STUDY OF DRILL CUTTING & FORMULATION OF DRILLING FLUID

Project undertaken at:Oil and Natural Gas Corporation

Limited (ONGC), Dehradun

Presented by: Keshar Dev SainiB.Tech 7th semI.T. GGV, Bilaspur

CONTENTS

About ONGC Drilling fluid Study of drill cutting CST MBC Equipment used Formulation of drilling fluid Parameters of drilling fluid Conclusion Bibiliography

ABOUT ONGC

• Oil and Natural Gas Corporation Limited (ONGC) is the premier company in the Indian upstream of Petroleum Sector, headquatered in Dehradun, Uttarakhand.

• It was incorporated on 23rd june, 1993 and became publicly held company in february 1994.

• It is India’s largest oil and gas exploration and production Company. It produces 70% of India’s crude oil and natural gas.

• It is involved in 26 sedimentary basins in India.

• Its international subsidiary ONGC videsh Limited (OVL) has 39 projects spread over 17 countries.

DRILLING FLUID (MUD)

It is defined as the fluid that is required to carryout the drilling operation with minimum possible damages.

FUNCTION OF DRILLING FLUID

Colling and lubrication: It is used to cool drill bit and lubricate its teeth and drill string.

Cutting removal: An important function of mud is to Carry cuttings out the hole.

Suspension of cuttings: There are times when circulation has to be stopped. Mud prevents drill cuttings from settling down.

Pressure control: The hydrostatic head of drilling fluid counters the formation pressure in order to avoid a blowout while drilling.

To reduce the friction between the drill string and the wall of bore hole.

Stabilise the wellbore to prevent it from caving in

TYPES OF DRILLING FLUID

Water based mud Oil based mud Gas based mud

PROPERTIES OF DRILLING FLUID

Density of fluid pH of fluid Plastic Viscosity Yield point Gel Strength Lubricity Fluid loss and fluid cake

.

STUDY OF DRILL CUTTINGS (of Ahmedabad Asset)

1. CAPILLARY SUCTION TIMER (CST) TEST:

• Used to determine the amount of electrolyte for maximum shale swelling inhibition

• Evaluating colloidal shale properties to study the reduction of permeability of the formation around the wellbore.

RESULTS OF CST (MIXED DEPTH)

S. No.

% KCl Solution CST Reading(sec.)

1 0% (d/w) 123.4

2 1% 42.0

3 2% 29.6

4 3% 23.7

5 4% 22.0

6 5% 21.2

7 6% 23.6

8 7% 25.8

Optimum dose of KCl is 5%

2. METHYLENE BLUE CAPACITY (MBC) TEST:

This test is performed to determine the amount of active clay in the drill cutting powder.

Active clay is the clay which is responsible for swelling.

It is determined by using Methylene blue, 3% H2O2, 5N H2So4 and D/W.

Bentonite equivalent = 1.4*Volume of MB Used

RESULT OF MBC

S

N

Well Depth (M) Vol. of MB

used (ml)

Bentonite

equivalent

(ml)

1 3300 -3325 11 15.4

2 3325-3350 9 12.6

3 3350-3365 10 14

4 3365-3380 7.5 10.5

5 3380-3400 5 7

6 MIXED DEPTH 8 8.4

EQUIPMENTS USED FOR PREPARATION & TESTING OF MUD

1. HEMILTON MIXER:

2. MUD BALANCE:

3. pH METER:

4. FANN VISCOMETER:

Apparent Viscosity (AV) = θ600/2 Plastic Viscosity (PV) = θ600 – θ300 Yield Point (YP) = θ300 – PV Gel0 and Gel10

5. API FILTER PRESS:

6. LUBRICITY TESTER

• Lubricity is inversely proportional to Lubricity coefficient.

• speed of rotation =60 RPM

• Pressure applied = 14psi

• Standard torque reading for water at 60 rpm = 34

• Lubricity coefficient = (C.F.*reading of torque for mud)/100

• Where, calibration factor (C.F.) = 34/reading of torque with d/w

7. HOT ROLLER OVEN

FORMULATION OF DRILLING FLUID (For Ankleshwar Asset)

34%NaCl brine (34gm NaCl in each 100ml of water)

Name of Additive

Formulation 1 Formulation 2 Formulation 3

Biocide 0.5% 0.5% 0.5%Soda Ash 0.1% 0.1% 0.1%XCP 0.3% 0.35% 0.4%PGS 3% 3% -LSP 5% 5% -MCC - - 5%Polyoil grade-1 - - 5%

Biocide Used - paraformaldehyde Soda Ash - Sodium Bicarbonate XCP - Xanthan gum polymerPGS - Pre Gelatinized StarchLSP - Lime Stone Powder

PARAMETERS FOR FORMULATION 1:

Name of the parameter Before Hot Roll (BHR) After Hot Roll (AHR)

Specific gravity (S.G.) 1.21 1.21

pH 8.64 8.32

Rheology-    

θ600 54 48

θ300 39 34

AV 27 24

PV 15 14

YP 24 20

Gel0 6 5

Gel10 8 6

API (fluid loss) 3.8ml 3.8ml

LC (Lubricity coefficient) - 0.15

PARAMETERS FOR FORMULATION 2:

Name of the parameter Before Hot Roll (BHR) After Hot Roll (AHR)

Specific gravity (S.G.) 1.20 1.20

pH 9.30 8.75

Rheology-    

θ600 50 61

θ300 36 46

AV 25 30.5

PV 14 15

YP 22 31

Gel0 7.5 12

Gel10 9 14

API (fluid loss) 3.6ml 3.8ml

LC (Lubricity coefficient) - 0.17

PARAMETERS FOR FORMULATION 3:Name of the parameter Before Hot Roll (BHR) After Hot Roll (AHR)

Specific gravity (S.G.) 1.21 1.21

pH 10.6 9.06

Rheology-    

θ600 33 30

θ300 24 22

AV 16.5 15

PV 9 8

YP 15 14

Gel0 6.5 7

Gel10 8 9

API (fluid loss) 6.6ml 6.8ml

LC (Lubricity coefficient) - .22

CONCLUSION AND RECOMMENDATIONFOR AHMEDABAD ASSET The drill cutting study in term of CST, MBC and XRD will help in

formulation of effective drilling fluid with low gelation for successful drilling of the wells of Ahmedabad Asset.

The optimum dose of KCl is 5% to prepare the mud for Ahmedabad Asset.

 

FOR ANKLESHWAR ASSET Formulation-2 is having satisfactory parameters as per the

requirement to drill bare foot in trap wash of padra, Ankleshwar Asset.

This drilling fluid is having very low solid content that will help to minimize the formation damage.

BIBLIOGRAPHY:-

Lectures by Major Janeshwar Prasad, DGM (Chemistry), IDT, ONGC, Dehradun.

Drilling Fluid: state of art Ryen Caenn, George V. Chillinger

Composition and properties of oil well Drilling fluids-George R.Gray, H.C.H. Darley

http://www.Wikipedia.org

http://www.ongcindia.com

THANK YOU