Relative permeability presentation

Relative Permeability Display VersionRelative Permeability Display Version

Relative Relative PermeabilityPermeability

April 2005April 2005

Presentation OverviewPresentation Overview What is relative permeability & UsesWhat is relative permeability & Uses Factors that affect relative permeabilityFactors that affect relative permeability How does relative permeability impact How does relative permeability impact

reservoir performance?reservoir performance? Proper design and interpretation of relative Proper design and interpretation of relative

permeability testspermeability tests Optimizing reservoir performance by Optimizing reservoir performance by

understanding relative permeability issuesunderstanding relative permeability issues Summary and conclusionsSummary and conclusions

Common Uses of Relative Common Uses of Relative Permeability DataPermeability Data

Evaluation of residual saturations and Evaluation of residual saturations and displacement efficiency for waterflood, gasflood displacement efficiency for waterflood, gasflood and various EOR processesand various EOR processes

Evaluation of flow characteristics in multiphase Evaluation of flow characteristics in multiphase reservoir situationsreservoir situations

Prediction of reservoir performance and Prediction of reservoir performance and recoverable reservesrecoverable reserves

Reservoir optimization for primary, secondary Reservoir optimization for primary, secondary and tertiary depletion operationsand tertiary depletion operations

Absolute Permeability – is defined Absolute Permeability – is defined asas

The Resistance to Fluid Flow Existing in a The Resistance to Fluid Flow Existing in a Porous Media When it is the Only Phase Porous Media When it is the Only Phase PresentPresent

Darcy’s Law for SINGLE Phase Darcy’s Law for SINGLE Phase Flow in Porous Media Can be Flow in Porous Media Can be

Expressed asExpressed as

K = Q x L x uA x DP

Relative Permeability – is defined Relative Permeability – is defined asas

The Resistance to Fluid Flow Existing in a The Resistance to Fluid Flow Existing in a Porous Media When it is in the presence Porous Media When it is in the presence of other mobile or immobile, immiscible of other mobile or immobile, immiscible fluidsfluids

Relative Permeability DefinitionRelative Permeability Definition

Kri = Ki(Si)Kabs

Measured Permeability to a SpecificPhase at a Given Saturation of that Phase

Absolute (single phase) Permeability of thePorous Media Under Consideration

Relative Permeability toA Given Phase at SaturationLevel ‘I’ Value of ThatPhase

ExampleExampleAbsolute Permeability = 100 mDPerm to Oil = 85 mDPerm to water = 21 mDPerm to gas = 14 mD

Kro = 85/100 = 0.85Krw = 21/100 = 0.21Krg = 14/100 = 0.14

‘‘Normalized’ Relative PermeabilityNormalized’ Relative Permeability

1.0

0.00.0 1.0SATURATION

KRO @ Swi = 1.00

‘‘Absolute’ Relative Perm BasisAbsolute’ Relative Perm Basis

1.0

0.00.0 1.0SATURATION

KRO @ Swi = KoKabs

Which Method of Representation is Which Method of Representation is the Bestthe Best

Either method is accurate as long as the Either method is accurate as long as the correct value of the reference ‘initial’ correct value of the reference ‘initial’ permeability is usedpermeability is used

Normalized basis is useful in many cases Normalized basis is useful in many cases where ‘absolute’ permeability is unknown where ‘absolute’ permeability is unknown (e.g. – preserved state core material)(e.g. – preserved state core material)

Saturation ConceptsSaturation Concepts

Sinit Scr it Sir r SmaxSinitial

Initial Saturation (Swi)Represents the initial water

Saturation present in the Reservoir before any man induced

External influences

Critical (Swcrit) Saturation refersTo the water saturation at

Which the water phase firstIs able to move – note in manyReservoirs than Swi is NOT the

Same as Swcrit (dehydratedOr undersaturated reservoir)

The maximum saturation (Swmax) is theMaximum water saturation present under

Floodout conditions (a residual oil or trappedGas saturation would comprise the

Remainder of the pore system)

The Irreducible or Trapped water saturation (Swirr) represents the water saturation

Present after the saturation has been increasedBeyond the critical value and then

Subsequently reduced – it is often (almost Always) greater than Scrit

Major Factors Impacting Relative Major Factors Impacting Relative PermeabilityPermeability

Fluid SaturationsFluid SaturationsRock PropertiesRock PropertiesWettabilityWettabilitySaturation HistorySaturation History

Other Factors Which Also Influence Other Factors Which Also Influence Relative PermeabilityRelative Permeability

Overburden PressureOverburden Pressure In-Situ Stresses and HydrationIn-Situ Stresses and Hydration TemperatureTemperature IFTIFT ViscosityViscosity Initial Fluid SaturationsInitial Fluid Saturations Immobile PhasesImmobile Phases Displacement RatesDisplacement Rates Core handling and PreservationCore handling and Preservation

Saturation Effects on Relative Saturation Effects on Relative PermeabilityPermeability

Water Saturation Gas Saturation Liquid Saturation

Saturation Effects on Relative Saturation Effects on Relative PermeabilityPermeability

Strongly dependant function of saturationStrongly dependant function of saturationRel perm is always expressed as a Rel perm is always expressed as a

saturation functionsaturation function

Pore GeometryPore GeometryRelative permeability is strongly impacted Relative permeability is strongly impacted

by the specific geometry/tortuosity of the by the specific geometry/tortuosity of the pore system under considerationpore system under considerationGrain sizeGrain sizePore size Pore size Aspect ratioAspect ratioPresence of vugs/natural fracturesPresence of vugs/natural fracturesWormholesWormholesHorizontal laminationsHorizontal laminations

Example of Rel Perm Curves for a Example of Rel Perm Curves for a System Dominated by System Dominated by

Macroporosity (e.g. – fractures)Macroporosity (e.g. – fractures)

More Uniform Intergranular/Matrix More Uniform Intergranular/Matrix Type Porosity SystemType Porosity System

Macroporous Flow System With Macroporous Flow System With MicroporosityMicroporosity

Anisotropic FlowAnisotropic Flow

Flow Parallel to Bedding PlanesFlow Parallel to Bedding Planes

Flow Perpendicular to Bedding Flow Perpendicular to Bedding PlanesPlanes

WettabilityWettabilityThe fluid that coats the rock poresAlso describes the wettability Nature of that reservoir

Wettability TypesWettability TypesWater WetWater WetOil WetOil WetNeutral WetNeutral WetMixed WetMixed WetSpotted/Dalmation WetSpotted/Dalmation Wet

Relative PermeabilityRelative Permeability

Water Saturation - Fraction

Rel

ativ

e P

erm

eabi

lity

- Fra

ctio

n

Swi 10%Crossover 22% SwKrw = 0.88

Swi approx 25%Crossover approx 68% Krw = 0.08

Typical Relative Typical Relative Permeability Curve Permeability Curve

Configurations for Other Configurations for Other Wettability TypesWettability Types

Neutral Wet FormationsNeutral Wet Formations

Swi 10-20%Crossover around 50%Krw = 0.45

Mixed WettabilityMixed WettabilityA fairly common wettability type in which A fairly common wettability type in which

tight microporosity is water saturated and tight microporosity is water saturated and water wet, while oil saturated macropores water wet, while oil saturated macropores are oil wetare oil wet

Typical Mixed Wettability Relative Typical Mixed Wettability Relative Permeability CurvesPermeability Curves

Swi = 40%Crossover approx 55%Krw = 0.70

Spotted/Dalmation WettabilitySpotted/Dalmation WettabilitySwi = 22%Crossover = 59%Krw = 0.28

Mobility & Mobility & Waterflood Waterflood

PerformancePerformance

Concept of ‘Mobility Ratio’Concept of ‘Mobility Ratio’

M = x Krw

w x K roMobility Ratio

Viscosity ofDisplaced Phase

Rel Perm ofDisplacingPhase

Viscosity ofDisplacing Phase

Rel Perm ofDisplaced Phase

Factors Improving MobilityFactors Improving Mobility

M = x Krw

w x K ro

Low Oil ViscosityLow Krw/Krg Value

High Displacing Phase ViscosityHigh Kro Value

Example – Waterflood in a Example – Waterflood in a Favorable Mobility System (M=0.5)Favorable Mobility System (M=0.5)

Example – Waterflood in a Example – Waterflood in a Unfavorable Mobility System Unfavorable Mobility System

(M=20)(M=20)

Residual Oil Saturations in Residual Oil Saturations in WaterfloodsWaterfloods

BREAKTHROUGH BREAKTHROUGH SorSorECONOMICECONOMIC Sor SorULTIMATEULTIMATE Sor Sor

Breakthrough SorBreakthrough SorRefers to residual oil saturation in the Refers to residual oil saturation in the

swept pattern at the time of swept pattern at the time of firstfirst water water productionproduction

INJ PROD

Economic SorEconomic SorRefers to residual oil saturation in the Refers to residual oil saturation in the

swept pattern at the time of swept pattern at the time of Maximum Maximum EconomicEconomic water cut water cut

INJ PROD

Ultimate (True) SorUltimate (True) SorRefers to residual oil saturation in the Refers to residual oil saturation in the

swept pattern if a near swept pattern if a near Infinite Infinite volume of volume of water were displaced to near zero oil cutwater were displaced to near zero oil cut

INJ PROD

Lab Measurements of SorLab Measurements of SorLab measurements of Sor generally give a Lab measurements of Sor generally give a

reasonable approximation of the reasonable approximation of the ULTIMATE Sor since usually a very large ULTIMATE Sor since usually a very large number of pore volumes of displacement number of pore volumes of displacement are conducted (10-100 typical)are conducted (10-100 typical)

Waterflooding in Differing Waterflooding in Differing Wettability ReservoirsWettability Reservoirs

Cumulative Pore Volumes of Injection

Per

cent

Rec

over

y O

OIP Breakthrough Sor

Economic Sor

Ultimate Sor



Per

cent

Rec

over

y O

OIP



Per

cent

Rec

over

y O

OIP



Per

cent

Rec

over

y O

OIP

Relative Permeability HysteresisRelative Permeability HysteresisRelative Permeability is not a unique Relative Permeability is not a unique

function of saturationfunction of saturationThe relative permeability value depends The relative permeability value depends

on the direction of saturation changeon the direction of saturation change

Example – Primary Drainage – Example – Primary Drainage – Initial Reservoir SaturationInitial Reservoir Saturation

Water Saturation – Fraction of Pore Space

Rel

ativ

e Pe

rmea

bilit

y

0 1.00

1.0WATER

OIL

Example – Primary Imbitition – Example – Primary Imbitition – (Waterflood)(Waterflood)


Rel

ativ

e Pe

rmea

bilit

y

0 1.00

1.0

WATER

OIL

Example – Primary Imbitition – Example – Primary Imbitition – (Waterflood)(Waterflood)


Rel

ativ

e Pe

rmea

bilit

y

0 1.00

1.0

WATER

OIL

Example –Secondary Drainage – Example –Secondary Drainage – (ie Gas flood)(ie Gas flood)


Rel

ativ

e Pe

rmea

bilit

y

0 1.00

1.0

WATER

OIL

Effect of Confining (Overburden) Effect of Confining (Overburden) Pressure on Relative PermeabilityPressure on Relative Permeability

Increased overburden pressure causes Increased overburden pressure causes compaction and compaction and a reductiona reduction in absolute in absolute permeabilitypermeability

Changes in Changes in pore geometrypore geometry may also affect may also affect relative permeabilityrelative permeability

Proper net overburden pressure should be Proper net overburden pressure should be used in all determinationsused in all determinations

Effect of Temperature on Relative Effect of Temperature on Relative PermeabilityPermeability

Modifies WettabilityModifies WettabilityChanges Viscosity RatioChanges Viscosity RatioChanges IFTChanges IFTMay Alter Rel PermMay Alter Rel PermTests Should be Run At Temp Of InterestTests Should be Run At Temp Of Interest

Effect of Interfacial Tension (IFT)Effect of Interfacial Tension (IFT)

IFT is a IFT is a very strong factorvery strong factor in controlling in controlling residual saturations and relative residual saturations and relative permeability curve endpoints and permeability curve endpoints and configurationsconfigurations

Proper IFT conditions are essential to a Proper IFT conditions are essential to a proper relative permeability determinationproper relative permeability determination

IFT EffectsIFT EffectsThe level of the IFT controls both the The level of the IFT controls both the

magnitude of the residual saturations in magnitude of the residual saturations in accessible pore spaceaccessible pore space and the degree of and the degree of ‘interference’ between phases‘interference’ between phases

Residual saturation is controlled by Residual saturation is controlled by capillary pressure, the lower the IFT, the capillary pressure, the lower the IFT, the lower the capillary pressurelower the capillary pressure

Effect of IFT on Rel Perm and SorEffect of IFT on Rel Perm and Sor

Is highly dependant on wettability, pore Is highly dependant on wettability, pore geometry and pore system accessibilitygeometry and pore system accessibility

Not all low/zero IFT systems give high Not all low/zero IFT systems give high recoveryrecovery

Concept of IFT vs. Mobility dominated Concept of IFT vs. Mobility dominated displacements in porous mediadisplacements in porous media

‘‘Classic’ IFT Effects on Relative Classic’ IFT Effects on Relative PermeabilityPermeability

Gas or Water Saturation - Fraction

Rel

ativ

e Pe

rmea

bilit

y



Rel

ativ

e Pe

rmea

bilit

y



Rel

ativ

e Pe

rmea

bilit

y

Using Proper IFTUsing Proper IFTAvoid treated fluidsAvoid treated fluidsAvoid surfactants and de-emulsifiersAvoid surfactants and de-emulsifiersLive reservoir fluids should be usedLive reservoir fluids should be used

Viscosity IssuesViscosity Issues

Viscosity IssuesViscosity Issues

Viscosity EffectsViscosity EffectsConsiderably controversy in the pastConsiderably controversy in the pastClassically rel perm considered to be Classically rel perm considered to be

purely a rock functionpurely a rock functionResearch has indicated that viscosity ratio Research has indicated that viscosity ratio

can strongly affect rel perm curve can strongly affect rel perm curve configuration and location of endpointsconfiguration and location of endpoints

Use of proper live reservoir fluids is Use of proper live reservoir fluids is required to mimic proper viscosity ratiorequired to mimic proper viscosity ratio

Favorable Viscosity Ratio (Favorable Viscosity Ratio (d d >>>>insitu)insitu)

Rel

ativ

e P

erm

eabi

lity

Water Saturation

Unit Viscosity Ratio (Unit Viscosity Ratio (d = d = insitu)insitu)R

elat

ive

Per

mea

bilit

y

Water Saturation

Unfavorable Viscosity Ratio (Unfavorable Viscosity Ratio (d d <<<<insitu)insitu)

Rel

ativ

e P

erm

eabi

lity

Water Saturation

Initial SaturationsInitial SaturationsProper level of initial water saturation in Proper level of initial water saturation in

the matrix for testing is essential for the matrix for testing is essential for accurate relative permeability accurate relative permeability measurementsmeasurements

Value of Swi can strongly effect original Ko Value of Swi can strongly effect original Ko or Kg endpoint permeabilityor Kg endpoint permeability

Incorrect values of Swi can have a laterally Incorrect values of Swi can have a laterally shifting effect on the entire relative shifting effect on the entire relative permeability curvepermeability curve

Example – Effect of Swi on Ko/KgExample – Effect of Swi on Ko/KgR

elat

ive

Per

mea

bilit

y

Water Saturation

Example – Effect of Swi on Rel Example – Effect of Swi on Rel Perm Curve ConfigurationPerm Curve Configuration

Rel

ativ

e P

erm

eabi

lity

Water Saturation

Presence of a Mobile or Immobile Presence of a Mobile or Immobile Third PhaseThird Phase

Generally free or trapped gas in a water-oil Generally free or trapped gas in a water-oil situationsituation

Trapped oil saturation may exist in some Trapped oil saturation may exist in some water-gas systemswater-gas systems

Trapped saturations generally reduce Trapped saturations generally reduce perm to both phasesperm to both phases

Mobile third saturations may selectively Mobile third saturations may selectively reduce perm more to one phase than reduce perm more to one phase than anotheranother

Example – Presence of Trapped Example – Presence of Trapped Initial Gas SaturationInitial Gas Saturation

Rel

ativ

e P

erm

eabi

lity

Water Saturation


Rel

ativ

e P

erm

eabi

lity

Water Saturation


Rel

ativ

e P

erm

eabi

lity

Water Saturation

Capillary End EffectsCapillary End EffectsCaused by a discontinuity in capillary Caused by a discontinuity in capillary

pressure at the outlet face of the core pressure at the outlet face of the core samplesample

Consequences of an End EffectConsequences of an End Effect

Commence WaterInjection

Delayed Production of Water& Dp due to End Effect

Consequences of an End EffectConsequences of an End EffectDelayed water breakthrough timesDelayed water breakthrough timesZone of ‘Stagnant’ fluid at end of sampleZone of ‘Stagnant’ fluid at end of sampleReduced apparent perm to water at lower Reduced apparent perm to water at lower

displacement ratesdisplacement rates

Mitigation of End EffectsMitigation of End EffectsHigh rates and delta PHigh rates and delta PLong coresLong coresPressure tapped coresPressure tapped coresSemi permeable membranesSemi permeable membranesNumerical simulation methodsNumerical simulation methods ‘‘Bump’ floodsBump’ floods

Measurement of Measurement of Relative Relative

Permeability DataPermeability Data

Common Determination MethodsCommon Determination Methods

Steady StateSteady StateUnsteady StateUnsteady StateCentrifugeCentrifugeAmbient vs. Reservoir Condition TestingAmbient vs. Reservoir Condition Testing

Sample SelectionSample SelectionRock typing and classificationRock typing and classificationSingle plug vs. composite stacksSingle plug vs. composite stacksPlug vs. full diameter testingPlug vs. full diameter testingVertical vs. horizontal flooding methodsVertical vs. horizontal flooding methods

Steady State Steady State MethodMethod

The Steady State Determination The Steady State Determination Method for Relative Permeability (2 Method for Relative Permeability (2

Phase)Phase)

Rel

ativ

e P

erm

eabi

lity

Water Saturation

Sample at Initial Conditions ofWater (Irreducible) and Oil(Maximum) Saturation


Phase)Phase)

Rel

ativ

e P

erm

eabi

lity

Water Saturation

Commence Injection of 100%Oil at Swi, Measure Ko atSwi


Phase)Phase)

Rel

ativ

e P

erm

eabi

lity

Water Saturation

Commence Injection of 90%Oil and 10% water, Measure Ko And Kw at New StabilizedHigher Sw


Phase)Phase)

Rel

ativ

e P

erm

eabi

lity

Water Saturation



Phase)Phase)

Rel

ativ

e P

erm

eabi

lity

Water Saturation



Phase)Phase)

Rel

ativ

e P

erm

eabi

lity

Water Saturation



Phase)Phase)

Rel

ativ

e P

erm

eabi

lity

Water Saturation

Commence Injection of 0%Oil and 100% water, Measure Kw at Sorw


Phase)Phase)

Rel

ativ

e P

erm

eabi

lity

Water Saturation

Advantages of the Steady State Advantages of the Steady State MethodMethod

Computationally very simpleComputationally very simple Inherently stable (no viscous effects)Inherently stable (no viscous effects)Test modifications can reduce or eliminate Test modifications can reduce or eliminate

impact of capillary end effectsimpact of capillary end effects ‘‘Classic’ method of relative permeability Classic’ method of relative permeability

determinationdetermination

Disadvantages of the Steady State Disadvantages of the Steady State MethodMethod

Complex and expensive method, very time Complex and expensive method, very time consumingconsuming

Difficult and expensive for full reservoir Difficult and expensive for full reservoir conditionsconditions

Large volumes of reservoir fluids requiredLarge volumes of reservoir fluids required In-situ saturation monitoring essential for In-situ saturation monitoring essential for

accuracyaccuracyMore of a research method in many cases More of a research method in many cases

than a viable commercial techniquethan a viable commercial technique

Typical Steady State ApparatusTypical Steady State Apparatus

Capillary Contact Paper

Inlet Section Outlet Section

Typical Steady State ApparatusTypical Steady State ApparatusPressure Taps

External Core SleeveFlow Head Flow Head

Steady State ApparatusSteady State Apparatus

Water Inj Pump

Oil Inj PumpInjection Pumps

Coreholder

In-Situ SaturationMonitoring

Three PhaseSeparator

BPR

PistonCylinders

Pressure Transducers

Core Sample

OVEN

Common In-situ Saturation Common In-situ Saturation Determination MethodsDetermination Methods

GravimetricGravimetricElectrical resistivityElectrical resistivityX-rayX-rayMRIMRIGamma rayGamma rayMicrowave attenuationMicrowave attenuation

X-Ray SaturationX-Ray Saturation

Mannville Samples 13A, 14B, 16, 19, 24A

2000

3000

4000

5000

6000

7000

8000

9000

10000

0 50 100 150 200 250 300 350

Distance, mm

X-R

ay c

ount

s

Typical Steady State Lab Typical Steady State Lab ApparatusApparatus

Displacement PumpsDisplacement Pumps

Unsteady Unsteady State MethodState Method

Unsteady State Method for Relative Unsteady State Method for Relative Permeability (2 Phase)Permeability (2 Phase)

Rel

ativ

e P

erm

eabi

lity

Water Saturation

Sample at Initial Conditions ofWater (Irreducible) and Oil(Maximum) Saturation

Unsteady Steady State Method for Unsteady Steady State Method for Relative Permeability (2 Phase)Relative Permeability (2 Phase)

Rel

ativ

e P

erm

eabi

lity

Water Saturation

Commence Injection of 100%Oil at Swi, Measure Ko atSwi

Unsteady Steady State Method for Unsteady Steady State Method for Relative Permeability (2 Phase)Relative Permeability (2 Phase)

Rel

ativ

e P

erm

eabi

lity

Water Saturation

Switch to Injection of 100%Water at Swi, Measure TransientPressure and Production History

Transient Pressure and Production Transient Pressure and Production HistoryHistory

Diff

eren

tial P

ress

ure

Cumulative Run Time

BreakthroughPoint


Prod

uctio

n R

ate

Cumulative Run Time

BreakthroughPoint


Prod

uctio

n Vo

lum

e

Cumulative Run Time

BreakthroughPoint

The Unsteady State Determination The Unsteady State Determination Method for Relative Permeability (2 Method for Relative Permeability (2

Phase)Phase)

Rel

ativ

e P

erm

eabi

lity

Water Saturation

Advantages of the Unsteady State Advantages of the Unsteady State MethodMethod

RapidRapidRelatively inexpensive, even for full Relatively inexpensive, even for full

reservoir condition HTHP testsreservoir condition HTHP testsLimited reservoir fluid requirementsLimited reservoir fluid requirementsEasy to run at full reservoir conditionsEasy to run at full reservoir conditionsSimpler equipment and procedures than Simpler equipment and procedures than

steady statesteady state

Disadvantages of the Unsteady Disadvantages of the Unsteady State MethodState Method

Unstable flow possibleUnstable flow possibleCapillary end effects possibleCapillary end effects possibleMore complex data reduction proceduresMore complex data reduction proceduresData may be poorly conditioned Data may be poorly conditioned

depending on computational method used depending on computational method used to regress transient lab resultsto regress transient lab results

Typical Unsteady State ApparatusTypical Unsteady State Apparatus

Injection Pump

Coreholder

Three PhaseSeparator

BPR

PistonCylinders

Pressure Transducers

Core Sample

OVEN

Typical Unsteady State ApparatusTypical Unsteady State Apparatus

Centrifuge MethodsCentrifuge Methods Use transient production vs. capillary pressure Use transient production vs. capillary pressure

history to generate psuedo rel perm curvehistory to generate psuedo rel perm curve Limited to very small samples and higher perm Limited to very small samples and higher perm

mediamedia Reservoir condition tests can not be easily Reservoir condition tests can not be easily

conductedconducted Common requirement to augment SS or USS rel Common requirement to augment SS or USS rel

perm experiments for evaluation of near Sor & perm experiments for evaluation of near Sor & Swir rel perm effects – always history matched Swir rel perm effects – always history matched for integration of the two methodsfor integration of the two methods

What is the Best Method to Use?What is the Best Method to Use?

What is the Best Method to UseWhat is the Best Method to UseMany of the limitations of the unsteady Many of the limitations of the unsteady

state method have been overcome in state method have been overcome in recent years by experimental and recent years by experimental and numerical modificationsnumerical modifications

95% plus of all commercial rel perm 95% plus of all commercial rel perm measurements are conducted using measurements are conducted using variants of the unsteady state methodvariants of the unsteady state method

Requirement for Two Phase FlowRequirement for Two Phase Flow

Fw

Average Sw

Water Saturation

Rel

ativ

e P

erm

eabi

lity

Results in HighlyCompressed SaturationRange


Fw

Average Sw

Water Saturation

Rel

ativ

e P

erm

eabi

lity


Fw

Average Sw

Water Saturation

Rel

ativ

e P

erm

eabi

lity Results in a More

Dispersed SaturationRange


Fw

Average Sw

Water Saturation

Rel

ativ

e P

erm

eabi

lity

Common Techniques Used in the Common Techniques Used in the Past to Disperse FlowPast to Disperse Flow

Viscous refines oils used instead of Viscous refines oils used instead of reservoir oil to ‘smear’ production profilereservoir oil to ‘smear’ production profile

Problem – wrong viscosity, IFT and Problem – wrong viscosity, IFT and possibly wettabilitypossibly wettability

High rate displacementsHigh rate displacementsProblem – unstable flowProblem – unstable flow

Overcoming These Overcoming These Deficiencies Using Deficiencies Using Modern Simulation Modern Simulation

MethodsMethods

Simulation or ‘History Matching’ Simulation or ‘History Matching’ Generation of Rel Perm DataGeneration of Rel Perm Data

Most common current techniqueMost common current techniqueBasically a numerical simulation study in Basically a numerical simulation study in

reversereverse

History Matching TechniqueHistory Matching Technique In a normal simulation we know the rel In a normal simulation we know the rel

perm curves and we use this, along with perm curves and we use this, along with other input data, to predict the reservoir other input data, to predict the reservoir pressure and production historypressure and production history

In the history matching method we know In the history matching method we know the pressure and production history from the pressure and production history from the lab tests, and we use this data in an the lab tests, and we use this data in an iterative fashion to generate the rel perm iterative fashion to generate the rel perm curvescurves

Typical History Match ModelTypical History Match ModelInput Physical Parameters (L, A, Kabs, Porosity, Pore Volume, # Blocks

Input Fluid Properties – Viscosity, Density, Rate, Initial Saturations

Input Test Properties – Endpoint Perms and Saturations, PressureHistory, Production History

Input Cap Pressureand OutletBoundary Cond-ition to ModelCapillary Effects

The History The History Matching Matching ProcessProcess

Time Time Saturation

Cum

ulat

ive

Pro

duct

ion

Diff

eren

tial P

ress

ure

Rel

ativ

e P

erm

eabi

lity

Step 1 – Pick Functional FormFor Rel Perm Curve

Step 2 – Pick Initial ‘Guess’For Rel Perm Curve Configuration


Cum

ulat

ive

Pro

duct

ion

Diff

eren

tial P

ress

ure

Rel

ativ

e P

erm

eabi

lity


Cum

ulat

ive

Pro

duct

ion

Diff

eren

tial P

ress

ure

Rel

ativ

e P

erm

eabi

lity


Cum

ulat

ive

Pro

duct

ion

Diff

eren

tial P

ress

ure

Rel

ativ

e P

erm

eabi

lity


Cum

ulat

ive

Pro

duct

ion

Diff

eren

tial P

ress

ure

Rel

ativ

e P

erm

eabi

lity


Cum

ulat

ive

Pro

duct

ion

Diff

eren

tial P

ress

ure

Rel

ativ

e P

erm

eabi

lity

History Matching ProcessHistory Matching ProcessContinue the iterative process until the Continue the iterative process until the

error between the stimulated and actual error between the stimulated and actual production and pressure data is as small production and pressure data is as small as possibleas possible

The resulting set of rel perm curves The resulting set of rel perm curves represent the best fit to the lab generated represent the best fit to the lab generated datadata

Algorithms to avoid localized or non-Algorithms to avoid localized or non-physical solutionsphysical solutions


Cum

ulat

ive

Pro

duct

ion

Diff

eren

tial P

ress

ure

Rel

ativ

e P

erm

eabi

lity

Conventional Relative Permeability Conventional Relative Permeability TestsTests

Only provide data in the range of mobile Only provide data in the range of mobile fluid saturationsfluid saturations

Presence and effect of critical fluid Presence and effect of critical fluid saturations is essential in many processessaturations is essential in many processes

Special tests and procedures are required Special tests and procedures are required to precisely measure these saturations to precisely measure these saturations and their effect on relative permeabilityand their effect on relative permeability

Specialty Rel Perm ExperimentsSpecialty Rel Perm Experiments

Critical condensate floodsCritical condensate floodsConstant IFT floodsConstant IFT floodsAbove are two examples of super normal Above are two examples of super normal

relative permeability experimentsrelative permeability experiments

Critical condensate floodsCritical condensate floods Rich gas condensatesRich gas condensates

Produced below dew point at near wellboreProduced below dew point at near wellbore Two stage experimentTwo stage experiment Stage 1: establish critical condensate satStage 1: establish critical condensate sat

Incremental pressure decrements in pore spacesIncremental pressure decrements in pore spaces Flood with equilibrium gasFlood with equilibrium gas Stop at first sign of condensate productionStop at first sign of condensate production

Stage 2: Steady state gas & condensate floodStage 2: Steady state gas & condensate flood Equilibrium gas & condensateEquilibrium gas & condensate Gas saturation decreasingGas saturation decreasing Stop at trapped gas – residual gas saturation Stop at trapped gas – residual gas saturation

Typical critical condensate Typical critical condensate apparatusapparatus

Constant IFT FloodsConstant IFT FloodsCreate high IFT injection gas & oilCreate high IFT injection gas & oil

ie models the near well bore for vaporizing driveie models the near well bore for vaporizing driveCreate low IFT injection gas & oilCreate low IFT injection gas & oil

ie models deep reservoir for vaporizing driveie models deep reservoir for vaporizing driveRun two floods on matched core stacksRun two floods on matched core stacksCompare results to determine IFT Compare results to determine IFT

domination versus other controls of domination versus other controls of incremental oil recoveryincremental oil recovery

Ie mobility, pore geometry…Ie mobility, pore geometry…

Vaporizing MiscibilityVaporizing Miscibility Fluid Preparation Fluid Preparation

Rich GasLean Gas

Low IFT Oil

High IFT Oil

Flood #1Made From:

Flood #2Made From:

Condensing MiscibilityCondensing Miscibility Fluid Preparation Fluid Preparation

Leaner GasRich Gas

High IFT Oil

Low IFT Oil

Flood #1Made from:

Flood #2Made From:

Constant IFT Flood Constant IFT Flood Reservoir Dominated by Reservoir Dominated by IFTIFT

Gas Saturation - Fraction

Rel

ativ

e P

erm

eabi

lity

Constant IFT Flood Constant IFT Flood Reservoir Dominated by Reservoir Dominated by MobilityMobility

Gas Saturation - Fraction

Rel

ativ

e P

erm

eabi

lity

ConclusionsConclusionsMany controls / influences on relative Many controls / influences on relative

permeabilitypermeabilityLive oil & reservoir conditions necessaryLive oil & reservoir conditions necessarySpecialty floods for extension of routine Specialty floods for extension of routine

relative permeability applicationsrelative permeability applications

Thank you!Thank you!

Science

Relative permeability presentation