16 and D84 are very

different. Many solids larger thanthe D50 are returned with the under-size solids and many solids smallerthan the D50 are discarded with theoversize solids.

If curves number 1 and 2 inFigure 3-3 illustrate typical removalgradients for two different types ofoilfield shale shakers screens, wecan draw conclusions about separa-tion performance. The area betweenthe curves marked “A” representssolids Screen No.1 removes andScreen No. 2 returns. Likewise, thearea marked “B” represents solidsrecovered by Screen No.1, but dis-carded by Screen No. 2.

This is not to say that Screen No.1

Figure 3-3 Separation Curve

3.6

is “better” than Screen No. 2, orvice versa; it simply illustrates thattwo devices with similar “cut point”(as measured by the D50 alone) mayperform very differently. As anexample, consider solids removalfrom a weighted drilling fluid usingvibrating screens.

An effective solids control pro-gram for weighted mud shouldremove as many undesirable, sand-sized solids as practical, whileretaining most of the desirable, silt-sized barite particles. Referring backto Figure 3-3, Screen No. 2 wouldreturn all the sand in area “A” thatScreen No.1 would catch, andScreen No. 2 would remove the silt-size material in area “B” (includingall weighting material) that ScreenNo.1 would recover.

Therefore, in a weighted mud,Screen No. 2 would not perform aswell as Screen No.1. Further, if thearea to the right of both curves(representing total mass solidsremoval) were calculated, ScreenNo.1 could prove superior in termsof mass solids removal.

As shown by this example, it isimportant to view “cut point” as acontinuous curve, rather than a sin-gle point. This concept is equallytrue with screens, hydrocyclones,centrifuges, or any other separationequipment — the relative slope andshape of the cut point curve aremore important than a single pointon the curve.

3.2 SEPARATION BY SCREENING

One method of removing solidsfrom drilling mud is to pass themud onto the surface of a vibratingscreen. Particles smaller than theopenings in the screen passthrough the holes of the screenalong with the liquid phase of themud. Particles too large to passthrough the screen are thereby sep-arated from the mud for disposal.Basically, a screen acts as a “go–nogo” gauge: Either a particle is smallenough to pass through the screenopening or it is not.

The purpose of vibrating thescreen in solids control equipmentis to transport the cuttings off thescreen and increase the liquid han-dling capacity of the screen. Thisvibrating action causes rapid sepa-ration of whole mud from theoversized solids, reducing theamount of mud lost with the solids.

For maximum efficiency, thesolids on the screen surface musttravel in a predetermined pattern —spiral, elliptical, orbital or linearmotion — in order to increase par-ticle separation efficiency andreduce blockage of the screenopenings. The combined effect ofthe vibration and the screen sur-faces result in the separation andremoval of oversized particles fromdrilling mud.

3.7

SCREENING SURFACES

Screening surfaces used in solidscontrol equipment are generallymade of woven wire screen cloth,in many different sizes and shapes.The following characteristics ofscreen cloth are important in solidscontrol applications.

Screens may be constructed withone or more Layers. Non-layeredscreens have a single layer, fine-mesh, screen cloth (reinforced bycoarser backing cloth) mounted ona screen panel. These screens willhave openings that are regular insize and shape. Layered screenshave two or more fine mesh screencloths, usually of different mesh(reinforced by coarser backingcloth), mounted on a screen panel.These screens will have openingsthat vary greatly in size and shape.

To increase screen life, especiallyin the 120–200 mesh range, manu-facturers have incorporated twodesign changes:1) A coarse backing screen to

support fine meshes, and2) Pre-tensioned screen panels.

The most important advance hasbeen the development of preten-sioned screen panels. Similar panelshave been used on mud cleanerssince their introduction, but earliershakers did not possess the engi-neering design to allow their usesuccessfully. With the advent ofmodern, linear-motion shakers, pre-

tensioned screen panels haveextended screen life and justifiedthe use of 200-mesh screens at theflowline. The panels consist of afine screen layer and a coarse back-ing cloth layer bonded to a supportgrid (Figure 3-4). The screen clothsare pulled tight, or tensioned, inboth directions during the fabrica-tion process for proper tension onevery screen. The pre-tensionedpanel is then held in place in thebed of the shaker.

Today, fine screens may be rein-forced with one or more coarsebacking screens. The cloth mayalso be bonded to a thin, perforat-ed metal sheet. This extra backingprotects the fine screen from beingdamaged and provides additionalsupport for heavy solids loads. Thescreens equipped with a perforatedplate may be available with severalsizes options for the perforation toallow improved performance for agiven situation.

Most manufacturers limit them-selves to one support grid opening

Figure 3-4 Pretensioned Screen

3.8

size to reduce inventory and pro-duction costs. The opening size istypically 1” for maximum mechani-cal support. Brandt / EPI™ providesscreen panels with a variety ofopenings to allow rig personnel tochoose the desired mechanical sup-port and total open area (translatingto more liquid flow), depending onthe application.

Mesh is defined as the number ofopenings per linear inch. Mesh canbe measured by starting at the cen-ter of one wire and counting thenumber of openings to a point oneinch away. Figure 3-5 shows a sam-ple 8 mesh screen. A screencounter is useful in determiningscreen mesh (see Figure 3-6).

SCREEN CLOTH

There are several types of wirecloth used in the manufacture ofoilfield screens. The most commonof these are Market Grade and

Tensile Bolting Cloth. Both of theseare square mesh weaves, differingin the diameter of wire used intheir construction.

Market grade cloths use largerdiameter wires and are more resis-tant to abrasion and prematurewear. Tensile bolting cloths usesmaller diameter wire and have ahigher Conductance. Since screen

Figure 3-5 Eight Mesh Screen

Figure 3-6 Screen counter and Magnified View of Screen mesh

3.9

selection is a compromise betweenscreen life, liquid capacity, and par-ticle separation, both types are inwide use.

OPENING SIZE

Size of Opening is the distancebetween wires in the screen clothand is usually measured in fractionsof an inch or microns. Figure 3-7shows a screen with a 1/2 inchopening.

Screens of the same mesh mayhave different sized openingsdepending on the diameter of thewire used to weave the screencloth. Smaller diameter wire results

in larger screen openings, with larg-er particles passing through thescreen. The larger the diameter ofthe wire, the smaller the particlesthat will pass through the screen.Remember, it’s the size of the open-ings in a screen, not the meshcount, that determines the size ofthe particles separated by thescreen. Also, normally the larger thediameter of the wire used in theweaving process, the longer thescreen cloth will last.

PERCENT OPEN AREA

Percent Open Area is the amountof the screen surface which is notblocked by wire. The greater thewire diameter of a given meshscreen, the less open spacebetween the wires. For example, a4 mesh screen made of thin wirehas a greater percent of open areathan a 4 mesh screen made of thickwire (see Figure 3-8).

The higher the percent of openarea of a screen the greater its theo-retical throughput. Open area can

Figure 3-7 One-half Inch Opening

Figure 3-8 Percent of Open Area

4 Mesh: .080 Wire46.2% Open Area



3.10

be increased for a given mesh byusing smaller diameter wire, but atthe sacrifice of screen life. Thechoice of any particular screen cloththerefore involves a compromisebetween throughput and screen life.

Calculating the percent open areafor layered screens is difficult andinaccurate. This is due to the ran-dom and wide variety of openingspresent. Conductance of a screen isan experimental measure of theflow capacity of a screen. The high-er the conductance of a screen, thegreater its flow capacity.

SHAPE OF OPENING

Shape of Opening is determinedby the screen’s construction.Screens with the same number ofhorizontal and vertical wires perinch produce square-shaped open-ings and are referred to as SquareMesh screens. Screens with a differ-ent number of horizontal andvertical wires per inch produce

oblong — or rectangular — shapedopenings and are referred to asRectangular (or Oblong) Meshscreens. This is illustrated in Figure3-9.

Use of a single number in refer-ence to a screen usually impliessquare mesh. For example, “20mesh” usually identifies a screenwith 20 openings per inch in eitherdirection. Oblong mesh screens aregenerally labeled with two num-bers. For example, a 60 x 20 screenhas 60 openings per inch in onedirection and 20 openings per inchin the other direction.

It has become common industrialpractice to add the two dimensionsof an oblong mesh screen and referto the sum of the two numbers asthe mesh of the screen.

For example, a 60 x 20 meshscreen is often called an “oblong80” mesh. This screen has oblongopenings measuring 1040 x 193microns, much larger than the

Figure 3-9 Shape of Opening

SQUARE MESH OBLONG MESH

3.11

square openings of a “square 80”mesh screen (177 x 177 microns).The “oblong 80” will allow muchlarger, irregularly-shaped particlesto pass through its openings thanthe 80 x 80 square mesh screen.

EQUIVALENT SCREEN MESH

Screen manufacturers now com-pare different types of screenthrough charts, such as the oneshown in Figure 3-10. The oblong-mesh screens listed in the left-handcolumn remove similar sized solidsas the square-mesh screens listed inthe right-hand column. Thesescreens are referred to as “equiva-lent”. In actual field use, theconductance and screen life of theoblong mesh screens is noticeablyhigher than the equivalent squaremesh screen, but the shape of thecut point curve discussed earlier isnot as sharp or distinct.

In a similar fashion, a layeredscreen will often be designated bya single number, e.g. “layered 210”mesh. This implies a screen with

openings smaller than a “square200” mesh screen (74 x 74microns). However, the actualopening size and shape of a lay-ered screen is a combination of themultiple screen layers and will pro-duce a wide variety of openingsizes and shapes. Therefore, the“layered 210” mesh screen willremove some solids smaller than 74microns, but will also allow someparticles larger than 74 microns topass through the screen openings.

SCREEN PLUGGING AND BLINDING

Screen Plugging and Blinding,while present to some degree onrig shakers fitted with coarserscreens, is most frequently encoun-tered on fine screen shakers. If themesh openings plug with near-sizeparticles or if the openings becomecoated over, the throughput capaci-ty of the screen can be drasticallyreduced and flooding of the screenmay occur.

Plugging can often be controlledby adjusting the vibratory motion ordeck angle, but sometimes requireschanging screens to a coarser orfiner mesh. A coarser screen shouldbe used only as a temporary solu-tion until the particular formationresponsible for near-size particlegeneration is passed. Changing to afiner mesh screen often presents abetter, more permanent solution.

Screen blinding is caused by

OBLONG MESH SQUARE MESH

B-20 S-16B-40 S-30B-60 S-40B-80 S-50

B-100 S-60B-120 S-80

Figure 3-10 Equivalent Screen Sizes

3.12

sticky particles in viscous mud coat-ing over the screen openings or bythe evaporation of water from dis-solved solids or from grease andrequires a screen wash-down tocure. This wash-down may simplybe a high pressure water wash, asolvent (in the case of grease, pipedope or asphalt blinding), or a mildacid soak (in the case of blindingcaused by hard water). Stiff brush-es should not be used to cleanfine screens because of the fragilenature of fine mesh screen cloth.

Screen life of fine mesh screensvaries widely from design todesign, even under the best of con-ditions, because of differences inoperating characteristics. Screen lifecan be maximized by followingthese general precautions:• Keep screens clean.• Handle screen carefully when

installing.• Keep screens properly ten-

sioned.• Do not overload screens.• Do not operate shakers dry.

SCREEN CAPACITY

Screen Capacity, or the volume ofmud which will pass through ascreen without flooding, varieswidely depending on shaker modeland drilling conditions. Drilling rate,mud type, weight and viscosity, bittype, formation type, screen mesh —all affect throughput to some degree.

Drilling rate affects screen capacitybecause increases in drilled solidsloading reduce the effective screenarea available for mud throughput.The mesh of the screen in use is alsodirectly related to shaker capacitybecause, in general (but not always),the finer a screen’s mesh, the lowerits throughput. Increased viscosity,usually associated with an increasein percent solids by volume and/orincrease in mud weight, has amarkedly adverse effect on screencapacity. As a general rule, for every10% increase in viscosity, there is a2–5% decrease in throughput capaci-ty. Figure 3-11 shows therelationship of mud weight, viscosity,and screen mesh on shaker capacity.

Mud type also has an effect onscreen capacity. Higher viscositiesgenerally associated with oil-baseand invert emulsion mud usuallyresult in lower screen throughput

Figure 3-11 Shaker Capacity v. Mud Weight, Viscosity, and Screen Mesh

3.13

than would be possible with a water-base mud of the same mud weight.Some mud components such as syn-thetic polymers also have an adverseeffect on screen capacity. As a result,no fine mesh screen can offer a stan-dard throughput for all operatingconditions.

Due to the many factors involvedin drilling conditions, mud charac-teristics and features of certainmodels, capacities on fine screenshakers can range from 50 to 800GPM. Multiple units, most common-ly dual or triple units, can be usedfor higher throughput requirements.Cascade shaker arrangements, withscalping shakers installed upstreamfrom the fine screen shakers, canalso increase throughput.

THREE-DIMENSIONALSCREEN PANELS

To increase screen capacity with-out increasing the size or numberof shale shakers, three-dimensionalscreen panels are available. Thedesign of these 3-D, Pinnacle™shaker screens:• Provides even distribution of

fluid across the screen surface• Eliminates unwanted fluid loss

near the screen edges• Improves dryness of solids dis-

charge• Allows the use of finer screens

3-D screen panels increase the

usable screen area of a screenpanel by corrugating the screen sur-face, similar to the surface of apleated air filter or oil filter. 3-Dscreen panels are most effectivewhen installed as the submerged,feed-end screen on linear-motionshakers to take full advantage ofthe additional screen area. Past thefluid end point, a three-dimensionalscreen tends to “channel” thedrilled solids and increases solidsbed depth and the amount of liquidcarried off the screen surface.Using a flat screen at the dischargeend of the shaker eliminates chan-neling, increases cuttings dryness,and decreases fluid loss.

STANDARDIZATION

Standardization of screen clothdesignations has been recommend-ed by the API committee onStandardization of Drilling FluidMaterials, in API RECOMMENDEDPRACTICE 13E (RP13E), THIRDEDITION, MAY 1, 1993. The pur-pose for this practice is to providestandards for screen labeling ofshale shaker screen cloths. The pro-cedures recommended for labelingallow a direct comparison of sepa-ration potential, the ability to passfluid through a screen, and theamount area available for screen-ing.

The API screen labeling includesof the following:

3.14

1. Manufacturer’s designation;2. Separation Potential and3. Flow Capacity.

The Manufacturer’s designationcontains the individual company’sprocedures for naming theirscreens. It may include the type ofscreen panel, composition andother data required by the manufac-turer.

The API separation potential isreported in the terms of three “Cut”points. The term “Cut” point is notthe same as the traditional cutpoint. The “Cut” point allows aranking of a screen’s separationpotential that can be used to com-pare screen performance. Threevalues (D50, D16, and D84) imply theopening sizes and variation inopening size of the screen.

Flow capacity is the rate at whicha shaker can process mud andsolids. Under constant conditions, ashale shaker has a flow capacitythat depends upon screen conduc-tance and area. The area availablefor screening is the net unblockedarea, in square feet, available forfluid passage through the screenpanel. Conductance defines theease of passage of a fluid through apiece of wire cloth. Conductance iscalculated from the mesh count andwire diameters of the screen.Transmittance is the product ofconductance times panels area.

These designations give the enduser a more accurate assessment ofsolids removal capability and liquidthroughput capacities of competi-tive screens.

3.3 SHALE SHAKERS

The first line of defense for a prop-erly maintained drilling fluid hasbeen, and will continue to be, theshale shaker. Without proper screen-ing of the drilling fluid during thisinitial removal step, reduced effi-ciency and effectiveness of alldownstream solids control equip-ment on the rig is virtually assured.

The shale shaker, in variousforms, has played a prominent rolein oilfield solids control schemesfor several decades. Shakers haveevolved from small, relatively sim-ple devices capable of running onlythe coarsest screens to the modelsof today. Modern, high-perfor-mance shakers of today are able touse 100 mesh and finer screens atthe flowline in most applications.

This evolutionary process hastaken us through three distinct erasof shale shaker technology and per-formance as shown in Figure 3-12.These eras of oilfield screeningdevelopment may be defined bythe types of motion produced bythe machines:• Elliptical, “unbalanced” design• Circular, “balanced” design.• Linear, “straight-line” design

3.15

The unbalanced, elliptical motionmachines have a downward slopeas shown in Figure 3-12, A. Thisslope is required to properly trans-port cuttings across the screen andoff the discharge end. However, thedownward slope reduces fluidretention time and limits the capaci-ty of this design. Optimumscreening with these types of shak-ers is usually in the 30–40 mesh(400–600 micron) range.

The next generation of machine,introduced into the oilfield in thelate 1960s and early 1970s, pro-duces a balanced, or circular,motion. The consistent, circularvibration allows adequate solids

transport with the basket in a flat,horizontal orientation, as shown inFigure 3-12, B. This design oftenincorporates multiple decks to splitthe solids load and to allow finermesh screens, such as 80–100square mesh (150–180 micron)screens.

The newest technology produceslinear, or straight-line, motion,Figure 3-12, C. This motion isdeveloped by a pair of eccentricshafts rotating in opposite direc-tions. Linear motion providessuperior cuttings conveyance and isable to operate at an uphill slope toprovide improved liquid retention.Better conveyance and longer fluidretention allow the use of 200square mesh (74 micron) screens.

Today, shale shakers are typicallyseparated into two categories: RigShakers and Fine Screen Shakers.

RIG SHAKERS

The rig shaker is the simpler oftwo types of shale shakers. A rigshaker (also called “Primary ShaleShaker” or “Coarse Screen Shaker”)is the most common type of solidscontrol equipment found on drillingrigs. Unless it is replaced by a finescreen shaker, the rig shaker shouldbe the first piece of solids controlequipment that the mud flowsthrough after coming out of thehole. It is usually inexpensive tooperate and simple to maintain.

Figure 3-12 Shale Shakers

3.16

Standard rig shakers generallyhave certain characteristics in com-mon (see Figure 3-13):• Single rectangular screening

surface — usually about 4’ x 5’in size. Some designs have uti-lized dual screens, dual decksand dual units in parallel toprovide more efficient solidsseparation and greaterthroughput. Depending on theparticular unit and screen meshused, capacity of rig shakerscan vary from 100–1600 GPMor more.

• A low-thrust horizontal vibratormechanism, using eccentricweights mounted above, orcentral to, the screen basket.

• Vibration supports to isolatethe screen basket from its skid.

• Skid with built-in mud box(sometimes called a “possumbelly”) and a bypass mecha-nism.

• Method of tensioning screensections.

Screen sizes commonly used withrig shakers range from 10 to 40mesh. Figure 3-14 shows the parti-cle sizes separated by these meshscreens. In this graph the area tothe left of each line representssolids which are smaller than thatmesh size. These would passthrough the screen and would notbe removed. The area to the rightof each line represents solids thatare larger than the mesh size andwould be removed from the mud.

In Figure 3-14, the area to the

Figure 3-13 Rig Shaker components

MUD TANK(POSSUM BELLY)

LIQUID and FINESOLIDS

DISCHARGECHUTE

MOTOR

BELTGUARD

VIBRATOR ASSEMBLY

COARSE SOLIDS DISCHARGE

SCREEN

BASKETASSEMBLY

3.17

right of the 10 mesh line is con-fined, because it is limited by thesize of the page. In actual usage,this area is unlimited. This meansthat a 10 mesh screen will removeall particles larger than 1910microns — it doesn’t matter if theyare the size of BBs, marbles orbaseballs — they will be removedand discarded by a 10 mesh screen.

Rig shakers are generally ade-quate for top hole drilling and forshallow and intermediate depthholes when backed up by othersolids control equipment. For deep-er holes and when using expensivemud systems, fine screen shakersare preferred.

FINE SCREEN SHAKERS

The fine screen shaker is themore complex and versatile of thetwo types of shale shakers. Fine

screen shakers remove cuttings andother larger solids from drillingmud, but are designed for greatlyimproved vibratory efficiency oversimple rig shakers. They are con-structed to vibrate in such a waythat they can use screens as fine as150–200 mesh and still give reason-able screen life.

They are versatile pieces of equip-ment and can operate on all typesof mud. Figure 3-15 shows therange of particle sizes separated bythe screens commonly used withfine screen shakers.

A fine screen shaker can beinstalled on the rig in one of fourways:1. Instead of the conventional rig

shaker for use from top hole tototal depth, if it is of a designcapable of using coarsescreens as well as fine screens.

Figure 3-14 Particle Removal by Rig Shaker Screens

3.18

2. Placed in series with the rigshaker by tapping into the flowline with a “Y”, thus keepingthe rig shaker available as a“scalping shaker”.

3. Replacing the rig shaker aftertop hole is completed.

4. Downstream from the rig shak-er to accept fluid after it passesthrough the coarse screenshaker (requires secondarypump).

Because fine screen shakers havea wide variety of designs, they havefew characteristics in common. Thevarious designs are differentiated byscreen orientation and shape,screen tensioning mechanism,placement and type of vibrator andother special features.

Screen Orientation and Shaperefers to the arrangement of the

screen or screens in the unit.Screens are usually rectangular andmay be single screens or multiplescreens placed in series or in paral-lel, as shown in Figure 3-16.

Single deck, single screens (Figure3-16 A & B) are the simplest design,with all mud passing over onescreen of uniform mesh. This typeof shaker requires efficient vibratormechanisms to function properlyunder all possible drilling condi-tions and requires high throughput(Conductance) per square foot ofscreen cloth.

Units with screens placed in par-allel (Figure 3-16 C, D & E) havetwo or more screen sections actingas one large screen so that no cut-tings can fall between them. Allscreen sections should be the samemesh, since the coarsest mesh sec-tion determines the unit’s screeningability.

Figure 3-15 Fine Screen Shaker Particle Separation

3.19

Shakers with screens stacked inseries (Figure 3-16 F) have a coarsescreen above a finer screen, with thefiner screen being the controllingmesh size. The operating theory isthat the top screen will removesome of the cuttings from the mudto take part of the load off the bot-tom screen and thereby increaseoverall screening efficiency.

SCREEN TENSIONING MECHANISMS

Shakers are designed to use eithera hookstrip or a rigid panel screen.Hook strip screens are made with-out a rigid frame and canprematurely fail if installed andallowed to operate with uneventension. The shaker manufacturer’sinstructions for screen installationshould be followed, but the follow-ing steps may apply:• Inspect the supports and ten-

sion rails to be sure they are ingood condition and clean

• Position the panel on the deckand inspect the screen to besure it lays flat

• Install both rails loosely to thehookstrip

• Push one side of the screenagainst the positioning blocks,if present; and fully tighten thescreen against these blocks

• Evenly tighten the tension boltson the other side

• Torque to the manufacturer’srecommended setting

Rigid panel screen installationshould proceed as per the manufac-turer’s instructions. Panel screenscan usually be installed or replacedmuch quicker than a hookstripscreen since the cloth is alreadypretensioned and the mechanicaldevices lock the panel with muchless manual effort.

Figure 3-16 Shaker Screen Configurations

3.20

VIBRATOR MECHANISMS

Vibrator Mechanisms vary widelyin design and placement and great-ly affect the throughput efficiencyof fine screen shakers. Most mod-ern shakers utilize linear motionvibration with the vibrator mecha-nism mounted above the screenbed. One important advantage oflinear motion is positive con-veyance of cuttings across thescreen surface even when the sur-face is at a positive angle. Thisgenerally allows the use of anuphill sloped screen deck, greatlyincreasing throughput capacity andcuttings dryness.

Most vibrators are electricallyoperated, although a few arehydraulically operated. In someunits the vibration-inducing eccen-tric weights are separated from thedrive motor, while in others theeccentric weights and motor forman integral assembly. In some units,the nature of the vibratory motionscan be easily modified to takeadvantage of specific solids-convey-ing characteristics, but most unitshave a fixed vibratory motion.

MAINTENANCE

Because of their greater complexi-ty and use of finer mesh screens,fine screen shakers generallyrequire more attention than rigshakers. Nonetheless, their moreeffective screening capabilities

more than justify the higher operat-ing cost. This is especially truewhen expensive mud systems areused.

Besides periodic lubrication, finescreen shakers require the sameminimum maintenance as rig shak-ers while making a trip:• Wash down screens.• Check screen tension.• Shut down shaker when not

drilling to extend screen life.• Dump and clean possum belly.

In addition, frequent checks mustbe made for screen plugging andblinding, screen flooding and bro-ken screens. All will occur morefrequently on fine screen shakersthan on coarse mesh rig shakers.

GENERAL GUIDELINES

General rules in operating shaleshakers — whether coarse screenrig shakers or fine screen shakers— which have not already beenmentioned, include the following:• Use the finest mesh screen

capable of handling the fullvolume from the flow lineunder the particular drillingconditions. This will reducesolids loading on downstreamhydrocyclones and screens,improving their efficiency.Several screen changes, nor-mally to progressively finermesh screens over the course

3.21

of the hole, are quite common.• Large cuttings which settle in

the mud box (possum belly) ofthe shaker should never bedumped into the mud system.(Dump them into the sump orwaste pit.)

• Except in extenuating circum-stances (such as the presenceof lost circulating material), allmud should be screened. Thisincludes make-up mud hauledin from other locations.

• Unless water sprays areabsolutely necessary to controlscreen blinding, water shouldnot be used on the screen sur-face while drilling. Watersprays tend to wash smallercuttings through the screenwhich would otherwise beremoved by their clinging tolarger particles (piggy-backeffect).

For a more complete analysis ofdifferent types of screens and shak-ers, ask your local Brandt / EPI™representative for copies of the lat-est Product Bulletins.

3.4 MUD CLEANERS ANDMUD CONDITIONERS

In many cases, combinations ofvibratory screening and settling/centrifugal force are used togetherto provide an effective separation.The most familiar combination sep-

arator is the Mud Cleaner or MudConditioner (Figure 3-17).

Mud cleaners were developed inthe early 1970s to remove finedrilled solids from weighted mudwithout excessive loss of barite andfluid. They have also proved valu-able tools in closed systems andother “dry” location” applications.These devices use a combination ofdesilting hydrocyclones and veryfine mesh vibrating screens(120–400 mesh) to remove finedrilled solids while returning valu-able mud additives and liquids backto the active mud system.

Traditional mud cleaners use mul-tiple 4” or 5” cyclones, mountedover a vibrating screen, and areable to effectively process 400–600GPM. The process capacity is limit-ed by screen capacity and its abilityto discard “dry” solids. With theintroduction of linear motion vibrat-ing screens, the capacity of themud cleaner screen has been great-ly increased. This, in turn, allowsthe use of additional hydrocyclonesand higher, overall process capaci-ties.

The combination of hydrocy-clones and linear-motion vibratingscreens is called a Mud Conditionerto differentiate these machines fromearlier mud cleaners. Mud condi-tioners often combine bothdesander and desilter cones mount-ed above the screen deck to take

3.22

full advantage of the higher processcapacity, usually 1000–1500 GPM,and reduce the overall size andweight of the unit, when comparedto mud cleaners.

After removal of large cuttingswith a shaker, feed mud is pumpedinto the mud cleaner/conditioner’shydrocyclones with a centrifugalpump. The overflow from thecyclones is returned to the mudsystem. Instead of simply discardingthe underflow, the solids and liquidexiting the bottom of the cyclonesare directed onto a fine screen.Drilled solids larger than the screenopenings are discarded; the remain-ing solids, including most barite ina weighted system, pass throughthe screen and are returned to themud system.

The cut point and amount of masssolids removed by a mud cleaner/conditioner depends primarily onthe mesh of the fine screen used,Figure 3-18. Since there are manydesigns of mud cleaners/condition-ers available, performance andeconomics will vary with machineand drilling variables.

APPLICATIONS

Mud cleaners/conditioners shouldbe considered in these applications:1. Whenever the application

requires finer screens than theexisting shaker can handle

2. Unweighted OBMFigure 3-17 Mud Cleaners and Mud Conditioners

3.23

3. Expensive polymer systems4. When the cost of water is high5. Unweighted WBM with high

disposal costs and/or environ-mental restrictions

6. When use of lost circulationmaterial requires bypassing theshaker

7. Workover and completion fluid

Mud cleaners/conditioners aresimply a bank of hydrocyclonesmounted over a fine-mesh screen.In many instances (even with mod-ern fine screen shakers), a finerseparation is required than can beprovided with existing shakers. The

question to answer becomes howto achieve the necessary level ofscreening at the lowest cost. Thealternatives are:

1) Add additional similar shakersto handle the flow rate, 2) Replacethe existing shakers with more effi-cient units or 3) Add a mudcleaner/conditioner downstreamfrom the existing shakers.

Any of these may be correct, buta thorough study of the capital cost(the actual cost of new equipment,plus transportation, rig modifica-tions, and installation) and theoperating cost (screens and otherexpendables, plus fuel) is necessary

Figure 3-18 Particle Removal by Mud Cleaner Screens

3.24

to make the proper choice. Also,because of the cut points producedby some “modern” layered screens,the use of mud cleaner/condition-ers may be indicated downstreamof linear motion shakers.

Salvage of the liquid phase of anunweighted drilling mud often cost-justifies use of a mud cleaner/conditioner when the fluid phase ofthe mud or disposal is expensive.Compared to desanders and desil-ters, whose cyclone underflow maybe as much as 15 bbl/hr or more,mud cleaners/conditioners canachieve efficient solids removalwhile returning most liquid back tothe active mud system. Use of ultra-fine screens (200 to 325 mesh)significantly improves solids controlin any high-value fluid system.

An increasingly important applica-tion of mud cleaners/conditioners isthe removal of drilled solids fromunweighted water-base mud insemi-dry form. This system is com-monly used in areas whereenvironmental restrictions prohibitthe use of earthen reserve pits, andexpensive vacuum truck waste dis-posal from steel pits is thealternative. The mud cleaner/condi-tioner is used to discard drilledsolids in semi-dry form which isclassified as legal landfill in mostareas and is subject to economicaldry-haul disposal techniques (dumptruck or portable waste containers).

When used for this purpose, thescreen underflow from the mudcleaner/conditioner is often divert-ed to a separate steel waste pit forvacuum truck disposal. This mayseem counterproductive, but sincea vacuum truck can only carry alimited amount of sand because ofthe over-the-road weight restric-tions, whenever a vacuum truckmust haul normal full-flow desilterwaste, the waste must be dilutedwith rig water to reduce density.The operator is then billed for thehaulage of a vacuum truck loadcomprised largely of rig water. Onthe other hand, since most of thesolids are removed in semi-dryform by the mud cleaner/condition-er screen, the remaining solids inthe screen underflow are diluteenough to be hauled away withoutwatering them back. Vacuum truckloads often can be reduced to asmall fraction of those requiredwith full-flow desilting.

This approach to dry-solids dis-posal can be carried further byusing a centrifuge with a mudcleaner/conditioner to form a“closed” system which eliminatesdiscarding of any fluid. These sys-tems are being used increasingly inareas where liquid mud waste mustbe hauled a significant distance andis subject to a high disposal fee.

In a closed system, underflowfrom the mud cleaner/conditioner

3.25

screen is diverted to a holding tankand then centrifuged, which resultsin disposal of very fine, semi-drysolids and return of liquid to theactive system. Such a system virtu-ally eliminates the need for reservepits, minimizes dilution, eliminatesvacuum truck services for disposalof liquid mud, and meets environ-mental constraints when drillingwithin ecologically sensitive areas.

One special mud cleaner/condi-tioner application is the use of adouble-deck unit for salvage ofcoarse lost circulation material(LCM). Usually when running LCM,the shale shaker is bypassed anddrilled solids build up rapidly in themud, necessitating a high level ofdilution and new mud. Use of atwo-deck mud cleaner/conditionerallows salvage of the LCM whileminimizing the increase in solidscontent.

Within the mud cleaner/condi-tioner, a coarse top screen is usedto pre-screen the mud and removethe lost circulation material. Thismaterial is discharged back into theactive system for recirculationdownhole. The drilled solids, mudadditives and liquid phase passthrough the top screen onto thelower, finer mesh screen, where thedrilled solids are separated out anddiscarded. The cleaned mud thenflows back into the mud systemand is re-blended with the salvaged

lost circulation materials.Another mud cleaner/conditioner

application is the clean up ofworkover and completion fluids. Inorder to reduce costs associatedwith this expensive task, a mudcleaner running one or two ultra-fine screens (200 over 325 mesh)can be used to remove most of thesolids before they reach cartridgetype filters.

This application can significantlyreduce filter replacement costs,reduce downtime in changing fil-ters, and allow larger volumes offluid to be cleaned at a faster rate.

INSTALLATION

Installation of the mudcleaner/conditioner is made down-stream of the shale shaker and thedegasser. The same pump used tofeed the rig’s desander or desilter isoften reconnected to feed the mudcleaner/conditioner when weightmaterial is added. (Most mud clean-er/conditioners are designed to alsofunction as desilter on unweightedmud by rerouting the cone under-flow or by removing or blanking offthe screen portion of the unit. Themud cleaner/conditioner may thenbe used to replace or augment therig’s desilter during top holedrilling.)

Follow these guidelines wheninstalling mud cleaner/conditionersto allow peak efficiency:

3.26

• Size the mud cleaner/condi-tioner cyclones to process110–125% of the full circulatingflow rate.

• Take the mud cleaner/condi-tioner suction from thecompartment receiving fluidprocessed by the degasser(Weighted Muds).

• When using mud conditionersthat have both desander anddesilter cones, use a separatefeed pump for the desandercones and another feed pumpfor the desilter cones. Thedesander cone suction shouldbe from the degasser dischargecompartment. The desiltercone suction should be fromthe desander discharge com-partment.

• Keep all lines as short andstraight as possible.

• Install a guard screen withapproximately 1/2” openings atthe suction to prevent largetrash from entering the unitand plugging the cones.

• Position the mud cleaner/con-ditioner on the pit highenough so the overflow mani-fold will gravity-feed fluid intothe next downstream com-partment at an angle ofapproximately 45°.

• Avoid vertical overflow dis-charge lines from hydrocyclones.

GENERAL GUIDELINES

To operate mud cleaner/condi-tioners at maximum efficiency,remember these fundamentals:• Operate mud cleaners/condi-

tioners continuously on the fullcirculating volume to achievemaximum drilled solidsremoval.

• Operate mud cleaners/condi-tioners within the limits of thescreen capacity. A mud clean-er/conditioner with a cyclonethroughput of 800 GPM is oflittle value if the cone under-flow exceeds the screencapacity, resulting in floodingand high mud additive losses.

• Feed the cone underflow to thescreen at a single point.Multiple feed points on thescreening surface minimize useof the available screen areaand reduce overall capacityand efficiency.

• Screen throughput is reducedby increased solids content andviscosity. The cyclone under-flow plays a critical role inoverall mud cleaner/condition-er efficiency. It is oftendesirable to modify the perfor-mance characteristics of thecones to decrease the amountof ultra fines in the cone under-flow. This minimizes near-sizescreen plugging and barite lossdue to “piggy-backing”.

3.27

• Do NOT judge screen efficien-cy simply on the basis ofcuttings dryness or color. Thetotal amount of drilled solids inthe discarded material, alongwith the ratio of barite todrilled solids, must be deter-mined to correctly evaluateeconomic performance.

• A technique for measuring andcalculating these values isgiven in Appendix B of thishandbook. (Note: This tech-nique is also important whenusing 100–mesh, or finer,screens on shakers since thesescreens can also remove apprecia-ble amounts.)

• Select the number of cones tobe operated and the particularmesh screen to be usedaccording to drilling condi-tions. As a general rule, usethe finest mesh screen possible(to process the full circulatingrate) and size the number ofcones accordingly.

In some instances, a number ofcones will have to be blanked off inorder for the desired screen mesh tobe used. This may involve an experi-mental determination of the numberof cones and screen mesh to opti-mize performance. In some cases,more than one mud cleaner/condi-tioner will be needed. The followingexample illustrates the point:

Earlier mud cleaner designs with12–16 cones over a single screenbed have not proven to be practi-cal: the ultra-fine mesh screenssimply cannot handle the under-flow volume from the cones.

One exception to this is the mudconditioner; a linear-motion shakercoupled with a manifold of proper-ly designed hydrocyclones yields ahigh-performance Mud Cleaner/Conditioner with sufficient capacityfor even the largest drilling rigs.

Follow these general guidelinesfor correct mud cleaner/conditioneroperation:• Run the mud cleaner/condi-

tioner continuously whiledrilling and for a short periodof time while making a trip for“catch-up” cleaning.

• Start up the shaker portion of themud cleaner/conditioner beforeengaging the feed pump(s).

• Shut down the feed pump(s)before turning off the vibratingscreen portion of the mudcleaner/conditioner. Permit thescreen to clear itself, then rinsethe screen with water or oilsprays before shutting downthe screen portion of the unit.

• For peak efficiency, operatethe cones with a spray ratherthan a rope discharge. This isjust as important with a mudcleaner/conditioner as withdesilters and desanders.

3.28

• Check cones regularly for bot-tom plugging or flooding, sincea plugged cone allows solidsto return to the mud system. Ifa cone bottom is plugged,unplug it with a welding rodor similar tool. If a cone isflooding, the feed is partiallyplugged or the bottom of thecone may be worn out.

• When a significant amount ofbarite is added to increase mudweight, shut down the mudcleaner/conditioner for one ortwo full circulations. This permitsthe fresh barite to thoroughlymix with the system and reducelosses over the screen.

• Use low-volume sprays on thescreen surface to reduce“piggy-backing” only if 1) thisliquid addition to the mud ispermissible, and 2) the resul-tant reduction in barite discardoutweighs the resultant reduc-tion in drilled solids discard.This must be determinedexperimentally on a case-by-case basis.

In some cases, adding a smallstream of cleaned mud from thehydrocyclone overflow (reflux) pro-vides the same reduction in“piggy-backing” without reducingthe overall efficiency of the unit.

MAINTENANCE

Maintenance of mud cleaners/conditioners generally combines therequirements of desilters and finescreen shakers: • Periodic lubrication • Check screen tension• Inspect the screen to ensure it

is free of tears, holes, anddried mud before start up

• Shut down unit when not cir-culating to extend screen life

• Check feed manifold for plug-ging of cyclone feed inlets

• Check cyclones for excessivewear and replace parts as nec-essary

3.5 SEPARATION BY SETTLING AND CENTRIFUGAL FORCE

Using vibrating screens to removedrilled solids from mud uses onlyone characteristic of solids particles— their size. Another factor whichaffects separation is particle density.

Solids control devices which takeadvantage of both particle size andparticle density speed up the set-tling process by application ofcentrifugal force.

These devices utilize Stoke’s Lawas the basis for their operation.Stoke’s Law defines the relationshipof factors governing the settlingvelocity of particles in a liquid. Thisrelationship may be stated in itssimplest form as:

3.29

• Larger particles (of the samedensity) settle more rapidlythan smaller ones.

• High density solids settle more quickly than low densityones.

• High acceleration and low vis-cosity speed up the settling rate.

Settling pits, hydrocyclones, andcentrifuges all utilize this principlein their operation. Settling pits sim-ply use the force of gravity toseparate solids. The larger and/orheavier a solid is, the faster it willsettle through fluid in a settling pit.There is no way to speed up thisnatural settling process other thanreducing the viscosity of the fluid,or flocculating the solid particleswith the addition of chemicals.Settling pits are often large andrequire closure or remediation. Thereduction in waste mud achievedthrough efficient solids control

greatly reduces the waste waterremediation treatment costs.

3.6 SAND TRAPS

A sand trap (Figure 3-19) is a set-tling tank, usually the firstcompartment of the first pit in themud system. A shale shaker wouldnormally sit on top of the sand trapand discharge into it.

Sand traps can serve an importantrole in solids control by protectingdownstream equipment against theresults of torn shale shaker screensor by-passed shakers by removinglarge particles which could plugcyclones or other equipment down-stream. In normal operation theyalso play a minor solids removalrole by settling out a portion of thecoarse drilled solids which passthrough the shaker screen.

Normally, sand traps should havea top weir over which mud canflow into the next compartment, a

Figure 3-19 Cutaway View of Sand Trap

3.30

slanted bottom, and a quick-open-ing, quick-closing dump valve orgate so that settled solids can be dis-charged with minimum fluid loss. Insome highly sensitive environments,the extra liquids lost from dumpingthe sand trap cannot be allowed andthe desander suction is arranged toallow processing of the sand withoutcreating a lot of liquid waste.

3.7 HYDROCYCLONES

Hydrocyclones (also referred to ascyclones or cones) are simplemechanical devices, without mov-ing parts, designed to speed up the

settling process. Feed energy istransformed into centrifugal forceinside the cyclone to accelerate par-ticle settling in accordance withStoke’s Law. In essence, a cycloneis a miniature settling pit whichallows very rapid settling of solidsunder controlled conditions.

Hydrocyclones are important insolids control systems because oftheir ability to efficiently removeparticles smaller than the finestmesh screens. They are also uncom-plicated devices, which make themeasy to use and maintain.

A hydrocyclone (see Figure 3-20)

Figure 3-20 Hydrocyclone

LIQUID DISCHARGE

FEED NOZZLE VORTEX FINDER

CLEANED DRILLING MUD(OVERFLOW)

SAND AND SILT(UNDERFLOW)

DRILLING MUD

DRILLING MUD MOVESINWARD AND UPWARD

AS SPIRALLING VORTEX

SAND AND SILT, DRIVENTOWARD WALL AND

DOWNWARD IN ACCELERATING SPIRAL

3.31

consists of a cylindrical/conicalshell with a small opening at thebottom for underflow discharge, alarger opening at the top for liquiddischarge through an internal “vor-tex finder”, and a feed nozzle onthe side of the body near the cylin-drical (top) end of the cone.

Drilling mud enters the cycloneusing energy created by a centrifu-gal feed pump. The velocity of themud causes the particles to rotaterapidly within the main chamber ofthe cyclone. Heavy, coarse solidsand the liquid film around themtend to spiral outward and down-ward for discharge through thesolids outlet. Light, fine solids andthe liquid phase of the mud tend tospiral inward and upward for dis-charge through the liquid outlet.

Design features of cyclone unitsvary widely from supplier to suppli-er, and no two manufacturers’cyclones have identical operatingefficiency, capacity or maintenancecharacteristics.

In the past, cyclones were com-monly made of cast iron withreplaceable liners and other wearparts made of rubber orpolyurethane to resist abrasion.Newer designs are made entirely ofpolyurethane, and are less expen-sive, last longer, and weigh less.

Most well designed oilfieldcyclones operate most efficientlywhen 75 feet of inlet head (±5 ft) is

applied to the cone inlet.Centrifugal pumps must be prop-

erly sized for cones to operateefficiently. Centrifugal pumps areconstant energy (head) devicesand not constant pressuredevices. Feed head is constantregardless of mud weight; pres-sure varies with mud weight.

Although centrifugal pump theoryand sizing exercises are beyond thescope of this text, if you are notable to properly size your centrifu-gal pump to create 75 feet of inlethead to your set of cyclones, it ishighly recommended that you con-tact the Technical Services Staff atBrandt / EPI™ for assistance.Remember, more errors in hydrocy-clone applications are made withcentrifugal pumps, rather than withthe cyclones themselves.

The size of oilfield cyclones com-monly varies from 4” to 12”. Thismeasurement refers to the insidediameter of the largest, cylindricalsection of the cyclone. In general— but not always — the larger thecone, the coarser its cut point andthe greater its throughput. Typicalcyclone throughput capacities arelisted in Figure 3-21.

Manifolding multiple cyclones inparallel can provide sufficientcapacity to handle the required cir-culating volume plus some reserveas necessary. Manifolding may ori-ent the cyclones in a vertical

3.32

position or nearly horizontal — thechoice is one of convenience, as itdoes not affect cyclone perfor-mance.

The internal geometry of acyclone also has a great deal to dowith its operating efficiency. Thelength and angle of the conical sec-tion (and the ratio of cone diameterto cone length), the size and shapeof the feed inlet, the size of the vor-tex finder, and the size andadjustment means of the underflowopening all play important roles ina cyclone’s effective separation ofsolids particles.

Operating efficiencies of cyclonesmay be measured in several differ-ent ways, but since the purpose of

a cyclone is to discard maximumabrasive solids with minimum fluidloss, both solids and liquid aspectsof removal must be considered. (Asimple technique for comparing theefficiencies of two cyclones is givenin Appendix B of this handbook.)

In a cyclone, larger particles havea higher probability of reporting tothe bottom underflow (apex) open-ing, while smaller particles aremore likely to report to the top(overflow) opening. The most com-mon method of illustrating particleseparation in cyclones is through acut point curve.

Figure 3-22 shows the approxi-mate cut point ranges for cyclonesused with unweighted water-base

CONESIZE 4Ó 5Ó 6Ó 8Ó 10Ó 12Ó(I.D.)

CAPACITY50Ð75 70Ð80 100Ð150 150Ð250 400Ð500 400Ð500(GPM)

FEEDPRESSURE 30Ð40 30Ð40 30Ð40 25Ð35 20Ð30 20Ð30

(PSI)

Figure 3-21 Hydrocyclone Capacities

CONESIZE 4Ó 5Ó 6Ó 8Ó 10Ó 12Ó(I.D.)

CUTPOINT 15Ð20µ 20Ð25µ 25Ð30µ 30Ð40µ 30Ð40µ 40Ð60µ

(MICRONS)

Figure 3-22 Hydrocyclone Capacities

3.33

mud and operated at 75 feet ±5 feetof inlet head.

HYDROCYCLONE CUT POINT

Particle separation in cyclones canvary considerably depending onsuch factors as feed head, mudweight, percent solids, and proper-ties of the liquid phase of the mud.Generally speaking, increasing anyof these factors will shift the cutpoint curve to the right, increasingthe size of solids actually separatedby the cyclone.

By itself, the cut point does notdetermine a cyclone’s overall effi-ciency because it ignores the liquidloss rate. The amount of fluid in thecone underflow is important; if thesolids are too dry, they can cause“roping” or “dry-plugging” of theunderflow.

In contrast, a cyclone operatingwith a spray discharge (see Figure3-23) gives solids a free path toexit. A cone operating in spray dis-charge will remove a significantlygreater amount of solids than acone in “rope” discharge.

ROPE DISCHARGE

Hydrocyclones should not beoperated in rope discharge becauseit will drastically reduce the coneseparating efficiency. In a rope dis-charge, the solids become crowdedat the apex, cannot exit freely fromthe underflow, and become caught

by the inner spiral reporting to theoverflow. Solids which otherwisewould be separated are forced intothe overflow stream and returnedto the mud system. This type of dis-charge can also lead to pluggedcones and much higher cyclonewear.

While a spraying cyclone appearsto discharge more fluid, the benefitsof more efficient solids removal andless cone wear outweigh the addi-tional fluid loss. In cases where adry discharge is required, theunderflow from hydrocyclones canbe screened or centrifuged torecover the free liquid.

3.8 DESANDERS

Desanders are hydrocyclones largerthan 5” in diameter (6”, 8”, 10” or 12”ID). Generally, the smaller the cone,the smaller size particles the conewill separate (see Figure 3-24).Desanders are primarily used to

feed

SPRAY DISCHARGE ROPE DISCHARGE

NO CROWDINGAT THE APEX

CROWDINGAT THE APEX

Figure 3-23 Spray v. Rope Discharge

3.34

remove the high volumes of solidsassociated with extremely fastdrilling of a large diameter hole.

Desanders are installed down-stream from the shale shaker anddegasser. The desander removessand sized particles and largerdrilled solids which have passedthrough the shaker screen and dis-cards them along with some liquidinto a waste pit. The partially cleanmud is discharged into the next pitdownstream.

INSTALLATION

When installing a desander, followthese general recommendations:• Size the desander to process

110–125% of the total mud cir-culation rate.

• Keep all lines as short andstraight as possible with a min-imum of pipe fittings. This willreduce loss of head on thefeed line and minimize back-pressure on the overflowdischarge line.

• Do not reduce the diameter ofthe overflow line from that ofthe overflow discharge mani-fold.

• Direct the overflow line down-ward into the next downstreamcompartment at an angle ofapproximately 45°. The over-flow discharge line should notbe installed in a vertical posi-tion — doing so may causeexcessive vacuum on the dis-charge header and pull solids

Figure 3-24Particle Removal by Desander Cyclones (200 Mesh Screen Included for Comparison)

3.35

through the cyclone overflow,reducing the cyclone’s efficien-cy.

• Keep the end of the dischargeline above the surface of themud to avoid creating a vacu-um in the line.

• Position the underflow troughto easily direct solids to thewaste pit.

• Install a low equalizer line topermit backflow into thedesander suction. Operatingdesanders at peak efficiency isa simple matter, since mostdesanders are relativelyuncomplicated devices.

Here are a few fundamental prin-ciples to keep in mind:• Operate the desander unit at

the supplier’s recommendedfeed head (usually around 75feet). Too low a feed headdecreases efficiency, whileexcessive feed head shortensthe life of cyclone wear parts.

• Check cones regularly toensure the discharge orifice isnot plugged.

• Run the desander continuouslywhile drilling and shortly afterbeginning a trip for “catch-up”cleaning.

• Operate the desander with aspray rather than a rope dis-charge to maintain peakefficiency.

MAINTENANCE

Maintenance of desanders normal-ly entails no more than checking allcone parts for excessive wear andflushing out the feed manifoldbetween wells. Large trash may col-lect in feed manifolds which couldcause cone plugging during opera-tion. Preventive maintenanceminimizes downtime, and repairsare simpler between wells than dur-ing drilling.

Use of desanders is normally dis-continued when expensivematerials such as barite and poly-mers are added to a drilling mud,because a desander will discard ahigh proportion of these materialsalong with the drilled solids.Similarly, desanders are not gener-ally cost effective when an oil-basemud is in use, because the conesalso discard a significant amount ofthe liquid phase.

3.9 DESILTERS

A desilter uses smaller hydro-cyclones (usually 4” or 5” ID) thana desander and therefore generallyremoves smaller particles. Thesmaller cones enable a desilter tomake the finest particle size separa-tion of any full flow solids controlequipment — removing solids inthe range of 15 microns and larger(Figure 3-25). This makes it animportant device for reducing aver-age particle size and removing

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abrasive grit from unweighted mud.The cyclones in desilter units

operate on the same principle asthe cyclones used on desanders.They simply make a finer cut, andthe individual cone throughputcapacities are less than desandercones. Multiple cones are usuallymanifolded in a single desilter unitto meet throughput requirements.Desilters should be sized to process110–125% of the full rig flow rate.

INSTALLATION

Installation of desilters is normallydownstream from the shale shaker,sand trap, degasser and desander,and should allow ample space formaintenance. Here are some funda-mentals for installing desilters:

• Take the desilter suction fromthe compartment receivingfluid processed by thedesander.

• Do NOT use the same pump tofeed both the desander anddesilter. If both pieces ofequipment are to be operatedat the same time, they shouldbe installed in series and eachshould have its own centrifugalpump.

• Keep all lines as short andstraight as possible.

• Install a guard screen withapproximately 1/2” openings atthe suction to the desilter toprevent large trash from enter-ing the unit and plugging thecones.

Figure 3-25Particle Removal by Desilter Cyclones (200 Mesh Screen Included for Comparison)

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• Position the desilter on the pithigh enough so the overflowmanifold will gravity-feed fluidinto the next downstream com-partment at an angle ofapproximately 45°. Remember— no vertical overflow dis-charge lines.

• Keep the end of the dischargeline above the surface of themud to avoid creating a vacu-um in the line.

• Install a low equalizer line forbackflow to the desilter’s suc-tion compartment.

• Position the underflow troughto easily direct solids to thewaste pit.

Running a desander ahead of adesilter takes a big load off thedesilter and improves its efficiency.If the drilling rate is slow and theamount of solids being drilled isonly a few hundred pounds perhour, then the desander may beturned off (to save fuel and mainte-nance costs) and the desilter maybe used to carry the total desand-ing/desilting load. Appendix Cincludes a chart to calculate thepounds per hour of solids generat-ed for a range of hole size and rateof penetration.

Operating efficiencies of competi-tive desilters vary widely accordingto differences in design features.The same technique described in

Appendix B for comparing twodesanders will work to compare theefficiencies of competing desiltersoperating on the same rig.

GUIDELINES

To operate desilters at maximumefficiency, follow these basic guide-lines:• Operate the cones with a spray

discharge. Never operate thedesilter cones with a rope dis-charge since a rope underflowcuts cone efficiency in half orworse, causes cone plugging,and increases wear on cones.Use enough cones and adjustthe cone underflow openingsto maintain a spray pattern.

• Operate the desilter unit at thesupplier’s recommended feedhead. This is generallybetween 70–80 feet of head.Too much energy will result inexcessive cone wear.

• Check cones regularly for bot-tom plugging or flooding, sincea plugged cone allows solidsto return to the mud system. Ifa cone bottom is plugged,unplug it with a welding rodor similar tool. If a cone isflooding, the feed is partiallyplugged or the bottom of thecone may be worn out.

• Run the desilter continuouslywhile drilling and also for ashort while during a trip. The

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extra cleaning during the tripcan reduce overload conditionsduring the period of highsolids loading immediatelyafter a trip.

MAINTENANCE

A desilter’s smaller cyclones aremore likely than desander cones tobecome plugged with oversizedsolids, so it is important to inspectthem often for wear and plugging.This may generally be donebetween wells unless a malfunctionoccurs while drilling. The feedmanifold should be flushedbetween wells to remove trash.Keep the shale shaker well main-tained — never bypass the shakeror allow large pieces of material toget into the active system.

A desilter will discard an appre-

ciable amount of barite, becausebarite particles fall within the siltsize range. Desilters are thereforenot recommended for use withweighted mud. Similarly, sincehydrocyclones discard someabsorbed liquid along with thedrilled solids, desilters are not nor-mally used with oil-base mud,unless another device (centrifuge ormud cleaner/conditioner) is used to“deliquor” the cone underflow.

3.10 DECANTING CENTRIFUGE

Centrifuges for oilfield applica-tions were first introduced in theearly 1950s. These early units wereadapted from existing industrialdecanting centrifuges. In the mid-1960s, a perforated rotor typemachine was developed which

Figure 3-26 Decanting Centrifuge

SCROLLSCROLL FEED CHAMBER

LIQUID DISCHARGESOLIDS DISCHARGEHOLLOWSHAFT

BOWL

WEIRS

FEED PIPE

DRILLINGMUD

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does not perform like a puredecanter. Commonly called “bariterecovery” centrifuges, these earlydesigns were limited in capacityand application. Today, the cen-trifuge is even more important partof solids control. In addition, theincreased use of low-solids mudand environmental dewateringapplications require higher processvolumes, greater clarification andsolids capacity, and additional finesolids removal.

Equipment selection is decided bysite specific requirements. Propersystem selection is the first step toeffective solids control.

SEPARATION PROCESS

A Decanting Centrifuge is sonamed because it Decants , orremoves, free liquid from separatedsolids. A decanting centrifuge con-sists of a conveyor screw inside arotating bowl, see Figure 3-26.

Decanting centrifuges operate onthe principle of exposing theprocess fluid to increased “G-forces”, thus accelerating thesettling rate of solids in the fluid. Arotating bowl creates high G-forcesand forms a liquid pool inside thebowl.

The free liquid and finer solidsflow toward the larger end of thecentrifuge and are removed throughthe effluent overflow weirs. Thelarger solids settle against the bowl

wall, forming a layer. These solidsare pushed by a screw conveyoracross a drainage deck, or beach.Dewatering actually takes place onthe beach, with the decanted solidsdischarged through a series ofunderflow ports. A gear boxchanges the relative speed of theconveyor to the bowl, causing themto rotate at slightly different rates.This speed differential is requiredto convey and discharge solids.

The bowl and conveyor are rotat-ed at speeds between 1500 and4000 rpm depending on bowl diam-eter. This rotation developscentrifugal force sufficient to settlesolids along the inner surface of thebowl wall. A gearbox is used torotate the conveyor and bowl atslightly different speeds (slower orfaster). This speed differential con-veys and discharges solids from themachine.

Mud, (sometimes diluted withwater), is pumped into the convey-or hub through the feed tube. Asthe conveyor rotates, centrifugalforce pushes the feed mud out thefeed ports into the bowl. Theheavy, coarse particles in the mudare forced against the inner surfaceof the bowl, where the scrapingmotion of the conveyor bladesmoves them toward the solids dis-charge ports. A drainage deck,called the beach, is where dewater-ing of the solids actually takes

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place. The deliquified solids arethen discharged through a series ofunderflow ports.

The light, fine solids tend toremain in suspension in the poolsbetween the conveyor flights andare carried out the overflow portsalong with the liquid phase of themud. The operating principle issimilar to that of the cyclone, but itis mechanical rotation rather thanfluid head which induces the cen-trifugal force required to acceleratethe particle settling rate. Residencetime of fluid in the bowl and amore “gentle” separation environ-ment differentiate separation in acentrifuge from that of a cyclone.Centrifuges make the finest cut ofany separation device used on therig, usually 2–5 microns.

Bowl sizes in common oilfieldapplications include diameters of14”, 15”, 18”, and 24”. Larger 24”diameter units generally have thehighest liquid throughput and solidstonnage capacity.

In unweighted mud applications,feed mud capacity can range from25–250 gpm, depending on unitcapability and fluid requirements.Solids tonnage rates range from1.25 tons/hour to 8 tons/hour.

In weighted mud applications,feed mud capacity rarely exceeds25 GPM. Total liquid throughputmay be as high as 40 GPM, includ-ing dilution liquid. Dilution liquid is

required to compensate for increas-ing viscosity, generally associatedwith increasing mud weight, inorder to maintain satisfactory sepa-ration efficiency. The raw mud feedrate is substantially decreased asmud weight increases.

In field operation, the decantingcentrifuge is fitted with a housingover the bowl, liquid and solidscollection hoppers, skid, feed slurrypump, raw mud and dilution liquidconnections, power source, metersand controls.

WEIGHTED MUDAPPLICATIONS

The classic application of cen-trifuges while drilling takesadvantage of their ability to make avery fine cut — on the order of5–10 microns — when treatingweighted water-base mud. In thisapplication, centrifuges are usedintermittently to process a smallportion of the volume circulatedfrom the well bore to reduce theamount of colloidal-sized andimprove the flow properties of themud. Viscosity can be effectivelycontrolled by discarding a relativelysmall amount of colloidal size solidsand replacing the discarded liquidwith fresh make-up water.

To remove these colloidal solids,the liquid fraction from thedecanter (or the lighter slurry frac-tion from the perforated cylinder

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centrifuge) is discarded. The sand-size and silt-size semi-dry solidsfraction from the decanter (or theheavier slurry fraction from the per-forated cylinder centrifuge) isreturned to the active system.

Installation of a centrifuge is usual-ly downstream from all other solidscontrol equipment. Ideally, suctionfor a centrifuge mud feed would betaken from the same pit or compart-ment which receives the dischargefrom a mud cleaner/conditioner.

The centrifuge underflow (solids)should be discharged to a well-stirred spot in the pit for thoroughmixing with whole mud before thesolids have a chance to settle out inthe bottom of the pit. This is espe-cially important with a decanter,which discharges damp solids, andof lesser importance with a perfo-rated cylinder centrifuge, whichdischarges a pumpable slurry. Witheither type of machine, the under-flow discharge should not be tooclose to the rig pump suction. Theoverflow (liquid/colloidal solids)gravity-feed down a constantlysloping chute or pipe to waste.Sufficient working space should beprovided for routine maintenanceand operating adjustments to thecentrifuge.

Operation of centrifuges in thisapplication is generally intermittentrather than continuous. This againrelates to the standard purpose of

the centrifuge — to control viscosi-ty by removal of colloidal sizeparticles. Centrifuges should be runwhen viscosity reaches the opera-tor-established maximum, and themachine’s operation should bestopped when viscosity reaches theestablished minimum.

The maximum and minimum lim-its should be established as part ofthe overall mud program. Viscositywill normally creep up when cen-trifuges are shut down due to thesize degradation of mud solids,hence the need for restarting theunit. Both over-centrifuging andunder-centrifuging should be avoid-ed, as the economics of operationare greatly reduced under these cir-cumstances.

When centrifuging a weightedmud, bentonite and chemicals mustbe added back to the mud system.The amount of replacement ben-tonite may be calculated exactlyfrom mass balance equations, but agood rule of thumb is to add aboutone sack of bentonite per hour ofcentrifuge operation. “Under-cen-trifuging” simply will not achievethe desired reduction in viscosity.

Other applications of decantingcentrifuges have become moreimportant in recent years because ofthe decanter’s ability to remove freeliquid from the solids discharge. Aspart of a “closed loop”, the decantingcentrifuge is used to dewater the

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under-flow from hydrocyclones andremove ultra-fine particles from theactive mud system. Multiple cen-trifuges are not uncommon, operatedeither in parallel or in series.Chemical enhancement (through theuse of coagulants, flocculants, andother chemicals) is becoming morepopular as an economical way toreduce dilution requirements andoverall waste volume for haul-offand disposal.

The main difference of centrifugeuse in these applications versustheir use for viscosity control inweighted mud is the continuoususe of the centrifuge and the rout-ing of the two discharge streams.

UNWEIGHTED MUD APPLICATIONS

In the classic weighted mud appli-cation the solids discharge(containing the majority of theweighting material) is returned tothe mud system. The liquid effluent(containing the majority of the col-loidal size solids) is discarded.

As part of a “closed loop”, largerhigh capacity (75–250 GPM)decanting centrifuges (and some-times standard centrifuges) are usedto maximize fine solids removal.The coarser solids fraction is dis-carded in dry form, while the liquidand colloidal solids fraction isreturned to the mud system.

Decanting centrifuges are becom-

ing more popular for processingunweighted oil mud, especially if 1)the mud has been brought in fromanother location and may contain alarge amount of fine drilled solids,2) slow, hard drilling with a gradualbuildup of ultra-fine solids is antici-pated or 3) the liquid mud phase isvaluable.

WEIGHTED OIL-BASE MUD APPLICATIONS

In weighted, oil-base mud applica-tions, decanting centrifuges areoperated in series. The first unitreturns the coarse solids fraction(weight material ) to the active sys-tem, with the light, liquid fractionbeing routed to a holding tank (ratherthan being discarded as in a classicweighted mud application). A secondunit, often a higher capacity machine,strips out the solids and discardsthem, returning the effluent to theactive system.

This process is not as effective asa single unit for viscosity control —a large portion of the colloidal sizesolids are returned to the activemud system in the effluent streamof the second unit — but the efflu-ent stream from the first unit is toovaluable to discard, especially withsynthetic oil muds. Usually thecoarse solids fraction is discardedand the base fluid is retained for re-use.

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OPERATING PROCEDURES

Operating procedures will varyfrom model to model, but a fewuniversal principles apply to almostall centrifuges: • Before starting a centrifuge,

rotate the bowl or cylinder byhand to be sure it turns freely.

• Start up the centrifuge beforestarting the mud feed pumpand dilution water feed.

• Set the raw mud and dilutionfeed rates according to themanufacturer’s recommenda-tions (usually variable withmud weight).

• Remember to turn the feed anddilution water off before themachine is stopped.

Centrifuges are relatively easy tooperate, but they require specialskills for repair and maintenance.Rig maintenance of centrifuges islimited to routine lubrication andspeed adjustment of the unit.

3.11 AUXILIARY EQUIPMENT

AGITATION/MIXING

All compartments in an activemud system other than the sandtrap must be agitated in order tosuspend solids and maintain a con-sistent mixture throughout thesurface system. Suspension of thesolids prevents their settling andkeeps them in the active mud sys-tem so that they can be separated

by mechanical solids control equip-ment.

MUD GUNS

For many years Mud Guns (seeFigure 3-27) were used as the solemeans of agitation. These devicesusually carry mud from a down-stream compartment and spray it athigh velocity into anupstream compart-ment to keep solidssuspended.

However, the truemixing effect of mudguns tends to belocalized around thepoint where the noz-zle spray discharges,leaving dead spots inother areas of thetank. Mud guns alsoincrease the load ondownstream solidscontrol equipment,since each nozzle may add 100—200 GPM of mud into the tankabove and beyond the normal flowfrom the well.

MECHANICAL AGITATORS

Mechanical Agitators (see Figure3-28) provide more thorough mix-ing of pits without the problemsassociated with mud guns. Agitatorsuse an electric motor to driveimpeller blades which flow themud in a pattern throughout thetank.

Figure 3-27Mud Gun

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Given proper tank design, agitatorsizing, and impeller placement, thismethod of agitation prevents set-tling, enhances the efficiency ofsolids removal devices, and main-tains a well blended mud system.

DEGASSERS

After passing through a shaleshaker and a sand trap, all drillingmud should be directed through adegasser, see Figure 3-29. Degassersare often essential to the solidsremoval process to ensure theproper performance of hydrocy-clones used in downstream solidscontrol devices. The centrifugalpumps that feed the cyclones havedifficulty maintaining their efficien-

cy when pumping gas-cut mud, andthe cones will not function properlyif feed head fluctuates or if there isgas in the incoming mud. Also,recirculation of gas-cut mud is dan-gerous and could result in ablowout, since the density of gas-cut mud is lighter than the mudweight that should be maintained inthe well bore.

There are three basic methods ofdegassing which can be utilizedseparately or in combination. Thethree degassing techniques are:atmospheric, vacuum and cyclonic.

ATMOSPHERIC DEGASSERS

Atmospheric Degassers sit in themud tank and consist of an elevat-ed spray chamber and a submergedcentrifugal pump. The gas-cut mudis pumped to the spray chamber athigh velocity through a disc valve.The mud strikes the inside wall ofthe spray chamber with enoughforce to drive most of theentrapped gas out of the mud. Theremoved gas is usually dischargedto atmosphere at pit level and thedegassed mud returned to theactive system. These devices aresimple to operate and maintain, buttheir effectiveness is often limitedby the ability of the centrifugalpump to handle gas-cut mud. Asecond method of degassing is pro-vided by the use of a vacuum.

Figure 3-28 Mechanical Agitator

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VACUUM-TYPE DEGASSERS

Vacuum-type Degassers separategas bubbles from drilling mud byspreading the gas-cut mud into thinlayers and then drawing off thegases with a vacuum pump. Themud is usually thinned by flowing itover a series of baffles or plates.Vacuum degassers are normallyskid-mounted and installed on topof the mud tanks.

Some models incorporate morethan one degassing technique with-in a single unit. For example, one

degasser spreads the mud into thinsheets through centrifugal force,sprays the mud onto an impactshield for residual gas separation,and draws off the gases with a vac-uum pump.

INSTALLATION

Actual placement of the degasserand related pump will vary with thedesign of the degasser, but theserecommendations may be used as ageneral rule:• Install a screen in the inlet pipe

to the degasser to keep large

Figure 3-29 Degassers

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objects from being drawn intothe degassing chamber. Locatethe screen about one footabove the pit bottom and in awell-agitated spot.

• There should be a high equal-izer line between the suctionand discharge compartment.The equalizer should be keptopen to allow backflow ofprocessed mud to the suctionside of the degasser.

• Route the liquid discharge pipeto enter the next compartmentor pit below mud level to pre-vent aeration.

• Install the gas discharge line tosafely vent the separated gas toatmosphere or to a flare line.

Maintenance of degassers variesconsiderably depending on makeand model. In general, the follow-ing guidelines apply:• Check to make sure the suction

screen is not plugged.• Routinely lubricate any pumps

and other moving parts andcheck for wear.

• Keep all discharge lines openand free from restrictions, suchas caused by solids builduparound valves.

• If the degasser utilizes a vacu-um, keep it at the properoperating level, according tothe manufacturer’s recom-mended range for the mudweight and process rate.

• Check all fittings for air leaks.• If the unit uses a hydraulic sys-

tem, check it for leaks, properoil level, and absence of air inthe system.

DRYING SHAKERS

A drying shaker, or dryer, is avibrating screen separator used toremove free liquid from cuttingsprior to discharge and recover theliquid for re-use. Drying shakers areusually installed to process the cut-tings discharged from primaryscalping and/or fine screen shakers.A typical drying shaker is a linear-motion, multi-screen unit, with afeed hopper in place of the tradi-tional back tank. Drying shakers areoptimized to provide maximumretention time and cuttings dryness.Large hole sizes or high penetrationrates may require more than onedrying shaker to provide acceptablecuttings dryness and liquid recovery.

Shale shakers are often the causeof excess mud loss during drillingoperations, primarily due to screen-ing too fine for drilling conditionsand the design of some shakers.This mud loss can greatly increasemud costs and site clean-up costs,especially when oil-base muds,OBM, or synthetic-base muds, SBM,are used. One characteristic of SBMis the increased amount of liquidretained on the cuttings, comparedto WBM or conventional OBM.

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The drying shaker is designed toexpose wet drilled cuttings to anadditional vibrating screen surfaceand separate some of the boundliquid coating the surface of thesolids. The liquid is then returnedto the active system or transferredto a storage tank for future use.

DRYING SHAKER DESIGN

The first drying shakers were“high-G” units, operating at 6.5 to 8Gs. Prevalent thinking was that theadditional impact force provided bythe higher G-force would improvecuttings dryness. Recent field stud-ies indicate this is not necessarilytrue.

Oil content on cuttings is primari-ly a function of retention time onthe screen surface and the exposureof the cutting to the vibrationalforce of the shaker. The G-forcegreatly affects the speed at whichcuttings move from the feed end ofthe screen surface to the dischargeend. At 4 Gs, the conveyance rate isclose to 1 inch per second, while at7 Gs the conveyance rate is about 5inches per second.

Given a screen length of 24 inch-es and operation at 4 Gs, a cuttingwill take approximately 24 secondsto travel from the feed end of thescreen to the discharge end.Increasing the G-force to 7 G’sreduces the exposure time to 6 sec-onds and will actually increase the

amount of oil remaining on the cut-tings!

Since the amount of oil remainingon the cutting is a function of expo-sure time, screen deck length anddeck angle will greatly influencecuttings dryness. Screen decklength determines the distance acutting must travel prior to dis-charge and deck angle influencesretention time — the longer thescreen deck and the steeper thedeck angle, the greater the reten-tion time. However, longer screendecks may not fit the availablespace and too steep a deck anglewill result in cuttings grinding andunacceptable build-up of finesolids.

Field tests indicate the optimumdryer design provides about 4–5 Gsof force, with a deck design that isflat at the feed end to reduce cut-tings grinding and maximizeusable screen area. The dischargescreens should be sloped uphill at2.5° to 5° to increase retention timeand maximize cuttings dryness.

INSTALLATION

• Locate the drying shaker(s) at alower level from the main lin-ear shakers and other solidscontrol equipment. Feed tothe drying shaker should bethrough open hopper sized toeliminate solids build-up orplugging. Cuttings should be

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evenly deposited as close tothe feed end of the dryingshaker as possible to maximizeusable screen area and cuttingsdryness.

• Provide slides or conveyors todirect “dry” cuttings to solidscollection bins or dischargechutes

• Supply a flooded pump suctionin the liquid collection tank fortransfer by pump to the desiredstorage or processing tank.

• The mesh of the screens on thedrying shaker should be closeto, or finer than, the screenson the main shakers to preventthe re-introduction of separat-ed solids to the active system.

* Use three-dimensional, Pin-nacle™ screen panels at thefeed end of the dryer to usableincrease screen area. The mid-dle screen panel may be eithera 3-D or flat panel, dependingon deck angle and desiredfluid end point. The dischargeend screen should be a flatscreen panel to minimize cut-tings bed depth and maximizeliquid recovery.

• Adjust screen deck angledesign to properly conveysolids, reduce liquid loss, andprevent cuttings grinding.

• The liquid recovered from thedrilled cuttings will containbase fluid, plus any solids finer

than the screen mesh of thedrying shaker. The recoveredliquid should be processedthrough a decanting centrifugeto remove ultra-fine solidsbefore the mud is returned tothe active system or storagetank. In some installations, thedecanting centrifuge may beeliminated, but only after care-ful consideration of cuttingssize and their effect on fluidproperties.

3.12 UNITIZED SYSTEMS

Since 1976, several solids controlmanufacturers have developedcomplete packages of skid-mountedsolids control devices, including allsupporting tanks, piping, pumps,motors and accessories. These “uni-tized” systems maximize solidscontrol efficiency, ease transporta-tion and installation, and oftenprovide a very high efficiency sys-tem for ecologically sensitivedrilling sites.

Components of unitized systemscan vary depending on manufactur-er and the particular drillingapplication, but most include oneor more of the basic separationdevices installed in series: finescreen shaker, degasser, desander,desilter, mud cleaner/conditioner,and centrifuge. Desilting require-ments are usually met by blankingoff the screens on the mud clean-

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er/conditioners and operating themas desilters as appropriate. Sandtraps and agitators are also standardequipment in most units (SeeFigure 3-30).

In well-designed systems, allpieces of equipment, includingpumps and motors, are properlysized to provide the greatest degreeof efficiency in the smallest amountof space. Piping is engineered foroptimum fluid handling with theshortest practical suction and dis-charge lines.

Normally the only installationrequired for these units is to feedthe flow line from the well into theshale shaker, connect a dischargeline from the unitized system intothe rig suction pit, and make theelectrical and water connections.The suction pit remains a necessarypart of the surface system in orderto provide mud volume capacityand as a place for mixing-in mudadditives.

3.13 RIG ENHANCED SYSTEMS

Recent advances in shaker design,along with the custom requirementsof operators and increasing empha-sis on environmental impact, havecreated another type of system —the Rig-Enhanced System. Like theunitized systems, Rig-EnhancedSystems (RES) are designed so allpieces of equipment, includingpumps and motors, are properlysized to provide the greatest degreeof efficiency in the smallest amountof space. However, RESs utilize asmuch of the existing rig equipmentand tanks as possible to simplifyinstallation, reduce equipment cost,and allow further customization ofa system for a specific application.

Suppliers of both systems com-monly provide 24 hour on-siteservice for all components in thesystem, which greatly improvesoverall efficiency and simplifiesmaintenance procedures from thedriller’s standpoint. Considering the

Figure 3-30 Brandt/EPI™ ISCS unitized System

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importance of solids control indeep drilling and the growing con-cern over environmental impact ofmud waste disposal, these systemswill be used more often in thefuture.

3.14 HIGH EFFICIENCY SOLIDS REMOVALSYSTEMS

The goal of high efficiency solidsremoval systems, often called“closed loop” systems, is to limitwaste discharge to disposable solidsand clear water. These systemscombine the equipment found inSection 3.12 with chemically-enhanced solids removal andspecialized solids handling tech-niques. The water is often recycledon location for building new mud,as rig wash water, or used for irri-gation. A “closed loop” systemoften includes multiple shale shak-ers and centrifuges to achieve ahigh efficiency of performance inthe large upper hole sections of thewell where wastes and circulatingvolumes are the greatest.

Enhanced solids removal isaccomplished with chemical addi-tion to “pre-treat” the fluid prior toscreening or centrifugation. Pre-treatment can include pHadjustment, flocculation/coagula-tion, or similar treatment.

Solids handling techniquesinclude washing cuttings to removeexcess chlorides or residual oil,

solidification, or cuttings dischargeinto water tight containers for trans-port to approved waste facilities.

In addition to their primary goal,“closed loop” systems minimizedrilled solids remaining in thedrilling fluid. This reduces dilutionrequirements, waste volume, anddrilling problems. Therefore,“closed loop” systems have manyapplications other than environ-mental ones.

The benefit of a “closed loop”system comes from increased solidsremoval efficiency with unweightedfluids, including clear brines, andreduced discharge volume withweighted fluids. This performancehas proven extremely effective inenvironmentally sensitive areas orwhenever cuttings and liquid mudmust be hauled from the locationprior to disposal. This system pro-vides best results when combinedwith constant, on-pit attention andsupervision. Solids RemovalEfficiency of 75–95% is typical, witha 50–55% Solids DischargeConcentration.

Proper installation and operationare equally important. Here are afew guidelines to keep in mind:• Fines stay with the liquid; that

is, the smallest particles (col-loidal sized) usually remainwith the liquid phase of themud, while the larger particles— sand, cuttings, etc. — areremoved from the liquid.

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• Size each piece of full-flowsolids control equipment,except the centrifuges, to han-dle 110–125% of circulatingvolume (in order to handlebackflow within compartments,volume from mud guns, etc.).

• Always use the finest meshscreen possible that will meetthroughput and screen liferequirements.

• Often when a solids controldevice fails to perform, as itshould, the cause is improperinstallation, not equipmentmalfunction.

• Install equipment in propersequence: as the mud movesdownstream, each deviceremoves progressively smallerparticles. Never try to make asingle device remove all parti-cle sizes — it is better to alloweach device to remove its par-ticular size range within anoverall solids control system.

• Each piece of solids controlequipment should dischargeinto the next compartmentdownstream from where itssuction is taken.

• All compartments other thanthe sand trap should be agitat-ed, preferably by mechanicalagitators.

• Keep all piping as short andstraight as possible.

• Never install a 90° elbow or

valve within 5 feet of suctionof a centrifugal pump, as thiswill drastically reduce the lifeof the pump.

• For maximum efficiency,cyclones should emit a spraydischarge rather than a ropedischarge.

• Use only as many cones on amud cleaner/conditioner asrequired to meet flow capacity,in order to extend screen lifeand to avoid flooding thescreen.

• Remember size constraints andpossible sloshing and spillagein rough seas when designingoffshore systems.

• Special winterizing measures— a shed around the pits,drains in pumps, steam lines,etc. — may be required inareas of extreme cold in orderto ensure proper functioning ofthe solids control equipment.

• Size it, install it, operate itRIGHT!

3.15 BASIC ARRANGEMENT RULES

Mechanical solids control is themost cost-effective method to con-trol drilled solids. The benefits ofproper solids control are discussedin detail in Section 2. Proper solidscontrol requires:• Proper planning before the

well begins

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• Proper selection, installation,and operation of availableequipment

• Routine monitoring of fluidproperties to optimize perfor-mance

• Sequential Treatment – It fol-lows from previous recom-mendations that the solids con-trol equipment should bearranged so that each piece ofequipment removes succes-sively finer solids.

• Compartment Mixing – To pro-vide a uniform solids load tothe equipment each compart-ment, except the sand trap,should be well stirred. If mudguns are used they should bearranged so that no flowbypasses the solids controlequipment. Agitators arepreferable.

• Arrangement – Each piece ofsolids control equipment mustbe arranged so that the suctionis taken from a compartmentupstream of the dischargecompartment, i.e., there mustbe a wall or division with anequalizer opening between thesuction and discharge, even ifit is boards placed in the tanktemporarily.

• Upstream Flow ThroughEqualizer – If the flow into thesuction compartment is greaterthan the rate of flow processedby the equipment, then mud isflowing downstream throughthe equalizer. In other words,the flow through compartmentequalizers should always befrom the discharge to the suc-tion. If it is not then mud isbypassing the equipment.

• Dedicated Feed Pumps – Manifolding pumps and equip-ment so that multipleconfigurations are availabledepending on valve positionsis always a mistake. Thereshould be only one button topush to begin the pump andthe discharge valve openedslowly to begin operation ofthe solids control unit.

• Use a separate centrifugalpump for each hydrocyclonedevice (do not use the samepump for more than one pieceof equipment).

Equipment selection is decided bysite-specific requirements. Propersystem selection is the first step toeffective solids control.

4.1

COMPANY PROFILE

4.1 Scope of Services:

Brandt/EPI™ specializes in thedesign, manufacture, and service ofsolid/liquid separation systems,related equipment, and site remedi-ation services for exploration,production, and industrial applica-tions. We have the technicalexpertise to provide engineeringservices, system design and opera-tion, and proprietary technologiesto our clients throughout the world.

For over 20 years, Brandt/EPI per-sonnel have been providingindustry with solid solutions to sep-aration and remediation problems.Our diversified experience andproven track record allow us tooffer a wide range of project capa-bilities including:

Equipment and SystemsVibrating Screen SeparatorsHydrocyclone SeparatorsCentrifugal SeparatorsDewatering Units Filtration UnitsIntegrated SystemsOther Products

Technical and EngineeringServices

EquipmentRecommendations

On-site Technical SupportPilot StudiesProject ProposalsProcess RecommendationsProject Installation and

Start-UpSystem and Equipment

DesignSite Remediation Services

BioremediationDewatering SystemsLandfarmingPond ClosuresSlurrification and InjectionSludge FixationSoil/Sand washingWaste minimizationWater Treatment

4.2 Business Relationships:

We believe in long-term partner-ships with clients and vendors, andplace strict emphasis on providingcost-effective products and servicesto meet the needs of our clients,regulatory agencies, our employees,and the community. Emphasis onquality and innovative solutions hasestablished Brandt/EPI as a perfor-mance-oriented company withstrong bottom-line focus.

4.3 Certifications:

Quality products and services areour priority. Through its parent

4.0 Equipment and Services for Solids Control and Waste Management

4.2

company, Brandt/EPI maintainsseveral corporate certificationsincluding ISO 9001, API, ASME,DNV, Gos-Standard and Gosgor-technadzor.

4.4 Personnel Resources:

Brandt/EPI has established a rep-utation for professional, consistent,safe performance and innovativesolutions to client needs. Our pro-fessionals are experienced insolid/liquid separations, site reme-diation, design engineering,petroleum geology, chemical pro-cessing, environmental law, andfinance. This expertise provides theability to offer a wide variety ofproducts and services, a positiveworking environment, and thefinancial capabilities to developlong-term relationships with clients,suppliers, and sub-contractors.

Brandt/EPI and its affiliated com-panies have over 400 operationsand technical support personnelstrategically located in local servicecenters throughout the world.Many personnel hold industry certi-fications in HAZWOPER, ProcessSafety, Offshore Operations, H2S,and CPR. Brandt/EPI also maintainsa wide network of technical expertsthrough participation in industry

organizations such as the AmericanPetroleum Institute, Society ofPetroleum Engineers, AmericanInstitute of Chemical Engineers,American Association of DrillingEngineers, International Associationof Drilling Contractors, NationalUtility Contractors Association, andothers.

PRODUCTS AND SERVICES

Brandt/EPI specializes infield-proven separation systems fora variety of applications. Theseinclude exploration and production,petrochemical, stone dewatering,pulp and paper, clay processing,and municipal sludge. High-perfor-mance screen separators,hydrocyclones, and centrifuges areavailable as separate units or ascomponents of custom-designedsystems. Brandt/EPI also providesquality replacement screen panelswith a wide range of screen clothfor all screen units. Brandt/EPI pro-vides a full range of siteremediation services through ourown operations and in partnershipwith Remediation Management,Services, Inc. We have successfullyclosed over 1,000 surface pits toLouisiana Rule 29-B standards orbetter in over eighteen years of siteremediation.

4.3

4.5 Linear Motion Screen Separators

ATL-1000 Screen Separator

The ATL-1000 combines a tandemscreen arrangement and linearmotion with a ramp-slope screendeck and flat Blue HexSM screenpanels (38-450 mesh) to maximizesolids separation in a single, com-pact unit that routinelyout-performs larger shakers. Theflat (no crown) screen deck reducesliquid loss down the sides of thescreens and maximizes usablescreen area. The ramp-slope designallows the feed end screens to beoperated downhill with the dis-charge end screens flat formaximum conveyance of stickysolids. With the feed end screensflat, the discharge end screens tiltuphill to improve cuttings drynessand increase capacity without theexcessive pool depths found withother designs. Deck angle is easilyadjusted with the pinned jacking

system (-5° to +5°), and screenchanges are quick with the exclu-sive screen latches. A single-motor/sealed gearbox drive systemreduce downtime and maintenancecosts. The ATL-1000 is only 93”from end to end, but has a full 35.8sq.ft. of screen area. Multiple unitscan be used to increase capacity.

ATL-1200 Screen Separator

Designed for smaller drilling rigsand workover units, the ATL-1200combines the performance of theATL-1000 Separator with a lowerweir height in a single, compactunit that routinely out-performslarger shakers. The flat (no crown)screen deck reduces liquid lossdown the sides of the screens andmaximizes usable screen area. Theramp-slope design allows the feedend screens to be operated down-hill with the discharge end screensflat for maximum conveyance ofsticky solids. With the feed end

Figure 4-1 ATL-1000 Linear Motion Screen Separator

Figure 4-2 ATL-1200 Linear Motion Screen Separator

4.4

screens flat, the discharge endscreens tilt uphill to improve cut-tings dryness and increase capacitywithout the excessive pool depthsfound with other designs. Deckangle is easily adjusted with thepinned jacking system (-5° to +5°),and screen changes are quick withthe exclusive screen latches. A sin-gle-motor/sealed gearbox drivesystem reduce downtime and main-tenance costs. The ATL-1200measures only 93” from end to end,but has a full 25.0 sq.ft. of screenarea. Multiple units can be used toincrease capacity.

LCM-2D Screen Separator

The LCM-2D Separator (patentpending) is designed for maximumscreening efficiency from 30 to 250mesh, higher process volumes, andminimum maintenance. The ramp-slope screen deck provides ahorizontal feed screen and aninclined discharge screen for maxi-mum solids separation without theexcessive pool depths found on

other designs. The adjustable angle(+5° to -10°), 33.7 sq.ft. screen deckincludes a unique dewateringscreen panel and a small-footprintdesign. The dual Vibra-motor drivesystem is simple, efficient, andrequires no maintenance. Multipleunits may be used to increasecapacity.

Linear Motion Cascade Screen Separators

ATL-CS Cascade Separator

The ATL-CS is designed to screenfine, sticky clays at high flowratesin a single, modular unit. Typicallyconstructed from corrosion-resistantstainless-steel, the ATL-CS combinesthe fine screening ability of a sin-gle-deck ATL-1200 with the circularmotion of the proven TandemScreen Separator into a unit withthe lowest weir height of any high-performance cascade separator.Figure 4-3 LCM-2D Linear Motion Screen Separator

Figure 4-4 ATL-CS Cascade Screen Separator

4.5

The ATL-CS provides a total of 65sq.ft. of screen area and usesrugged hook-strip screens on thescalping decks and Blue HexSM

screen panels on the lower deck toimprove efficiency and reducescreen costs. Multiple units may beused to increase capacity. Ifdesired, combination stainless/car-bon steel or full carbon steelconstruction are available.

LCM-2D Cascade Separator

The LCM-2D Cascade (patentpending) combines the fine screen-ing ability and simplicity of theLCM-2D with a circular motionscalping shaker to screen fine,sticky clays at high flowrates in asingle, modular unit. The LCM-2DCascade uses the same screens onthe upper scalping deck and thelower linear unit to reduce screeninventories and costs. Total screen

area is 56.3 sq.ft. Multiple units maybe used to increase capacity.

Linear Motion Drying Shakers

ATL Drying Shaker

The ATL Drying Shaker is a com-pact “low-G” drying shaker. The ATLDryer has proved to be superior tolarger, “high-G” designs due tolonger retention time on the screensurface and less liquid retained onthe cuttings. The lower “G” forcesalso cause significantly less particlesize degradation of the cuttings.Cuttings and fluids from the primaryrig shakers are fine screened by anadjustable linear screen deck result-ing in drier solids and cleanerreclaimed base mud. The recoveredfluid is captured in an agitated tankand is returned to the active systemby an integral centrifugal pump.Pump operations are automatic andcontrolled by a float valve switchmechanism. If desired, the recoveredfluid may be centrifuged before it isreturned to the active system.

Figure 4-5 LCM-2D Cascade Linear Motion Screen Separator

Figure 4-6 ATL Drying Shaker

4.6

SDW-25 Drying Shaker

In cases where additional screenarea or higher G-forces are desired,the SDW-25 Dryer provides screen-ing to 500 mesh. The SDW-25 is afour-panel version of the provenfamily of ATL linear motion separa-tors, and has 33.3 sq.ft. of screenarea. Deck angle is easily adjustedwith a hydraulic jacking system.The independent dual-motor drivesystem eliminates pulleys, belts, orgearboxes to simplify operation andmaintenance.

Linear Motion MudConditioners

Mud Conditioners combine thefine screening ability and smallfootprint of Brandt/EPI’s linearmotion separators with Brandt/EPI’sproven hydrocyclone separators toremove fine solids from weightedmuds and to minimize waste vol-umes from unweighted muds. Mud

Conditioners may be configured asa two-stage separator with eitherdesander or desilter cones only, oras a three-stage separator with bothdesander and desilter cones to pro-vide up to 1500 GPM processcapacity in a single unit. The mostpopular models are described here;other configurations are also avail-able.

ATL-16/2 Mud Conditioner

The ATL-16/2 Mud Conditioner isa three-stage separator rated at 1000GPM. The ATL-16/2 has twodesander cones and sixteen desiltercones mounted over an ATL-1200linear motion screen deck. Twoseparate feed pumps are used toprovide proper fluid processingthrough the cones. The cone under-flow from both the desander anddesilter may be processed througha fine mesh, 120-325 mesh, screento remove fine solids and minimize

Figure 4-7 SDW-25 Drying Shaker

Figure 4-8 ATL-16/2 Mud Conditioner

4.7

liquid waste volume. If desired, thecone underflow may be discardeddirectly to waste. Total screen areais 25.0 sq.ft.

ATL-2800 Mud Conditioner

The ATL-2800 Mud Conditioner isa two-stage separator rated at 1680GPM. The ATL-2800 has twenty-eight desilter cones mounted overan ATL-1200 linear motion screendeck. A centrifugal feed pump is

used to provide proper fluid pro-cessing through the cones. Thecone underflow may be processedthrough a fine mesh, 120-325 mesh,screen to remove fine solids andminimize liquid waste volume. Ifdesired, the cone underflow maybe discarded directly to waste. Totalscreen area is 25.0 sq.ft.

LCM-2D Mud Conditioner

The LCM-2D Mud Conditionercombines the fine screening abilityand simplicity of the LCM-2D linearmotion separator (patent pending)with Brandt/EPI’s proven hydrocy-clone separators to remove finesolids from weighted muds and tominimize waste volumes fromunweighted muds. The LCM-2DMud Conditioner may be config-ured with desander and/or desilterhydrocyclones to provide eithertwo- or three-stage separations upto 1680 GPM in a single unit. Totalscreen area is 33.7 sq.ft.

4.6 Orbital Screen Separators

Tandem Screen Separator

The dual-deck Tandem ScreenSeparator is designed to processhigh volumes between 20 and 120mesh. The horizontal screen deckand circular motion provide excel-lent conveyance of solids,especially sticky clays. High capaci-

Figure 4-9 ATL-2800 Mud Conditioner

Figure 4-10 LCM-2D Mud Conditioner

4.8

ty and efficient separation areachieved because the top screenseparates large solids from the mudand improves the separating perfor-mance and screen life of thebottom screen. The reliability, lowmaintenance requirements andquiet, dependable operation havemade these machines industry stan-dards for over 20 years. TandemSeparators are available in single,dual, and triple units. Junior unitsare available for workover and sim-ilar operations.

Standard Screen Separator

The single-screen StandardSeparator is designed to process

low to moderate capacities of mate-rials requiring coarse screenseparations, 30 to 50 mesh or larg-er. A rugged, single motor design iscombined with unbalanced, ellipti-cal motion to provide years oftrouble-free operation. The stan-dard separator may also be used asa scalping shaker to reduce equip-ment costs. Standard Separators areavailable in single, dual, and tripleunits.

Junior units are available forworkover and similar operations.

Mud Cleaners

Brandt/EPI Mud Cleaners are afield-proven, two-stage separatordesigned to process up to 600 GPMover a single basket. Their horizon-tal screen deck and circular motionprovide excellent conveyance ofsolids, especially sticky clays. Thereliability, low maintenance require-

Figure 4-11 Tandem Screen Separator

Figure 4-12 Standard Screen Separator

Figure 4-13 Mud Cleaners

4.9

ments and quiet, dependable oper-ation have made these machinesindustry standards for over 20years. Mud Cleaners are available insingle or dual units and with one ortwo pre-tensioned (PT) screendecks. Mud Cleaners are availablewith 10, 12, 16, or 20 DesilterCones.

4.7 Screen Panels

Blue HexSM Screen Panels

Brandt/EPI’s exclusive Blue HexSM

screen panels are flat — there is nocrown. This design increases usablescreen area and reduces liquid lossalong the sides of screen panels.

Blue HexSM screen panelseliminate the leading

causes of screen failures — screenflex, propagation of tears, impropertensioning, blinding and contamina-tion from process fluids. Blue HexSM

screens are available in single- andmulti-layer configurations. Thewirecloth is factory pre-tensionedfor longer screen life. These screensuse a rigid support frame and gridto eliminate screen flex and sag.The result is longer screen life and

more efficient solids separation.The support grid also preventssmall tears from spreading acrossthe entire screen surface. When atear does occur, it can be easilyrepaired with Brandt/EPI’s exclu-sive screen plugs. Finally, thebonding process results in a screenpanel that is impervious to degrada-tion from high temperatures,chemicals, or oils.

Pinnacle™ Three-dimensionalScreen Panels*

Pinnacle™ screen panels offer upto 40% more screening area withoutincreasing the overall size of thescreen panel or adding additionalshakers. This concept, similar to thedesign of a pleated air filter hasseveral advantages:• Provides even distribution of

fluid across the screen surface• Eliminates unwanted fluid loss

near the screen edges• Improves dryness of solids dis-

charge• Allows the use of finer screens,

usually 2–3 mesh sizes finer

The increased usable screen areaof Pinnacle™ screens is best uti-lized when combined with flatscreen panels on linear motionshaker with an uphill basket slope.Pinnacle™ screens may alsoimprove performance on scalpingshakers and other orbital shakers

Figure 4-14 Blue HexSM Screen Panels

4.10

when used in offshore (floater)applications to reduce the effects ofswell and heave. Pinnacle™ screenpanels are available for most popu-lar fine screen shakers in severalcombinations of screen layers andmesh size, from 84 mesh to 250mesh.

* Pinnacle is a trademark of Advanced Wirecloth, Inc.

PT Screen Panels

PT screen panels are used onBrandt/EPI™ Mud Cleaners. Thistwo-panel screen consists of one ormore layers of fine-mesh screencloth, pretensioned and bonded toa metal frame for strength and longscreen life. PT screens are availablefrom 80 mesh to 325 mesh, in mar-ket grade and tensile bolting cloths.

Hook-Strip Screen Panels

Brandt/EPI™ also supplies a fullline of hook-strip screens availablein single-layer or multi-layer config-urations. Hook-strip screen panelsare available from 8-mesh to 500-mesh, and may be manufacturedfrom square-mesh market grade ortensile bolting cloths, proprietaryoblong or rectangular weaves, andthe latest, high-conductance weavesfor special applications. Urethanescreens, equivalent to 50-140 meshcloths are also available.

4.8 Hydrocyclone Units

Desanders

Available in 500 GPM, 1000 GPM,and 1500 GPM models, Brandt/EPI™Desanders offer excellent high tem-perature tolerance, resistance toabrasion, and low-cost replacement.They incorporate superior involutefeed entry, preferred flanged designfor tight, leak-proof performance,all-polymer construction, and stan-dard Victaulic® connections. Thesefeatures make them a popularchoice for retrofit of existing units.Each desander cone is 12” diameterwith a 2-1/8” diameter, fixed solidsdischarge apex for maximum solidsremoval. 1-3/4” and 1-1/2” apexsizes are also available. For extreme-ly abrasive conditions, a molded-inceramic insert may be specified.

Figure 4-15 Desander

4.11

Desilters

Available to process 60 gpm to1440 gpm, Brandt/EPI™ Desiltersoffer excellent high temperature tol-erance, resistance to abrasion, andlow-cost replacement. They incor-porate involute feed entry,preferred flanged designs for tight,leak-proof performance, all-poly-mer construction, and standardVictaulic® connections. These fea-tures make them the preferredchoice for both contractors andoperators. Each desilter cone is 4”diameter with an adjustable solidsdischarge apex for maximum solidsremoval. All desilter cones have amolded-in ceramic insert to reducewear and extend the life of thecone.

4.9 Centrifuges

Brandt/EPI™ offers several mod-els of reliable, high-performancecentrifuges to meet your two-phaseliquid/solid separation requirements— fine solids removal fromunweighted muds, viscosity control(barite recovery) for weightedmuds, and dual centrifuge systemsfor synthetic oil base muds andother critical applications. AllBrandt/EPI™ decanting centrifugescan be used in both unweightedand weighted mud applications. Allunits feature high capacity contourbowls, hard-faced conveyor feedports and scroll flight tips, hard-faced solids discharge ports, andvariable pond depth orifices. Forsafe operation, all units includesafety shut-down devices, explo-sion-proof electrics, and heavy-dutyguards over all rotating compo-nents.

SC-1 Decanting Centrifuge

The SC-1 centrifuge has an 18” x28” bowl and is designed primarilyfor barite recovery from fluids

Figure 4-16 Desilter

Figure 4-17 Desilter Cone

Figure 4-18 Decanting Centrifuge

4.12

weighing up to 26 ppg. The SC-1can also process up to 150 gpm ofunweighted muds, removing up to6 tons per hour (TPH) of low gravi-ty solids.

SC-4 Decanting Centrifuge

The SC-4 centrifuge has a 24” x40” bowl and a double-lead con-veyor designed for maximum solidstonnage removal (up to 8 TPH)and process rates up to 250 gpmfor unweighted muds. The SC-4 isalso an excellent dewatering cen-trifuge and barite recoverycentrifuge due to its 59:1 gearbox.If desired, an electric back drive tovary conveyor/bowl speed ratio isavailable as an option.

HS3400 High Speed Decanting Centrifuge

For applications that requirehigh-speed, high G-force separa-tions, the HS3400 decantingcentrifuge has become the industrystandard for high-speed perfor-mance and reliability. The HS3400has a 14” x 49.5” bowl and is

designed for ultra fine solidsremoval from unweighted muds atprocess rates up to 160 GPM and 5TPH. Top recommended bowlspeed is 3250 RPM. Stainless steelconstruction and sintered tungstencarbide wear tiles provide years oftrouble-free operation.

The HS3400 is available in all-electric, hydraulic main drive, orall-hydraulic (main and back drive)configurations. The all-electric driveprovides simple, reliable perfor-mance. The hydraulic drive systemsoffer additional separation versatili-ty and flexibility to optimizesolids/liquid separation over a widevariety of drilling conditions.

SC-35HS Decanting Centrifuge

The SC-35HS decanting centrifugeis designed for better high-speedperformance, longer life, and lessmaintenance than competitive

Figure 4-20 HS3400 Centrifuge with Hydraulic Drive

Figure 4-19 HS3400 Centrifuge with Electric Drive

4.13

designs. Compared to other “high-speed designs, the SC-35HScentrifuge’s 15” x 48” contour bowland the proprietary gearbox pro-vide several advantages — higher“G-forces at a given speed, highersolids capacity (6 TPH), higherflowrates (up to 180 GPM), finerseparations, and greater settlingarea in a smaller, more compactfootprint. Top recommended speedis 3,500 RPM. Stainless steel con-struction and tungsten carbide weartiles provide years of trouble-freeoperation. The SC-35HS is availablein all-electric, hydraulic main drive,or all-hydraulic (main and backdrive) configurations.

HS-5200 High SpeedDecanting Centrifuge

The HS5200 is a “third-generation”high-speed decanting centrifugecapable of 4000 Gs and 4200 RPMoperation. Based on the provenHS3400 design, the HS5200 has a16” x 49.5” contour bowl and hightorque drive system for higher

capacity and sharper separations —up to 250 GPM and 8 TPH. TheHS5200’s all-hydraulic drive systemcan be easily adjusted for optimumperformance in all fluid processingconditions. Main bowl speed is infi-nitely variable up to the maximum4200 RPM, and the bowl/ conveyordifferential is also adjustablebetween 1 RPM and 100 RPM.Stainless steel construction andtungsten carbide wear tiles alongthe entire scroll length provideyears of trouble-free operation.

Roto-Sep Centrifuge

The Roto-Sep Centrifuge is a per-forated rotor design to removeundesirable fine solids from weight-ed drilling fluids. The rotatingseparation chamber increases solidssettling rate to remove these finesolids and recover barite with up to92% efficiency. Available in skid- ortrailer-mounted units, the Roto-Sepprovides slurrified solids, thusallowing the unit to be located a

Figure 4-21 SC-35HS Decanting Centrifuge

Figure 4-23 HS-5200 High Speed Decanting Centrifuge

4.14

distance away from the solidsreturn tank and simplifying installa-tion.

4.10 Dewatering Units

Brandt/EPI offers several modelsof dewatering units, from simple,skid-mounted metering pump andtank modules, to the DWU-250Dewatering Unit. The DWU-250 is aself-contained, portable system thatincludes all mixing and polymeraging tanks, metering pumps, pip-ing and connection points, controls,and quality check points in a mod-ular, weatherized containerenclosure. The DWU-250 is usedwith one or more decanting cen-trifuges as part of the Chemically-Enhanced Dewatering process. TheDWU-250 may be equipped with

climatized laboratory and officeareas, including tropic or Arcticconditions.

4.11 Filtration Units

The Brandt/EPI Super-Flo™ filtra-tion system is a DE (diatomaceousearth) unit designed for clear filtratequality, faster cycle times, and high-er efficiency. The unique tubularelements provide maximum flow inminimum space; and the moreeffective pre-coat and cleaningcycles increase throughput andreduce downtime. The Super-Flofiltration unit is available in electricor diesel/pneumatic power models.

Figure 4-26 Inside the DWU-250

Figure 4-27 Filtration Unit

Figure 4-24 Roto-Sep Centrifuge

Figure 4-25 Self-contained DWU-250

4.15

4.12 Vacuum Degassers

The DG-5 (500 gpm) and DG-10(1000 gpm) vacuum degassers havebeen rated by an independentstudy as the best-performingdegassers for drilling fluid service.These degassers are compact, low-profile, and provide maximumrelease and removal of entrainedgas by flowing the gas-cut fluid invery thin sheets across a series ofstacked plates. While an eductor jetremoves the degassed mud, arugged, H2S-rated vacuum pumpprovides positive removal of gas.There is no remixing of mud andgas as found in other, low-efficien-cy methods. Interior parts aretreated to resist corrosion.

4.13 Mud Agitators

Brandt / EPI MA Series mechani-cal agitators are available from 3 HPto 25 HP, with flat or canted

impeller blades for complete mixingaction. Their low profile minimizesheadroom requirements and pro-vides stability and safety. Brandt/EPI agitators use a single-reduction,worm/worm gear drive for higherefficiency, dependable service, andsmooth vibration-free operation.The Agitator Sizing Chart forDrilling Muds, another Brandt/EPIinnovation, simplifies proper agita-tor sizing and selection, and islocated in Appendix D.

4.14 Portable Rig Blowers

Brandt/EPI developed these quiet,efficient blowers especially forimproved comfort and safety ondrilling rigs. Designed to meetapplicable OSHA specifications,

Figure 4-28 Vacuum Degasser

Figure 4-29 Mud Agitator

4.16

these blowers are used to dispersepotentially dangerous gasses andbothersome insects. Available inthree sizes — 15,000 cfm, 25,000cfm, and 40,000 cfm — Brandt/EPIBlowers move high volumes of airwith minimal noise or vibration. Toensure safe operation, all blowersfeature non-sparking aluminumblades, heavy-gauge safety guardsand explosion-proof electrics.Blowers are available in floor-mounted, wall-mounted, or hanger-mounted units.

4.15 Integrated Systems

Closed Loop Processing Systems

All Brandt / EPI™ equipment canbe integrated into systems designedfor specific applications. We haveover 20 years’ experience design-ing, manufacturing, and operatingsystems for “Closed Loop” process-ing of drilling fluids, dewateringsystems, cuttings wash systems,product classification systems, andother waste reduction/managementsystems. Brandt / EPI equipment iscurrently in service throughout theworld, providing excellent results inland and offshore installations,remote areas, processing plants,in-plant installations, and site reme-diation projects.

Brandt / EPI Closed Loop MudSystems (CLMS) are custom-designed for your specificapplication, based on operational,environmental, and economicneeds. A typical CLMS may include

Figure 4-31 Closed Loop Mud System

Figure 4-30 Portable Rig Blower

4.17

one or more primary ScreenSeparators, Drying Shakers, MudConditioner, and DecantingCentrifuge. Dual centrifuge installa-tions for special applications —such as weighted oil base mudsand synthetic oil- or water-basedrilling fluids — are also readilyavailable.

Coiled Tubing (CT)Processing Systems

CT Processing Systems aredesigned for the specific require-ments of coiled tubing operations,both drilling and workover. Theirmodular design makes it easy toselect the total mud volume, typeand number of fluid processingequipment, mixing equipment, andtank configuration. All compart-ments are mechanically agitated toprevent settling of weighting mate-rials and maintain a homogenousfluid mixture. The integrateddegasser (not shown) is speciallydesigned to remove large amountsof entrained gas safely and effec-tively.

Trenchless TechnologyProcessing Systems

Brandt/EPI CLMS are also rapidlybecoming the preferred choice forTrenchless Technology MudSystems. We have successfully com-pleted over 75 trenchless projects inNorth America, ranging from smalldiameter fiber-optic cable installa-tions to large natural gas pipelineprojects. We have also providedsystems and operators for horizon-tal wells to neutralize undergroundcontamination plumes and otherenvironmental remediation projects.

Live Oil Systems

Brandt/EPI offers a proprietarysystem to process three-phasesolids/water/oil separations whendrilling underbalanced through pro-ducing zones. The Brandt/EPI “LiveOil” System is a modular tank sys-tem, complete with pressure controland solids separation equipment.Water and oil are separated andrecovered in separate tanks forfuture re-use or transportation.

4.16 Remediation Management Services

Remediation ManagementServices, a Brandt/ EPI company,provides a full range of site remedi-ation services throughout the world.In over eighteen years of site reme-diation, we have successfully closedover 1,000 surface pits to LouisianaFigure 4-32 Coiled Tubing (CT) Processing System

4.18

Rule 29-B standards or better.Techniques available include:• Closed loop mud systems• Chemically Enhanced

Dewatering• Landfarming / landspreading• Bioremediation• Cuttings slurrification and

injection systems• Sludge stabilization and

fixation• Soil/sand washing• Surface pit closure• Waste minimization• Water treatment• Construction equipment• Pump rental• Water Discharge Permit No. 5259

Each service typically includes allnecessary excavation equipment,process equipment, tanks, transferpumps and related equipment,chemicals, power source, labor,onsite testing and analytical data,site closure, and necessary state orfederal permits, reports, and otherdocumentation.

4.17 Technical and Engineering Services

Brandt/EPI™ offers a full range oftechnical and engineering servicesto ensure optimum application andperformance of separation andother, related equipment. These ser-vices range from periodic, on-siteinspections to complete design pro-posals and continuous on-sitetechnical support, depending onproject and client requirements.Technical and engineering servicesinclude:• Project pre-planning• Rig surveys • Project recommendations• On-site system operation and

maintenance• Brandt’s exclusive RECAP™

Report (Removal EfficiencyCost Analysis Program)

• CAD-based engineering• PC-based particle size analysis • Pilot testing• Technical education and

training Any Brandt/EPI™ product may be

custom-manufactured to meet yourproject requirements. All equipmentcan be supplied in full carbon steel,carbon/stainless steel combination,or full stainless steel in a variety offinishes and colors. Explosion-proofelectrical components are standard,but other styles may be requested.Call your local Brandt/EPI represen-tative for a quotation.

Figure 4-33 Site Remediation Services

A.1

APPENDICES

Glossary ..................................................................................................................A.2

Mud Solids Calculations

Standard Calculations........................................................................................B.1

Field Calculations to Determine Total Solids Discharge.................................B.4

Field Calculations to Determine High and Low Gravity Solids Discharge ....B.5

Solids Control Performance Evaluation ...........................................................B.6

Method for Comparison of Cyclone Efficiency .............................................B.10

Mud Engineering Data

Conversion Constants and Formulas ...............................................................C.1

Density of Common Materials ..........................................................................C.2

Hole Capacities .................................................................................................C.3

Pounds per Hour Drilled Solids — Fast Rates ................................................C.4

Pounds per Hour Drilled Solids — Slow Rates...............................................C.5

Solids Content Chart .........................................................................................C.6

Equipment Selection

Pre-well Project Checklist ................................................................................D.1

Screen Cloth Comparisons ...............................................................................D.2

Brandt/EPI™ Equipment Specifications ..........................................................D.3

Selecting Size and Number of Agitators ..........................................................D.7

Brandt/EPI™ Sales & Service Locations ..........................................................D.8

A.2

A

ADSORBED LIQUIDThe liquid film that adheres to the sur-faces of solids particles which cannotbe removed by draining, even centrifu-gal force.

AERATION*The mechanical incorporation and dis-persion of air into a drilling fluidsystem. If not selectively controlled, itcan be very harmful.

AIR CUTTINGSee Preferred Term: AERATION

AIR LOCKA condition causing a centrifugal pumpto stop pumping due to a ball of air (orgas) in the impeller center that will notlet liquid enter (usually caused by aera-tion).

AMPLITUDE +The distance from the mean position tothe point of maximum displacement. Inthe case of a vibrating screen with cir-cular motion, amplitude would be theradius of the circle. In the case ofstraight-line motion or elliptical motion,amplitude would be one-half of thetotal movement of the major axis of theellipse; thus one-half stroke. See relat-ed term: STROKE.

ANTIFOAM -A substance used to prevent foam bygreatly increasing the surface tension.Compare: DEFOAMER.

APERTURE +An opening. In a screen surface, theclear opening between wires. See relat-ed term: MESH.

APEXSee Preferred Term: UNDERFLOWOPENING.

APEX VALVESee Preferred Term: UNDERFLOWOPENING.

API SANDSolids particles in a drilling fluid thatare too large to pass through a U.S.Standard 200 Mesh Screen (74 micronopenings). See related term: SANDCONTENT.

APPARENT VISCOSITY -The viscosity a fluid appears to haveon a given instrument at a stated rateof shear. It is a function of the plasticviscosity and the yield point. See also:VISCOSITY, PLASTIC VISCOSITY, andYIELD POINT.

AXIAL FLOW*Flow from a mechanical agitator inwhich the fluid first moves along theaxis of the impeller shaft (usually down

GLOSSARY

LEGEND+ API Bul 13C- API Bul D11* IADC Mud Equipment Manual

A.3

toward the bottom of a tank) and themaway from the impeller.

B

BACKPRESSURE +The pressure opposing flow from asolids separation device. See relatedterm: DIFFERENTIAL PRESSURE.

BALANCE (as a Hydrocyclone)*To adjust a balanced design hydrocy-clone so that it discharges only a slightdrip of water at the underflow open-ing.

BALANCE DESIGN(Hydrocyclone)A hydrocyclone designed so it can beoperated to discharge solids whenthere are solids to separate, but willautomatically minimize liquid dischargewhen there are no separable solids.

BALANCE POINT * (of a Hydrocyclone)That adjustment at which exactly noliquid will discharge at the underflowopening, yet any greater opening at allwould result in some liquid discharge.

BARITE, BARYTESNatural barium sulfate, used forincreasing the density of drilling fluids.The barite mineral occurs in many col-ors from white through grays, greens,and reds to black, according to theimpurities. API standards require a min-imum of 4.2 average specific gravity.

BARREL (API)A unit of measure used in the petrole-um industry consisting of 42 U.S.gallons.

BASKET

That portion of a shale shaker contain-ing the deck upon which the screen(s)is mounted; supported by vibration iso-lation members connected to the bed.

BEACHArea between the liquid pool and thesolids discharge ports in a decantingcentrifuge or hydrocyclone.

BED *Shale shaker support member consist-ing of mounting skid, or frame with orwithout bottom, flow diverters to directscreen underflow to either side of theskid and mountings for vibration isola-tion members.

BENTONITEA hydratable colloidal clay, largelymade up of the mineral sodium mont-morillonite, used in drilling fluids tocreate viscosity. See related term: GEL.

BLADESee Preferred Term: FLUTE.

BLINDING +A reduction of open area in a screen-ing surface caused by coating orplugging. See related terms: COATING,PLUGGING.

BLOWOUT -An uncontrolled escape of drillingfluid, gas, oil, or water from the wellcaused by the formation pressure beinggreater than the hydrostatic head of thefluid in the hole.

BOTTOM (Cyclone)See Preferred Term: UNDERFLOWOPENING.

BOTTOM FLOODINGThe behavior of a hydrocyclone when

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the underflow discharges whole mudrather than separated solids.

BOUND LIQUIDSee Preferred Term: ADSORBED LIQ-UID.

BOWL +The outer rotating chamber of adecanting centrifuge.

C

CAKE THICKNESS -The measurement of the thickness ofthe filter cake deposited by a drillingfluid against a porous medium mostoften following the standard API filtra-tion test. Cake thickness is usuallyreported in 32nds of an inch. See relat-ed term: WALL CAKE.

CAPACITYThe maximum volume rate at which asolids control device is designed tooperate without detriment to separa-tion. See related terms: FEEDCAPACITY, SOLIDS DISCHARGECAPACITY.

CASCADEFluid movement on a single deck, mul-tiple screen sloping shale shaker basketwhich flow is parallel to screens.

CAVING *Caving is a severe degree of sloughing.See related term: SLOUGHING.

CENTIPOISE (cp)A unit of viscosity equal to 1 gram percentimeter-second. The viscosity ofwater at 20°C is 1.005 cp.

CENTRIFUGAL FORCE +That force which tends to impel matter

outward from the center of rotation.See related term: G-FORCE.

CENTRIFUGAL SEPARATOR +A general term applicable to anydevice using centrifugal force to short-en and/or to control the settling timerequired to separate a heavier massfrom a lighter mass.

CENTRIFUGAL PUMPA device for moving fluid by means ofa rotating impeller which spins thefluid and creates centrifugal force.

CENTRIFUGEA centrifugal separator, specifically: adevice rotated by an external force forthe purpose of separating materials ofvarious specific gravities and/or particlesizes or shapes from a slurry to whichthe rotation is imparted primarily byrotating bowl.

CERAMICSA general term for heat-hardened clayproducts which resist abrasion: used toextend the useful life of wear parts inpumps and cyclones.

CHOKE *An opening, aperture, or orifice used torestrict a rate of flow or discharge.

CIRCULATION -The movement of drilling fluid fromthe suction pit through pump, drillpipe, bit, annular space in the hole,and back again to the suction pit. Thetime involved is usually referred to ascirculation time.

CIRCULATION RATE -The volume flow rate of the circulationdrilling fluid, usually expressed in gal-lons or barrels per minute.

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CLAY-SIZE, CLAY (Particles)Any solids particles less than 2 micronsin diameter. Natural clay particles arecommonly (but not limited to) ahydrous silicate of alumina, formed bythe decomposition of feldspar andother aluminum silicates. Clay mineralsare essentially insoluble in water butdisperse into extremely small particlesas a result of hydra-small particles as aresult of hydration, grinding, or velocityeffects.

COARSE (Solids) +Solids larger than 2000 microns indiameter.

COATINGA condition wherein undersize particlescover the openings of a screening sur-face by virtue of stickiness. See relatedterm: BLINDING.

COLLOIDAL (Solids)Particles so small that they do not settleout when suspended in a drilling fluid.Commonly used as a synonym for“clay.”

CONESee Preferred Term: HYDROCYCLONE.

CONTAMINATIONThe presence in a drilling fluid of anyforeign material that may tend to harmthe desired properties of the drillingfluid.

CONTINUOUS PHASEThe fluid phase of a drilling mud,either water or oil.

CONVEYORA mechanical device for moving mater-ial from one place to another. In a

decanting centrifuge, a hollow hubwith flutes designed to move thecoarse solids out of the bowl.

CROWNThe curvature of a screen deck or thedifference in elevation between its highand low points.

CUT POINTA general term for the effectiveness ofa liquid-solids separation deviceexpressed as the particle size that isremoved from the feed stream at agiven percentage under specified oper-ating conditions. See related term:MEDIAN CUT.

CUTTINGSSmall pieces of formation that are theresult of the chipping and crushingaction of the bit. Field practice is to callall solids removed by the shaker screen“cuttings,” in spite of the fact that suchsolids may include sloughed materialsand may be smaller than the screenopenings.

CYCLONESee Preferred Term: HYDROCYCLONE.

D

DECANTING CENTRIFUGE +A centrifuge which continuouslyremoves solids that are coarse enoughto be separated from their free liquid.

DECKThe screening surface in a shale shakerbasket.

DEFLOCCULATIONBreakup of flocs of gel structures byuse of a thinner or dispersant.

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DEFOAMER -Any substance used to reduce or elimi-nate foam by reducing the surfacetension. Compare: ANTIFOAM.

DEGASSERA device that removes entrained gasfrom a drilling fluid.

DENSITYMatter measured as mass per unit ofvolume expressed in pounds per gallon(lbs/gal), pounds per square inch perthousand feet of depth (psi/1000 ft.),grams per liter (g/l), and specific gravi-ty. Density is commonly referred to as“weight.”

DESANDTo remove the API sand from drillingfluid.

DESANDERA hydrocyclone capable of removingthe API sand (particles greater than 74microns) from a drilling fluid.

DESILTTo remove most particles larger than15-20 microns from a drilling fluid.

DESILTERA hydrocyclone capable of remov-ing most particles larger than 15-20microns from a drilling fluid.

DIFFERENTIAL PRESSURE(Hydrocyclone)The difference between the inlet andoutlet pressures measured near the inletand outlet openings of a hydrocyclone.

DIFFERENTIAL PRESSURE (Wall)STICKINGSticking which occurs because part ofthe drill string (usually the drill collars)

becomes embedded in the filter cake,resulting in a non-uniform distributionof pressure around the circumferenceof the pipe. The conditions essential forsticking require a permeable formationand a pressure differential across thefilter cake and drill string.

DILUENTLiquid added to dilute or thin a drillingfluid.

DILUTIONIncreasing the liquid content of adrilling fluid by addition of water or oil.

DILUTION RATIO *Ratio of volume of dilution liquid to thevolume of raw mud in the feed to a liq-uid-solids separator.

DILUTION WATERWater used for dilution of water-basedrilling mud.

DIRECT-INDICATING VISCOMETERSee VISCOMETER, DIRECT INDICAT-ING.

DISCHARGE SPOUT OR LIPExtension at the discharge area of ascreen. It may be vibrating or stationary.

DISPERSANTAny chemical which promotes disper-sion of particles in a fluid.

DISPERSE *To separate in component parts.Bentonite disperses by hydration intomany smaller pieces.

DISPERSION (of Aggregates)-Disintegration of aggregates. Dispersionincreases the specific surface are ofsolids resulting in an increase in viscos-ity and gel strength.

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DIVIDED DECK +A deck having a screening surface lon-gitudinally divided by partition(s).

DOUBLE FLUTE +The flutes or leads advancing simultane-ously at the same angle and 180° apart.

DRILLED SOLIDSFormation particles drilled up by thebit. See related term: LOW SPECIFICGRAVITY SOLIDS.

DRILLING INThe operation during the drilling proce-dures at the point of drilling into theproducing formation.

DRILLING MUD OR FLUIDA circulating fluid used in rotary drillingto carry cuttings out of the hole andperform other functions required in thedrilling operation. See related term:MUD.

DRILLING OUTThe operation during the drilling proce-dure when cement is drilled out of thecasing before further hole is made orcompletion attempted.

DRILLING RATEThe rate at which hole depth progress-es, expressed in linear units per unit oftime (including connections) asfeet/minute or feet/hour. See relatedterm: PENETRATION RATE.

DRY BOTTOMReferring to a hydrocyclone, an adjust-ment of the underflow opening thatcauses a dry beach, usually resulting insevere plugging.

DRY PLUGThe plugging of the underflow opening

of a hydrocyclone caused by operatingwith a dry bottom.

DYNAMICThe state of being active or in motion;opposed to static.

E

EDUCTORA device using a high velocity jet tocreate a vacuum which draws in liquidor dry material to be blended withdrilling mud.

EFFECTIVE SCREENING AREAThe portion of a screen surface avail-able for solids separation.

EFFLUENTSee Preferred Term: OVERFLOW.

ELASTOMERAny rubber or rubber-like material(such as polyurethane).

ELEVATION HEADThe pressure created by a given heightof fluid. See related term: HEAD.

EMULSIFIER or EMULSIFYINGAGENTA substance used to produce an emul-sion of two liquids which ordinarilywould not mix.

EMULSIONA substantially permanent mixture oftwo or more liquids which do not nor-mally dissolve in each other. They maybe oil-in-water or water-in-oil types.

EQUIVALENT SPHERICAL DIAMETER (ESD) +The theoretical dimension usuallyreferred to when the sizes of irregularlyshaped small particles are discussed.

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These dimensions can be determinedby several methods, such as: settlingvelocity, electrical resistance, and lightreflection. See related term: PARTICLESIZE.

F

FEED, or FEED SLURRYA mixture of solids and liquid enteringa liquid-solids separation device,including dilution liquid if used.

FEED CAPACITY *The maximum feed rate that a solidsseparation device can effectively han-dle, dependent upon particle size,particle concentration, viscosity, andother variables. See related terms:CAPACITY, SOLIDS DISCHARGECAPACITY.

FEED CHAMBER +The part of a device which receives themixture of diluents, mud and solids tobe separated.

FEED HEADThe pressure (expressed in feet ofhead) exerted by the drilling fluid in aheader. See related term: HEAD.

FEED HEADER +A pipe, tube, or conduit to which twoor more hydrocyclones are connectedand from which they receive their feedslurry.

FEED OPENINGSee Preferred Term: INLET.

FEED PRESSURE +The actual gauge pressure measured asnear as possible to, and upstream of,the inlet of a device.

FILTER CAKEThe suspended solids that are deposit-ed on a porous medium during theprocess of filtration, such as the stan-dard API fluid loss test. It may alsorefer to the solids deposited on the wallof the hole. See related term: WALLCAKE.

FILTER CAKE THICKNESSA measurement of the solids depositedon filter paper in 32nds of an inch dur-ing the standard 30-min. API filter test.This term also refers to the cakedeposited on the wall of a hole.

FILTER PRESSA device for determining fluid loss of adrilling fluid.

FILTRATIONThe process of separating suspendedsolids from their liquid by forcing thelatter through a porous medium. Twotypes of fluid filtration occur in a well:dynamic filtration while circulating, andstatic filtration when at rest.

FILTRATION RATESee FLUID LOSS.

FINE (Solids) +Particles whose diameter is between44-74 microns.

FINE SCREEN SHAKERA vibrating screening device designedfor screening drilling fluids throughscreen cloth finer than 40 mesh.

FISHINGOperations on the rig for the purposeof retrieving sections of pipe, collars,junk, or other obstructive items whichare in the hole and would interferewith drilling.

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FLIGHT +On a decanting centrifuge, one full turnof a spiral helix, such as a flute orblade of a screw-type conveyor.

FLOCCULATING AGENTA substance, such as most electrolytesand certain polymers, that causes floc-culation.

FLOCCULATIONLoose association of particles in lightlybonded groups, or non-parallel associa-tion of clay platelets. In drilling fluids,flocculation results in thickening gela-tion.

FLOODINGThe effect created when a screen orcentrifuge is fed beyond its capacity.Flooding may also occur on a screen asa result of blinding.

FLUID LOSS -Measure of the relative amount of fluidloss (filtrate) through permeable forma-tions or membranes when the drillingfluid is subjected to a pressure differen-tial. For standard API filtration-testprocedure, see API RP 13B.

FLUTEThe curved metal blade wrappedaround a shaft as on a screw conveyorin a centrifuge.

FOAMA light frothy mass of fine bubblesformed in or on the surface of a liquid;usually caused by entrained air or gas.

FORMATION DAMAGE -Damage to the productivity of a wellresulting from invasion into the forma-tion by mud particles or mud filtrate.

FREE LIQUIDThe layer of liquid that surrounds eachseparate particle in the underflow of ahydrocyclone. The thickness of thisfilm depends upon the cyclone and theviscosity of the fluid.

FUNNEL VISCOSITY -The time, in seconds, for a quart (orliter) of drilling mud to flow out thebottom of a Marsh Funnel. Used in thefield as a rough measure of apparentviscosity. See related terms: MARSHFUNNEL, APPARENT VISCOSITY.

G

GAS-CUT (Mud)Drilling fluid containing entrained gas.

GEAR RATIO +On a decanting centrifuge, the ratio ofthe outer bowl speed to the differencein speed between the outer bowl andthe screw conveyor, normallyexpressed as the number of revolutionsof the outer bowl for a given differenceof one complete revolution between theouter bowl and the screw conveyor.

GEAR UNIT +On a centrifuge, a reduction deviceconnected to the rotating bowl and dri-ving the conveyor at a slightly differentrate.

GEL -A term used to designate high col-loidal, high-yielding, viscosity-buildingcommercial clays, such as bentoniteand attapulgite clays.

GEL STRENGTHThe ability or the measure of the abilityof a colloid to form gels. Gel strength

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is a pressure unit usually reported inlbs/100 sq. ft. It is a measure of thesame interparticle forces of a fluid asdetermined by the yield point underdynamic conditions.

GEL STRENGTH, INITIALThe measured initial gel strength of afluid is the maximum reading (deflec-tion) taken from a direct-readingviscometer after the fluid has beenallowed to sit for 10 minutes.

G-FORCE *The acceleration of gravity (32.2ft/sec/sec, 9.8 m/sec/sec). Multipliedacceleration due to centrifugal force isusually expressed as 1G, 2G, 3G,11,000G etc.

GUMBO *Any relatively sticky shale formationencountered while drilling.

GUNNING THE PITSAgitation of the drilling fluid by meansof mud guns.

H

HEADThe height (in feet) of a column offluid necessary to develop a specificpressure. Commonly used to refer tothe pressure put out by a centrifugalpump.

HIGH SPECIFIC GRAVITY SOLIDSSolids whose specific gravity is greaterthan 4.2 which are added to a drillingfluid specifically to increase mud densi-ty. Barite is the most common, butothers such as iron oxides are alsoused. See related Term: LOW SPECIFICGRAVITY SOLIDS.

HOOK STRIPS +The hooks on the edges of a screensection which accept the tension mem-ber.

HOPPERSee MUD HOPPER.

HORSEPOWERA measure of the rate at which work isdone. Motor nameplate horsepower isthe maximum steady load that themotor can pull without damage.

HYDRATIONThe act of a substance to take up waterby means of absorption and/or adsorp-tion; usually results in swelling,dispersion and disintegration into col-loidal particles.

HYDROCYCLONEA liquid-solids separation device whichutilizes centrifugal force to speed upsettling. Drilling fluid is pumped tan-gentially into a cone and the rotation ofthe fluid provides centrifugal force toseparate particles by mass weight - theheavier solids being separated from thelight solids and liquid.

HYDROCYCLONE SIZE *The maximum inside working diameterof the cone part of a hydrocyclone.

I

INERTIA *That force which makes a moving parti-cle tend to maintain its same direction.

INHIBITED MUD -A drilling fluid having a aqueous phasewith a chemical composition that tendsto retard and even prevent (inhibit)appreciable hydration (swelling) or dis-

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persion of formation clays and shalesthrough chemical and/or physicalmeans. See INHIBITOR (mud).

INHIBITOR (mud) -Substances generally regarded asdrilling mud contaminants, such as saltand calcium sulfate, are calledinhibitors when purposely added tomud so that the filtrate from the drillingfluid will prevent or retard the hydra-tion of formation clays and shales.

INLETThe opening through which the feedmud enters a solids control device.

INTERMEDIATE (Solids) +Particles whose diameter is between250-2000 microns.

INVERT OIL-EMULSION MUD -An invert emulsion is a water-in-oilemulsion where fresh or salt water isthe dispersed phase and diesel, crude,or some other oil is the continuousphase. Water increases the viscosityand oil reduces the viscosity.

L

LEADIn a decanting centrifuge, the slurryconducting channel formed by theadjacent walls of the flutes or blades ofthe screw conveyor.

LIGNOSULFONATESOrganic drilling fluid additives derivedfrom by-products of sulfite paper man-ufacturing process from coniferouswoods. Commonly used as dispersantsand anti-flocculants. In large quantities,may be used for fluid-loss control andthe shale inhibition.

LIQUID *Fluid that will flow freely, takes theshape of its container.

LIQUID-CLAY PHASESee Preferred Term: OVERFLOW

LIQUID DISCHARGESee Preferred Terms: OVERFLOW(Hydrocyclones); UNDERFLOW(screens).

LIQUID FILMThe liquid surrounding each particledischarging from the solids discharge ofcyclones and screens. See related term:FREE LIQUID.

LOST CIRCULATIONThe result of whole mud escaping intoa formation, usually in cavernous, fis-sured, or coarsely permeable beds,evidenced by the complete or partialfailure of the mud to return to the sur-face as it is being circulated in thehole.

LOST CIRCULATION MATERIALS(LCM)Materials added to drilling fluid to con-trol mud loss by bridging or pluggingthe lost circulation zone.

LOW SILT MUDAn unweighted mud that has all thesand and high proportion of the siltsremoved and has a substantial contentof bentonite or other water-loss-reduc-ing clays.

LOW SOLIDS MUDSLow solids muds are unweightedwater-base muds containing less than10% drilled solids (1-4% is a normalrange). They are used whenever it isdesirable to increase penetration rate.

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In general, the lower solids content ina mud, the faster a bit can drill.

LOW SPECIFIC GRAVITY SOLIDSDrilled solids of various sizes, commer-cial colloids, salts, lost circulationmaterials, i.e., all solids in drilling fluid,except barite or other commercialweighting materials. Typical S.G. is 2.6.

M

MANIFOLD (Cyclone)A piping arrangement through whichliquids, solids or slurries from one ormore sources can be fed to or dis-charged from a solids separationdevice.

MARSH FUNNELAn instrument used in the field todetermine funnel viscosity of a drillingfluid. See related term: FUNNEL VIS-COSITY.

MASSThe effective weight of a particle, con-sidering both its specific gravity andparticle size.

MECHANICAL AGITATORA device used to mix, blend, or stir flu-ids by means of a rotating impellerblade.

MEDIAN CUT *In separating solids particles from aspecific liquid-solids slurry under speci-fied conditions, the effectiveness of theseparation device expressed as the par-ticle size that reports 50% to theoverflow and 50% to the underflow.

MEDIUM (solids) +Particles whose diameter is between74-250 microns.

MESHThe number openings per linear inchin a screen. For example, a 200 meshscreen has 200 openings per linearinch.

MESH COUNTThe count is the term most often usedto describe a square or rectangularmesh screen cloth. A mesh count suchas 30 x 30 (or often 30 mesh) indicatesa square mesh, while a designationsuch as 70 x 30 mesh indicates a rec-tangular mesh.

MESH EQUIVALENTAs used in oilfield drilling applications,the U.S. Sieve number which has thesame size opening as the minimumopening of the screen in use.

MICRON (µ)A unit of length equal to one thou-sandth of a millimeter; used as ameasure of particle size.MUDMud is the term most commonly givento drilling fluids; used for circulatingout cuttings and many other functionswhile drilling a well.

MUD ADDITIVE -Any material added to a drilling fluid toachieve a particular purpose.

MUD BALANCE -A beam-type balance used in determin-ing mud density. It consists primarily ofa base, graduated beam with constant-volume cup, lid, rider, knife edge andcounterweight.

MUD BOXThe feed compartment on a shale shak-er into which the mud flow line

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discharges, and from which the mud iseither fed to the screens or is bypassed.Also called Backtank or Possum Belly.

MUD CLEANERA solids separation device which com-bines several manifolded hydrocyclonesand a fine mesh vibrating screen toremove valuable mud additives and liq-uids to the active mud system.

MUD CONESee Preferred Term: HYDROCYCLONE.

MUD ENGINEER -One versed in drilling fluids whoseduties are to manage, implement, andmaintain the various types of oilwellmud programs.

MUD FEED +Drilling fluid, with or without dilution,for introduction into a liquid-solids sep-arator.

MUD GUNSA system of pumps and piping inwhich drilling mud is pumped throughnozzles at a high velocity. Used formixing, blending and stirring the mudpits.

MUD HOPPER *A device used for mixing mud chemi-cals and other products into a fluidstream. It usually consists of a mud jet,an open top hopper, and downstreamventuri.

MUD HOUSE -A structure at the rig to store and shel-ter sacked materials used in drillingfluids.

MUD MIXING DEVICESThe most common device for adding

solids to the mud is by means of themud hopper. Some other devices formixing are: eductors, mechanical agita-tors, electric stirrers, mud guns, andchemical barrels.

MUD PIT -Earthen or steel storage facilities for thesurface mud system. Mud pits whichvary in volume and number are of twotypes: circulating and reserve. Mud test-ing and conditioning is normally donein the circulating pit system.

MUD PUMPSSee RIG PUMPS.

MUD SCALESSee MUD BALANCE.

MUD STILLSee RETORT.

N

NEAR SIZEThe material very nearly the size of ascreen opening, generally consideredas plus or minus 25% of the opening.

O

OBLONG (Mesh)Screen cloth having more wires perinch in one direction than in another.For example, 70 x 30 mesh has 70wires per inch in one direction and 30wires per inch in the other direction.(Also called “rectangular” mesh.)

OIL-BASE MUDA drilling fluid containing oil as its liq-uid phase, usually including 1-5%water emulsified into the system.

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OPEN AREASee PERCENT OPEN AREA.

OVERFLOWThe discharge stream from a centrifugalseparation device that contains a higherpercentage of liquids than does thefeed.

OVERFLOW HEADER *In hydrocyclone operation, a pipe intowhich two or more hydrocyclones dis-charge their overflow.

OVERLOAD +To feed separable solids to a separatingdevice at a rate greater than its solidsdischarge capacity.

OVERSIZE (Solids)Particles, in a given situation, that canbe separated from the liquid phase bycentrifugal force or which will not passthrough the openings of the screen inuse.

P

PARTICLEIn drilling mud work, a small piece ofsolid material.

PARTICLE SIZEParticle diameter, usually expressed inmicrons. See related term: EQUIVA-LENT SPHERICAL DIAMETER.

PARTICLE SIZE DISTRIBUTION +The fraction or percentage of particlesof various sizes or size ranges. Seerelated term: SIEVE ANALYSIS.

PARTICLE SURFACE AREASee SPECIFIC SURFACE AREA.

PENETRATION RATEThe rate at which the drill bit pene-

trates the formation, expressed in linearunits, i.e., feet/minute or feet/hour. Seerelated term: DRILLING RATE.

PERCENT OPEN AREARatio of the area of the screen open-ings to the total area of the screensurface.

PERFORATED CYLINDER CENTRIFUGE +A mechanical centrifugal separator inwhich the rotating element is a perfo-rated cylinder (the rotor) inside of andconcentric with an outer stationarycylindrical case.

PERFORATED ROTOR +The rotating inner cylinder of the per-forated cylinder centrifuge.

PERMEABILITYNormal permeability is a measure ofthe ability of a formation to allow pas-sage of a fluid.

PLASTICITYThe property possessed by somesolids, particularly clays and clay slur-ries, of changing shape or flowingunder applied stress without develop-ing shear planes or fractures; that is, itdeforms without breaking.

PLASTIC VISCOSITYPlastic viscosity is a measure of theinternal resistance to fluid flow attribut-able to the amount, type, and size ofsolids present in a given fluid. Whenusing a direct-indicating viscometer,plastic viscosity is found by subtractingthe 300-rpm reading from the 600-rpmreading.

PLUGGING (Screen Surface)The wedging or jamming of openings

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in a screening surface by particles, pre-venting passage of undersize material.See related term: BLINDING.

POLYMERA synthetic mud additive used to main-tain viscosity, control fluid loss andmaintain other desirable mud properties.

POLYURETHANEA high performance elastomer polymerused in construction of hydrocyclonesfor its unique combination of physicalproperties, especially abrasion, tough-ness and resiliency.

POOLThe reservoir or pond of fluid, or slur-ry, formed inside the wall ofhydrocyclones and centrifuges and inwhich classification or separation ofsolids occurs due to the settling effectof centrifugal force.

PORTS +The openings in a centrifuge for entryor exit of materials. Usually applied inconnection with a descriptive term, i.e.,feed ports, overflow ports, etc.

PRESSURE HEAD *Pressure within a system equal to thepressure exerted by an equivalentheight of fluid (expressed in feet). Seerelated term: HEAD.

R

RADIAL FLOW *Flow from a mechanical agitator inwhich fluid moves away from the axisof the impeller shaft (usually horizon-tally toward a mud tank wall).

RATE OF PENETRATIONSee PENETRATION RATE.

RAW MUDMud, before dilution, that is to beprocessed by solids removal equip-ment.

RECTANGULAR OPENING (ScreenCloth)See OBLONG MESH.

RETENTION TIME (Screen) +The time any given particle of materialis actually on a screening surface.

RETENTION TIME + (CentrifugalSeparators)The time the liquid phase is actually inthe separating device.

RETORTAn instrument used to distill oil, water,and other volatile material in a mud todetermine oil, water, and total solidscontent in volume-percent. Also called“mud still”.

RHEOLOGYThe science that deals with deforma-tion and flow of matter.

RIG PUMPS (or Mud Pumps)The reciprocating, positive displace-ment, high pressure pumps used tocirculate drilling fluid through the hole.

RIG SHAKERA general term for a shale shaker usingcoarse mesh screen.

ROPE DISCHARGEThe characteristic underflow of ahydrocyclone operating inefficientlyand so overloaded with separablesolids that not all the separated solidscan crowd out the underflow opening,causing those that can exit to form aslow-moving, heavy, rope-like stream.

A.16

(Also referred to as “rope” or “ropeunderflow.”)

ROTARY DRILLINGThe method of drilling wells thatdepends on the rotation of a drill bitwhich is attached to a column of drillpipe. A fluid is circulated through thedrill pipe to flush out cuttings and per-form other functions.

RPM *Revolutions per minute.

S

SALT-WATER MUDS -A drilling fluid containing dissolved salt(brackish to saturated). These fluidsmay also include native solids, oil,and/or such commercial additives asclays, starch, etc.

SAMPLES -Cuttings obtained for geological infor-mation from the drilling fluid as itemerges from the hole. They arewashed, dried, and labeled as to thedepth.

SAND CONTENTThe sand content of a drilling fluid isthe insoluble solids content retained ona 200-mesh screen. It is usuallyexpressed as the percentage bulk vol-ume of sand in a drilling fluid. This testis an elementary type in that theretained solids are not necessarily silicaand may not be altogether abrasive.

SAND TRAPThe first compartment and the onlyunstirred compartment in a well-designed mud system; intended as asettling compartment to catch large

solids which may get past the shaleshaker.

SCREEN CLOTHA type of screening surface, woven insquare or rectangular openings. Seerelated term: WIRE CLOTH.

SCREENINGA mechanical process which accom-plishes a separation of particles on thebasis of size, through their acceptanceor rejection by a screening surface.

SCREENING SURFACEThe medium containing the openingsfor passage of undersize material.

SCROLLSee Preferred Term: FLUTE.

SETTLING VELOCITYThe velocity a particle achieves in agiven fluid when gravity forces equalthe friction forces of the moving parti-cle.

SHALEStone of widely varying hardness,color, and compaction that is formed ofclay-sized grains.

SHALE SHAKERA general term for devices which use avibrating screen to remove cuttings andother large solids from drilling mud.

SHEAR (Shearing Stress)An action, resulting from appliedforces, which causes or tends to causetwo contiguous parts of a body to sliderelatively to each other in a directionparallel to their plane of contact - as inparticles within a mud.

SIEVESee Preferred Term: TESTING SIEVE.

A.17

SIEVE ANALYSISA measurement of particle size andpercentage of the amount of material invarious particle size groupings. Seerelated term: PARTICLE SIZE DISTRIB-UTION.

SILTMaterials whose particle size generallyfalls between 2 microns and 74microns. A certain portion of dispersedclays and barite falls into this particlesize range as well as drilled solids.

SIZE DISTRIBUTIONSee Preferred Term: PARTICLE SIZEDISTRIBUTION.

SLOUGHINGA situation in which portions of a forma-tion fall away from the walls of a hole,as a result of incompetent unconsolidat-ed formations, high angle of repose,wetting along internal bedding planes,or swelling of formations caused by fluidloss. See related term: CAVING.

SLURRYA mixture or suspension of solid parti-cles in one or more liquids.

SOLIDS +All particles of matter in the drillingfluid, i.e., drilled formation cuttings,barite, etc.

SOLIDS CONTENTThe total amount of solids in a drillingfluid as determined by distillation,including both the dissolved and thesuspended (or undissolved) solids. Thesuspended-solids content may be acombination of high and low specificgravity solids and native or commercialsolids. Examples of dissolved solids are

the soluble salts of sodium, calcium,and magnesium. The total suspendedand dissolved solids content is com-monly expressed in percent by volume.

SOLIDS DISCHARGE +That stream from a liquid-solids separa-tor containing a higher percentage ofsolids than does the feed.

SOLIDS DISCHARGE CAPACITYThe maximum rate at which a liquid-solids separation device can dischargesolids without overloading.

SPECIFIC GRAVITYThe weight of a particular volume ofany substance compared to the weightof an equal volume of water at a refer-ence temperature.

SPECIFIC SURFACE AREAThe effective surface area per unit ofweight of some sample or grouping ofparticles of matter, usually expressed inunits of area per units of weight suchas square feet per pound, or acres perpound, square meters per gram, etc. Itcan be a valuable indicator of theamount of liquid certain particles canattract and retain on their surface.

SPEED +The frequency at which a vibratingscreen operates, usually expressed inRPM or CPM; the bowl rpm of adecanting centrifuge; the rotor rpm of aperforated cylinder centrifuge.

SPRAY DISCHARGEThe underflow of hydrocyclones whennot overloaded with separable solids.

SPUDDING IN -The starting of the drilling operationsof a new hole.

A.18

SPUD MUD -The fluid used when drilling starts atthe surface, often a thick bentonitelime slurry.

SPURT LOSS *The flux of fluids and solids whichoccurs in the initial stages of any filtra-tion before pore openings are bridgedand a filter cake is formed.

STROKEThe distance between the extremitiesof motion; viz., the diameter of a circu-lar motion. See related term:AMPLITUDE.

STUCK -A condition whereby the drill pipe, cas-ing, or other devices inadvertentlybecome lodged in the hole.

SUMPA pit or tank into which a fluid drainsbefore recirculation or in which wastesgather before disposal.

SURGE LOSSSee Preferred Term: SPURT LOSS.

SWABBINGWhen pipe is withdrawn from the holein viscous mud or if the bit is balled, alow pressure is created below the bit.

T

TENSIONING +The stretching of the screening surfacewithin the vibrating frame.

TENSION RINGA rigid hoop surrounding a stretchedscreen cloth used for maintainingscreen tension and mounting thescreen to a shaker frame.

TEST SIEVEA cylindrical or tray-like container witha screening surface bottom of standardaperture.

THINNER -Any various organic agents (tannins,lignins, lignosulfonates, etc.) and inor-ganic agents (pyrophosphates,tetraphosphates, etc.) that are added toa drilling fluid to reduce the viscosityand/or thixotropic properties.

THIXOTROPY -The ability of a fluid to develop gelstrength with time. That property of afluid which causes it to build up a rigidor semirigid gel structure if allowed tostand at rest, yet can be returned to afluid state by mechanical agitation.

THRUSTThe force that pushes on the mud ason a shale shaker screen.

TOTAL DEPTH (or TD) -The greatest depth reached by the drillbit.

TOTAL HEAD *The sum of all heads within a system(Total Head = velocity head + pressurehead + elevation head.)

U

ULTRA-FINE (Solids) +Particles whose diameter is between 2-44 microns.

UNDERFLOW (Hydrocyclone)The discharge stream from centrifugalseparators that contains a higher per-centage of solids than does the feed.See general term: SOLIDS DISCHARGE.

A.19

UNDERFLOW (Screen)The discharge stream from a screeningdevice which contains a greater per-centage of liquids than does the feed.

UNDERFLOW HEADER +A pipe, tube, or conduit into whichtwo or more hydrocyclones dischargetheir underflow.

UNDERSIZE (Solids)Particles that will, in a given situation,remain with the liquid phase whensubjected to centrifugal force, or willpass through the openings of thescreen in use.

UNWEIGHTED (Mud)A drilling fluid which has not had sig-nificant amounts of high gravity solidsadded and whose density and whosedensity is generally less than 11 poundsper gallon.

V

VELOCITY HEAD *Head (relating to pressure when multi-plied by the density of the fluid)created by the movement of a fluid,equal to an equivalent height of staticfluid.

VENTURI *Streamlining up to a given pipe sizefollowing a restriction (as in a jet in amud hopper) to minimize turbulenceand pressure drop.

V.G. METERSee VISCOMETER, DIRECT-INDICAT-ING.

VIBRATING SCREENA screen with motion induced as anaid to solids separation.

VISCOMETER, DIRECT-INDICATING -Commonly called a “V-G meter.” Theinstrument is a rotational-type devicepowered by means of an electric motoror handcrank, and is used to determinethe apparent viscosity, plastic viscosity,yield point, and gel strengths of drillingfluids. The usual speeds are 600 and300 rpm. See API RP 13B for opera-tional procedures.

VISCOSITY -The internal resistance offered by a fluidto flow. This phenomenon is attributableto the attractions between molecules of aliquid, and is a measure of the combinedeffects of adhesion and cohesion to theeffects of suspended particles, and to theliquid environment. The greater thisresistance, the greater the viscosity. Seerelated terms: APPARENT VISCOSITY,PLASTIC VISCOSITY.

VORTEX +A cylindrical or conical shaped core ofair or vapor lying along the central axisof the rotating slurry inside a hydrocy-clone.

VORTEX FINDERA hollow cylinder extending axiallyinto the barrel of a hydrocyclone. Theoverflow exits from the separatingchamber through the vortex finder, andthe vortex is centered in the hydrocy-clone by the hole in the vortex finder,hence the name.

W

WALL CAKE -The solid material deposited along thewall of the hole resulting from filtrationof the fluid part of the mud into the

A.20

formation. See related terms: CAKETHICKNESS, FILTER CAKE.

WALL STICKINGSee Preferred Term: DIFFERENTIALPRESSURE STICKING.

WATER-BASE MUDThe conventional drilling fluid contain-ing water as a the continuous phase.

WATER FEED +Water to be added for dilution of themud feed into a centrifugal separator.See related term: DILUTION WATER.

WEIGHT (Mud Weight)In mud work, weight refers to the den-sity of a drilling fluid. This is normallyexpressed in lbs/gal or specific gravity.See related term: DENSITY.

WEIGHT MATERIALAny of the heavy solids (specific gravi-ty of 4.3 or more) used to increase thedensity of drilling fluids. This materialis most commonly barite but can begalena, etc. In special applications,limestone is also called a weight mater-ial (even though its specific gravity is2.6).

WEIGHTED (Mud)A drilling fluid to which heavy (over4.3 specific gravity) solids have beenadded to increase its density.

WEIGHT UP *To increase the weight of a drilling

mud, usually by the addition of weightmaterial.

WETTING -The adhesion of a liquid to the surfaceof a solid.

WIRE CLOTH +Screen cloth of woven wire.

WORKOVER FLUID -Any type of fluid used in the workoveroperation of a well.

Y

YIELDAs applied to drilling mud, a term

used to define the quality of a clay bydescribing the number of barrels of agiven centipoise slurry that can bemade from a ton of the clay.

YIELD POINTThe resistance to initial flow, represent-ing the stress required to start fluidmovement. This resistance is due toelectrical charges located on or nearthe surfaces of the particles. The valuesof the yield point and thixotropy,respectively, are measurements of thesame fluid properties under dynamicand static states. The Bingham yieldvalue, reported in lbs/100 sq. ft, isdetermined by the direct-indicating vis-cometer by subtracting the plasticviscosity from the 300-rpm reading.

B.1

STANDARD CALCULATIONS

I. MUD VOLUME

• Capacity of annulus in bbl/ft = [(hole size)2 - (pipe OD)2] * 0.00097

• Approximate capacity of hole in bbl/1000 ft = (diameter of hole)2

• Approximate pipe displacement, bbl/100 ft = Weight of pipe (lb/ft) * 0.0364

• Pit volume in cu ft = Length * Width * Depth

• Pit volume in bbl = cu ft5.6

• Hole volume in bbl = [hole capacity(bpf) * depth(ft)] - pipe displacement (bbl)

• Annular volume in bbl = hole volume - capacity and displacement of drill pipe

• Total Volume = hole volume + pit volume

II. CIRCULATION DATA

• Pump output in bpm = bbl/stroke * strokes/minute

• Annular velocity in fpm = pump output (bpm * 100)annular volume (bbl/100 ft)

• Bottoms up in minutes = annular volume (bbl)pump output (bpm)

• Hole cycle in minutes = pump output (bpm * 100)pump output (bpm)

• Mud cycle in minutes = total volume (bbl)pump output (bpm)

B.2

III. SOLIDS DETERMINATION

A. Low weight muds without barite

• Percent solids by volume = (mud weight - water weight) * 7.5

• Correct for oil: For each 1% of oil, add 0.1 to % solids by volume

• Correct for NaCl: For each 10,000 ppm salt, deduct 0.3% solids by vol-ume. Ignore if salt content is less than 10,000 ppm. Convert Cl ppm tosalt ppm (* 1.65)

B. Weighted Muds

• Percent by volume desired solids = (mud weight - 6) * 3.2

C. Drilled Solids Per Foot of Hole

• Barrels per foot = (hole size + washout)2* 0.00097

• Pounds per foot = bpf * 910.7

IV. SOLIDS CONTROL EVALUATION CALCULATIONS

A. Average specific gravity of solids in WBM

1. Freshwater muds

Sa = (12 * Dm) - VwVs

2. Sa = (12 * Dm) - (Vwc * Sw)(100-Vwc)

B. Volume percent solids in freshwater muds, without weight-ing material

Vs = 7.5 * (Dm - 8.34)

OR

7.5 * (Dm - 62.55)

B.3

C. Volume percent solids in freshwater muds containingbarite, S.G. = 4.2

Vb = (Sa - 2.6) * Vsc * 0.625

Vlg = Vsc - Vb

D. Volume percent solids in freshwater muds containinghematite, S.G. = 5.0

Vh = (Sa-2.6) * Vsc * 0.417

Vlg = Vsc - Vh

E. Volume percent in muds containing oil > 1% or salt >10,000 ppm

Vlg = [(Vw * Swc) + (Vo * So) + (Vsc * Shg)] - (100 * Sm)(Shg - Slg)

F. Bentonite and reactive clay correction

CECa = 7.69 * (MBTm)Vlg

Vben = Vlg * (CECa - CECds)(CECben - CECds)

Terms:CECa = Cation Exchange Capacity (CEC),

averageCECben = CEC of bentonite, typically 60CECds = CE of drilled solids, typically 10Cl = Total Chlorides, in mg/lDm = Mud density, in ppgMBTm = Methylene Blue Test, in lbs/bblSa = Specific gravity of solids, averageShg = Specific gravity of high gravity

solidsSlg = Specific gravity of low gravity

solidsSm = Specific gravity of mudSo = Specific gravity of oil

Sw = Specific gravity of waterSwc = Specific gravity of water, corrected

for chloridesVb = Volume percent barite (50% = 50,

not .50)Vh = Volume percent hematiteVhg = Volume percent high gravity

solidsVlg = Volume percent low gravity solidsVs = Volume percent total solidsVsc = Volume percent solids, corrected

for chloridesVw = Volume percent waterVwc = Volume percent water, corrected

for chlorides

B.4

Field Calculations to Determine Total Solids Discharge

Note:This method is only a quick approximation of solids removal rate andshould be used only for unweighted muds or where quick comparisonsneed to be made on a mud system to see what results when conditionschange, i.e., is solids removal rate increasing, decreasing, or stayingthe same?

1. Use a one-quart container and wristwatch to determine how manyseconds (R) it takes to collect one quart of slurry from a cycloneunderflow or a screen discharge.

2. Use a mud balance to obtain the density (D) of the slurry in poundsper gallon.

3. Use the following equations to calculate the rate of solids removed inpounds per hour.

(D - 8.3) * 1450 = Total Solids Removed in #/hrR

D = Density of slurry in #/gal.R = Rate of solids slurry discharge in sec/qt8.3 = Density of Water

Example:

D = 12.3 #/galR = 8 sec

(D - 8.3) * 1450 = R

(12.3 - 8.3) * 1450 = 8

4 * 1450 = 725 #/hr8

B.5

Field Calculations to Determine High and Low Gravity Solids Discharge

1. Use a one-quart container and wristwatch to determine how manyseconds (R) it takes for one quart of solids to be discharged.

2. Use a mud balance to obtain the density (D) of the sand slurry inpounds per gallon.

3. Retort the sand slurry to determine the volume fraction solids (Vs) andthe volume fraction liquids (V1)

4. Use the following equations to calculate the rate of solids removed inpounds per hour.

A. Total pounds per hour Solids Removed = [D - (8.34 * V1)] 900

R

B. Average Specific Gravity of Solids = [D - (8.34 * V1)]

(8.34 • Vs)

C. Weight % Low Gravity Solids = 4.3 - ASG

1.6

D. Lbs/hr Low Gravity Solids = Total #/hr solids * weight % LGS

E. Lbs/hr Barite = Total #/hr solids - #/hr LGS

D = Density of solids slurry in #/gal

R = Rate of removal in sec

V1 = Volume fraction liquid

Vs = Volume fraction solids

ASG = Average Specific Gravity

LSG = Low Gravity Solids

B.6

SOLIDS CONTROL PERFORMANCE EVALUATION

There are several methods used to determine economic performance. Thisappendix describes a method to compare the cost of dilution versusmechanical removal. It utilizes the concept of a dilution factor (theamount of mud required to maintain a given solids concentration for everybarrel of solids that remain in the mud) to determine dilution require-ments. This method may be used to determine economic efficiency of anytype of solids control equipment. Note: Effluent is defined as the processstream returned to the active mud system. The underflow is defined as thewaste stream removed from the mud system and discarded.

Example:

Given: Feed Rate = 30 gpm

Underflow Density = 17.0 ppgFeed Density = 10.0 ppg

Effluent Density = 9.0 ppgTotal Low Gravity Solids = 6%

Mud Cost = $15./bblDisposal Cost = $10./bbl

Equipment Cost per Day = $600

Determine the economic performance.

Feed Rate, Vf = 30 gpm

Feed Density, Df = 10.0 ppg

Underflow Rate, Vu = ?

Underflow Density, Du = 17.0 ppg

Effluent Rate, Ve = ?

Effluent Density, De= 9.0

B.7

1) Determine the Effluent and Underflow Volume Rates.2) Calculate the Low Gravity Solids Removed per minute.3) Calculate the equipment effectiveness & cost, compared to dilution4) Calculate economic benefits

1) Determine the Effluent and Underflow Volume Rates.Df * Vf = (Du * Vu) + (De * Ve);

& let X = Underflow Rate, Vu

(10.0 * 30) = (17.0 * X) + [9.0 * (30-X)] =

300 = 17X + 270 - 9X30/8 = X

X = 3.75 gallons per minute Underflow Rate Volume

(30 - X) = (30 - 3.75) = 26.25 gallons per minute Effluent Rate Volume

Feed Rate, Vf = 30 gpm

Feed Density, Df = 10.0 ppg

Underflow Rate, Vu = 3.75

Underflow Density, Du = 17.0 ppg

Effluent Rate, Ve = 26.25

Effluent Density, De= 9.0

B.8

2) Calculate the Low Gravity Solids Removed per minute.

a) Calculate the low gravity solids in the underflow:

Let X = the decimal fraction low gravity solids

17/8.33 = X(2.6) + (1-X)2.04 = 2.6X + 1 - X1.04 = 1.6X

X = 1.04/1.6 = .65 or 65% solids in underflow

b) Calculate the low gravity solids removed:

3.75 * .65 = 2.44 gallons of low gravity solids removed per minute

3) Calculate the equipment effectiveness, compared to dilution

a) Dilution: Assume the 9.0 ppg fluid is the desired fluid. It contains5% solids. The equivalent dilution required to treat the solidsremoved is the volume removed divided by the desired fraction ofsolids.

2.44/.05 = 48.8 or 49 gallons per minute dilution required to match the machines effectiveness

or (49 gal./min. * 60 min./hr.)/ 42 gal./bbl. = 70 bbls per hour equivalent dilution

Dilution Cost = Volume * (Mud Unit Cost + Disposal Unit Cost)

Cost: $ = 70 * ($15 + $10)

$1,750 per hour is Equivalent Dilution Cost

B.9

b) Mechanical Treatment Cost =[Liquid Volume Lost * (Mud Unit Cost + Disposal Unit Cost)] + Equipment Cost

3.75 X (1-.65) = 1.3 gallons of liquids removed per minute OR

(1.3 X 60 min/hr)/ 42 gal/bbl = 1.85 bbl/hr liquids removed

Cost: $ = [ 1.85 X ($15 + $10) ] + $600/24

$71.25 = Cost to Remove the LGS

4) Calculate the economic benefits

$ = (cost to remove) - (cost to dilute)

$ = $71.25 - $1,750

$ = $(1,678.75)

$ in ( ) = Savings, Removal compared to Dilution

Therefore, in this example, prompt and continuous removal of drilledsolids will save $1,679 per hour!

B.10

Method for Comparison ofCyclone Efficiency

Assuming Identical: MudFeed VolumeFeed Pressure

Where: D = DensityV = Volume Rate

UF = Underflow

CASE #1: When DUF1 = DUF2 Then higher VUF = Greater Efficiency,since a greater volume of solids isbeing removed at the sameliquid/solids ratio.

CASE #2: When VUF1 = VUF2 Then higher DUF = Greater Efficiency,since more solids (and less liquid) arebeing removed in the same underflowvolume.

CASE #3: When one cone has higher DUF and higher VUF, then that coneis operating at significantly greater efficiency.

Note: When none of the above conditions occur, or for specific numericalaccuracy, See Appendix A.

C.1

Conversion Constants and Formulas

A. Conversion ConstantsSpecific Gravity (SG) Water ............................................1.01 Gallon of Water ............................................................8.34 lb1 cu. ft. of Water..............................................................62.4 lb1 Barrel (42 gallons) of Water.........................................350 lb100’ Column of Water Exerts Hydrostatic

Pressure of.....................................................................43.3 psiClay (SG=2.5)...................................................................875 ppbBarite (SG=4.3) ................................................................1506 ppbCalcium Carbonate (SG=2.7) ..........................................945 ppb1 Barrel (42 Gallons) .......................................................5.6146 cu ft1 Cubic Foot ....................................................................7.48 gal

B. Conversion FormulasMULTIPLY BY TO OBTAIN

sp gr (specific gravity) ..............62.4 ............pcf (pounds/cubic feet)sp gr .............................................8.34 ..........ppg (pounds/gallon)ppg (pounds/gallon)...................0.052 ........psi/ftbbl (barrels) .................................0.157 ........m3 (cubic meters)bbl ..............................................42.0 ............galbbl ................................................5.615 ........ft3 (cubic feet)ft3 (cubic feet) ..............................0.0283 ......m3

ft3 ..................................................7.48 ..........galgal (gallons).................................0.00379 ....m3

lb (pounds)..................................0.454 ........kg (kilograms)miles.............................................1.609 ........km (kilometers)ft (feet) .........................................0.305 ........m (meters)in. (inches)...................................2.54 ..........cm (centimeterspsi (pounds/in2)...........................6.895 ........kPa (kilo-Pascals)psi.................................................0.069 ........barpsi.................................................0.07 ..........kg/cm2

kg/m.............................................0.01 ..........kP/msp gr .......................................1000.0 ............kg/m3

ppg (pounds/gallon) ...............119.8 ............kg/m3

ppg...............................................0.1198 ......kg/literpcf (pounds/cubic feet) ............16.02 ..........kg/m3

ppb (pounds/barrel) ...................2.85 ..........kg/m3

psi/ft ...........................................22.61 ..........kPa/m

C.2

Density of Common Materials

Specific Gravity of Common Materials (Average)

MATERIAL SP GR PPG PPB

Barite 4.3 35.9 1506

Bentonite 2.4 20.0 840

Calcium Carbonate 2.7 22.5 945

Cement 3.2 26.7 1120

Clays, Drilled Solids 2.6 21.7 911

Diesel Oil 0.84 7.0 294

Dolomite 2.9 24.2 1016

Fresh Water 1.0 8.33 350

Galena 6.5 54.1 2272

Gypsum 2.3 19.2 806

Iron 7.8 65.0 2730

Iron Oxide 5.1 42.5 1785

Lead 11.4 95.0 3990

Limestone 2.8 23.3 980

Salt 2.2 18.3 769

Sand (Silica) 2.6 21.7 911

C.3

Hole Capacities

HOLEDIAMETER CAPACITY CAPACITY(INCHES) (BPF) (GPF)

4 3/4 .0219 .92

5 5/8 .0307 1.29

5 7/8 .0335 1.41

6 .0350 1.47

6 1/8 .0364 1.53

6 1/4 .0379 1.59

6 1/2 .0410 1.72

6 5/8 .0426 1.79

6 3/4 .0442 1.86

6 7/8 .0459 1.93

7 3/8 .0528 2.22

7 5/8 .0564 2.37

7 3/4 .0583 2.45

7 7/8 .06.2 2.53

8 3/8 .0681 2.88

8 1/2 .0701 2.94

8 5/8 .0722 3.03

8 3/4 .0734 3.12

9 1/2 .0876 3.68

9 5/8 .0899 3.78

9 7/8 .0947 3.98

10 5/8 .1096 4.60

12 1/4 .1456 6.12

13 1/2 .1769 7.43

14 3/4 .2112 8.87

17 1/2 .2973 12.49

26 .6563 27.56

Formula: Volume (Barrels) = (Hole Diameter in Inches)2

* Length in Feet1029.44

OR (Hole Diameter in Inches)2 * .(Length in Feet) * 0.00097

C.4

Pounds per Hour Drilled Solids — Fast Rates

C.5

Pounds per Hour Drilled Solids — Slow Rates

C.6

Solids Con

tent C

hart

MUD WEIGHT - LBS/GAL

010 11 12 13 14 15 16 17 18 19

10

20

30

40

50

60

70

SO

LID

S C

ON

TE

NT

- %

BY

VO

LUM

E

Solids C

ontent usin

g Low Gravit

y Solid

s & W

ater

maximum solids

Approximate Range of Field Muds in Good Condition

minimum solids

Solids Content using High Gravity Solids & Water

D.1

Pre-well Project Checklist

Well Design: Where is the well being drilled?What type of well is it — wildcat, development, injection, etc.What problems are anticipated?

Drilling Program: What are the hole size, casing points, and washout factors?What is the expected rate of penetration?What type bit?What is the mud program?Are there any environmental restrictions?What rig is being considered?Any anticipated hole problems?

Equipment andVendor Capability: What size and type of solids need removal?

What equipment is already installed?What is its process rate and expected removal efficiency?Are there sufficient mud compartments?Is the equipment installed properly?What additional equipment is needed?What is expected downtime?What are the power and fuel requirements?What rig modifications are required?What is vendor experience and safety record?Is H&S Plan available?

Logistics: Where is the location?Where is the local stock/service base?What on-site spares are required?How many additional people are required?Do they need housing or meals?What personal protective equipment is required?

Environmental Issues: What are the preferred mud treatment and disposal options?

What are preferred cuttings treatment and disposal options?Is analytical testing required?

Economics: What is the mud cost?What is the equipment acquisition and installation cost?What is the expected operating cost?What is the expected disposal and site remediation cost?

What are the expected savings?

D.2

Screen Cloth Comparisons

SCREENCLOTH TYPE

SCREENDESIGNATION

SEPARATION POTENTIAL, IN µ CONDUCTANCEIN KD/MMD16 D50 D84

MARKETGRADE CLOTH

10x1020x2030x3040x4050x5060x6080x80

100x100120x120150x150200x200250x250325x325

1777889531392287241182144120108766345

49.6815.938.324.892.882.401.911.441.241.390.680.780.44

TENSILEBOLTINGCLOTH

2030405060708094

105120145165200230

10116624573573012612181751601431161048472

10416814703683102692241801651471191078674

10717004833793192772301851701511221108876

0.9324.3311.637.945.605.253.882.842.772.512.031.861.491.30

EXTRA FINECLOTH, 3-LAYERED

2438507084

110140175210250

50831723417113110786665751

715429324234181151118958172

82452839027422318514311310085

20.6911.866.774.733.623.002.381.861.671.45

HIGHCONDUCTANCECLOTH, 3-LAYERED

4550607080

100125150180200230265310

27021618415814511292786252473935

3532742402081861421201078569605045

3793012672211921541311179377695551

9.817.665.755.014.083.002.532.151.821.551.270.960.82

1678839501370271227172136114102725943

1727864516381279234177140117105746244

D.3

MODEL MOTION DECKS SCREENS/DECK

SCREENANGLE

DECK TYPE SCREENTYPE

SCREENAREA, SQ FT

VIBRATOR G-FORCE WEIRHEIGHT

DIMENSIONSLXWXH

WEIGHT,LBS

Brandt/EPI Vibrating Screen Separators

ATL-1000 L 2 1/3 A O/F H/P 10.8/25 G 4.2 43 93x71x64 4,300

ATL-1200 L 1 3 A F P 25 G 4.2 40 93x71x49 4,100

ATL-CS C/L 3 1/1/3 F/F/A O/U/F H/H/P 20/20/25 B/G 4.9/4.2 79 93x77x87 8,000

ATL-CS/LP C/L 3 1/1/3 F/F/A O/U/F H/H/P 20/20/25 B/G 4.9/4.2 67 93x77x74 7,750

LCM-2D L 1 3 A O P 33.7 C 2.5-6.4 52 120x69x62 5,200

LCM-2D/CS C/L 3 1/1/3 F/F/A O/U/F H/H/P 20/20/33.7 B/C 4.9/2.5-6.4 70 120x80x80 9,385

LM-3 L 1 3 A O P 33.7 B 4 32 141x69x62 5,000

Tandem C 2 1 F U/U H 20/20 B 4.9 38 79x72x52 2,865

Standard E 1 1 F U H 20 B 2 36.25 79x64x44 1,800

COMMENTS

Scalping deck, also avail-able as drying shaker

Low profile ATL

Cascade tandem over ATL

Low profile cascade shaker

Dewatering deck (patent pending)

Cascade version of LCM-2D

Dual, triple, and quad available

Dual units available

Motion L = linear, C = circular, E = unbalanced ellipticalScreens/deck number of screen panels in each deck, beginning with the top deckScreen Angle F = fixed, A = adjustableDeck Type O = overslung screens, U = underslung screens, F = flat

Screen Type H = hook strip screen, P = pre-tensioned panelScreen Area Total screen area, beginning w/ top deck. If Pinnacle® screens are used, multiply area X 1.4Vibrator B = belt, G = gear box, C = canister direct driveG-Force Total acceleration, beginning with the top screen basket.

D.4

ATL-Dryer L 1 3 A F P 25 G 4.2 N.A. 93x77x49 7,500 includes liquid recoverytank and pump

SDW-Dryer L 1 4 A F P 33.3 G 4.2-7.0 N.A. 134x78x66 8,300 includes liquid recoverytank and pump

Brandt/EPI Liquid Recovery Shakers

Motion L = linear, C = circular, E = unbalanced ellipticalScreens/deck number of screen panels in each deck, beginning with the top deckScreen Angle F = fixed, A = adjustableDeck Type O = overslung screens, U = underslung screens, F = flat

Screen Type H = hook strip screen, P = pre-tensioned panelScreen Area Total screen area, beginning w/ top deck. If Pinnacle® screens are used, multiply area X 1.4Vibrator B = belt, G = gear box, C = canister direct driveG-Force Total acceleration, beginning with the top screen basket.

MODEL MOTION DECKSSCREENS/

DECKSCREENANGLE

DECK TYPESCREENTYPE

SCREENAREA, SQ FT

VIBRATOR G-FORCEWEIR

HEIGHTDIMENSIONS

LXWXHWEIGHT,

LBSCOMMENTS

ATL-16/2 L 1 3 A F P 25 G 4.2 40 115x77x93 7,500 1000 gpm, three-stage mudconditioner

ATL-2800 L 1 3 A F P 25 G 4.2 40 122x77x92 7,500 1680 gpm, two-stage mudconditioner

LCM-2DMC L 1 3 A O P 33.7 C 2.5-6.4 52 130x80x90 6,335 1000 gpm, three-stage mud

conditioner

Brandt/EPI Mud Conditioners

D.5

MODEL TYPENOMINAL FLOW,

GPMVACUUM RANGE

INCHES HGBAFFLE AREA,

SQ. INDIMENSIONS,

LXWXH WEIGHT, LBS COMMENTS

DG-5 VJ 500 7-20 - 29 max 9,956 88x54x62 2,390 Rated top performing unit in comparative degasser testconducted by Amoco Production Research.

DG-10 VJ 1,000 7-20 - 29 max 32,060 100x60-x77 3,900 Similar design to DG-5, larger capacity.

MODELDIAMETER,

INCHESINLET TYPE CONSTRUCTION

UNDERFLOWADJUSTMENT

FEETHEAD

FLOW RATE,GPM

COMMENTS

Desander 12.2 Circular involute Poly Fixed, available in 1.5”,1.75”, and 2.125” apex 75 495 Three piece cone, available as 1, 2, or 3-cone units,

upright or canted header configuration

Desilter 3.9 Rectangular involute

Poly w/ ceramicliner

Adjustable0.125” to 0.69” 75 66 Two piece cone, available in 4-32 cone units

Brandt/EPI Degassers

Type VJ = vacuum, emptied by jet pump Drive E = electric, H = hydraulic

Brandt/EPI Hydrocyclones

D.6 Brandt/EPI Decanting Centrifuges

COMMENTS

Barite recovery, viscosity control 6 TPH (tons per

hour) solids capacity

SC-1 18x28 Contour CS E 1350-2000 80:1 Fixed/ double lead

1350/4662000/1022

9.0/15010.0/70.017.0/20

103x46x32 3,920

Barite recovery, viscositycontrol 4 TPH (tons per


CF-1 18x28 Contour CS E 1600-2000 40:1 Fixed/single lead

1600/6541650/6962000/1022

9.0/9012.0/6016.0/3018.0/25

111x63x61 4,700

Barite recovery, viscositycontrol 6 TPH (tons per



1350/4662250/1294

9.0/150 116x53x61 4,500

Unweighted muds, dewa-tering 6 TPH (tons perhour) solids capacity

CF-2 24x38 Contour CS E 1400-2000 80:1 Fixed/single lead

1400/6682000/1363

9.0/17512.0/6016.0/3018.0/25

130x66x63 7,500

Excellent all-purpose cen-trifuge, 8 TPH (tons per



1150/4511350/6211950/1296

9.0/250 135x62x93 7,200

Rugged high speeddecanter. 5 TPH (tons per


HS3400 14x49.5 Contour SS EH

1750-40001750-4000

52:1Variable

Fixed/ single leadVariable/

single lead

1750/6092400/11452900/16723500/24354000/3181

9.0/16012.0/7515.0/2018.0/10

98x69x46 4,100

High capacity, high speeddecanter. 6 TPH (tons per


SC-35HS 15x48 Contour SS EH

1750-32501750-3250

59:1Variable

Fixed/single leadVariable/

single lead

2000/8522500/13313000/19173250/2100

9.0/15012.0/4515.0/3018.0/20

120x61x60 6,105

8 TPH (tons per hour)solids capacity

HS5200 16x49.5 Contour SS H 1750-4000 Variable Variable/single lead

2000/9092500/14203000/20453500/27844000/36364200/4000

9.0/250 95x69x40 7,720

Rotating Assy CS = Carbon steel, SS = Stainless steel Drive E = electric, H = hydraulic

MODELBOWL SIZE,

INBOWL TYPE

ROTATINGASSY

DRIVESPEED RANGE,

RPMGEARBOX

RATIOBOWL/CONVEYORDIFFERENTIAL

RPM/G-FORCE

CAPACITY, MUDWT/GPM

DIMENSIONSLXWXH WEIGHT, LBS

D.7

Selection of Agitator Size and Number

Select the right size agitator by first locating the tank width on the rightside of the graph. A recommended impeller diameter is shown across theleft side. This impeller size is correlated to the mud weight and therequired horsepower. Simply follow a horizontal line from the impellerdiameter to the curve showing the heaviest anticipated mud weight. Nowlocate the nearest vertical line to the right of this point and note therequired horsepower at the top of the graph.

Example:Agitators are required for a 10-foot-wide tank, 30 feet long, to maintain

weighting materials in suspension for a 12 lbs/gal mud:

Find the tank width (10 ft) and the recommended correspondingimpeller diameter (36 in) on the graph. Follow a horizontal line from theimpeller diameter to the curve of the given mud weight (12 lbs/gal mud —use the curve on the next higher mud weight). From the intersection of themud weight curve and the impeller diameter, locate the nearest verticalline to the right and note the horsepower at the top of the graph.

This particular application will require a 7.5-hp size Brandt Agitator foreach 10 feet of tank length — a total of three 7.5-hp agitators.

Solids

Documents

mud solids

functions of drilling

properties of drilling

mud engineers

drilling efficiency

nd edition

rd edition

mud cleanersconditioners