Relative permeability presentation

Relative Permeability Display VersionRelative Permeability Display Version
RelativeRelative
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 impactHow does relative permeability impact
reservoir performance?reservoir performance?
 Proper design and interpretation of relativeProper design and interpretation of relative
permeability testspermeability tests
 Optimizing reservoir performance byOptimizing reservoir performance by
understanding relative permeability issuesunderstanding relative permeability issues
 Summary and conclusionsSummary and conclusions

Common Uses of RelativeCommon Uses of Relative
Permeability DataPermeability Data
 Evaluation of residual saturations andEvaluation of residual saturations and
displacement efficiency for waterflood, gasflooddisplacement efficiency for waterflood, gasflood
and various EOR processesand various EOR processes
 Evaluation of flow characteristics in multiphaseEvaluation of flow characteristics in multiphase
reservoir situationsreservoir situations
 Prediction of reservoir performance andPrediction of reservoir performance and
recoverable reservesrecoverable reserves
 Reservoir optimization for primary, secondaryReservoir optimization for primary, secondary
and tertiary depletion operationsand tertiary depletion operations

Absolute Permeability – is definedAbsolute Permeability – is defined
asas
 The Resistance to Fluid Flow Existing in aThe Resistance to Fluid Flow Existing in a
Porous Media When it is the Only PhasePorous Media When it is the Only Phase
PresentPresent

Darcy’s Law for SINGLE PhaseDarcy’s Law for SINGLE Phase
Flow in Porous Media Can beFlow in Porous Media Can be
Expressed asExpressed as
K = Q x L x u
A x DP

Relative Permeability – is definedRelative Permeability – is defined
asas
 The Resistance to Fluid Flow Existing in aThe Resistance to Fluid Flow Existing in a
Porous Media When it is in the presencePorous Media When it is in the presence
of other mobile or immobile, immiscibleof other mobile or immobile, immiscible
fluidsfluids

Relative Permeability DefinitionRelative Permeability Definition
Kri = Ki(Si)
Kabs
Measured Permeability to a Specific
Phase at a Given Saturation of that Phase
Absolute (single phase) Permeability of the
Porous Media Under Consideration
Relative Permeability to
A Given Phase at Saturation
Level ‘I’ Value of That
Phase

ExampleExample
Absolute Permeability = 100 mD
Perm to Oil = 85 mD
Perm to water = 21 mD
Perm to gas = 14 mD
Kro = 85/100 = 0.85
Krw = 21/100 = 0.21
Krg = 14/100 = 0.14

‘‘Normalized’ Relative PermeabilityNormalized’ Relative Permeability
1.0
0.0
0.0 1.0SATURATION
KRO @ Swi = 1.00

‘‘Absolute’ Relative Perm BasisAbsolute’ Relative Perm Basis
1.0
0.0
0.0 1.0SATURATION
KRO @ Swi = Ko
Kabs

Which Method of Representation isWhich Method of Representation is
the Bestthe Best
 Either method is accurate as long as theEither 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 casesNormalized basis is useful in many cases
where ‘absolute’ permeability is unknownwhere ‘absolute’ permeability is unknown
(e.g. – preserved state core material)(e.g. – preserved state core material)

Saturation ConceptsSaturation Concepts
Sinit Scrit Sirr SmaxSinitial
Initial Saturation (Swi)
Represents the initial water
Saturation present in the
Reservoir before any man induced
External influences
Critical (Swcrit) Saturation refers
To the water saturation at
Which the water phase first
Is able to move – note in many
Reservoirs than Swi is NOT the
Same as Swcrit (dehydrated
Or undersaturated reservoir)
The maximum saturation (Swmax) is the
Maximum water saturation present under
Floodout conditions (a residual oil or trapped
Gas 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 increased
Beyond the critical value and then
Subsequently reduced – it is often (almost
Always) greater than Scrit

Major Factors Impacting RelativeMajor Factors Impacting Relative
 Fluid SaturationsFluid Saturations
 Rock PropertiesRock Properties
 WettabilityWettability
 Saturation HistorySaturation History

Other Factors Which Also InfluenceOther 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 RelativeSaturation Effects on Relative
Water Saturation Gas Saturation Liquid Saturation

Saturation Effects on RelativeSaturation Effects on Relative
 Strongly dependant function of saturationStrongly dependant function of saturation
 Rel perm is always expressed as aRel perm is always expressed as a
saturation functionsaturation function

Pore GeometryPore Geometry
 Relative permeability is strongly impactedRelative permeability is strongly impacted
by the specific geometry/tortuosity of theby the specific geometry/tortuosity of the
pore system under considerationpore system under consideration
Grain sizeGrain size
Pore sizePore size
Aspect ratioAspect ratio
Presence of vugs/natural fracturesPresence of vugs/natural fractures
WormholesWormholes
Horizontal laminationsHorizontal laminations

Example of Rel Perm Curves for aExample of Rel Perm Curves for a
System Dominated bySystem Dominated by
Macroporosity (e.g. – fractures)Macroporosity (e.g. – fractures)

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

Macroporous Flow System WithMacroporous Flow System With
MicroporosityMicroporosity

Anisotropic FlowAnisotropic Flow

Flow Parallel to Bedding PlanesFlow Parallel to Bedding Planes

Flow Perpendicular to BeddingFlow Perpendicular to Bedding
PlanesPlanes

WettabilityWettability
The fluid that coats the rock pores
Also describes the wettability
Nature of that reservoir

Wettability TypesWettability Types
 Water WetWater Wet
 Oil WetOil Wet
 Neutral WetNeutral Wet
 Mixed WetMixed Wet
 Spotted/Dalmation WetSpotted/Dalmation Wet

Relative PermeabilityRelative Permeability
Water Saturation - Fraction
RelativePermeability-Fraction
Swi 10%
Crossover 22% Sw
Krw = 0.88
Swi approx 25%
Crossover approx 68%
Krw = 0.08

Typical RelativeTypical Relative
Permeability CurvePermeability Curve
Configurations for OtherConfigurations for Other
Wettability TypesWettability Types

Neutral Wet FormationsNeutral Wet Formations
Swi 10-20%
Crossover around 50%
Krw = 0.45

Mixed WettabilityMixed Wettability
 A fairly common wettability type in whichA fairly common wettability type in which
tight microporosity is water saturated andtight microporosity is water saturated and
water wet, while oil saturated macroporeswater wet, while oil saturated macropores
are oil wetare oil wet

Typical Mixed Wettability RelativeTypical Mixed Wettability Relative
Permeability CurvesPermeability Curves
Swi = 40%
Crossover approx 55%
Krw = 0.70

Spotted/Dalmation WettabilitySpotted/Dalmation Wettability
Swi = 22%
Crossover = 59%
Krw = 0.28

Mobility &Mobility &
WaterfloodWaterflood
PerformancePerformance

Concept of ‘Mobility Ratio’Concept of ‘Mobility Ratio’
M = µο x Krw
µ w x K r o
Mobility Ratio
Viscosity of
Displaced Phase
Rel Perm of
Displacing
Phase
Viscosity of
Displacing Phase
Rel Perm of
Displaced Phase

Factors Improving MobilityFactors Improving Mobility
M = µο x Krw
µ w x K r o
Low Oil ViscosityLow Krw/Krg Value
High Displacing Phase Viscosity
High Kro Value

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

Example – Waterflood in aExample – Waterflood in a
Unfavorable Mobility SystemUnfavorable Mobility System
(M=20)(M=20)

Residual Oil Saturations inResidual Oil Saturations in
WaterfloodsWaterfloods
 BREAKTHROUGHBREAKTHROUGH SorSor
 ECONOMICECONOMIC SorSor
 ULTIMATEULTIMATE SorSor

Breakthrough SorBreakthrough Sor
 Refers to residual oil saturation in theRefers to residual oil saturation in the
swept pattern at the time ofswept pattern at the time of firstfirst waterwater
productionproduction
INJ PROD

Economic SorEconomic Sor
swept pattern at the time ofswept pattern at the time of MaximumMaximum
EconomicEconomic water cutwater cut
INJ PROD

Ultimate (True) SorUltimate (True) Sor
swept pattern if a nearswept pattern if a near InfiniteInfinite volume ofvolume of
water were displaced to near zero oil cutwater were displaced to near zero oil cut
INJ PROD

Lab Measurements of SorLab Measurements of Sor
 Lab measurements of Sor generally give aLab measurements of Sor generally give a
reasonable approximation of thereasonable approximation of the
ULTIMATE Sor since usually a very largeULTIMATE Sor since usually a very large
number of pore volumes of displacementnumber of pore volumes of displacement
are conducted (10-100 typical)are conducted (10-100 typical)

Waterflooding in DifferingWaterflooding in Differing
Wettability ReservoirsWettability Reservoirs
Cumulative Pore Volumes of Injection
PercentRecoveryOOIP
Breakthrough Sor
Economic Sor
Ultimate Sor

Waterflooding in DifferingWaterflooding in Differing
Wettability ReservoirsWettability Reservoirs
Cumulative Pore Volumes of Injection
PercentRecoveryOOIP

Relative Permeability HysteresisRelative Permeability Hysteresis
 Relative Permeability is not a uniqueRelative Permeability is not a unique
function of saturationfunction of saturation
 The relative permeability value dependsThe 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
RelativePermeability
0 1.0
0
1.0
WATER
OIL

Example – Primary Imbitition –Example – Primary Imbitition –
(Waterflood)(Waterflood)
0 1.0
0
1.0
WATER
OIL

Example –Secondary Drainage –Example –Secondary Drainage –
(ie Gas flood)(ie Gas flood)
0 1.0
0
1.0
WATER
OIL

Effect of Confining (Overburden)Effect of Confining (Overburden)
Pressure on Relative PermeabilityPressure on Relative Permeability
 Increased overburden pressure causesIncreased overburden pressure causes
compaction andcompaction and a reductiona reduction in absolutein absolute
permeabilitypermeability
 Changes inChanges in pore geometrypore geometry may also affectmay also affect
relative permeabilityrelative permeability
 Proper net overburden pressure should beProper net overburden pressure should be
used in all determinationsused in all determinations

Effect of Temperature on RelativeEffect of Temperature on Relative
 Modifies WettabilityModifies Wettability
 Changes Viscosity RatioChanges Viscosity Ratio
 Changes IFTChanges IFT
 May Alter Rel PermMay Alter Rel Perm
 Tests 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 aIFT is a very strong factorvery strong factor in controllingin controlling
residual saturations and relativeresidual saturations and relative
permeability curve endpoints andpermeability curve endpoints and
configurationsconfigurations
 Proper IFT conditions are essential to aProper IFT conditions are essential to a
proper relative permeability determinationproper relative permeability determination

IFT EffectsIFT Effects
 The level of the IFT controls both theThe level of the IFT controls both the
magnitude of the residual saturations inmagnitude of the residual saturations in
accessible pore spaceaccessible pore space and the degree ofand the degree of
‘interference’ between phases‘interference’ between phases
 Residual saturation is controlled byResidual saturation is controlled by
capillary pressure, the lower the IFT, thecapillary 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, poreIs highly dependant on wettability, pore
geometry and pore system accessibilitygeometry and pore system accessibility
 Not all low/zero IFT systems give highNot all low/zero IFT systems give high
recoveryrecovery
 Concept of IFT vs. Mobility dominatedConcept of IFT vs. Mobility dominated
displacements in porous mediadisplacements in porous media

‘‘Classic’ IFT Effects on RelativeClassic’ IFT Effects on Relative
Gas or Water Saturation - Fraction

Using Proper IFTUsing Proper IFT
 Avoid treated fluidsAvoid treated fluids
 Avoid surfactants and de-emulsifiersAvoid surfactants and de-emulsifiers
 Live reservoir fluids should be usedLive reservoir fluids should be used

Viscosity IssuesViscosity Issues

Viscosity EffectsViscosity Effects
 Considerably controversy in the pastConsiderably controversy in the past
 Classically rel perm considered to beClassically rel perm considered to be
purely a rock functionpurely a rock function
 Research has indicated that viscosity ratioResearch has indicated that viscosity ratio
can strongly affect rel perm curvecan strongly affect rel perm curve
configuration and location of endpointsconfiguration and location of endpoints
 Use of proper live reservoir fluids isUse of proper live reservoir fluids is
required to mimic proper viscosity ratiorequired to mimic proper viscosity ratio

Favorable Viscosity Ratio (Favorable Viscosity Ratio (µµdd
>>>>µµinsitu)insitu)RelativePermeability
Water Saturation

Unit Viscosity Ratio (Unit Viscosity Ratio (µµd =d = µµinsitu)insitu)RelativePermeability
Water Saturation

Unfavorable Viscosity Ratio (Unfavorable Viscosity Ratio (µµdd
<<<<µµinsitu)insitu)RelativePermeability
Water Saturation

Initial SaturationsInitial Saturations
 Proper level of initial water saturation inProper level of initial water saturation in
the matrix for testing is essential forthe matrix for testing is essential for
accurate relative permeabilityaccurate relative permeability
measurementsmeasurements
 Value of Swi can strongly effect originalValue of Swi can strongly effect original
Ko or Kg endpoint permeabilityKo or Kg endpoint permeability
 Incorrect values of Swi can have aIncorrect values of Swi can have a
laterally shifting effect on the entirelaterally shifting effect on the entire
relative permeability curverelative permeability curve

Example – Effect of Swi on Ko/KgExample – Effect of Swi on Ko/KgRelativePermeability
Water Saturation

Example – Effect of Swi on RelExample – Effect of Swi on Rel
Perm Curve ConfigurationPerm Curve ConfigurationRelativePermeability
Water Saturation

Presence of a Mobile or ImmobilePresence of a Mobile or Immobile
Third PhaseThird Phase
 Generally free or trapped gas in a water-Generally free or trapped gas in a water-
oil situationoil situation
 Trapped oil saturation may exist in someTrapped oil saturation may exist in some
water-gas systemswater-gas systems
 Trapped saturations generally reduceTrapped saturations generally reduce
perm to both phasesperm to both phases
 Mobile third saturations may selectivelyMobile third saturations may selectively
reduce perm more to one phase thanreduce perm more to one phase than
anotheranother

Example – Presence of TrappedExample – Presence of Trapped
Initial Gas SaturationInitial Gas SaturationRelativePermeability
Water Saturation

Capillary End EffectsCapillary End Effects
 Caused by a discontinuity in capillaryCaused by a discontinuity in capillary
pressure at the outlet face of the corepressure at the outlet face of the core
samplesample

Consequences of an End EffectConsequences of an End Effect
Commence Water
Injection
Delayed Production of Water
& Dp due to End Effect

Consequences of an End EffectConsequences of an End Effect
 Delayed water breakthrough timesDelayed water breakthrough times
 Zone of ‘Stagnant’ fluid at end of sampleZone of ‘Stagnant’ fluid at end of sample
 Reduced apparent perm to water at lowerReduced apparent perm to water at lower
displacement ratesdisplacement rates

Mitigation of End EffectsMitigation of End Effects
 High rates and delta PHigh rates and delta P
 Long coresLong cores
 Pressure tapped coresPressure tapped cores
 Semi permeable membranesSemi permeable membranes
 Numerical simulation methodsNumerical simulation methods
 ‘‘Bump’ floodsBump’ floods

Measurement ofMeasurement of
RelativeRelative
Permeability DataPermeability Data

Common Determination MethodsCommon Determination Methods
 Steady StateSteady State
 Unsteady StateUnsteady State
 CentrifugeCentrifuge
 Ambient vs. Reservoir Condition TestingAmbient vs. Reservoir Condition Testing

Sample SelectionSample Selection
 Rock typing and classificationRock typing and classification
 Single plug vs. composite stacksSingle plug vs. composite stacks
 Plug vs. full diameter testingPlug vs. full diameter testing
 Vertical vs. horizontal flooding methodsVertical vs. horizontal flooding methods

Steady StateSteady State
MethodMethod

The Steady State DeterminationThe Steady State Determination
Method for Relative Permeability (2Method for Relative Permeability (2
Phase)Phase)
Water Saturation
Sample at Initial Conditions of
Water (Irreducible) and Oil
(Maximum) Saturation

Phase)Phase)
Water Saturation
Commence Injection of 100%
Oil at Swi, Measure Ko at
Swi

Phase)Phase)
Water Saturation
Oil and 10% water, Measure Ko
And Kw at New Stabilized
Higher Sw

Phase)Phase)
Water Saturation
Higher Sw

Phase)Phase)
Water Saturation
Oil and 100% water, Measure
Kw at Sorw

Phase)Phase)
Water Saturation

Advantages of the Steady StateAdvantages 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 eliminateTest modifications can reduce or eliminate
impact of capillary end effectsimpact of capillary end effects
 ‘‘Classic’ method of relative permeabilityClassic’ method of relative permeability
determinationdetermination

Disadvantages of the Steady StateDisadvantages of the Steady State
MethodMethod
 Complex and expensive method, very timeComplex and expensive method, very time
consumingconsuming
 Difficult and expensive for full reservoirDifficult and expensive for full reservoir
conditionsconditions
 Large volumes of reservoir fluids requiredLarge volumes of reservoir fluids required
 In-situ saturation monitoring essential forIn-situ saturation monitoring essential for
accuracyaccuracy
 More of a research method in many casesMore 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 Apparatus
Pressure Taps
External Core Sleeve
Flow Head Flow Head

Steady State ApparatusSteady State Apparatus
Water Inj Pump
Oil Inj Pump
Injection Pumps
Coreholder
In-Situ Saturation
Monitoring
Three Phase
Separator
BPR
Piston
Cylinders
Pressure Transducers
Core Sample
OVEN

Common In-situ SaturationCommon In-situ Saturation
Determination MethodsDetermination Methods
 GravimetricGravimetric
 Electrical resistivityElectrical resistivity
 X-rayX-ray
 MRIMRI
 Gamma rayGamma ray
 Microwave 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-Raycounts

Typical Steady State LabTypical Steady State Lab
ApparatusApparatus

Displacement PumpsDisplacement Pumps

UnsteadyUnsteady
State MethodState Method

Unsteady State Method for RelativeUnsteady State Method for Relative
Permeability (2 Phase)Permeability (2 Phase)
Water Saturation
Sample at Initial Conditions of
Water (Irreducible) and Oil
(Maximum) Saturation

Unsteady Steady State Method forUnsteady Steady State Method for
Relative Permeability (2 Phase)Relative Permeability (2 Phase)
Water Saturation
Oil at Swi, Measure Ko at
Swi

Unsteady Steady State Method forUnsteady Steady State Method for
Relative Permeability (2 Phase)Relative Permeability (2 Phase)
Water Saturation
Switch to Injection of 100%
Water at Swi, Measure Transient
Pressure and Production
History

Transient Pressure and ProductionTransient Pressure and Production
HistoryHistory
DifferentialPressure
Cumulative Run Time
Breakthrough
Point

HistoryHistory
ProductionRate
Cumulative Run Time
Breakthrough
Point

HistoryHistory
ProductionVolume
Cumulative Run Time
Breakthrough
Point

The Unsteady State DeterminationThe Unsteady State Determination
Phase)Phase)
Water Saturation

Advantages of the Unsteady StateAdvantages of the Unsteady State
MethodMethod
 RapidRapid
 Relatively inexpensive, even for fullRelatively inexpensive, even for full
reservoir condition HTHP testsreservoir condition HTHP tests
 Limited reservoir fluid requirementsLimited reservoir fluid requirements
 Easy to run at full reservoir conditionsEasy to run at full reservoir conditions
 Simpler equipment and procedures thanSimpler equipment and procedures than
steady statesteady state

Disadvantages of the UnsteadyDisadvantages of the Unsteady
State MethodState Method
 Unstable flow possibleUnstable flow possible
 Capillary end effects possibleCapillary end effects possible
 More complex data reduction proceduresMore complex data reduction procedures
 Data may be poorly conditionedData may be poorly conditioned
depending on computational method useddepending on computational method used
to regress transient lab resultsto regress transient lab results

Typical Unsteady State ApparatusTypical Unsteady State Apparatus
Injection Pump
Coreholder
Three Phase
Separator
BPR
Piston
Cylinders
Pressure Transducers
Core Sample
OVEN

Typical Unsteady State ApparatusTypical Unsteady State Apparatus

Centrifuge MethodsCentrifuge Methods
 Use transient production vs. capillary pressureUse 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 permLimited to very small samples and higher perm
mediamedia
 Reservoir condition tests can not be easilyReservoir condition tests can not be easily
conductedconducted
 Common requirement to augment SS or USS relCommon 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 matchedSwir 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 Use
 Many of the limitations of the unsteadyMany of the limitations of the unsteady
state method have been overcome instate method have been overcome in
recent years by experimental andrecent years by experimental and
numerical modificationsnumerical modifications
 95% plus of all commercial rel perm95% plus of all commercial rel perm
measurements are conducted usingmeasurements 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
Results in Highly
Compressed Saturation
Range

Fw
Average Sw
Water Saturation

Fw
Average Sw
Water Saturation
Results in a More
Dispersed Saturation
Range

Common Techniques Used in theCommon Techniques Used in the
Past to Disperse FlowPast to Disperse Flow
 Viscous refines oils used instead ofViscous refines oils used instead of
reservoir oil to ‘smear’ production profilereservoir oil to ‘smear’ production profile
 Problem – wrong viscosity, IFT andProblem – wrong viscosity, IFT and
possibly wettabilitypossibly wettability
 High rate displacementsHigh rate displacements
 Problem – unstable flowProblem – unstable flow

Overcoming TheseOvercoming These
Deficiencies UsingDeficiencies Using
Modern SimulationModern 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 technique
 Basically a numerical simulation study inBasically a numerical simulation study in
reversereverse

History Matching TechniqueHistory Matching Technique
 In a normal simulation we know the relIn a normal simulation we know the rel
perm curves and we use this, along withperm curves and we use this, along with
other input data, to predict the reservoirother input data, to predict the reservoir
pressure and production historypressure and production history
 In the history matching method we knowIn the history matching method we know
the pressure and production history fromthe pressure and production history from
the lab tests, and we use this data in anthe lab tests, and we use this data in an
iterative fashion to generate the rel permiterative fashion to generate the rel perm
curvescurves

Typical History Match ModelTypical History Match Model
Input Physical Parameters (L, A, Kabs, Porosity, Pore Volume, # Blocks
Input Fluid Properties – Viscosity, Density, Rate, Initial Saturations
Input Test Properties – Endpoint Perms and Saturations, Pressure
History, Production History
Input Cap Pressure
and Outlet
Boundary Cond-
ition to Model
Capillary Effects

The HistoryThe History
MatchingMatching
ProcessProcess

Time Time Saturation
CumulativeProduction
Step 1 – Pick Functional Form
For Rel Perm Curve
Step 2 – Pick Initial ‘Guess’
For Rel Perm Curve Configuration

Time Time Saturation
CumulativeProduction

History Matching ProcessHistory Matching Process
 Continue the iterative process until theContinue the iterative process until the
error between the stimulated and actualerror between the stimulated and actual
production and pressure data is as smallproduction and pressure data is as small
as possibleas possible
 The resulting set of rel perm curvesThe resulting set of rel perm curves
represent the best fit to the lab generatedrepresent the best fit to the lab generated
datadata
 Algorithms to avoid localized or non-Algorithms to avoid localized or non-
physical solutionsphysical solutions

Conventional Relative PermeabilityConventional Relative Permeability
TestsTests
 Only provide data in the range of mobileOnly provide data in the range of mobile
fluid saturationsfluid saturations
 Presence and effect of critical fluidPresence and effect of critical fluid
saturations is essential in many processessaturations is essential in many processes
 Special tests and procedures are requiredSpecial tests and procedures are required
to precisely measure these saturationsto 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 floods
 Constant IFT floodsConstant IFT floods
 Above are two examples of super normalAbove 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 saturationStop at trapped gas – residual gas saturation

Typical critical condensateTypical critical condensate
apparatusapparatus

Constant IFT FloodsConstant IFT Floods
 Create 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 drive
 Create low IFT injection gas & oilCreate low IFT injection gas & oil
ie models deep reservoir for vaporizing driveie models deep reservoir for vaporizing drive
 Run two floods on matched core stacksRun two floods on matched core stacks
 Compare results to determine IFTCompare results to determine IFT
domination versus other controls ofdomination versus other controls of
incremental oil recoveryincremental oil recovery
Ie mobility, pore geometry…Ie mobility, pore geometry…

Vaporizing MiscibilityVaporizing Miscibility
Fluid PreparationFluid Preparation
Rich Gas
Lean Gas
Low IFT
Oil
High IFT
Oil
Flood #1
Made From:
Flood #2
Made From:

Condensing MiscibilityCondensing Miscibility
Fluid PreparationFluid Preparation
Leaner GasRich Gas
High IFT
Oil
Low IFT
Oil
Flood #1
Made from:
Flood #2
Made From:

Constant IFT FloodConstant IFT Flood
Reservoir Dominated byReservoir Dominated by IFTIFT
Gas Saturation - Fraction

Constant IFT FloodConstant IFT Flood
Reservoir Dominated byReservoir Dominated by MobilityMobility
Gas Saturation - Fraction

ConclusionsConclusions
 Many controls / influences on relativeMany controls / influences on relative
permeabilitypermeability
 Live oil & reservoir conditions necessaryLive oil & reservoir conditions necessary
 Specialty floods for extension of routineSpecialty floods for extension of routine
relative permeability applicationsrelative permeability applications

Relative permeability presentation

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Relative permeability presentation