Lesson 8 Aerated Fluid Drilling

Lesson 8DEA-101DEA-101

Aerated Fluid DrillingAerated Fluid DrillingChapter 4.1Chapter 4.1

Lesson 8DEA-101DEA-101

Aerated Fluid DrillingAerated Fluid DrillingChapter 4.1Chapter 4.1

PETE 689 PETE 689 Underbalanced Underbalanced

Drilling UBDDrilling UBD

Harold Vance Department of Petroleum Engineering

DefinitionDefinition

Introduction of gas Introduction of gas into a drilling fluid for into a drilling fluid for the purpose of the purpose of reducing the reducing the hydrostatic head.hydrostatic head.


Gaseated MudGaseated Mud

Control lost circulation.Control lost circulation. Avoid differential Avoid differential

pressure sticking.pressure sticking. Increase drilling rate.Increase drilling rate. Reduce or avoid Reduce or avoid

reservoir damage.reservoir damage.


UsesUses

Equivalent Mud Weight Equivalent Mud Weight reduction down to 4ppg.reduction down to 4ppg.

Simple system.Simple system. Not much can go wrong Not much can go wrong

that can’t be fixed.that can’t be fixed.


Gaseated MudGaseated MudAdvantageAdvantage

ss

Pressure Surges.Pressure Surges. Velocity Surges.Velocity Surges.

• These can lead to hole caving These can lead to hole caving and/or reservoir damage.and/or reservoir damage.


Gaseated MudGaseated MudHole Hole

ProblemsProblems

Gaseated MudGaseated MudEnvironmental Environmental

ProblemsProblems

Gaseated MudGaseated MudEnvironmental Environmental

ProblemsProblems Large volumes of water or Large volumes of water or

oil.oil. Oil emulsifying into mud.Oil emulsifying into mud. Residual HResidual H22S in cuttings.S in cuttings. Foaming with oil.Foaming with oil. Room on location.Room on location.


FRESH WATERFRESH WATER

OIL BASE MUDOIL BASE MUD

OILOIL

GASEATED MUDGASEATED MUD

LWSALWSA

FOAM WITH BACK-PRESSFOAM WITH BACK-PRESS

STABLE FOAMSTABLE FOAM

MISTMIST

AIR, GASAIR, GAS

00 11 22 33 44 55 66 77 88 99

FLUID DENSITY (PPG)FLUID DENSITY (PPG)

Gaseated MudGaseated MudFluid Density RangeFluid Density Range


Aerated SystemsAerated SystemsAerated SystemsAerated Systems

Historical preference - drilling Historical preference - drilling mud.mud.

Future use - clear fluids and mud.Future use - clear fluids and mud.• Diesel oil.Diesel oil.• Other synthetic or light oils.Other synthetic or light oils.• Water.Water.• Water w/polymers.Water w/polymers.


Gaseated SystemsGaseated SystemsGeneral Pressure General Pressure

andandVolume RequirementsVolume Requirements

Maximum pressure: Maximum pressure:

+/- 10,000 kPa (1,500 psi)+/- 10,000 kPa (1,500 psi) Volume: Volume:

20-45 m20-45 m33 (700-1,500 scfm) (700-1,500 scfm)


Annular Velocity RulesAnnular Velocity Rules of Thumb for Hole of Thumb for Hole

CleaningCleaning Conventional AV > 120 fpm Conventional AV > 120 fpm (vertical).(vertical). Conventional AV > 150 fpm Conventional AV > 150 fpm (Horizontal).(Horizontal). This should be enough to clean the bit This should be enough to clean the bit

and the bottom of the hole.and the bottom of the hole.


Planning - Initial Planning - Initial VolumesVolumes

Start with 2/3 the Start with 2/3 the amount of mud amount of mud needed for 120 needed for 120 ft/min annular ft/min annular velocity. velocity.

This can be This can be increased for increased for horizontal wells or horizontal wells or other problems.other problems.


Planning - Initial Planning - Initial VolumesVolumes

Start with 30 Start with 30 times as much air times as much air at STP as mud.at STP as mud.

30 X (Mud gpm X 30 X (Mud gpm X 7.5) = SCF air at 7.5) = SCF air at STP.STP.


Gaseated Injection Gaseated Injection RatiosRatios

Injection ratio at Injection ratio at STP varies.STP varies.• 5 gas/1 liquid.5 gas/1 liquid.

oLess doesn’t Less doesn’t do much do much good.good.

• 40 gas/1 liquid.40 gas/1 liquid.oMore is very More is very unstable.unstable.Harold Vance Department of Petroleum Engineering

55

11

11

4400

DefinitionDefinitionDefinitionDefinition

RatioRatio - at surface - at surface conditions, the Ratio of gas conditions, the Ratio of gas to fluid, where fluid is to fluid, where fluid is expressed as 1 (e.g. 20/1)expressed as 1 (e.g. 20/1)


QualityQuality - The % gas in a - The % gas in a system. (This is ordinarily a system. (This is ordinarily a foam term). foam term).

This may be expressed as a %, This may be expressed as a %, a decimal, or as a number.a decimal, or as a number.


DefinitionDefinitionDefinitionDefinition

Gaseated Injection Gaseated Injection RatiosRatios

Upper limit of Upper limit of stability is about stability is about 10/1 or 90% 10/1 or 90% Quality at the Quality at the top of the hole. top of the hole. Beyond that Beyond that there is severe there is severe surging.surging.


Surface InjectionSurface Injection Ratio vs. Downhole “Foam” Ratio vs. Downhole “Foam”

QualityQuality

Surface InjectionSurface Injection Ratio vs. Downhole “Foam” Ratio vs. Downhole “Foam”

QualityQuality

8,000 ft Hole8,000 ft Hole

9 ppg “Mud”9 ppg “Mud”

Surface Surface RatioRatio 10:1 (Gas: “Mud”) 10:1 (Gas: “Mud”)

QualityQuality: 91% at Surface - 3% at the : 91% at Surface - 3% at the bitbit


Foam Quality and Mud Foam Quality and Mud RatioRatio

SurfacSurfaceeQ = 91%Q = 91%

R = 1.4/1R = 1.4/1

2000’ Q = 18%2000’ Q = 18%

4000’ Q = 8%4000’ Q = 8%

6000’ Q = 5%6000’ Q = 5%

8000’ Q = 3%8000’ Q = 3%

1000’ Q = 58%1000’ Q = 58%

R = 0.23/1R = 0.23/1

Based

on

9 lb

/gal

Based

on

9 lb

/gal

Mu

dM

ud

R = 0.09/1R = 0.09/1

R = 0.05/1R = 0.05/1

Air/Mud Ratio =10/1Air/Mud Ratio =10/1

R = 0.03/1R = 0.03/1



(-) (-) Gas causes Gas causes reductionreduction in in bottom hole bottom hole pressure. pressure.

(+)(+)Friction due to Friction due to velocity velocity causes causes additionaddition to to

bottom hole bottom hole pressure.pressure.


CalculationsCalculationsGeneral Gas LawGeneral Gas Law

CalculationsCalculationsGeneral Gas LawGeneral Gas Law


PP11 * V * V11 P P22 * V * V22

TT11 * Z * Z11 T T22 * Z * Z22

==

Foam Quality and Mud Foam Quality and Mud RatioRatio

SurfacSurfaceeQ = 91%Q = 91%

R = 1.4/1R = 1.4/1

2000’ Q = 18%2000’ Q = 18%

4000’ Q = 8%4000’ Q = 8%

6000’ Q = 5%6000’ Q = 5%

8000’ Q = 3%8000’ Q = 3%

1000’ Q = 58%1000’ Q = 58%

R = 0.23/1R = 0.23/1

Based

on

9 lb

/gal

Based

on

9 lb

/gal

Mu

dM

ud

R = 0.09/1R = 0.09/1

R = 0.05/1R = 0.05/1

Air/Mud Ratio =10/1Air/Mud Ratio =10/1

R = 0.03/1R = 0.03/1


p =P(circp =P(circ11) - P(circ) - P(circ22))

p p = = decrease in BHPdecrease in BHP P(circP(circ11) = mud circulating ) = mud circulating pressure.pressure. P(circP(circ22) = gaseated circulating ) = gaseated circulating pressure. pressure.

Gaseated Bottom Hole Gaseated Bottom Hole Pressure Check (more or Pressure Check (more or

less)less)


p = p = VVmudmud / (V / (Vann ann x x

fg)fg)

Vmud = Vmud = in pits in bbls in pits in bblsVann = Vol ann bbl/ftVann = Vol ann bbl/ft fg = Fluid gradient fg = Fluid gradient

psi/ftpsi/ft


Gaseated Bottom Hole Gaseated Bottom Hole Pressure Check (more or Pressure Check (more or

less)less)

Typical Volume Requirement ChartTypical Volume Requirement ChartTypical Volume Requirement ChartTypical Volume Requirement Chart

180180 160160 2020 00140140 120120 100100 8080 6060 4040

1,000 2,000 9,000 10,0003,000 4,000 5,000 6,000 7,000 8,000

Cubic Ft of Air at 14.7 Psia and 60°F Per Barrel of Cubic Ft of Air at 14.7 Psia and 60°F Per Barrel of MudMud

Drilling Depth in FeetDrilling Depth in Feet

Desired FluidDesired FluidWeight, PpgWeight, Ppg

10

4

5.0

0.50.5

Req'D. Reduction, PpgReq'D. Reduction, Ppg

4.04.0 3.03.0

2.02.0

1.01.0

(After Phillips Pet. (After Phillips Pet. Co.)Co.)

No Dynamic effects:No Dynamic effects:FrictionFriction

SeparationSeparation



Single Biggest Single Biggest ProblemProblem

Pressure Pressure SurgesSurges


Aerated System Aerated System Pressure SurgesPressure SurgesAerated System Aerated System Pressure SurgesPressure Surges

TimeTime

Pre

ssu

reP

ressu

re

Hydrostatic Hydrostatic

PressurePressure

Reservoir Reservoir

PressurePressure

Pre

ssu

reP

ressu

re

Connections/SlugsConnections/Slugs

Typical Bottomhole Pressure Typical Bottomhole Pressure Survey During an Survey During an

Underbalanced Drilling Underbalanced Drilling OperationOperation

Reservoir Reservoir PressurePressure

TimeTime

Typical Bottomhole Pressure Typical Bottomhole Pressure Survey During an Underbalanced Survey During an Underbalanced

Drilling OperationDrilling Operation(N2 Circulation Prior to Connections)

HydrostatiHydrostatic Pressurec Pressure


Flow Regimes Flow Regimes Depend on Velocity Depend on Velocity

VariationsVariations

Flow Regimes Flow Regimes Depend on Velocity Depend on Velocity

VariationsVariations

BubbleBubbleFlowFlow

SlugSlugFlowFlow

ChurnChurnFlowFlow

AnnularAnnularFlowFlow


Threshold Velocities forThreshold Velocities for Maintaining a Mixture of Gas and Maintaining a Mixture of Gas and

FluidFluid

Threshold Velocities forThreshold Velocities for Maintaining a Mixture of Gas and Maintaining a Mixture of Gas and

FluidFluid

0.10.1 11 1010 100100 10001000

100100

1010

11

0.10.1

0.010.01

AnnularAnnularAnnularAnnular

ChurnChurnChurnChurnSlugSlugSlugSlug

BubbleBubbleBubbleBubbleA

AB

B

C

Gas Velocity Gas Velocity ft/secft/sec

Liq

uid

Velo

cit

y

Liq

uid

Velo

cit

y

ft/s

ec

ft/s

ec

Separation of Gas and Separation of Gas and FluidFluid

Large hole - low velocityLarge hole - low velocity• Polymer to increase Polymer to increase

viscosity.viscosity.• Increase velocity as Increase velocity as

much as reasonable.much as reasonable.


Small hole - high Small hole - high velocity.velocity.

Medium depth.Medium depth. Best use of gaseated Best use of gaseated

systems.systems.


Separation of Gas and Separation of Gas and FluidFluid

Keeping the System Keeping the System TogetherTogetherKeeping the System Keeping the System TogetherTogether

Gas retention in the mixture.Gas retention in the mixture.• Viscosity.Viscosity.

o Polymers.Polymers.o Gel strength.Gel strength.

• Fluid velocity.Fluid velocity.• Small bubbles.Small bubbles.

o Jet bit.Jet bit.o Shut blooie line on connections.Shut blooie line on connections.


Gas Fluid Mixing Gas Fluid Mixing SystemSystem

Gas Fluid Mixing Gas Fluid Mixing SystemSystem


Separating the Gas from Separating the Gas from the Mud at the Surfacethe Mud at the Surface

Spin in the separator.Spin in the separator. Time.Time. Shale shaker screen.Shale shaker screen. Gentle mixing.Gentle mixing. Low viscosity.Low viscosity. Low gel strength.Low gel strength. Deep rather than shallow Deep rather than shallow

pits.pits. Harold Vance Department of Petroleum Engineering

Vertical Separator with Vertical Separator with SpinSpin

Vertical Separator with Vertical Separator with SpinSpin

GasGas

Gas BaffleGas Baffle

InletInletTangentTangent

To Shaker orTo Shaker orMud PitMud Pit

OptionalOptional3 psi Pressure Flapper3 psi Pressure Flapper

Spin ShelfSpin Shelf

LinkageLinkage

FloatFloat

Outlet ValveOutlet Valve

LevelLevelControlControl


MethodsMethods of Controlling of Controlling

SurgesSurges


Aerated System Aerated System Pressure SurgesPressure SurgesAerated System Aerated System Pressure SurgesPressure Surges

TimeTime

Pre

ssu

reP

ressu

re

Hydrostatic Hydrostatic

PressurePressure

Reservoir Reservoir

PressurePressure

Pre

ssu

reP

ressu

re

Connections/SlugsConnections/Slugs

Typical Bottomhole Pressure Typical Bottomhole Pressure Survey During an Survey During an

Underbalanced Drilling Underbalanced Drilling OperationOperation

Reservoir Reservoir PressurePressure

TimeTime

Typical Bottomhole Pressure Typical Bottomhole Pressure Survey During an Underbalanced Survey During an Underbalanced

Drilling OperationDrilling Operation(N2 Circulation Prior to Connections)

HydrostatiHydrostatic Pressurec Pressure


Boosting TechniquesBoosting Techniques

ConnectionConnection• Fill DP with gas.Fill DP with gas.• Turn off gas.Turn off gas.• Fill DP with mud to Fill DP with mud to

first string float.first string float.• Turn off liquid.Turn off liquid.• Make connection.Make connection.


Special Downhole Special Downhole Equipment to Limit Equipment to Limit

SurgingSurging Jet sub.Jet sub. Parasite string.Parasite string. Dual casing string.Dual casing string. Dual drill pipe.Dual drill pipe. Constant circulating Constant circulating

subs.subs.


Jet Sub AdvantagesJet Sub Advantages

No preplanning or changes.No preplanning or changes. Easier to start circulation.Easier to start circulation. Lower pressure surges.Lower pressure surges. Gas injection pressure is Gas injection pressure is

lower.lower. Lowest gas use.Lowest gas use.


Jet sub.Jet sub. Parasite string.Parasite string. Dual casing string.Dual casing string. Dual drill pipe.Dual drill pipe. Constant circulating Constant circulating

subs.subs.Harold Vance Department of Petroleum Engineering


SurgingSurging

Basic ConceptBasic ConceptBasic ConceptBasic Concept

Most expansion occurs above Most expansion occurs above 3,000’.3,000’.

Below 3,000’ there is no Below 3,000’ there is no advantage to increasing gas advantage to increasing gas injection above 200 scf/bbl injection above 200 scf/bbl (ratio of 35:1).(ratio of 35:1).


Advantages of Parasite Advantages of Parasite StringString

Avoid heads by circulating Avoid heads by circulating during connections and trips.during connections and trips.

Easy to get circulation started.Easy to get circulation started. Simple operations. Simple operations.


Problems Problems With Parasite String With Parasite String

Need to drill larger surface Need to drill larger surface hole.hole.

Slows down casing running and Slows down casing running and makes it more complex.makes it more complex.

Always the possibility of Always the possibility of smashing or plugging the smashing or plugging the string when running it.string when running it.

Uses more gas than a jet sub.Uses more gas than a jet sub.Harold Vance Department of Petroleum Engineering

Casing SpiderCasing Spider Adapter For Parasite Adapter For Parasite

StringString

Casing SpiderCasing Spider Adapter For Parasite Adapter For Parasite

StringString

3”3”3”3”

Slot Cutfor 2 1/16”Tubing




subs.subs.


Wellhead Setup Wellhead Setup for Dual Casing Stringfor Dual Casing String


Advantages of Dual Advantages of Dual CasingCasing

Minimizes the chance of Minimizes the chance of crushing the string.crushing the string.

Inner string retrieved and Inner string retrieved and used again.used again.

Can be set very deep.Can be set very deep.


Problems with a Dual Problems with a Dual StringString

Requires change in well Requires change in well head.head.

Extra string of stream line Extra string of stream line casing.casing.

Gas volume storage will Gas volume storage will unload well.unload well.




subs.subs.Harold Vance Department of Petroleum Engineering

Dual Drill PipeDual Drill Pipe

It is a mining tool and It is a mining tool and seldom used in the oil seldom used in the oil field.field.


Constant Circulating Constant Circulating SubsSubs

Used in the late 1960’s, Used in the late 1960’s, no longer available.no longer available.

Good for connections.Good for connections. No advantage on trips.No advantage on trips. Lots of extra subs.Lots of extra subs.


2” Airline2” Airline

Quick connectQuick connect

Float PinsFloat Pins

Full opening floatFull opening float

Tool Joint O.D.Tool Joint O.D.

Constant Circulating SubConstant Circulating Sub


Fluids and GassesFluids and Gasses


Gaseated SystemsGaseated SystemsGasesGases

AirAir NitrogenNitrogen

• CryogenicCryogenic• ManufactureManufacturedd

Natural GasNatural Gas Exhaust GasExhaust Gas


Gaseated SystemsGaseated SystemsClear FluidsClear Fluids

Diesel oil.Diesel oil. Water.Water. Saline.Saline. Other light oils.Other light oils.

• Mineral oils.Mineral oils.• Synthetic Synthetic oils.oils.Harold Vance Department of Petroleum Engineering

Gaseated SystemsGaseated SystemsDrilling MudDrilling Mud

Gaseated SystemsGaseated SystemsDrilling MudDrilling Mud

Conventional gel based mud.Conventional gel based mud. Low lime mud.Low lime mud. Xanthan gum mud.Xanthan gum mud.

• Thixotropic (holds gas).Thixotropic (holds gas).• Easily broken gel strength.Easily broken gel strength.• (Several commercial systems (Several commercial systems

available).available).


CorrosionCorrosion


Always Remember: Always Remember: Corrosion cannot be Corrosion cannot be

stopped. stopped. It can only be It can only be

controlledcontrolled

Always Remember: Always Remember: Corrosion cannot be Corrosion cannot be

stopped. stopped. It can only be It can only be

controlledcontrolled


Corrosion Control pHCorrosion Control pHKeep pH above 9Keep pH above 9Steel becomes passive Steel becomes passive

above pH = 11above pH = 11


Don’t use air.Don’t use air. Oxygen corrosion is the Oxygen corrosion is the

most common type of most common type of corrosion.corrosion.

There are other types of There are other types of corrosion and scaling.corrosion and scaling.


Corrosion ControlCorrosion Control

Corrosion Corrosion InhibitorsInhibitors


Organo-Phosphate Organo-Phosphate EstersEsters

Organo-Phosphate Organo-Phosphate EstersEsters

Foamer compatible.Foamer compatible. Good solubility.Good solubility. Limited scale inhibition.Limited scale inhibition. Relatively high temperature.Relatively high temperature. Biodegradable.Biodegradable. Excellent oxygen control.Excellent oxygen control. 500-2,000 ppm concentration.500-2,000 ppm concentration.

ANIONICANIONIC


ChromatesChromatesChromatesChromates

Extremely soluble in water.Extremely soluble in water. Foamer compatible.Foamer compatible. Relatively high temperature.Relatively high temperature. 200-1,200 ppm 200-1,200 ppm

concentration.concentration. Low solids system.Low solids system. pH > 8pH > 8 Heavy metal carcinogen.Heavy metal carcinogen.

ANIONICANIONIC


NitratesNitratesNitratesNitrates

Foamer compatible.Foamer compatible. 60-70% chromate 60-70% chromate

effectiveness.effectiveness. Require high pH.Require high pH. Require high concentration.Require high concentration.


ANIONICANIONIC

PhosphatesPhosphatesPhosphatesPhosphates

Primary scale inhibitor.Primary scale inhibitor. Foamer compatible.Foamer compatible. Raise pH to 8-12.Raise pH to 8-12. Not sufficient by themselves.Not sufficient by themselves. Produce calcium phosphate. Produce calcium phosphate.

scale in high calcium fluid.scale in high calcium fluid.


ANIONICANIONIC

AminesAminesAminesAmines

Effective In Effective In Mud Mud Systems.Systems.

Work Well In Work Well In Gas/Air.Gas/Air. Form Protective Film.Form Protective Film. Film Easily Penetrated Film Easily Penetrated

by Monatomic Oxygen.by Monatomic Oxygen. Foamer Incompatible.Foamer Incompatible.

CationicCationic


Equipment for Equipment for Gaseated SystemsGaseated Systems


Rotating HeadRotating HeadRotating HeadRotating Head


Drill String FloatsDrill String FloatsDrill String FloatsDrill String Floats


SeparatorsSeparators


Typical Closed System UBD Typical Closed System UBD Operation Operation

Simple Aerated Mud Simple Aerated Mud SeparatorSeparator

Simple Aerated Mud Simple Aerated Mud SeparatorSeparator

De-AeratorDe-Aerator

Mud Flow LineMud Flow Line

Overflow Overflow PipePipe


Vertical Separator with Vertical Separator with BafflesBaffles

Vertical Separator with Vertical Separator with BafflesBaffles

GasGas


Inlet flowInlet flow

Mud BaffleMud Baffle

MudMudFrom ChokeFrom ChokeManifold (2,3 or 4 Manifold (2,3 or 4

inlets)inlets)

Solids or CleanoutSolids or Cleanout~8 Fee t~8 Fee t

From Choke ManifoldFrom Choke Manifold

Mud to PitMud to Pit

Gas to FlareGas to Flare

14 Feet14 FeetGas ventGas vent


Vertical Separator with SpinVertical Separator with SpinVertical Separator with SpinVertical Separator with Spin

GasGas


InletInletTangentTangent

To Shaker orTo Shaker orMud PitMud Pit

OptionalOptional3 psi Pressure Flapper3 psi Pressure Flapper

Spin ShelfSpin Shelf

LinkageLinkage

FloatFloat

Outlet ValveOutlet Valve

LevelLevelControlControl


SWACO Super Mud Gas SWACO Super Mud Gas SeparatorSeparatorSWACO Super Mud Gas SWACO Super Mud Gas SeparatorSeparator

““U” TubeU” TubeLevel ControlLevel Control

83 Mmcf/d83 Mmcf/d

Gas OutGas Out

FromFromWell Well

Fluid OutFluid Out50,000 bpd50,000 bpd



Closed Closed SeparatorSeparator

Schematic of Closed Schematic of Closed SeparatorSeparator

GasGas

SolidsSolids

SolidsSolidsTransfer Transfer

PumpPump

AdjustableAdjustablePartitionPartition

PlatePlate

OilOil

MudMud

Well EffluentsWell EffluentsInIn

Gas OutGas Out


Typical Horizontal Typical Horizontal SeparatorSeparator

9’ x 50’ (3m x 15m).9’ x 50’ (3m x 15m). 50 psi (345 kpa) wp.50 psi (345 kpa) wp. 5 mmcf/d and 500-600 bbls.5 mmcf/d and 500-600 bbls.

• 141,000 m141,000 m33/d and 87m/d and 87m33 liquid. liquid. Orifice meter run.Orifice meter run.


Vertical Vertical SeparatorSeparator


Typical Vertical Typical Vertical SeparatorSeparator

4’ x 15’ (1.3m x 3m).4’ x 15’ (1.3m x 3m). 500 psi (3450 kPa).500 psi (3450 kPa). 25 MMcf/d and 10,000 bbls/d25 MMcf/d and 10,000 bbls/d

• (700,000(700,000 mm3 3 gas/d and gas/d and 1,590 m1,590 m33/d liquid)./d liquid).

Orifice Meter, Level Control, Orifice Meter, Level Control, Dump Valves.Dump Valves.


SurfaceSurface Equipment Closed Equipment Closed

SystemSystem


Underbalance Drilling Underbalance Drilling SpreadSpread


Gas Separator Gas Separator SystemSystem

Gas Separator Gas Separator SystemSystem

Ensures all fluid is degassed prior to return to the system.Ensures all fluid is degassed prior to return to the system.


Gas Separation Gas Separation SystemSystem

Open SkimmerOpen Skimmer

SolidsSolids

Drilling Fluid/WaterDrilling Fluid/Water

Oil TrapOil Trap

Oil OverflowOil Overflow


Sample Catcher for Closed Sample Catcher for Closed SystemSystem

(Alpine, 1996)(Alpine, 1996)



Gaseated Drilling Gaseated Drilling TechniquesTechniques


TechniquesTechniques

Flowline returns do not Flowline returns do not represent downhole represent downhole conditions.conditions.


Initiating Gaseated Initiating Gaseated DrillingDrilling

Unloading the HoleUnloading the Hole Start Pumping gas/mud system.Start Pumping gas/mud system. When pump pressure gets too When pump pressure gets too

high for the air compressor, high for the air compressor, stop pumping air.stop pumping air.

Pump mud until the pressure Pump mud until the pressure goes back down.goes back down.


DrillingDrilling

There will be alternate There will be alternate heads of gas and mud.heads of gas and mud.

Heading cycle may be Heading cycle may be as long as 5 minutes.as long as 5 minutes.


Control HeadingControl Heading

Increase viscosity.Increase viscosity. Increase mud volume(velocity)Increase mud volume(velocity) Decrease gas.Decrease gas. Add 2 TO 3 atm of Add 2 TO 3 atm of

backpressure 30 to 50 psi.backpressure 30 to 50 psi. Decrease bit jet size.Decrease bit jet size.


ConnectionsConnections

Gas and fluid will separate.Gas and fluid will separate. Fill the drill pipe with gas Fill the drill pipe with gas

before connection.before connection. Then fill to first string float Then fill to first string float

with mud to keep connection with mud to keep connection dry.dry.


Pressure on the AnnulusPressure on the Annulus

Shut in the well on connections Shut in the well on connections to keep the gas under pressure.to keep the gas under pressure.

If the well is strongly flowing, If the well is strongly flowing, the choke may have to be left the choke may have to be left slightly open.slightly open.


Gaseated System Gaseated System Making a TripMaking a Trip

For lost circulation (well not For lost circulation (well not flowing) no problem with trip.flowing) no problem with trip.

For flowing well:For flowing well:• Displace clean clear fluid Displace clean clear fluid

over reservoir and kill with over reservoir and kill with a floating mud cap.a floating mud cap.

• Use a deployment valve.Use a deployment valve.


Gaseated SystemGaseated System

Stripping is a reasonable Stripping is a reasonable and safe techniqueand safe technique

Planning on snubbing out Planning on snubbing out the pipe light stands is a the pipe light stands is a bad planning practice bad planning practice because of the time because of the time expense.expense.


After a TripAfter a Trip

Go to bottom and unload hole Go to bottom and unload hole with alternate mud and gas.with alternate mud and gas.

Working back to bottom while Working back to bottom while gassing us each zone will not be gassing us each zone will not be successful unless you keep the successful unless you keep the well shut and bleed a little well shut and bleed a little pressure.pressure.


EndEnd


Date post:	13-Apr-2015
Category:	Documents
Upload:	omar-ezzat
View:	56 times
Download:	4 times

Lesson 8 Aerated Fluid Drilling

Documents