43389096

7/30/2019 43389096

1/13

Oil Base Mud. Part I: Synthesis of Some Local SurfactantsUsed as Primary Emulsifiers for Oil Base Mud andEvaluation of Their Rheology Properties

A. M. Al-Sabagh, M. R. Noor El-Din, and H. M. MohamedDepartment of Petroleum Applications, Egyptian Petroleum Research Institute (EPRI), Nasr City,

Cairo, Egypt

Six oil soluble nonionic surfactants with different HLBs have been prepared. Their HLBs situatebetween 3.9 and 6.7. Transesterification was carried out for glycerol and triethanol amine witholeic acid at different moles to obtain six emusilifiers. They named glycerol momooleate (I),glycerol diooleate (II), glycerol trioleate (III), triethanol amine mono-, di- and tri-oleate (IV),(V,) and (VI). The chemical structure was confirmed using; the elemental analysis, FTIR and1HNMR. They were evaluated as a primary emulsifiers (PE) for thdrilling fluids (oil basemud) comparing with a currently used primary emulsifier (Fc). The water in oil base mud(w/o emulsions) was prepared. The concentration of emulsifiers and their HLB exhibited interest-

ing rheology properties including shear-thinning behavior, yield value, viscoelastic effects,thixtropy, gel strength, and filtration loss. The rheology properties of such emulsions stronglydepended on the average size distribution of the dispersed droplets that could be varied both withthe bulk concentration and HLB value of the emulsifiers. The interfacial and surface properties ofthese emulsifiers suggest that the droplet size of the dispersed phase and bulk concentration arestrongly related to the HLB value of emulsifiers. The w/o emulsion (mud formulation) stability issensitive to the droplet size of the dispersed phase and HLB value of the used emulsifier. Theresults were discussed on the light the chemical structure of the primary emulsifiers and theemulsion ingredients.

Keywords Drilling fluids, drilling mud, filtration loss, gel strength, interfacial properties, oilsoluble emulsifiers, rheology

INTRODUCTION

In many wells drilled with aqueous drilling fluids sufferserious decreases in permeability of oil bearing zones asresults of water blocking of the pore spaces and swellingof anhydrous clays within the pore spaces. This watercontamination difficulty can be avoided by the use of oil,such as crude petroleum oil as a drilling fluid. This meansusually involve adding materials such as blown finallydivide solids to the oil to increase the density, viscosityand gel strength, and to give the fluid plastering propertiesto decrease loss of the fluid to the permeable formation.[1,2]

The success of any well drilling operation depends onmany factors; one of the important of which is the drillingfluid. The fluid performs a variety of functions that

influence the drilling rate and the cost, efficiency and safetyof the operation. Drilling fluids generally are composed of

fluids (water and gas-oil) and suspended fierily divided

solid of various types. The proportions determine thetreatment strategy, the efficiency of the mud- handlingequipment, and affect the amounts of materials needed tobull up density and viscosity.[46] No additives are used indry-air-, or gas-drilling operation. Gas based fluids arenot recalculated and materials are added continuously.[7]

The functional properties include water loss, gel strength,viscosity and thixotropy, and resistance to salts and alka-line earth ions.[8,9] One of the most widely used ingredientsin water base drilling mud is carboxy methyl cellulose. It isvery effective in preventing water loss and in controllingthe viscosity.[10,11]

Freshwater mud may be operated at pH levels ranging

from 7 to 11. When drilling flocculent may be added toremove drill solids in large settling with clear, and a smallamount of pit in order to maintain a clean fluid for fastdrilling. Generally, seawater mud is formulated andmaintained in the same way that freshwater mud is used.However, because of the presence of salts in seawater, moreadditives are needed to achieve the desired flow andfiltration properties.[12,13] Fresh- or seawater mud may be

Received 24 January 2008; accepted 6 February 2008.Address correspondence to A. M. Al-Sabagh, Department of

Petroleum Applications, Egyptian Petroleum Research Institute(EPRI), 1 Ahmed El- Zomor St., Nasr City, Cairo 11727, Egypt.E-mail: [email protected]

Journal of Dispersion Science and Technology, 30:10791090, 2009

Copyright# Taylor & Francis Group, LLC

ISSN: 0193-2691 print=1532-2351 online

DOI: 10.1080/01932690802598754

1079

7/30/2019 43389096

2/13

treated with gypsum on lime to alleviate or clay bearing

problems that may arise from drilling water-sensitive shale

or clay bearing formation.[1418] Fluid with less than (5 to

10vol% water) is called oil base mud. Most oil mud

maintain a fixed oil-water ratio depending on the desired

properties. Oil mud are employed for high temperature

wells, where water-based system may be unstable and a

problem may be raised from sensitive shale formations,

or where corrosive gases such as hydrogen sulfide and

carbon dioxide may be encountered. Usually, the cutting

removal efficiency increase with increasing the viscosity

and the density. Viscosity depends on the concentration,

quality, and state of dispersion of suspended colloidal

solids.[1922] Most concentrated emulsions show shear rate

dependent non-Newtonian type shear thinning behavior

at low and intermediate shear rate domain, where the shear

viscosity (g) decays exponentially as a function of shear

rate. On the contrary, at high shear rate domain, these

emulsions show Newtonian type shear rate independent

shear viscosity. Materials with such mixed flow profiles,

viscosity shear rate in steady state shear mode are usuallyknown as pseudoplastic materials,[23] and these generally

show a combination of shear thinning behavior and yield

stress, it means that flow on these materials can only be

induced with the application of a certain minimum amount

of force=stress which is referred to as yield stress. Highvalue of yield stress is indicative of higher degree of

material structuring and good emulsion stability [24] Rheol-

ogy of most viscoelastic materials, including surfactants

solution,[25] and surfactant stabilized emulsions tend to

show Maxwell model type fluid flow behavior.[26] The first

goal of this work is focusing on the preparation of some

primary emulsifiers based on glycerol and triethanol amine

with oleic acid. The second goal is to make six formula-tions of oil base mud using the prepared emulsifiers to

increase the plstic and dynamic viscosity, yield value,

thixtropy, gel strength, and filtration loss properties.

EXPERIMENTAL

Preparation of Emulsifiers Based on Glycerol andTriethanol Amine

Into three-necked flask, 1.0 mol of glycerol and trietha-

nol amine were added to (1.0, 2.0, 3.0 mol) of oleic acid

individually. The reaction was carried out in the presence

of 0.1% p-toluenesulfonic acid as a catalyst and xylene asa solvent. The reaction was heated with continuous stirring

and the reflux of solvent was carried out until the theoreti-

cal amount of water was collected. The product was

purified by washing it with 5% worm solution sodium car-

bonate then was dissolved in petroleum ether (4060C),

and the organic layer was separated. The solvent was

distilled off. This method was carried out to obtain six

emulsifiers named; glycerol monooleate (I), glycerol

dioleate (II), and glycerol trioleate (III), triethanol amine

monooleate (IV), triethanol amine dioleate (V) and trietha-

nol amine trioleate (VI).

Emulsion Preparation

To 100 ml of gas-oil, 1, 2, and 3% of the prepared

primary emulsifier (I to VI) was added individually at room

temperature with continuous stirring and then 10% of

distal water was added gradually with continuous stirring

until a milky emulsions were formed. The solids added to

form the mud formulation were (3.5% guiletane, 1.4%

durtane and 1.4% soda lime, wt=wt) were added and theymixed gradually. Finally, 1.2% of E.Z mud as a second

emulsifier was added with stirring. The ingredients were

mixed well for 10 minutes to form six different formula-

tions (F1 to F6).

Surface and Interfacial Tension Measurements

The surface tension of surfactants solutions was mea-

sured at 25

C against the hydrocarbon system (gas-oil)using a Kruss made surface tensiometer K12. An oil bath

was used in this case to maintain the temperature. The Du

Nouy ring method was employed, where the ring is dipped

into the solution whose surface tension is to be measured

and pulled out afterward. The maximum force needed to

pull the ring through the interface is expressed as the surface

tension in mN=m. On the other hand, the interfacial tensionat the w=o interface was measured at 25C using Krussmade Drop Volume Tensiometer DVT 10.

Droplet Size Measurements

The droplet sizes distribution can be measured with help

of optical microscopy. An account of the use the opticalmicroscopy to measure the emulsion droplet size is

extensive.[27] In this study, a German made leica DMRXP

light polarizing microscopy was used. This system consists

of a high voltage beam source, a polarizing unit and a

detector unit. The detector unit is interfaced with a camera.

Note that the images were focused both under the dark and

bright field mode as well as between the cross polarizer

using long working distance objectives with magnification

ranging from 20 to 50 to 100. This microscope unit

is controlled by computer which is equipped with image

analysis software. This software not only helps capture

images from the stage of the microscope, but with its help

one can process these images as electronic documentsincluding measuring droplet size.

High PressureHigh Temperature Filter PressMeasurements

High pressure-high temperature filter press is especially

designed for testing mud at elevated temperature and

pressure. It consists of a heating unit with a thermostat,

1080 A. M. AL-SABAGH ET AL.

7/30/2019 43389096

3/13

250 ml filter cell, and the pressure unit. The fluid loss value

obtained with this apparatus more truly represents the

actual fluid loss in the well pore. For tests which are to

be run above 200 F, the back pressure receiver must be used

in place of the graduated cylinder to prevent evaporation of

the filtrate.

Procedure

Into a clean aging cell, 200 ml of the mud formulation

was transferred. Be sure that the sealing edge of the cell

is clean and put the inner cap in its place. Then use an

Allen Wrench to tighten the small center screw in the

middle of the screw cap. The cell was placed in a portable

aging oven and adjusted to the desired aging temperature.

A hot air oven may also be used provided a constant

temperature (200F). A graduated dry cylinder was placed

under the filtrate tube. A 500 psi pressure was applied to

the cell, and the time of the test was started. At the end

of 30 minutes, first close of the pressure source valve was

carried out and then the safety bleeder value was opened

to release the pressure from entire the system. The volumeof filtrate was collected and expressed on the filtration

loss in ml.

Rheology Properties Measurements

The rheological properties of emulsions were measured

using a rotational viscometer with coaxial cylinders

(Rheotest 2, Germany). Samples were placed in the

temperature-controlled measurement vessel and equilibra-

ted to required temperature for 5 min period to making the

measurements. The rheological behavior of the emulsions

was measured 24 hours after preparation. The measure-

ments were only accepted when the emulsion had not

shown any coalescence before and after shearing. The shear

rate (D.S1) was changed from 3 to 1024 (s1).

Determination of Gel Strength and Thixotropy of Mud

The gel strength of mud using the rheometer was deter-

mined. The mud sample was stirred at high speed

(4000 rpm) for 15 seconds. The mud emulsion left to rest

about 10 minutes and then the gel strength knob was

turned on the hub of the speed change level clockwise

slowly and steadily. The maximum deflection of the dial

before the gel breaks is considered the gel strength in

1 b=100 ft2. The difference between the low readings after10 seconds and 10 minutes is considered to be the measure

of thixotropy of the undertaken mud formulations (F1 to

F6Fc).

RESULTS AND DISCUSSION

FTIR and1

HNMR Spectroscopes for Chemical StructureJustification

The FTIR of glycerol dioleate is shown in Figure 1, The

characteristic broad bands are 3498 cm1 assigned to OH

group stretching vibration, two bands at 2921 and

2862 cm1 for asymmetric and symmetric aliphatic CH

stretching vibration of fatty acid moiety, respectively.

A band at 1732cm1 characteristic for CO stretching

of the ester group confirming the ester formation, a band

at 1490cm1 pair for CC stretching absorption. The1HNMR spectra in Figure 2 for triethanol amine dioleate

FIG. 1. FTIR spectra of glycerol dioleate (II).

OIL BASE MUD. PART I 1081

7/30/2019 43389096

4/13

shows splitting at chemical shift d 5.345.27 ppm (s, 1H,

1OH), d 4.974.38 (s, 1H, of CHCH of oleic alkyl

group, d 2.712.35 (s, 2H, CH2 of oleic alkyl group),

d 1.451.40 (s, 2H, CH2 adjacent to oxygen or nitrogen

atom in the tri ethanolamine structure, and d 0.990.64

(s, 3H, of CH3 of the alkyl group). The elemental analysis

(C, H, and N) for all the prepared emulsifiuers was carried

out and the data are presented also in Table 1. The all

used analysis tools together introduced the evident of the

chemical structure as excepted.

Interfacial PropertiesThe HLB values of the emulsifiers employed in this

work is given in Table 2. The HLB value is the balance

between the hydrophilic and lipophilic strength of the

emulsifier. It can be calculated using Griffin approach

as:[28]

HLB 20MH

MS

Where MH is the molecular weigh of the hydrophilic head

group and Ms is the total molecular weight of the emulsi-

fier, this relation suggests that the HLB value is closely

related to the size and molecular weight of the head group.The hydrophobic effect of an emulsifier is better described

by its surface and interfacial properties. The surface and

interfacial properties of these emulsifiers are given in

Table 2, which suggests that the critical micelle concentra-

tion (CMC) value of these emulsifiers is related to their

HLB values. With decreasing HLB value, the CMC of gly-

cerol and triethanol amine series of emulsifiers shifts to a

higher bulk concentration. Since the alkyl tail hydrophilic

head of the emulsifier tested here is different, it is evident

that the head group polarity and the hydrophopicity of

the alkyl chain play a strong role in the micellization and

adsorption processes. The lower the CMC of an emulsifier

enhances its performs as emulsifying agent. From the data

obtained in Table 2, it was found that the CMC increased

by the degree of estrification with oleic acid in the two

groups of emulsifiers; glycerol (I and II) or triethanolamine

derivatives (IV and VI). In this case the surface tension was

measured in gas-oil. From the obtained results, it was

found that the decrease in HLB increases the CMC because

in the emulsifiers IIII, the hydrophobes were mono-, di-,and trioleate groups. The increase of hydrophobe branch

leads to increase the solubility of the emulsifier in the oil

phase, therefore the CMC increased. This behavior has

been seemed also for the second series (IVVI). By inspec-

tion the data of Table 2, it was found that, the decrease of

HLB and increases the Amin as a result of the increase

hydrophopic tail. These results reflected on the data of

Cmax, which decreased by decreasing of HLB. The Cmaxand Amin were calculated as:

Cmax 1

Rt

dr

dln c

T

Amin 1016

CN

Whereas, R is the gas constant in Joul, d is the surface

tension at 25C, C is the surfactant concentration and N

is the Avogadros number.

The surface tension decreased from 40 mNm1 (gas-oil)

to 31 and 29 mNm1 against the glycerol monooleats (I)

FIG. 2. 1HNMR spectra of triethanolamine dioleate of (V).


7/30/2019 43389096

5/13

TABLE1

Generalcharacterizationoftheinvestigatede

mulsifiers

Elementala

nalysis

Oilmud

formulation

C%

H%

N%

Primaryemulsifier(E

x)

Chemica

lstrcuture

M.Wt.Found

Calc.Found

Calc.Found

Calc.

Glycerolmonooleate(I)

HO-CH2-CHOH-CH2CO2-CH17H33

F1

356

69.9

70.74

11.2

11.3

Glyceroldioleate(II)

CH17H33CO2CHO

HCH2CO2CH17H33

F2

606

74.5

75.19

11.3

11.6

Glyceroltrioleate(III)

C17H33CO2CH(CH

2CO2C17H33)2

F3

885

74.8

75.69

11.1

11.03

Triethanolaminemon

ooleate(IV)

[HO-(CH2)2]2N(CH2)2CO2C17H33

F4

328

69

69.4

11.52

11.65

3.9

4.2

Triethanolaminedioleate(V)

HO-(CH2)2N[(CH2)2CO2C17H33]2

F5

678

73.8

74.34

11.81

11.74

1.9

2.06

Triethanolaminetrioleate(VI)

N[(CH2)2CO2C17H

33]3

F6

942

75.7

76.45

11.92

11.87

1.2

1.48

Envermol,commercia

lsample(PEc)

n

.a

Fc

n.a.

n.a.

n.a.

n.a.

n.a.

n.a.

n.a.

n.a.notavailable.

TABLE2

Surfaceandthermodynamicpropertiesofprima

ryemulsifier

Emulsifiercode

HLB

CMC

103,

(moldm3)

rcmc,

(m

Nm1)

Pcmc

(mNm1)

Amin

(nm2)

CmaxX

1010

(cm2)

DGad,

(Kjmol1)

ceq.

int

(mNm1)

I

6.7

0.016

31

7

61.5

2.7

27

.6

0.11

II

4.4

0.038

29

9

66.4

2.5

25

.6

0.01

III

3.9

0.049

34

4

79.1

2.1

24

.8

0.55

IV

6.3

0.011

29

9

47.4

3.5

28

.6

0.14

V

5.9

0.020

26

12

48.8

3.4

27

.2

0.02

VI

4.9

0.045

31

7

53.6

3.1

25

.0

0.78

1083

7/30/2019 43389096

6/13

and glycerol dioleate (II), respectively, then it increased

again with the glycerol trioleate (III) [34 mNm1]. This

behavior also was noticed with triethanol amine mono,

di, and trioleate (r 29, 26, and 31 mNm1, respectively).

This may be explained as; in emulsifiers (I) and (IV) one

tail hydrophope and the two hydrophils terminate by

two hydroxyl group. In this case the structure is look like

surfactant structure (head and tail). In the case of (II) and

(V), the surfactant molecule has tow hydrophope tails and

one terminal hydrophil OH group. In this case the emulsi-

fier molecule is look like to gemmini surfactant molecule

(excellent surfactant model), so that these surfactants

pronounced a maximum reduction in the surface tension.

But in the case of (III) and (VI) the molecule is completely

surrounded by three hydrophope and the hydrophil is not

terminal but may be concentrate on the carbonyl group in

(III) or carbonyl and nitrogen atom in (VI). This structure

may be deactivates the molecule to adsorb regularly on

the surface to reduce the surface tension.

This observation was noticed also for the equilibrium

interfacial tension (ceq.int), the Amin increased by increasingof hydrophope branch which increases the molecular

weight of the emulsifier molecule.

As can be seen, the Gibbs free energy of adsorption

DGad, also varies strongly with the variation of HLB value

of the used emulsifiers. The DGad, increased with decreas-

ing of HLB. The increasing of the negative value ofDGadwith increasing of HLB value in its turn indicates that a

higher degree of interface stabilization is achieved with

increasing HLB value in the water-in-oil emulsion case.

This can be accounted for the fact that owing to enhance

the degree of hydrophobic interactions with decreasing

HLB value, the adsorption at the given w=o interface

decreases with decreasing HLB value. The more negativethe DGad the greater the degree of interfacial adsorption.

The DGad was calculated by:

DGad DGmic 0:6032 AminpCMC

Where; DGmicRT lin CMC

pCMC p of solvent (40 mNm1) p surfactant

(measured).

The greater the degree of interfacial adsorption, the

greater the emulsifying effect. The interfacial adsorption

Cmax, also referred to as surface excess concentration.

The value ofCmax imply that all emulsifiers examined here

tend to adsorb strongly at the given interface, and that thedegree of adsorption enhanced with increasing the HLB

value of the emulsifiers. The equilibrium interfacial tension,

(ceq.int) also varied strongly with HLB value of the surfac-

tant. As shown in Table 2, a higher degree of reduction

of (ceq.int) is achieved with decreasing HLB value from

6.7 to 4.4 then the value increased against HLB 3.9 for the

different glycerol derivatives (I), (II), and (III) respectively.

The same behavior had been also seen for the triethanol

amine oleate derivatives as cleared in Table 2. This is afurther indication that given the hydrophope tail branch

is strongly related to adsorb the surfactants molecule on

the w=o interface and to reduce the interfacial tension.

Rheoloigy Characterization of Oil Base Emulsions

The viscosity concepts were firstly announced by Isaac

Newton. It is synonymous with internal friction and a

measure of the resistance to the flow. The force per unit

area, s (donated as a required shear stress). The gradient

producing the motion is proportional to the viscosity

gradient (denoted as shear rate coefficient dd=dt).The constant of proportionality, g, is called the viscosity

coefficient, that is,

s gdd

dt

FIG. 3. Viscosity shear rate curves for mud formulations obtainedwith 2% PE 10:90 water oil ratio at 25C.

FIG. 4. Flow curves of mud formulations prepared with PEs.


7/30/2019 43389096

7/13

A fluid is said to be Newtonian, if the viscosity indepen-

dent on the shear rate. The viscosity decreases with inc-

reasing the shear rate, which is called shear thinning or

pseudo- plasticity, while the increasing of the viscosity with

shear rate is called shear thickening or dilatancy. In this

work, the shear stress and the dynamic viscosity againstthe shear rate were measured at different temperatures

(25C to 65C), different primary emulsifier concentrations

(1, 2, and 3%), and different water content (5, 10, 20%).

The emulsifiers were compared using measurements of

the flow properties of the model emulsions (Fc). Figures 3

and 4 show the rheolograms (viscosity and shear stress

against shear rate plots) of the emulsion systems at differ-

ent values of the dispersed phase concentration and HLB

of the emulsifier used. The shape of the hysteresis loop is

characteristic for the viscoelastic fluids e.g. concentrated

emulsions.[11,12] From the data illustrated in Figures 3

and 4, it was found that the rheological behavior of the

oil base mud (w=o) emulsion is the data observed almostNewtonian nearly above 150 D.sec-1 and the non-Newto-

nian behavior appears before this limit. The increasing

tendency toward Newtonian behavior was obtained by

increasing the applied temperature for the oil mud. The

dynamic viscosities, gd, and Bingham yield values, sB,

for the six complete oil base mud emulsions (F1 to F6)

and the control sample (Fc) at different temperatures

(25C to 65C), 2% and 10=90 w=o are listed in Table 3and illustrated in Figure 3. F1, F2, F4, and F5 exhibited

dynamic viscosity closed to that obtained by the control

sample (75 mPa.s). But the F3 and F6 exhibited (90 and

85 mPas), respectively at 25C. By increasing the tempera-

ture from 25C to 65C, the viscosity temperature coeffi-cient (Dg=C) decreasing for the F1, F2, F4, and F5 was0.08, 0.10, 0.1, and 0.13 was nearly close to Fc. Meanwhile,

the other samples F3 and F6 recorded Dg=C higher thanthe former samples (0.17 and 0.18). This means that the

formulations which used the primary emulsifiers I, II, IV,

and V are most tolerance to the increase of the temperature

program than the others. This is a good property of the oil

base mud. Otherwise, the Dsb=C for the F1, F2, F4, andF5 were 0.21, 0.24, 0.22, and 0.21, respectively. They were

also closely with the Dsb obtained by the Fc (0.29). But the

other samples F3 and F6 recorded Dsb=C 0.43 and 0.37.This mean that the former formulations are most tolerance

to the decrease of yield value of the mud emulsions than theothers. The formulations F1, F2, F4, and F5 were selected

as the best formulations to investigate the effect of the pri-

mary emulsifiers concentration on the mud property.

The chemical structure of the corresponding primary

emulsifier was mono- and dioleate of glycerol and mono-

and dioleate of triethanol amine, respectively. In spite of

the trioleate esters gave a late results comparing with the

former mono- or dioleate esters. This means that the che-

mical structure plays a central role to stabilize and enhance

the rheological properties of the oil base mud formulations.

Thixotropy of the Oil Base Mud

Generally, the most drilling fluids contain clays that

exhibit thixotropic properties. Thixotropic of fluid from

gels upon in quiescence static condition and region their

fluidity under dynamic conditions.

The shear- or gel-strength of drilling fluids in a

measurement of the minimum shearing stress necessary to

produce slip-wise movement of the fluid.

TABLE 3

Viscosity Shear rate and shear stress of mud emulsions with 2% PE and 10:90 water oil ratios at different temperature

Temp. C

25C 35C 45C 55C 65C

Dg=C DsB=Cgd sB gd sB gd sB gd sB gd sB

Fc 75 42.4 74 40.4 73 35.7 72 33.6 70 30.6 0.13 0.29

F1 70 39.5 69 39.3 69 38.4 68 30.2 67 31.3 0.10 0.21

F2 78 40.3 77 40.2 76 33.9 74 28.8 74 30.8 0.10 0.24

F3 90 52.2 85 50.2 87 48.2 86 44.2 84 35.2 0.17 0.43

F4 65 39.5 64 36.3 63 35.2 62 35.9 63 30.6 0.10 0.22

F5 70 40.1 69 40.1 68 38.1 66 35.2 65 31.6 0.13 0.21

F6 85 55.0 82 52.1 80 45.6 79 40 78 35.1 0.18 0.37

TABLE 4

Thixotropy for mud complete emulsion formulations at 2%

PE and (10=90) w=o ratio

Temp. C Fc F1 F2 F3 F4 F5 F6

25 1 0 0 1 0 0 1

35 1 0 0 1 0 0 1

45 0 0 0 1 0 0 1

55 0 0 0 1 0 0 1

65 0 0 0 1 0 0 1


7/30/2019 43389096

8/13

The data listed in Table 4 clear the thrixotropy of the

prepared six oil base mud formulations. From the repre-

sented data in Table 4, it was found that F1, F2, F4, and

F5 have not thixotropy, while the formulations F3 and

F6 exhibited thixothropy along the term of temperature

(25C to 65C). On the other hand, the control sample

(Fc), F3 and F6 exhibited a thixotropy at two temperatures

25

C and 35

C, but they recorded no thixotrpy at highertemperature (45C t o 6 5C). This behavior means that

there are four emulsifiers in the oil base mud (F1, F2, F4,

and F5 are time- independent viscosity. It was also

found that Fc, F3 and F6 have thixotropy and are time-

dependant viscosity at low temperatures (25C and 45C),

then their behavior changed at high temperature (55C to

65C), this means that they are time- independent viscosity

at high temperature. By analysis the data in Table 4, it was

found that the mono and diester of glycerol (F1 and F2)

and of triethanol amine (F4 and F5), are time-independent

materials especially in the oil base mud formulation (no

thixatropy obtained). This means that, these primary emul-

sifiers can be used successfully in the oil base mud at highrange of applied temperatures. Meanwhile, the emulsifiers

(III) glycerol trioleate ester, and (VI) triethanol amine

monooleate esters are time dependent at low temperature

(25C and 35C) but at temperatures (45C to 65C) exhib-

ited a non-thixotropy behavior. At the same time, F3 and

F6 were nearly closed with the control sample Fc. Regard-

ing to the chemical structure and the thixotropy behavior,

the emulsifiers can be ranked in the order of the best beha-

vior as, I, II, IV, and V > III, VI corresponding to the oilbase mud, F1, F2, F4, and F5 >F3 and F6, respectively.

Gel Strength of the Oil Base Mud

The data in Table 5 reveal the gel-strength for thecomplete emulsion formulation (oil base mud) at different

temperatures. From the data listed in Table 5, it can be

concluded that the six investigated formulations are having

gel strength greater than the control sample (Fc). In

general, the increasing of the temperature leads to decrease

the gel-strength for all the investigated formulations (oil

base mud).

Table 6 shows the stability the mud formulations

expressed by Gel strength=1=T after 10 seconds and 10minuets. By inspection the presented data in Table 6, it

can be concluded that the maximum stability of the oil base

mud may be exhibited emulsifiers I, II, IV and V corre-

sponding to the formulations F1, F2, F4, and F5. Other-

wise, the F3 and F6 exhibited the lowest stability. On the

other hand, this finding may be justified by the emulsiondroplet size (mm) as shown in Table 6. The droplet size of

the internal phase of emulsion plays an important role in

the stability of this emulsion. The low droplet sizes were

obtained from F1, F2, F4, F5, and Fc (4.2, 3.1, 4.6, 3.2,

and 3.5mm), respectively. These formulations exhibited

the highest stability. The formulations F3 and F6 gave

droplet size 6.3 and 8.3 mm, respectively. These formula-

tions pronounced the lowest emulsion stability. The con-

centration effect of the primary emulsifier on the stability

and droplet size of mud emulsion is shown in Table 7.

From the obtained data, it was found that the stability

(expressed by G=t1) increases by increasing of PE concen-

trations. The stability increased with decreasing the dropletsize of emulsion. The 2% PE exhibited maximum stability

and minimum droplet size. So that, 2% PE is the most

effective concentration on the stability and the emulsions

droplet size of mud emulsion.

TABLE 5

Gel strength for mud formulation at 2% PE and (10=90) w=o ratio

Temp, C

Fc F1 F2 F3 F4 F5 F6

10 sec 10 min 10 sec 10 min 10 sec 10 min 10 sec 10 min 10 sec 10 min 10 sec 10 min 10 sec 10 min

25 8 8 9 9 8 8 12 12 9 9 9 9 14 14

35 8 8 9 9 8 8 11 11 9 9 9 9 14 13

45 7 7 8 8 7 6 10 9 6 6 8 8 13 12

55 7 7 8 8 7 6 10 8 6 6 8 8 12 11

65 7 6 8 7 6 6 9 7 6 6 7 7 11 10

TABLE 6

Stability of mud formulations expressed by GS=(1=T) andthe average droplet size during 90 days at 2% PE

Formulations

GS=1=T

Droplet size (mm)10 sec 10 min

F1 2.7 3.1 4.2

F2 2.5 3.2 3.1

F3 6 7 6.3

F4 3.5 4 4.6

F5 3.2 4.5 3.2

F6 8 8.5 8.3

Fc 2.7 3.5 3.5


7/30/2019 43389096

9/13

Filtration Losses of the Base Mud

The effect of filtration on oil base mud was shown in

Table 8 for the six investigated formulations and the con-

trol sample (Fc). The data show that the F1, F2, F4, and

F5 exhibited 5 ml filtrate at high pressure and temperature

(500 psi and 200F) and 2% primary emulsifier, respec-

tively. Meanwhile, the filtration loss of the control sample

was 9 ml. But, the formulations F3 and F6 exhibited filtra-

tion loss 10 and 11 ml at 2% emulsifier concentration and

10% water in oil emulsion. This means that the formula-

tions (F1, F2, F4, and F5) are greater than the formula-tions (F3 and F6). This is the obvious evident that the

derived emulsifiers from the locally materials can be used

as good primary emulsifiers in the formulation of oil base

mud. This means also that there are a direct proportion

relationship between the stability of the oil base mud

formulations and their filtration loss.

The effect of PE concentration on the filtration loss is

clearly from the same Table 8. From the obtained data, it

was found that the filtration loss increased at 1 and 3%

PE. But the optimum loss was exhibited at 2% PE. This

means that at 2% PE, the maximum stability of the emul-

sion was exhibited so that, at which may be the droplet size

of the emulsion particles are nearly the same size.The ordered adsorption of the PE molecules around the

droplet makes it more regular size and further the stability

increases. Therefore, the distance between the pores

decreases leading to decrease the filtration loss. The low

or high concentration of the PE may enhance the coales-

cence properties of the emulsion particles and the destabi-

lization may be obtained quickly, therefore the filtration

losses increased.

On increasing the dispersed phase concentration of

emulsion, the viscosity was found to increase in all the

TABLE 7

Relation of G=(1=T) for F5 at different concentrations andthe average droplet size during 90 days

PE Conc. 10 sec 10 min Droplet size (mm)

1% 6.4 10.2 6.3

2% 3.2 4.5 3.2

3% 4.3 7 3.4

TABLE 8

Filtration loss, [ml] for the mud formulations at different

PE concentrations and 10:90 water oil ratio

PE conc. FC F1 F2 F3 F4 F5 F6

1% 9 5.5 5.5 10 7 5 11

2% 6 5 5 8 5 5 9

3% 6 5.5 5.5 9 5.5 5.5 10

FIG. 5. Viscosity shear rate curves for F5, Fc at 2% PE and differentwater: oil ratios.

FIG. 6. Pesidoplatic behavior of (a) Fc, F2, F5, and (b) F3 and F6 at2% PE concentration and 10:90 water oil ratio.


7/30/2019 43389096

10/13

emulsion systems studied as shown in Figure 5. When log

viscosity is plotted against log shear rate, the resulting

curve has a shape similar to that for pseudoplastic flow

and shear thinning as shown in Figure 6b for the mud

emulsions F6 and F3. But the plots in Figure 6a show

pesudoplastic flow without shear thinning. For the control

sample (Fc) and the tested mud emulsions (F2 and F5).

The effect of water content on the filtration loss for F1,

F2, F4, and F5 was remarked also in Table 9. From the

data presented in this table, the increasing of water content(5% to 20% water) leads to increase the filtration loss. This

may be due to decrease the internal distance between the

droplets, which leads to increase of the water coalescence

which followed by deformation of the emulsion. Some

investigators (ref) found that as the water content in

the emulsion increases, the distance between the water

droplets decreases. This leads to adjust themselves to regu-

lar shape of pores, followed by decrease in the filtration

loss. In this study at 10% water, the best results was

obtained, but when the concentration of water in the oil

mud increased to 20% the distance between the droplets

TABLE 9

Filtration loss, [ml] for the mud formulations at different

water content

Water

content, %

Filtration loss, [ml]

FC F1 F2 F3 F4 F5 F6

5 8 6 6.5 9 7.5 6.5 10

10 6 5 5 8 5 5 9

20 7 5.5 5.5 9.5 6.5 7 10.5

FIG. 7. Effect of temperature on viscosity for F5 evaluated fordifferent shear rates (D.s1) 2% PE and 10:90 water oil ratio.

FIG. 8. The relationship between viscosity of mud emulsions andHLB of PE; at 25C, (a) HLB-g at shear rate 64 s1 and (b) HLB-sB.

FIG. 9. Effect of PE concentratin on (a) gd and (b) sB for F5.


7/30/2019 43389096

11/13

decrease and adjusting themselves to the irregular shape of

the pores, which leads to increase the filtration loss.

Effect of Temperature on the Property of Oil Base Mud

The relation between viscosity and shear rates at differ-

ent temperatures is shown in Figure 7. From the shown

plots, it can be concluded that the increase of shear rate

and temperature decrease the viscosity. The obtained rela-

tion is following Arrhenius-type relationship. The relation-

ship between viscosity and shear rate versus HLB

properties of the synthesized emulsifiers is shown in Figures

8a and 8b at shear rate was 64 s1. A decrease of emulsion

viscosity with increase of HLB is shown in Figure 8a. But

the same decrease was seen against the shear stress in

Figure 8b for HLBs (3.9, 4.4, and 4.9) and the curve

became steady with HLBs (5.9, 6.3, and 6.7). Figure 9a

shows the effect of temperature on the viscosity of the

emulsion and Figure 9b shows the effect of temperature

on the shear stress for F5 at different concentrations of

PE with water content. An increase in temperature

evidently decreases the viscosity significantly. The viscosity

and shear stress versus the temperature data followed on

Arrhenius- type relationship. The increase of PE concen-

tration increases the viscosity and shear stress.

The effect of temperature after 10 seconds and 10 min-

utes for the prepared emulsions on gel strength is shown

in Figures 10a and 10b. The effect of temperature on the

concentration is shown in Figures 11a and b. the plots

in Figures 10 and 11 are following also Arrhenius-type rela-

tionship. By inspection of Figures 10a and 10b, it was

found that the F1, F2, F4, and F5 have a better results

than of Fc.

Emulsion Stability

The mud emulsion stability was expressed by gel

strength against HLB, ceq.int, Amin and DGad by inspection

the plots in Figures 12a through 12d. It was found that, the

maximum stability of mud emulsions was obtained at

HLB 5.9 and 6.7 (F5 and F1). The same results were

exhibited on plots of mud stability against Amin, DGad,

and ceq.int. This finding may be used to evaluate and classifythe stability of mud emulsions formulations. Also, it can be

concluded that the stability of mud emulsion is strongly

related to the surface active properties of the used primary

emulsifier (PE).

FIG. 10. Gel strength 1=T relationship; (a) after 10 seconds and(b) after 10 minutes.

FIG. 11. Effect of PE concentration on gel strength for F5 (a) after10 seionds and (b) after 10 mmutes.


7/30/2019 43389096

12/13

REFERENCES

[1] Rodolfo, J. and Tailleur, (1955) U.S. Patent No. 2,713, 032,

C.A. 49, 15224 b.

[2] Bataafsh, N.N. (1954) Ger. Patent No. 76,028, C.A

44,7844d.

[3] Paul, W. and Fischer (1951) U.S. Patent No. 2,542,019, C.A.

45, 5396I.

[4] API Buletin an Oil and Gas Well Drilling Fluid Chemicals,API Bull. 13 F 1st Ediheion, American PETROLEUM

Institute Dallas, TX, August, 1978.

[5] Delmar, H. and Larsen, (1952) U.S. Patent No. 2, 596,085,

C.A 46, 7754 h.

[6] Tie, H. and Morrow, N.R. (2003) The effect of differ-

ent crude oil=brine=rock combination on wettabilitythrough spontantaneous immbitition. In Procceding of

the SCA International Symposium, September 2225, Pau,

France.

[7] Bergman, W.E. and Fisher, H.B. (1950) Ind. Eng. Chem., 42:

18951900.

[8] Headley, J.A., Walker, T.E., and Jonkins, R.W. (1995)

Society of Petroleum Engineers (SPE), USA P. 605. 612.

[9] Cary, R.W. (1951) U.S. Patent No. 2.536, 113, C.A. 44, 8631 A.[10] Lguly, G., Reese, M., and Abend, S. (1999) Appl. Clay Sci.,

14: 88103.

[11] Xie, X.N.R. (2001) Petrophysics, 42(4): 313322.

[12] Tadros, T.F. (1994) Colloids Surf, A., 91: 3955.

[13] Zhang, Y., Wang, Morrow, N.R., and Bucklet, G.S. (2005)

Fuels, 19: 14121416.

[14] Lee, L.T. and Rahhari, R. (1991) J. Colloid Interf. Sci., 147:

351.

[15] Goddard, E.D. (1985) J. Colloid Surf., 13: 87103.

[16] Besra, L., Roy, S.K., and Ay, P. (2002) Int. J. Miner. Process,

66: 203232.

[17] Sjoblom, J., Aske, N., Brandal, O., Johnsen, T.E., and

Kallevik, H. (2003) Colloid Interf. Sci., 100: 399473.

[18] Angle, C.W. (2001) In Encyclopedic Handbook of Emulsion

Technology, edited by J. Sjoblom; New York: Marcel

Dekker, chap. 24.

[19] Ezzat, A.M. and Al-Buraik, K.A. (1973) Society of Petro-

leum Engineers (SPE) R. Chardsan; TX, USA, pp. 353361.

[20] Hoffman, H. (1994) Viscoelastic Surfactant Solution;

Washington, DC: American Chemical Society.

[21] Barry, B.V. (1974) Rheology of Pharmaceutical and Cosmetics

Semisolids; London: Academic Press.

[22] Steven, C.C. (1957) J. Am. Oil Chem. Soc., 34: 181185.

[23] Mounts, T.L., Worner, K., and Heating, A. J. (1978) J. Am.

Oil Chem. Soc., 55(1): 277.

[24] Markley, K.S. (1961) Fatty Acids, Part 2; New York: Wiley

Interscience, p. 757.

[25] Hoffman, H. and Ulbricht, W. (1997) Viscoelastic Surfactant

Solutions; New York: Dekker.

[26] Tadros, T.F. (1993) In Fundamental Principles of Emulsion

Rheology and their Application, First World Congress on

Emulsion; New York: Marcel Dekker; vol. 4, pp. 237265.

[27] Pal, R. (1997) Chem. Eng., 67: 3744.

[28] Griffin, W.C. and Drummond, J. (1949) J. Soc. Cosmet,

Chem., 311326.

[29] Kamogawa, K., Akatsuka, H., Matsumoto, M., Yokoyama,

S., Sakai, T., Sakai, H., and Abe, M. (2001) Colloids and

Surf. A, 180: 4153.

FIG. 12. Mud stability [gel strength=(1=T)] against (a) HLB; (b) Amin; (c) DGad and (d) ceq. int.


7/30/2019 43389096

13/13

43389096

Documents