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Drilling FluidsRemove cuttings

cool and clean bit

lubricate drill assemblycontrol formation pressure

maintain wellbore stability

prevent lost circulation

Types of Drilling Fluids

Water-based mudsMost common and least costly

Bentonite dispersants and !a"# added

"il-based mud$ lots of %&sand &s'see (andout)

*ir drilling 'see (andout) +, psi .-/ cfm

-Dry air-Misting

-Foam

Uses

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ppg 0 pounds per gallon

1ommon

normal

subsurface

pressuregradient

pcf 0 pounds per cubic ft

"ver-

pressured

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Drilling a Well

Whether drilling vertical or horizontal,

making hole depends on:

Dip of beds

#ardness and roc2 composition

Bit design

Drilling parameters

Faulting

Fracturing

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Terminology of

a directionally

drilled well

'slant-(ole)

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3(ort laterals 4

few (undred ft5

6ntermediate

laterals 4 few

t(ousand ft5

7ong laterals 4

several t(ousand ft5

Typical build rates for (ori8ontal wells

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Bit deflection using whipstocks

7imited control

Missed targets

9ositive-displacement motor PDM 6mproved directional control

6nefficient

3teerable drilling motor

Rotary and slidingmodesc controlled at surface

6mproved directional control

Tortuosity from slidedrilling limits

f (ori8ontal reac(

Rotary steerable system

1ontinuous rotation

:;cellent directional control

6mproved bore(ole

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Bit deflection usingwhipstocks

7imited control

7imited applications

:arly but still utili8ed tec(nology

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PDMor positive

displacement

'mud) motor

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T(ese directional

drillingassemblies use

down-(ole

(ydraulic motors

'mud motors)

w(ic( utili8e

circulated drilling

mud pumped from

t(e surface5 T(e

tool is positioned

and t(en (eld

stationary w(ile(ole is made by

sliding t(e drill

string downward

and forward5

3teerable 'non-rotating)

drilling assemblies

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9us(ing a bit 9ointing a bit

3teerable drilling met(ods

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PDC bit on a modern rotar steerable

drill sstem !"D#

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MWD $ %WD

measure w(ile

drilling

7og w(ile drilling

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*lternatively some

systems use (ydraulic

power from t(e mud

system to power t(e bit

'mud motor)

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W(at?

Horizontal wells.

Schlumberger Power Drive RotarySteerable Assembly

MudMotor

+MWD

+LWD=

COSTLY horizontal

wells.

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@rand Directions 771

3(ort Radius Drilling ToolReduce the cost of horizontal

wells.

Rotary steerableassembly

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Rotary steerable systems in A C

C EC ,,C from 3c(lumberger

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MaGor drilling tool

suppliers 3c(lumberger

Ba2er-#ug(es

#alliburton

Weat(erford