HandoutRoles of Drilling Fluid

8/22/2019 HandoutRoles of Drilling Fluid

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Global Research & Technology Centre/ GRTC

Training Department

Roles of Drilling Fluids:Roles of Drilling Fluids:Functions andFunctions andMeasurementMeasurement

Roles of Drilling Fluids:Roles of Drilling Fluids:Functions andFunctions andMeasurementMeasurement

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THE DRILLING TEAM


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Drilling a Hole

Drilling out formationwith bit

The MUD bring thecuttings up to surface

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Logging in Production Hole

Pulling Out Of Hole (POOH)the Drilling Assembly

Running-In Logging Tools

Logging-up the formation

Circulation condition hole prepare MUD in the hole forstatic condition before loggingoperation


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Casing & Cementing

SURFACE CASING

Pulling Out Of Hole (POOH) theDrilling Assembly

INTERMEDIATE CASING

Running - In Hole (RIH)the Intermediate Casing

Pumping Cement

Displacing Cement with MUD

Waiting On Cement (WOC) to dry

Circulation condition hole prepareMUD in the hole for static conditionbefore running-in casing

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Why Do We Need Mud ?

TO CLEAN THE HOLE

How?How?

By bring the drillcuttings up to surface

How can the mud bringHow can the mud bring

the cutting?the cutting?Mud Viscosity


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What if it failed?

Drill cuttings slipped downto bottom

Drill string get STUCK !!

Drill cuttings filled up theannulus and bottom of thehole

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Why Do We Need Mud ?

TO CONTROL FORMATIONPRESSURE

How?How?

By provides HydrostaticPressure of the fluids column

How can the mud giveHow can the mud giveHydrostatic Pressure?Hydrostatic Pressure?

Mud Density


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What if it failed ?

FORMATION FLUIDS (WATER/OIL/GAS) FLOWS INTO THE WELLBOREUNCONTROLLABLE

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K+

K+

What does the mud do inside the hole?

Chemical ion toinhibit the clayfrom swelling ordispersion

Polymer toencapsulate drillcutting andpreventing it toabsorb water

Form mud cakeas a thin wall toprotect formationfrom mud filtrateinvasion

formation wellbore


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Function of Drilling Fluids

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MudCirculating

System

MudCirculating

System


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Mud Pump

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SHALE SHAKER


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Density

When we drill the wellbore wereplace a cylinder of rock with acylinder of mud.

The first critical step towardsdesigning a drilling fluid is to

establish the mud weight requiredto provide the correct level of borehole pressure support.

Pm - mud pressure

Pf - formation pressure

Bore hole pressure support

Pm > Pf

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Rheology/Viscosity

PLASTIC VISCOSITY As low as possible elevated plastic viscosity

levels are detrimental to everyaspect of thedrilling process. Every endeavor must bemade to control and minimise the plasticviscosity value.

6 RPM value

Low shear rate rheology, i.e. representative ofthe flow regime in the annulus.

Control 6 rpm value on the basis of hole size,well profile, anticipated pump rates andallowable drill string rotation (RPM).

YIELD POINT Yield point is driven by the appropriate low shear rheology, ie

the 6 rpm viscometer dial reading, for optimum hole cleaningefficiency.


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Filtration / Fluids Loss Control

API Filter Press HTHP Filter Press

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Filtration

The passage of filtrate into the formation due to thedifferential pressure

If the solids cannot block the pores and/or fractures thenmud will flow into the formation (lost circulation)

The solids in the mud usually forms as a filter cake whichprevents excessive fluid loss, the filter cake should :

Be thin

Have a low permeability - correct solids distribution

Have a low friction coefficient


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Filtration

Dynamic Filtration

cake builds until rate of erosion equals rate of deposition

when filter cake reaches equilibrium thickness fluidloss is constant

Static Filtration

cake growth with time

rate of filtration continues to decrease

static cake is thicker than dynamic cake

static rate of filtration is less

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Mud Composition (Retort Kit)

H2O

salt

100%


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Sand Content

Sand is abrasive, could createproblem in drilling equipment

Field practice : < 2% by volume

H2O

4.5 %

5.0 %

5.3%

Barite

Sand

Chemicals

Sand Content = 0.5%

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What is mud

LIQUID MUDSOLIDS

WATER

OIL

SALT

CHEMICALS

BARITE

BENTONITE/GEL

DRILL SOLIDS

WATER-BASE MUD

OIL-BASE MUD


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What is mud

LIQUID MUDSOLIDS

WATER

OIL

SALTCHEMICALS

BARITE

BENTONITE/GEL

DRILL SOLIDS

WATER-BASE MUD

OIL-BASE MUD

PRODUCTS PRODUCTS MUD SYSTEM

WATER

OIL

SALTCHEMICALS

BARITE

BENTONITE/GEL WATER-BASE MUD

OIL-BASE MUD

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Mud Component

1. Base fluids

2. pH Control

3. Viscosifier

4. Filtration Control

5. Weighting agent

6. Additional product :

Shale Control AdditiveCorrosion Inhibitor

Lubricants

Dispersants


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How to mix mud

Base Fluids

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How to mix mud (on the rig site)


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What should it do with drill cutting

To be separated out from themud

How?How?

Using Solid ControlEquipments

What equipment?What equipment?

Screen

Hydroclones

Centrifuge

Solids to

discard

Clean

mud to be

recycle

Mud + Drill

cutting from

hole

screen

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Solid Control Equipments

SHALE SHAKER

CENTRIFUGE

DESANDER

DESILTER


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Relation of Particle Size to Solids RemovalEquipments

SHALE SHAKERDESANDERDESILTERCENTRIFUGE

HandoutRoles of Drilling Fluid

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