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L.D COLLEGE OF ENGENEERING Page 1
“Design of drilling fluid using polymers along with
soil-fluid interaction.”
GUIDED BY: – Dr. M.V. SHAH
SUBMITTED BY
Name (Enrollment no.)
SARANG V.PATEL (110280106005)
ANIRUDH S. SABOO (110280106008)
NILIPT A. PATEL (110280106019)
SHOBHIT D.DUBEY (110280106044)
YEAR : 2014-15
CIVIL ENGINEERING DEPARTMENT
L.D. COLLEGE OF ENGINEERING, AHMEDABAD.
L.D COLLEGE OF ENGENEERING Page 2
CERTIFICATE OF EXAMINER
The project report entitled
Design of drilling fluid using polymers along with
soil-fluid interaction
Submitted By
SARANG PATEL(110280106005)
ANIRUDH SABOO (11020106008)
NILIPT PATEL (110280106019)
SHOBHIT DUBEY(110280106044)
As a partial fulfilment of the requirement
For the
Subject: PROJECT-II (180605)
Semester – VIIIth
Of Gujarat Technological University in the field of
“CIVIL ENGINEERING”
is hereby approved.
Internal Examiner External Examiner
Date:
Place:
L.D COLLEGE OF ENGENEERING Page 3
L. D. COLLEGE OF ENGINEERING
Civil Engineering
2015
CERTIFICATE
Date:
This is to certify that the Report of Project work entitled “Design of
drilling fluid using polymers along with soil-fluid interaction” has been
successfully completed by SARANG PATEL, ANIRUDH SABOO, NILIPT
PATEL AND SHOBHIT DUBEY, under my guidance, in the partial
fulfilment of the degree of Bachelor of Engineering in CIVIL (8th
semester) of
Gujarat Technological University, Ahmedabad during the academic year 2015.
Dr M V Shah Dr S P Dave
Internal Guide Head of Department
L.D COLLEGE OF ENGENEERING Page 4
ACKNOWLEDGEMENT
We are thankful to Dr S. P. DAVE (Head of Department, Applied
Mechanics Department) for giving this opportunity. It was possible due to
her co-operation and help. I would like to place on record appreciation for
all those who are connected with this report. With great pleasure, I
express my deep sense of gratitude to respected Dr. M.V.SHAH and all
other staff members of Applied Mechanics Department for the co-
operation.
PROJECT CONDUCTED BY
STUDENT OF CIVIL
8TH
SEMESTER
L.D COLLEGE OF ENGENEERING Page 5
ABSTRACT
Drilling fluids are used for drilling oil/gas from high density underground geological
formations. Water based drilling fluid are most extensively used nowadays everywhere in
India because they are easy to design, economic to maintain and can be applied to a high
versatile areas. Any drilling fluid should be designed in such a way that proper control over
pressure can be done, should be able to transport cuttings and finally it should support and
stabilize the well-bore. For depths greater than 600m, polymers fluids are mostly used,
because of the fluid dispersion problems encountered in shale. The aim of the present
research work is to formulate low cost polymer drilling fluid on the basis of soil-fluid
interaction with good dispersion efficiency. It is aim to design low cost drilling fluid by
adding polymers which are highly soluble in water and which can cover more specific area .
The objective of present study is to enhance various fluid properties like mud density,
viscosity, rheology, gel strength, filtration, pH of drilling fluids by using locally available low
cost polymers. The above objective will be satisfied in two phases. In 1st phase, detail
laboratory investigation will be carried out only on bentonite fluids with water as a medium.
In 2nd
phase the investigation will be carried out on polymer fluids and its dispersion
efficiency will be verified on shale specimens. Overall results of phase I and phase II indicate
that bentonite as a drilling fluid has very less dispersion efficiency in shale and it can be
better improved by using low cost polymers based on soil-fluid interaction.
The main objective of this project
To design bentonite and polymer based drilling fluid using soil fluid interaction and to study
its effect on shale rocks having dispersivity problems.
L.D COLLEGE OF ENGENEERING Page 6
TABLE OF CONTENTS
CHAPTER 1
INTRODUCTION
1.1 GENERAL.......................................................................................................................................10
1.2 MOTIVATION OF THE STUDY...................................................................................................11
1.3BRIEF DESCRIPTION....................................................................................................................12
1.4SCOPE & OBJECTIVE OF WORK…………………………...………….…………………..…..14
CHAPTER 2
LITERATURE REVIEW.........................................................................................................15
CHAPTER 3
EXPERIMENTAL SETUP
3.1 EXPERIMENTAL PROGRAMME
PART I : MATERIAL…………………………………………………………………...……………21
PART II : METHODOLOGY………………………………………………………….……………..24
3.2 STANDARD CODES USED…..……………………………..…………………....….…….……25
CHAPTER 4
EXPERIMENTAL INVESTIGATION
PHASE: I BENTONITE-WATER SYSTEM…………………….………………………………..…26
PHASE: II POLYMER-WATER SYSTEM……………………….……………………….................27
PHASE: III SHALE FLUID INTERACTION…………………………………..……………………28
4.1 SPECIFIC GRAVITY OF BENTONITE CLAY…………………………………….…………...29
4.2LIQUID LIMIT ON BENTONITE CLAY………………………………….………………….…30
4.3 PLASTIC LIMIT ON BENTONITE CLAY………………...........................................................32
4.4 FREE SWELL INDEX ON BENTONITE CLAY…..................................................................... 33
4.5 MUD WEIGHT OF BENTONITE SLURRY................................................................................ 34
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4.6MUDVISCOSITY OF BENTONITE SLURRY……..………………………………….....…..…36
4.7PLASTIC VISCOSITY OF BENTONITE SLURRY….................................................................37
4.8 YIELD POINT OF BENTONITE SLURRY…............................................................................. 38
4.9 GEL STRENGTH OF BENTONITE SLURRY…………………………………………....……..39
4.10 FILTRATION (WATER LOSS) IN BENTONITE SLURRY…...……..…………………….....40
4.11 pH VALUE OF BENTONITE SLURRY………...……………………………..……………….41
4.12 CEC VALUE OF BENTONITE SLURRY………....……………………..…………………….42
CHAPTER 5
RESULT & ANALYSIS& DISCUSSION
5.1.1 SPECIFIC GRAVITY OFBENTONITECLAY,,,…………...………..…………....…….…….43
5.1.2LIQUID LIMIT OF BENTONITE CLAY ….............................................................................43
5.1.3 PLASTIC LIMIT OF BENTONITE CLAY……………….........................................................44
5.1.4 FREE SWELL INDEX OF BENTONITE CLAY..................................................................... ..44
5.1.5 MUD WEIGHT OF BENTONITE SLURRY…………………………………………..………45
5.1.6 MUD VISCOSITY OFBENTONITE SLURRY..………………...…………….……..…..…....45
5.1.7 PLASTIC VISCOSITY OF BENTONITE SLURRY .................................................................46
5.1.8 YIELD POINT OF BENTONITE SLURRY…...........................................................................46
5.1.9 GEL STRENGTH OF BENTONITE SLURRY………………….…………………………….47
5.1.10 FILTRATION (WATER LOSS) IN BENTONITE SLURRY………….……….…..…….…..47
5.1.11 pH VALUE OF BENTONITE SLURRY…………………………….………….….………...48
5.1.12 CEC VALUE OF BENTONITE SLURRY……………………………………………….…..48
5.2.1 MUD WEIGHT OF BENTONITE SLURRY………………………………….………………50
5.2.2 MUD VISCOSITY OFBENTONITE SLURRY..…………………….……..…………...….....50
5.2.3 PLASTIC VISCOSITY OF BENTONITE SLURRY ................................................................51
5.2.4 YIELD POINT OF BENTONITE SLURRY…..........................................................................52
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5.2.5 GEL STRENGTH OF BENTONITE SLURRY…………………………….………………….53
5.2.6 FILTRATION (WATER LOSS) IN BENTONITE SLURRY…………………………….……53
5.2.7 pH VALUE OF BENTONITE SLURRY…………………………….…….…………………...54
5.3.1 CEC VALUE OF SHALE………………………………………………………..……………..55
5.3.2 SHALE DISPERSION TEST…………………………………………….……………………..56
5.3.3 SOIL-FLUID INTERACTION…………………………………………….…………….……...57
5.3.4 COMPARATIVE PLOTS OF BENTONITE MUD PROPERTIES………….………....……...58
5.3.5 COMPARATIVE PLOTS OF POLYMER MUD PROPERTIES……………………..……….59
CHAPTER 6
CONCLUSION………………………………………………………………………………61
REFERENCES………….........................................................................................................64
TABLE OF FIGURES
1. OIL BASED DRILLING FLUID……………………….………………...…………..…...…10
2. WATER BASED DRILLING FLUID……………………………………………….....……10
3. BENTONITE SLURRY……………………………………………………………………...21
4. POLYMER SLURRY…………………………………….…………………………………..22
5. SHALE………………………………………………….…………………………………….23
6. SPECIFIC GRAVITY……………………..………….………………………………..…….29
7. LIQUID LIMIT……………………………………………………………….………………31
8. PLASTIC LIMIT……………………………………………………………………………..32
9. FREE SWELL VOLUME……………………………………………………………………33
10. MUD WEIGHT………………………………………………………………………………34
11. MUD VISCOSITY…………………………………………………………………………...36
12. PLASTIC VISCOSITY……………………………………………………………………....37
13. YIELD POINT…………………………………………………………………….………….38
14. GEL STRENGTH………………………………………………………………….………....39
15. FILTRATION LOSS…………………………………………………………………………40
16. pH VALUE……………………………………………………………………….…………..41
17. CEC VALUE……………………………………………………………………….………...42
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LIST OF GRAPHS
PHASE: I BENTONITE - WATER SYSTEM
1. SPECIFIC GRAVITY (G) v/s NO. OF SAMPLES……………………………………….…43
2. LIQUID LIMIT (%) v/s NO. OF SAMPLES……………………………….………………..43
3. PLASTIC LIMIT (%) v/s NO. OF SAMPLES……………………………………….………44
4. FREE SWELL VOLUME v/s NO. OF SAMPLES………………………………….………44
5. MUD WEIGHT v/s NO. OF SAMPLES…………………………………………….………45
6. MUD VISCOSITY v/s NO. OF SAMPLES………………………………………….………45
7. PLASTIC VISCOSITY v/s NO. OF SAMPLES………………………………………….….46
8. YIELD POINT v/s NO. OF SAMPLES…………………………………………….………..46
9. NO. OF SAMPLES v/s GEL STRENGTH………………………….…………………...…..47
10. FILTRATION LOSS v/s NO. OF SAMPLES……………………………….……………….47
11. pH VALUE v/s NO. OF SAMPLES…………………………………….……………………48
12. CEC VALUE V/S NO. OF OBSERVATIONS……………………………………………...48
PHASE: II POLYMER – WATER SYSTEM
1. MUD WEIGHT v/s NO. OF SAMPLES………………………………………….…………50
2. MUD VISCOSITY v/s NO. OF SAMPLES……………………………………………….…50
3. PLASTIC VISCOSITY v/s NO. OF SAMPLES………………………………………….….51
4. YIELD POINT v/s NO. OF SAMPLES………………………………………………….…..52
5. NO. OF SAMPLES v/s GEL STRENGTH……………………………………………....…..53
6. FILTRATION LOSS v/s NO. OF SAMPLES……………………………………………….53
7. pH VALUE v/s NO. OF SAMPLES…………………………………………………………54
PHASE: III SHALE
1. CEC VALUE V/S NO. OF OBSERVATIONS………………………………………..…….55
2. PERCENTAGE RECOVERY V/S NO. OF OBSERVATIONS………………………….....57
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CHAPTER 1
INTRODUCTION
1.1 GENERAL
Various crude oil oriented companies are indulged in extracting the crude oil
through the earth by using various kinds of drilling fluids and jetting technology. Up to
certain limit under the earth the usage of bentonite slurry as drilling fluid is sufficient but
after that it becomes difficult to extract the crude oil through the earth so to enhance the
properties of slurry (drilling fluid) polymers are added to it in some proportion which are
costly and limited upto some extent in some areas which is governed by the soil fluid
interaction and the basic soil properties of the drilling fluid.
OIL BASED MUD ( FIG A) WATER BASED MUD (FIG B)
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1.2 MOTIVATION OF THE STUDY
Various types of drilling fluids are available in the market today
both water based and oil based having their own limitation and advantages.
Out of many drilling fluids Bentonite-Water drilling fluid system is very commonly
used for drilling oil from shallow depth i.e. up to600 m. After that as fine clay particles
increases with depth, the problem of dispersivity increases, the problem further
magnifies when shale is determined. To overcome this problem generally polymers are
used instead of bentonite for greater depths. (> 600-800 m). Though lot of research work
is done by various Indian companies including RIL, ONGC etc. still a lot of research
work is needed on drilling fluids penetrability and efficiency. Presently our aim by this
research project is to formulate a drilling fluid which is economical and versatile to used
when dispersivity problems are magnified. The dispersing of any drilling fluid is a
function of viscosity, mud weight and pH value which further plays a very important role
in soil-fluid interaction. Through this research project an attempt is made to design most
efficient drilling fluid using bentonite in first phase and polymer in second phase based
on soil-fluid interaction. The aim is to design a drilling fluid based on physical and
rheological behavior of this fluids. The role of soil-fluid interaction helps in estimating
best polymer based drilling fluids which mitigate dispersivity issues.
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1.3 BRIEF DESCRIPTION
Bentonite is a locally available soil in Gujarat so it is generally used as a main constituent of
drilling fluid.
Due to its inherent properties like swelling after coming in contact of water it perfectly suits
as a drilling fluid.
Following are the properties of bentonite slurry:
1. Mud Weight
2. Mud Viscosity
3. Rheology
4. Yield point
5. Gel Strength
6. Filtration properties
7. pH value
1.3.1 Polymers to be used
XC POLYMER
PAC-LV POLYMER
PAC-RG POLYMER
PHPA POLYMER
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1.3.2 Ingredients to be used
• Hydration agent : Caustic soda
• Weighing agent : Barite ( specific gravity :- 4.26)
• Viscofying agent : Xanthan Gum
• Liquefying agent : Polyanionic cellulose
LVG RG
(Low viscosity grade) (Regular grade)
1.3.3 SCHEME OF WORK
PHASE – I
BASIC TESTS ON BENTONITE AND BENTONITE SLURRY.
PHASE – II
BASIC TESTS ON POLYMER BASED DRILLING FLUIDS.
STUDYING THE INTERACTION OFPOLYMERS BASED DRILLING
FLUIDS ON THE SHALEROCK.
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1.4 SCOPE& OBJECTIVE OF WORK
The scope of the research work is to design most economical drilling fluid based
on soil fluid interaction so as to remediate dispersivity problems.
In the first phase our aim is to determine various physical and rheological
properties of raw drilling fluid viz. Specific gravity, Liquid limit, Plastic limit,
Free Swell Index, Mud Weight, Mud Viscosity, Plastic Viscosity, Yield Point,
Gel Strength, Filtration (water loss), pH value using bentonite and water as basic
constituents.
To compare the various physical and rheological properties of raw fluid using
bentonite and water to obtain most efficient proportioning of drilling fluids. Also
to verify the efficiency/applicability of drilling fluid with respect to depth of well.
In second phase the efficiency of drilling fluid will be further announced using
locally available polymers viz. XC POLYMER, PAC-LV,PAC-RG, PHPA.
To determine the various physical and rheological properties of raw drilling fluid
using polymers and to compare their value with bentonite drilling fluid.
To verify the efficiency of polymer based drilling fluid by applying on shale rock
with major dispersivity problems.
To observe the solid-fluid interaction between shale rock and drilling fluids.
OBJECTIVE OF THE WORK
To design bentonite and polymer based drilling fluid using soil fluid interaction and to study
its effect on shale rocks having dispersivity problems.
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CHAPTER 2
LITERATURE REVIEW
TITLE OF PAPER:- “Flow properties of water-based drilling fluids”
AUTHOR:-Aleksander Kristenen
NAME OF JOURNAL:-Thesis of master of science(Norwegian University
Of Science & Technology), 2013
• The objective of this master paper was to investigate the flow properties of water
based drilling fluids, utilizing measurements in both the micro and macro scale.
Rheology is defined as the science of deformation and flow of matter. Important
properties of drilling fluid are viscosity (PV, YP, GS), mud weight, filtration. Mud
shearing concept is adopted for fluidity which results in breaking of structure of
water-based drilling fluids.
• Viscosity is the representation of the internal resistance to deformation, a fluid shows
under stress. Thixotropic fluids are showing signs that the viscosity is reduced when
the shear force is constant for some time, i.e. the fluid flows easier with time under
static shear stress. They develop a solid state structure when at rest or with decreasing
shear rate, like a gel.
• The gel structure strength depends on the time at rest and when sheared. The gel will
begin to break as shear is initiated, and will ultimately break completely when
exposed higher and prolonged shear. There are different methods and equipment for
measuring the rheological properties of a fluid. In the drilling business the most
common way is by using a Fann 35 Viscometer.
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TITLE OF PAPER :- Polymer systems for fluid supported excavations
AUTHOR: - Stephan Jefferies, Carlos Ram, VirTroughton
NAME OF JOURNAL: -Geotechnical Issues in Construction, 2009
Excavation support fluids are used in a wide variety of civil engineering operation
including piling, ·diaphragm walling, slurry tunneling, horizontal directional drilling,
oil and water well drilling, drilling site investigation boreholes and the formation of
cutoff walls and drainage walls.
In each of these applications the role of the fluid is to keep the hole open until a
permanent element (concrete, lining etc.) is installed. This paper will focus on the use
of polymer excavation fluids for piling though polymers can and have been used in all
the applications cited except for low permeability cut-off walls, which remain an area
of need and opportunity .Polymer is good because it is bio degradable. (Xantham
gum and guar gums).It should be designed to prevent dispersion of fines from the
soil into the fluid.
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TITLE OF PAPER:-“Shale Stability: Drilling Fluid Interaction and
Shale strength
AUTHOR :- Manohar Lal
NAME OF JOURNAL: - Special publication on petroleum engineering
by Society of Petroleum Engineers (Amoco-SPE 54356), 1999
• This paper presents main results of a shale stability study, related to the understanding
of shale/ fluid interaction mechanisms, and discusses shale strength correlation. The
major shale/ fluid interaction mechanisms: Capillary, osmosis, hydraulic, swelling and
pressure diffusion. Shale make up over 75% of the drilled formations, and over 70%
of the borehole problems are related to shale instability.
• The problems include hole collapse, tight hole, stuck pipe, poor hole cleaning, hole
enlargement, plastic flow, fracturing, lost circulation, well control. While drilling,
shale becomes unstable when the effective state of the stress near the drilled hole
exceeds the strength of the hole. Shale stability is affected by properties of both shale
(e.g. mineralogy, porosity) and of the drilling fluid contacting it.
• Shale with certain properties (including strength) normally lies buried at depth. It is
subjected to in situ stresses and pore pressure, with equilibrium established between
the stress and strength. When drilled, native shale is exposed suddenly to the altered
stress environment and foreign drilling fluid.
• The main fluid interactions are as follows: Capillary pressure, Osmosis,
Swelling/Hydration pressure, Fluid penetration. The main objective to improve
shale stability is to prevent, minimize, delay or use to our advantage the interaction of
the drilling fluid with shale. For fractured shale stability, use effective sealing agents,
thixotropic drilling fluid (high viscosity for low shear rates), and lower mud weight.
PHPA and strongly adsorbing cationic polymers and components like poly glycerol
can limit the dispersion of shale cuttings or spallings in the well.
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TITLE OF PAPER :- Development of water based drilling fluids
customized for shale reservoirs
AUTHOR:-Jay P Deville, Brady fritz, Michael Jarrett
NAME OF JOURNAL: -Special publication on petroleum engineering by
Society of Petroleum Engineers(Amoco-SPE), 2011
• Customized WBMs have been developed for three major North American shale plays:
Haynesville, Fayetteville and Barnett. The WBMs were customized with a rational,
bottom-up approach that allowed for precise matching of the chemistry of the fluid to
the formation being drilled. Excellent laboratory data and field performance for the
fluids customized for these three shale plays have validated the effectiveness of the
fluid design approach. The success of these fluids gives operators an environmentally
advantageous and potentially economically advantageous alternative to NAFs, which
had previously dominated the unconventional shale drilling market.
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TITLE OF PAPER :-Experimental Analysis of Shale for Evaluating
. Shale Drilling Fluid Interaction in Agbada Formation
AUTHOR:- Okoro Emeka Emmanueland Adewale Dosunmu
NAME OF JOURNAL:- British Journal of Applied Science
&Technology4(35):2014
Wellbore instability in shale formations has been a significant problem in the
petroleum industry for over a century. It is believed that the main cause of shale
instability stems from unfavourable interactions between the drilling mud and shale
formations. Shale instability is generally caused by pore pressure changes and
mechanical property alterations around the wellbore, induced by both chemical and
hydraulic effects. All of these alterations are caused by water and ion movement into
or out of the shale formations.
The shale dispersion test (rolling test) is a common procedure that is used to measure
the interactions between drilling fluids and shales. The shale rolling test depend on
the moisture content of the shale, the shale composition, the viscosity of the test fluid,
the rotation speed of the rollers, and the test temperature. This test is used to design
fluids and screen the effectiveness of inhibitor additives to maintain the integrity of
the cuttings and minimize the interaction of fluids with the shale sections during the
drilling and completion operations. It gives an indication of how the cuttings might
survive in the drilling fluid as they travel up the annulus and it does provide some
measure of the ability of the drilling fluid to inhibit shale. Shale dispersion is a
process by which shale cuttings disintegrate into smaller sizes.
Percent recovery, a measure of shale recovered after dispersion tests were calculated.
The dispersion is a function of changes in structure of the shale matrix and in the
bound and crystalline water caused by the hydration of the cores.
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TITLE OF PAPER :-Characterization of Egyptian Smectitic Clay
Deposits by Methylene Blue Adsorption
AUTHOR:- Salwa D. Abayazeed and Essam El-Hinnawi Department
Of Geological Sciences, National Research Centre, Dokki, Cairo, Egypt
NAME OF JOURNAL:- American Journal of Applied Sciences 8 (12):
1282-1286, 2011 ISSN 1546-9239 © 2011 Science Publications
• The characterization of smectitic clays has been traditionally made using physical and
chemical methods which are time-consuming and require costly equipment.
Adsorption of methylene blue by these clays has been introduced as a quick and
cheap method for the estimation of cation exchange capacity.
• Methylene blue is a large polar organic molecule which is adsorbed onto the
negatively charged surfaces of clay minerals. It has high selectivity for adsorption by
smectite and is also adsorbed by the smectite component of mixed-layer clays, but is
largely unaffected by other clay minerals. Adsorption of methylene blue is a common
method used to estimate the cation exchange capacity. The methylene blue test has
been used routinely by the drilling industry to estimate the percentage of bentonite
mud in the circulation of fluids.
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CHAPTER 3
EXPERIMENTAL SETUP
3.1 EXPERIMENTAL PROGRAMME:
PART : I MATERIAL
BENTONITE
Bentonite is a locally available soil in Gujarat so it is generally used as a main constituent of
drilling fluid. Bentonite is an absorbent aluminium phyllosilicate, impure clay consisting
mostly of montmorillonite.
Due to its inherent properties like swelling after coming in contact of water it perfectly suits
as a drilling fluid.
Following are the properties of bentonite
slurry:
1. Mud Weight
2. Mud Viscosity
3. Rheology
4. Yield point
5. Gel Strength
6. Filtration properties
7. pH value
8. CEC value
Bentonite Slurry
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POLYMER
Polymers to be used
XC POLYMER
PAC-LV POLYMER
PAC-RG POLYMER
PHPA POLYMER
Ingredients to be used
Hydration agent : Caustic soda
Weighing agent : Barite ( specific gravity :- 4.26)
Viscofying agent : Xanthan Gum
Liquefying agent : Polyanionic cellulose
LVG RG
(Low viscosity grade) (Regular grade)
Polymer Slurry
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SHALE
Shale is a fine-grained, sedimentary rock composed of mud that is a mix of flakes of clay
minerals and tiny fragments ( silt-sized particles) of other minerals, especially quartz and
calcite . The ratio of clay to other minerals is variable. Shale is characterized by breaks along
thin laminae or parallel layering or bedding less than one centimetre in thickness, called
fissility. Mudstones, on the other hand, are similar in composition but do not show the Shale
is a fine-grained, sedimentary rock composed of mud that is a mix of flakes of clay minerals
and tiny fragments ( silt-sized particles) of other minerals, especially quartz and calcite . The
ratio of clay to other minerals is variable. Shale is characterized by breaks along thin laminae
or parallel layering or bedding less than one centimetre in thickness, called fissility.
Mudstones, on the other hand, are similar in composition but do not show the fissility.
SHALE PROBLEMS
Borehole instability
Cuttings instability
Bit balling
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PART : II METHODOLOGY
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3.2 STANDARD CODES USED:-
1. ISO 9001:2008 QMS
2. OHSAS 18001:2007
3. ISO 14001:2004 EMS
4. IS:2720 (PART 3/ SEC 1)1980 (SPECIFIC GRAVITY OF
BENTONITE)
5. IS:2720 (PART 5) 1985 ( LIQUID LIMIT OF BENTONITE)
6. IS:2720 (PART 5) 1985 (PLASTIC LIMIT OF BENTONITE)
7. IS:2720 (PART 40) 1977 ( FREE SWELL INDEX OF BENTONITE)
8. API (AMERICAN PETROLEUM INSTITUTE) 18th
Edition 2010
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CHAPTER 4
EXPERIMENTAL INVESTIGATION
Phase I
Bentonite-Water system
Preparation of sample:
Bentonite clay used during the experiment was collected locally from Ahmedabad region in
powder form. Bentonite sample prepared by us consisted of 8% of bentonite in 100% water
by volume. The mixture prepared is agitated until thorough mixture is formed.
The following physical and rheological properties of bentonite-water system are
determined and their observations are noted.
Table 1
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Phase II
Polymer-Water system
Composition of sample:
FOR 1 LITRE OF WATER
45 gram of NAHCO3 (To remove hardness of water)
Caustic soda (pH: 8.5-9)
KCL (5 -7 % by volume or 50-70 gm by weight)
PAC-LVG (0.8% by volume or 8 gm by weight)
PAC-RVG (0.4% by volume or 4 gm by weight)
XC polymer (0.25% – 3% by volume or 2.5 to 3 gm by weight)
PHPA (0.3%-0.4% by volume or 3 to 4 gm by weight)
Preparation of sample:
The constituents of polymer-water system were taken in proportions given
above. They were added one by one and agitated simultaneously until
homogeneous solution was formed.
The following physical and rheological properties of polymer-water system are
determined and their observations are noted.
Table 2
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Phase III
Shale fluid Interaction
The following physical and chemical properties of Shale-XC polymer system are
determined and their observations are noted.
Table 2
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4.1 SPECIFIC GRAVITY OF BENTONITE CLAY
CONCEPT: The specific gravity of the clay is known as the ratio of weight density
of the clay to the weight density of the water.
PURPOSE: The specific gravity of the bentonite clay is determined to know the
quantity of bentonite to form slurry for drilling.
FIG 4.1.1 Determination of Specific gravity
APPARATUS: Density Bottle, Weighing Balance, Bentonite clay, Kerosene, Water
& MATERIALS
L.D COLLEGE OF ENGENEERING Page 30
4.2 LIQUID LIMIT ON BENTONITE CLAY
CONCEPT: Liquid limit is the water content at which the soil changes from liquid
state to plastic state.
PURPOSE: Bentonite used in drilling mud has to flow like liquid through annular
spacing, but while return flow it forms mud-cakes, which keeps wellbore stable.
These properties depend on liquid limit of bentonite.
Results: The flow index of the bentonite clay is 363.37%.
0
100
200
300
400
500
600
700
1 10 100 1000
liquid limit
liquid limit
Log. (liquid limit)
L.D COLLEGE OF ENGENEERING Page 31
Fig 4.2.1 Determination of Liquid limit
Fig 4.2.2 Determination of Liquid limit
APPARATUS: Casagrande’s liquid limit device, Grooving tool, Oven, Glass sheet
&MATERIALS Spatula, 425 micron IS sieve, Weighing Balance, Wash bottle, Bentonite
Clay, Water.
L.D COLLEGE OF ENGENEERING Page 32
4.3 PLASTIC LIMIT ON BENTONITE CLAY
CONCEPT: Plastic limit is the minimum water content at which soil remains in
plastic state. It is the water content at which the soil thread of 3 mm diameter starts
crumbling.
PURPOSE: Plastic limit of the bentonite clay is determined to find the plasticity
index of the bentonite clay.
Fig 4.3.1 Determination of Plastic Limit
APPARATUS : Flat glass plate, Oven, Spatula, Bentonite clay, Water
& MATERIALS
L.D COLLEGE OF ENGENEERING Page 33
4.4 FREE SWELL INDEX ON BENTONITE CLAY
CONCEPT: Free swell index is the increase in volume of soil, without any external
constraints, on submergence in water.
PURPOSE: The free swell index is determined to know the swelling properties of the
bentonite clay used as a drilling mud.
Fig 4.4.1 Determination of Shrinkage Limit
APPARATUS: Graduated glass cylinder, Oven, Balance, Sieve, Bentonite
& MATERIALS Clay, Water, Kerosene etc
L.D COLLEGE OF ENGENEERING Page 34
4.5 MUD WEIGHT OF BENTONITE SLURRY
CONCEPT: Mud Weight is the weight per unit volume of the mud. In water base
Mud density can be regarded as a measure of the suspended solids.
PURPOSE: Mud Weight property of drilling fluid is determined to design the drilling
fluid in such a way that the hydrostatic force developed by the mud in the drilled hole
will balance the formation pressure and thus support the surrounding hole.
Fig 4.5.1 Determination of Mud Weight
L.D COLLEGE OF ENGENEERING Page 35
Fig 4.5.2 Determination of Mud Weight
APPARATUS : Mud balance, Bentonite slurry etc
& MATERIALS
L.D COLLEGE OF ENGENEERING Page 36
4.6 MUD VISCOSITY OF BENTONITE SLURRY
CONCEPT: The viscosity of drilling mud may be defined as it’s resistance to flow.
PURPOSE: The viscosity of the drilling fluid is determined effectively control the
cleaning at the bit face and rapid settling of cuttings at the surface. Sometimes drilling
fluid having low viscosity is desired at the toe of the bit and sometimes high viscosity
of drilling fluid is necessary to remove coarse sand from hole or to stabilize gravel.
Fig 4.6.1 Determination of Mud Viscosity
APPARATUS& MATERIALS: Marsh Cone funnel, Stop Watch, Measuring tub,
Bentonite Slurry etc.
L.D COLLEGE OF ENGENEERING Page 37
4.7 PLASTIC VISCOSITY OF BENTONITE SLURRY
CONCEPT: Plastic viscosity is that part of the resistance to flow in mud caused by
the friction between suspended particle and the viscosity of the base liquid.
PURPOSE: Plastic viscosity is determined to control equivalent circulating density,
surge and swab pressure, differential sticking, rate of penetration etc. while drilling.
Fig 4.7.1 Determination of Plastic Viscosity
APPARATUS & MATERIALS: FANN Viscometer, Bentonite Slurry etc
L.D COLLEGE OF ENGENEERING Page 38
4.8 YIELD POINT OF BENTONITE SLURRY
CONCEPT: Yield point is resistance of initial flow of fluid or stress required in order
to move the fluid. It is an attractive force among colloidal particles in drilling fluid.
PURPOSE: Yield point indicates the ability of the drilling mud to carry the cuttings
to the surface. Also frictional pressure loss is directly related to the yield point. If you
have higher Yield point, you will have high pressure loss while the drilling mud is
being circulated.
Fig 4.8.1 Determination of Yield Point
APPARATUS& MATERIALS: FANN viscometer, Bentonite Slurry
L.D COLLEGE OF ENGENEERING Page 39
4.9 GEL STRENGTH OF BENTONITE SLURRY
CONCEPT: The gel strength is the shear stress of drilling mud that is measured at
low shear rate after the drilling mud is static for a certain period of time.
PURPOSE: The gel strength of the drilling fluid is determined because it
demonstrates the ability of the drilling mud to suspend drill solid and weighting
material when circulation is ceased.
Fig 4.9.1 Determination of Gel Strength
APPARATUS & MATERIALS: FANN viscometer, Bentonite Slurry
L.D COLLEGE OF ENGENEERING Page 40
4.10 FILTRATION (WATER LOSS) OF BENTONITE SLURRY
• The filtration property of the drilling fluid is determined to estimate the filtration loss
in to the formation.
• Thus the objective of measuring the filtration properties is to design the fluid in such a
way that the tough filter cake is deposited on the walls of the hole which will prevent
the loss of the drilling fluid.
Fig 4.10.1 Determination of Filtration Loss
APPARATUS & MATERIALS: Filtration Measuring Equipment, Bentonite Slurry
L.D COLLEGE OF ENGENEERING Page 41
4.11 pH VALUE OF BENTONITE SLURRY
CONCEPT: pH is a value representing the hydrogen ion conc. in liquid. It is used to
indicate acidity or alkalinity of drilling mud. The pH is presented in a numerical value
(0-14) which means an inverse measurement of hydrogen ion concentration in the
fluid.
PURPOSE: pH value is determined to indicate whether the drilling fluid is acidic or
alkaline so that it may not raise any serious consequences like rusting of drilling
assembly.
Fig 4.11.1 Determination of pH
APPARATUS & MATERIALS : pHydrion paper
L.D COLLEGE OF ENGENEERING Page 42
4.12 CEC VALUE OF BENTONITE SLURRY
CONCEPT: In soil science, cation-exchange capacity or CEC is the number of exchangeable
cations per dry weight that a soil is capable of holding, at a given pH value and available for
exchange with the soil water solution.
PURPOSE: CEC is used as a measure of soil fertility, nutrient retention capacity, and the
capacity to protect groundwater from cation contamination.
Fig 4.12.1 Determination of CEC
APPARATUS & MATERIALS: Measuring flask, funnel ,glass rod, Methylene blue, filter
paper
L.D COLLEGE OF ENGENEERING Page 43
CHAPTER 5
RESULT, ANALYSIS& DISCUSSION
5.1.1 SPECIFIC GRAVITY OF BENTONITE CLAY
Fig 5.1 Specific gravity G vs. No. of samples
Result: From the experiment performed on the density bottle, the specific gravity of
the bentonite clay is 2.66.
5.1.2 LIQUID LIMIT OF BENTONITE CLAY
Fig 5.2 Liquid Limit (%) v/s No. of samples
Result: From the experiment performed on the casagrande apparatus, the liquid limit
of the bentonite clay is 595%.
0
0.5
1
1.5
2
2.5
3
1 2 3
Spe
cifi
c G
ravi
ty (
G)
No. of samples
Specific Gravity
0%
100%
200%
300%
400%
500%
600%
700%
1 2
Liq
uid
Lim
it(%
)
No. of samples
Liquid Limit
L.D COLLEGE OF ENGENEERING Page 44
5.1.3 PLASTIC LIMIT OF THE BENTONITE CLAY
Fig 5.3 Plastic Limit (%) v/s No. of samples
Result: The plastic limit of the bentonite clay is 73.33%.
The plasticity index of the bentonite clay is 521.67%.
The toughness index of the bentonite clay is 1.43.
5.1.4 FREE SWELL VOLUME OF THE BENTONITE CLAY
Fig 5.4 Swelling Volume (%) v/s No. of samples
Result: From the experiment performed on free swell apparatus, the free swell
volume of the bentonite clay is 533.2%.
0%
10%
20%
30%
40%
50%
60%
70%
80%
90%
1 2
Pla
stic
Lim
it(%
)
No. of samples
Plastic Limit
0%
100%
200%
300%
400%
500%
600%
1 2
Swe
llin
g V
olu
me
(%)
No. of samples
Free Swell Volume
L.D COLLEGE OF ENGENEERING Page 45
5.1.5 MUD WEIGHT OF THE BENTONITE SLURRY
Fig 5.5 Mud Weight (G) v/s No. of samples
Result: From the experiment performed on mud balance, the mud weight of the
bentonite slurry comes out to be 1.02.
5.1.6 MUD VISCOSITY OF THE BENTONITE SLURRY
1
Fig5.6 Mud Viscosity(s) v/s No. of samples
Result: From the experiment performed on marsh cone funnel, the mud viscosity of
the bentonite slurry obtained is 28.74 s.
0
0.2
0.4
0.6
0.8
1
1.2
1 2 3
Mu
d W
eig
ht(
G)
No. of samples
Mud Weight
0
5
10
15
20
25
30
35
1 2 3
Mu
d V
isco
sity
(s)
No. of samples
Mud Viscosity
L.D COLLEGE OF ENGENEERING Page 46
5.1.7 PLASTIC VISCOSITY OF THE BENTONITE SLURRY
Fig 5.7 Plastic Viscosity (cp) v/s No. of samples
Result: From the experiment performed on fann viscometer, the plastic viscosity of
the bentonite slurry obtained is 10 centipoises which is as per the codal provinces
given in API 13A 11.1.
5.1.8 YIELD POINT OF THE BENTONITE SLURRY
Fig 5.8 Yield point(lb/100 ft^2) v/s No. of samples
Result: From the experiment performed on fann viscometer, the yield point of the
bentonite slurry obtained is 12 lb/100 ft2 which is as per the codal provinces given in
API 13A 11.1.
0
2
4
6
8
10
12
1 2 3
Pla
stic
Vis
cosi
ty(c
p)
No. of samples
Plastic Viscosity
0
2
4
6
8
10
12
14
16
1 2 3
Yie
ld P
oin
t(lb
/10
0 f
t^2
)
No. of samples
Yield Point
L.D COLLEGE OF ENGENEERING Page 47
5.1.9 GEL STRENGTH OF THE BENTONITE SLURRY
Fig 5.9 No. of samples v/s Gel Strength
Result: From the experiment performed on fann viscometer, the gel strength of the
bentonite slurry is G0= 4 lb/100ft^2& G10 = 10 lb/100ft^2 which is as per the codal
provinces given in API 13A 11.1.
5.1.10 FILTRATION (WATER LOSS) OF THE BENTONITE
SLURRY
Fig 5.10 Filtration Loss (ml) v/s No of samples
Result: From the experiment performed on filtration apparatus, the filtration (water
loss) of the bentonite slurry is 8 ml. The maximum limit of filtration loss is 16ml as
per API 13 A.
0 2 4 6 8 10 12 14
1
2
3
Gel Strength(lb/100 ft^2)
No
. of
sam
ple
s
Gel Strength
G10
G0
0
2
4
6
8
10
1 2
Filt
rati
on
Lo
ss(m
l)
No. of samples
Filtration Losses
L.D COLLEGE OF ENGENEERING Page 48
5.1.11 pH VALUE OF THE BENTONITE SLURRY
Fig 5.11 pH (-log (mol/lit)) v/s No. of samples
Result:-From the test of pHydrion paper the pH value obtained for raw bentonite
slurry is 9.
5.1.12 CEC VALUE OF BENTONITE SLURRY
Fig 5.11 CEC VALUE (meq/100g) v/s No. of observation
Result:-CEC value of bentonite is 39 meq/100g.
0
2
4
6
8
10
1 2 3
pH
(-Lo
g(m
ol/
lit)
No of samples
pH
0
10
20
30
40
50
60
1 2 3
Ce
c va
lue
(me
q/1
00
g)
No of observations
Cec value of Bentonite
L.D COLLEGE OF ENGENEERING Page 49
Analysis & Discussion:-
The specific gravity, liquid limit, plastic limit and free swell volume of the bentonite
clay are 2.66, 595%, 73.33% and 533.2% respectively. From the above geotechnical
properties we conclude that bentonite has high swelling characteristics so it can be
used as a drilling fluid.
The mud weight, mud viscosity of the bentonite slurry are 1.02, 28.74s. From the
above physical properties, we conclude that bentonite slurry can be used as a drilling
fluid as per API 13A 11.1.1.
Plastic Viscosity, Yield Point, Gel Strength and Filtration of the bentonite slurry are
10 centipoise, 12 lb/100 ft2, 4 lb/100ft
2(G0) & 10 lb/100ft
2(G10) and 8 ml. From these
hydraulic properties, we conclude that given drilling mud has ability to lift the
borehole cuttings.
The pH value of the bentonite slurry is 9 which indicates that bentonite slurry can be
used as drilling fluid due to its high alkalinity.
L.D COLLEGE OF ENGENEERING Page 50
5.2.1MUD WEIGHT OF THE POLYMER SLURRY
Fig 5.12 Mud Weight (G) v/s No. of samples
Result: From the experiment performed on mud balance, the mud weight of the
polymer slurry comes out to be 1.33.
5.2.2MUD VISCOSITY OF THE POLYMER SLURRY
Fig5.13Mud Viscosity(s) v/s No. of samples
Result: From the experiment performed on marsh cone funnel, the mud viscosity of
the polymer slurry obtained is 55 s.
0
0.2
0.4
0.6
0.8
1
1.2
1.4
1.6
1 2 3
Mu
d W
eig
ht(
G)
No of observations
Mud weight
0
10
20
30
40
50
60
1 2 3
Mu
d V
isco
sity
(s)
No of observations
Mud Viscosity
L.D COLLEGE OF ENGENEERING Page 51
5.2.3PLASTIC VISCOSITY OF THE POLYMER SLURRY
Fig 5.14 Plastic Viscosity (cp) v/s No. of samples (with and without KCL)
Result: From the experiment performed on fann viscometer, the plastic viscosity of
the polymer slurry obtained are 20 and 12 centipoise respectively.
0
5
10
15
20
25
1 2 3
PV
(cP
)
No of observations
PV (without KCl)
0
2
4
6
8
10
12
14
16
1 2 3
PV
(cP
)
No of observations
PV (with KCl)
L.D COLLEGE OF ENGENEERING Page 52
5.2.4YIELD POINT OF THE POLYMER SLURRY
Fig 5.15 Yield point(lb/100 ft^2) v/s No. of samples
Result:The experiment performed on fann viscometer, the yield point of the polymer
slurry obtained are 38 and 16 lb/100 ft2.
0
10
20
30
40
50
60
1 2 3
YP
(lb
/10
0ft
^2)
No of observations
YP(without KCl)
0
5
10
15
20
1 2 3
YP
(lb
/10
0ft
^2)
No of observations
YP (with KCl)
L.D COLLEGE OF ENGENEERING Page 53
5.2.5GEL STRENGTH OF THE POLYMER SLURRY
Fig 5.16No.of samples v/s Gel Strength
Result: From the experiment performed on fann viscometer, the gel strength of the
polymer slurry is G0= 10 lb/100ft^2& G10 = 14 lb/100ft^2.
5.2.6FILTRATION (WATER LOSS) OF THE POLYMER SLURRY
Fig 5.17 Filtration Loss (ml) v/s No of samples
Result: From the experiment performed on filtration apparatus, the filtration (water
loss) of the polymer slurry is 6 ml.
0 5 10 15 20
1
2
3
1 2 3
G-10 12 14 16
G-0 8 10 12
Gel Strength
0
1
2
3
4
5
6
7
1 2
Filt
rati
on
Lo
ss (
ml)
No of observations
Filtration Loss
L.D COLLEGE OF ENGENEERING Page 54
5.2.7 pH VALUE OF THE POLYMER SLURRY
Fig 5.18pH (-log(mol/lit)) v/s No. of samples
Result:From the test of pHydrion paper the pH value obtained for raw polymer slurry
is 9.
Analysis & discussion:-
The mud weight, mud viscosity, of the polymer slurry are 1.33, 55s. These physical
properties indicate that polymer water slurry can replace bentonite water system.
The plastic viscosity, yield strength of the polymer slurry with KCl and w/o KCl are
20 and 12 centipoise, 38 and 16 lb/100ft2 respectively. These hydraulic properties
indicate that polymer water slurry can replace bentonite water system.
Gel Strength of the polymer slurry is 10 and 14 lb/100ft2 for G0 and G10, which
indicates the ability of drilling mud to suspend the drill solids.
Filtration of the polymer slurry is 6ml getting from filtration apparatus, which
indicates less filtration loss. Thus the drilling fluid will be able to form tough mud
cakes on the walls of bore hole, hence providing the required formation stability.
The pH value of the polymer slurry is 9 which indicates that polymer slurry can be
used as drilling fluid due to its high alkalinity.
0
2
4
6
8
10
1 2 3
pH
No of observations
pH
L.D COLLEGE OF ENGENEERING Page 55
5.3.1 CEC value of Shale
Fig 5.19 CEC VALUE(meq/100g) v/s No. of observation
Result:-CEC value of shale is 20 meq/100g.
Analysis & Discussion:- The given CEC value of shale indicates that it is of
moderately reactive type.
0
5
10
15
20
25
1 2 3
Ce
c va
lue
(m
eq
/10
0g)
No of observations
CEC Value of shale
L.D COLLEGE OF ENGENEERING Page 56
5.3.2 SHALE DISPERSION TEST
Polymer slurry with full
dispersion of shale after 24 hrs of
shale dispersion test
Polymer slurry including shale
particles w/o KCL and PHPA At
the beginning of shale dispersion
test
Polymer slurry including shale
particles with KCL and PHPA At the
beginning of shale dispersion test
Polymer slurry with undispersed
shale after 24 hrs of shale
dispersion test
L.D COLLEGE OF ENGENEERING Page 57
Fig 5.20 Percentage Recovery% v/s No of observations
Result: The percentage recovery of shale in case of polymer slurry w/o KCL is 25% and in
case of polymer slurry with KCL and PHPA is 85%.
5.3.3 SOIL FLUID INTERACTION
We tested the reactive shale with 2 samples according to the procedure of shale dispersion
test. The first sample was formed using 3 polymers Pac LV, Pac RG &XC polymer in their
respective proportions & the second sample was prepared with the polymers as above but
including KCl & PHPA.
From the above results it can be clearly stated that the percentage recovery of the shale with
the polymer including the KCl & PHPA is quite high.
This is due to encapsulation of PHPA and KCL (fluid) over the shale (soil) which decreases
the dispersivity of shale and results in more borehole stability.
0
10
20
30
40
50
60
70
80
90
100
1 2
Pe
rce
nta
ge R
eco
very
(%)
No of observations
Shale dispersion test
Without KCl With KCl and PHPA
L.D COLLEGE OF ENGENEERING Page 58
COMPARATIVE PLOTS OF BENTONITE MUD
PROPERTIES
Fig 5.21
0
25
50
75
100
125
150
175
200
225
250
275
300
325
350
375
400
425
450
475
500
525
550
575
600
625
650
675
700
Bentonite Mud Properties
L.D COLLEGE OF ENGENEERING Page 59
COMPARATIVE PLOTS OF POLYMER MUD PROPERTIES
Fig 5.21
0
5
10
15
20
25
30
35
40
45
50
55
60
Polymer Mud Properties
L.D COLLEGE OF ENGENEERING Page 60
Analysis & Discussion:-
From the above comparative plot of graphs following results are drawn:-
As the depth of drilling increases the probability of borehole instability increases
which leads to collapse of the hole so it becomes inevitable to increase the mud
weight of slurry to withstand the formation pressure. The percentage increase in the
value of mud weight for polymer based mud is 30.39%.
The mud viscosity is determined to get the idea of the lifting (the cuttings) capacity of
drilling fluid. The percentage increase in the value of mud viscosity for polymer mud
is 91.36%.
Plastic viscosity is determined to control equivalent circulating density, surge and
swab pressure, differential sticking, rate of penetration etc. while drilling. The
percentage increase in the value of plastic viscosity for polymer mud with KCL and
w/o KCl is 20% and 100% respectively.
Yield point indicates the ability of the drilling mud to carry the cuttings to the surface.
Also frictional pressure loss is directly related to the yield point. If you have higher
Yield point, you will have high pressure loss while the drilling mud is being
circulated.The percentage increase in the value of yield point for polymer mud with
KCL and w/o KCl is 216%and 33% respectively.
The gel strength of the drilling fluid is determined because it demonstrates the ability
of the drilling mud to suspend drill solid and weighting material when circulation is
ceased. The percentage increase in the value G0 is 150% and in the value of G10 is
40%.
Thus the objective of measuring the filtration properties is to design the fluid in such a
way that the tough filter cake is deposited on the walls of the hole which will prevent
the loss of the drilling fluid. The decrease in filtration loss is 25%.
From the above results we conclude that polymer drilling fluid is better than bentonite
drilling system for depth greater than 600 m.
L.D COLLEGE OF ENGENEERING Page 61
CHAPTER 7
CONCLUSION
From the above results and analysis following conclusions are drawn for
Bentonite-water system (PHASE I):-
Geo technical properties
The specific gravity of the bentonite clay is 2.66.
The liquid limit of the bentonite clay is 595%.
The plastic limit of the bentonite clay is 73.33%.
The free swell volume of the bentonite clay is 533.2%
Physical properties
The mud weight of the bentonite slurry is 1.02.
The mud viscosity of the bentonite slurry is 28.74 s.
The plastic viscosity of the bentonite slurry is 10 centipoises.
The yield point of the bentonite slurry is 12 lb/100 ft2.
The gel strength of the bentonite slurry is g0= 4 & g10 = 10.
The filtration (water loss) of the bentonite slurry is 8 ml.
Chemical properties
The pH value of the bentonite slurry is 9.
The CEC value of bentonite slurry is 39 meq/100 gm.
L.D COLLEGE OF ENGENEERING Page 62
Polymer-Water system (Phase II):-
Physical properties
The mud weight of the polymer slurry is 1.33.
The mud viscosity of the polymer slurry is 55 s.
The plastic viscosity of the polymer slurry obtained are 20 and 12 centipoise with
KCL and w/o KCL respectively.
The yield point of the polymer slurry obtained are 38 and 16 lb/100 ft2with KCL and
w/o KCL respectively.
The gel strength of the polymer slurry is G0= 10 lb/100ft^2& G10 = 14 lb/100ft^2.
Chemical properties
The filtration (water loss) of the polymer slurry is 6 ml.
The pH value of the polymer slurry is 9.
Shale (Phase III):-
Chemical properties
CEC value of shale is 20 meq/100g.
The percentage recovery of shale in case of polymer slurry w/o KCL is 25% and in
case of polymer slurry with KCL and PHPA is 85%.
L.D COLLEGE OF ENGENEERING Page 63
The result indicates the deficiency of bentonite to act as a efficient drilling fluid when used in
oil wells, for depths greater than 600-800m. The present values obtained are valid only for
bentonite water system where dispersion of the fluid into the formation is not a major issue.
The dispersion criteria of drilling fluid given as per petroleum standards (API 13A 11.1.1)
suggest that present designed bentonite drilling fluid is suitable up to a depth of 600m only. It
is further observed that when shale formations are encountered bentonite as a drilling fluid
shows very less dispersion and therefore it is to be replaced by Polymer system, whose
laboratory investigation work will be carried out in phase II.
From the result of shale dispersion test it can be clearly stated that the percentage recovery of
the shale with the polymer including the KCl & PHPA is quite high as nearly as 240%
compared to bentonite drilling fluids. This is due to encapsulation of PHPA and KCL (fluid)
over the shale(soil) which decreases the dispersivity of shale and results in more borehole
stability.
Polymer drilling fluid provide inhibition against reactive formations by providing viscosity,
without the need for bentonite, when using inhibitors as KCL, PHPA. Bentonite will not
yield in the presence of the inhibition agents. Thus from the above research study it reveals
that if proper selection of polymer is done on the basis of soil polymer interaction & polymer
chemistry, a reproductive/efficient drliing fluid can be designed to substitute bentonite
drilling fluids and other costly imported polymer drilling fluids particularily where shale
dispersibility problems are very high at greater depths.
L.D COLLEGE OF ENGENEERING Page 64
REFERENCES
The following literature has been studied to support the study:
Soil Mechanics & Foundation Engineering -K R ARORA
AMOCO drilling manual-ONGC
ISO 14001:2004 EMS
IS:2720 (PART 3/ SEC 1)1980 ( SPECIFIC GRAVITY OF BENTONITE)
IS:2720 (PART 5) 1985 ( LIQUID LIMIT OF BENTONITE)
IS:2720 (PART 5) 1985 (PLASTIC LIMIT OF BENTONITE)
IS:2720 (PART 40) 1977 ( FREE SWELL INDEX OF BENTONITE)
API (AMERICAN PETROLEUM INSTITUTE) 18th
Edition 2010
AADE 41
AADE-04-DF-HO-30
AADE-11-NTCE-39
Few research papers have also been studied to know the properties of water based
drilling fluids, shale stability, shale interaction etc
GOOGLE for few images.
L.D COLLEGE OF ENGENEERING Page 65
NOTES
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