4. Drilling Fluids (Mud)

Habiburrohman abdullah

Mud

• Properties and measurements

• Types:

- Pneumatic-air, gas, mist. Foam

- Water based

- Oil based

What is a drilling fluid?

Drilling fluid is any fluid that is used in a drilling operation in which that fluid is circulated or pumped from the surface, down the drill string, through the bit and back to the surface via the annulus.

– A Fluid Can Either Be a Gas or a Liquid.• Air is a gaseous fluid.

• Foam is an aerated liquid.• Water is a liquid fluid.

• Oil is a liquid fluid. (Diesel and Mineral oils)• Synthetic Polymeric Liquids are also used as drilling fluids. (Olefins and

Esters)

Functions of Drilling Fluids

1. Remove cuttings from the well. 2. Control formation pressure.3. Suspend and release cuttings. 4. Seal permeable formations.5. Maintain well bore stability.6. Minimize reservoir damage.

7. Cool, lubricate and support the bit and drilling assembly.

8. Transmit hydraulic energy to tools and bit.

9. Ensure adequate formation evaluation.

10. Control corrosion.

11. Facilitate cementing and completion.

12. Minimize impact on environment.

13. Prevent gas hydrate formation.

Choice of Drilling Fluid

• Performance – choose the fluid that does the job

– Inhibition

– Rheology

– Fluid Loss

– Temperature

• Environment – damage to the environment should be avoided

• Safety – To all personnel

• Cost – Average DF Costs = 10% well costs

• Availability – Check first

• Storage – Can be easily forgotten

Choice of Drilling Fluid

Lubricity

Tolerance to Contaminants

Environmental Footprint

Drilling Performance

Corrosion Inhibition

Thermal Stability

Shale Inhibition

Formation Protection

Oil Based MudEster Based MudLAO SystemKCl/PHPAKCl/Glycol System

Operator’s Objectives

Environmental compliance

Lower cost / higher efficiency - focus on shale control

Better productivity - focus on formation damage

Mud Circulating System

Common Types of Drilling Fluids

Water Based Drilling Fluids

Invert Emulsion Drilling Fluids (NADF)

Oil Base Muds

Synthetic Base Muds

Water Base Drilling Fluids

COMPO NENTS O F W ATER BASE MUDS

SolubleChem icals

FreshWater

ChloridesCalcium

Magnesium

SeaWater

ChloridesCalcium

Potassium

Salt EnhancedWater

W ater

Com m ercial C laysPolym ers

Chem icals

Low Gravity

W eight Material

H igh Gravity

NecessarySolids

Sm ectite C laysContam inants

Reactive

MISC.

Inert

DrilledSolids

Solids

Oil/Synthetic Base Drilling Fluids

CO MPO NENTS O F NO N - AQ UEO US FLUIDS

SurfactantsR heo. M odifersL iq . Polymers

Thinners

O il SolubleL iquid A dditives

D iesel O ilM inera l O il

R efined LP 's

Oil BaseFluid

O lefinsEsters

Synthetic LP 's

SyntheticFluid

ExternalPhase

C a2+ and O H -from L im e

G lycolsC a2+ and M g2+

AcetatesN itra tes

N on-C hlorideA ctiv ity R educers

25% - 30%

CaCl2Activity =

0.747 - 0 .637

InternalPhase

O rganophyllic C layW eight Materia l

Salt (C aC l2)FLC Additives

NecessarySolids

MISC .

DrilledSolids

Solids

FLUIDS Technology DevelopmentFLUIDS Technology Development

Drilling Fluid Properties

The tests and reporting procedures for drilling fluids are documented in the API Specification 13 B.

Physical properties

• Density or mud weight – ppg or SG.

• Marsh Funnel Viscosity – seconds per quart.

• Plastic viscosity – centipoise.

• Yield point – lbs per 100 sq. ft or as pascal

• Gels – centipoise, 10 seconds & 10 minutes.

• Fluid loss or filtration rate - mls per 30 mins.

• HTHP filtration rate - mls per 30 mins.

Chemical properties

• pH

• Alkalinities, filtrate. –Pf/Mf.

• Alkalinity, mud. - Pm

• Total hardness – calcium and magnesium ions.

• Calcium concentration – calcium ion.

• Total chloride ion.

Solids analysis • % volume, oil.

• % volume, water.

• % volume, solids.

• % volume, solids corrected.

• Average specific gravity solids – as S.G.

• %, low gravity solids.

• %, high gravity solids.

• % sand content.

• % clay.

• MBT (CEC) gives the amount of clay in the mud expressed as ppb, equivalent clay.

Other analyses depending on mud

type.• %, KCl concentration. (KCl PHPA)

• Potassium chloride, ppb. (KCl PHPA)

• Excess polymer, ppb. (KCl PHPA)

• %, glycol. (KCl PHPA)

• Excess lime, ppb. (Lime muds)

• Oil / Water ratio. (SBM, OBM)

• Electrical stability, volts. (SBM, OBM)

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