lesson 2 introduction to ubd.ppt

8/12/2019 Lesson 2 Introduction to UBD.ppt

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Introduction toUnderbalanced DrillingTechnology

Lesson 2

Harold Vance Department of Petroleum Engineering


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Wellsite UBD Equipment

Camp

GeologyNitrogen

Separator

Mud Treatment

Rotating Head

UB operators



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UB Drilling - Jobs

1997 Underbalanced Dri l l ing Jobs

Geographic Distribution

Canada

US Europe

South America

M idd le East

Far East



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Underbalanced Drilling in theUnited States

YEAR95 96 97 98 99 00 01 02 03 04 05

0

2,000

4,000

6,000

8,000

10,000

12,000

14,000

16,000

LOW

HIGH



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Underbalanced DrillingWells by Region



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Formation Pressure is

Equal to or Greaterthan CirculatingPressure.


UBD Definition


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Normally Pressured Reservoirs.

Applications for normal to above normalpressured reservoirs utilizing fluid systems in

a controlled flow (mudcap) drillingtechnique.

Depleted Reservoirs.

Where a multi-phase circulating fluid isnecessary to achieve required Bottom HoleCirculating Pressure (BHCP)- underbalancedor with minimal overbalance.

UBD - Types



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Barriers to UB Drilling



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Regulatory Barriersto

Underbalance Drilling

The regulators

need assuranceand details.



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Barriers To UB D&C

Regulatory

Lack of standards.Lack of knowledge.

Little statistical history.

Concern about well control.Environmental questions.



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Operators Barriers

The operatorneeds experienceand confidence.



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Operators Problems

Unfamiliar with the system:

Risk of the new.

Lack of experienced people.

Economics - Too expensive.

Concern- liability. Concern- well bore stability.



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Reasons For UB Growth

There are driving

economic reasons.



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UBD Forecast by Region

UBD Forecast by Region

-

200

400

600

800

1,000

1,200

1996 1997 1998 1999 2000 2001 2002

Wells

US

Can

Eur

SoAm

ME/Afr

FE



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Depleted reservoirs.

Awareness of skin damage. Limits of lost circulation

material.

Cost of differential sticking.



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Service company

competition. Trade journal publications.

Horizontal drilling.

Consultants available.



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Technical Improvements

We were not

ready to put allof thistogether until

the 1990s.



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Compressor evolution.

Hammer drills.

Nitrogen.Increased availability.

Reduced cost.On site generation.



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Recyclable foam systems.

Better gas separators.

Closed loop circulation.

Hydraulics models.

Improved rotating heads.

Wire line wet connect.



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Improved MWD.

Rig assist snubbing units.

Coiled tubing equipment.

Non-damaging drilling fluids.

Top drive.



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Working On

Well control concepts.

Deployment valves.

Casing drilling.

Expandable casing.

Expandable sand screens. Retractable bit.



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Completion Techniques

Improved gravel packing fluids.

Improved completion fluids.

General technique improvement.



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Reasons For UB Drilling

Lost circulation.



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Lost circulation.

Faster drilling.



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Lost circulation.

Faster drilling.

No differential

sticking.



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...

Reduce

reservoirdamage



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...

Reduce reservoirdamage.


Improve productionevaluation.


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Effect Of Skin On ProductionRates

0

200

400

600

800

1,000

SKIN

BOPD

5 10-2 0 15-3 -1



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Physical Limits to UB Drilling

Borehole

instability Poor casing point



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UBD is another tool in the toolbox, not a Panacea.

Physical Limitation to UBD

Borehole Instability.

Unconsolidated sands.

Weak formations.

Geopressured shales.

Salt beds.

Inadequate Casing.



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Production Limits to UBD

Permeability is so

low the zone needsto be fractured.

Zones must beisolated.



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MISTFOAMLIQUID GASAERATEDLIQUID

Types of Flow Regimes



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Fluid Phase Continuity

MIST(97-100 % AIR)

FOAM(0-97 % AIR)

AIR/GAS

WATER



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GeneralizedFluid Systems



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Shaffer rotating blow-out preventor.2,500 psi rotating - 5,000 psi static.

Equipment - Rotating Head


Cl d L Ci l ti


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Closed Loop CirculationSystem

SEPARATOR

OILTANKS

WATERTANKS

NITROGENPUMPERS

MUDTANKS

RIG

RIGPUMPS

R-BOP

TOPDRIVESYSTEM

CATCHERSSAMPLE

CHOKEMANIFOLD

FLARESTACK

N 2/ FLUID MIX

CUTTING

RETURN



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Choke Manifold



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Equipment - Separators



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Liquid Nitrogen(-320OF)

Carbon Steel

Gaseous N2to well80OF, 0-10,000 psi

Pump

Vaporizer

Equipment - Gas Source


Stainless Steel


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Equipment - Lots More

Samplecatchers

Willis choke

Manifold

Flare

Separator200 psi vessel

Oil storage/transport

Water returned to tanks

Flare pitChoke

ChokeRig Manifold

ESD

To shale shaker

HCR



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AIR DRILLINGA Brief Summary



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Air Drilling

Air/Gas drilling (dust) is a techniqueused in areas where the formations are

Dry i.e., there is no influx of water orliquid hydrocarbons.

This medium requires significant

compressed gas volumes to clean thewell with average velocities of over3,000 ft. per minute.



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Air Drilling Dusting



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Air Drilling Benefits

Increased Rate of Penetration.Reduced Formation Damage.Improves Bit Performance.Lost Circulation Control.

Continuous Drill Stem Test.



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Air/Dust Drilling Layout



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Air Drilling Waited Upon Large

Portable Compression

Simple and convenient to drill with airinexpensively and anywhere.



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Misting

Addition of 6 to 30 bbl/hr of fluidto the air stream.

Clean and lubricates the bit.

Carries the cuttings to thesurface as a mist or more

normally in a modified two phaseflow.



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FOAM DRILLING


F D illi


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Foam DrillingBasic Comments

The most versatile of the gas-generatedsystems.

Effective operating range from 0.2 to 0.6 s.g.

Mixture of gas phase and foaming solution. Foam flow varies with depth in the hole.

Adjustable effective BHP.

Enhanced lifting and well bore cleaning.

A displacing medium, not a propellingmedium.



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Foam (Heading)



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Improved Hole Cleaning



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Foam Drilling Benefits

Faster penetration rate.

Low air requirements.

Low fluid requirements. Low hydrostatic head.

No damage to formation.

Continuous Drill Stem Test. Best for large holes.



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Mist or Foam Drilling Layout



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Foam Drilling


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Gaseated

Mist

TransitionWater

Gas


Gaseated or Aerated Drilling


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Aerated Fluid

Gasification of primary drilling fluid. Initially designed as a technique to

lighten mud to reduce lost circulation.

Methods.Standpipe injection.Jet Sub.Parasite String.Dual Casing String.

As an UB fluid, it is easiest to controlin small holes.



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Small injection string run

simultaneously with intermediatecasing.

Injected gas does not affectbit hydraulics.

Injected gas does not effectMWD.

Parasite String



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Jet Sub

Similar to parasite string.

Gas induced thru drill pipe.

Selective jet sizing dictatesamount of air to beinjected.

Jets are Similar to Bit Jets.



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Parallel Casing String(Teichrob)


N /air2

N /water2

N /air/water/oil2

89-mm (3-1/2 in.) Drill Pipe

244.5-mm (9-5/8 in.) Intermidiate Casing

177.8-mm (7 in.) Tie Back Liner

724 m MD at64 inclination

12 m Slotted

Joint

892 m MD

at 90 Inclination694 m TVD

150 m TVD, 150 m MD

Foam Cement

TD = 1,440 m MD at 90Inclination, 696 m TVD

159-mm (6-1/4 in.)Hole Diameter

o

o

o

o

o


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Aerated Fluid Layout


A t d D illi P bl


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Aerated Drilling Problems


Compressor/N2Cost

Rotating BOPs

Solid/Liquid/GasSeparation

Corrosion

Vibration

High Torque/Drag

Borehole StabilityMWD Transmission

Hydraulic Calculations

Cuttings Lifting

Fluid InfluxFire/Explosions

UnderbalancedCompletion


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UB Drilling & Completions

Manual

Candidate selection.

Air/gas/N2/mist drilling. Foam drilling.

Aerated fluid drilling.

Flow live drilling.



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UB Drilling & Completions

Manual

Surface equipment.

Downhole equipment.

Field operations.

Downhole problems.

Environment, safety,

regulations.



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lesson 2 introduction to ubd.ppt

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