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Relative permeability presentation

The document discusses relative permeability, which describes the ability of fluids to flow through porous media in the presence of other fluids. It covers factors that affect relative permeability like fluid saturations, rock properties, wettability, and pressure. Different wettability types can impact relative permeability curves and residual saturations. Mobility ratios also influence waterflood performance. Proper representation and measurement of relative permeability is important for reservoir evaluation and optimization.

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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 PermeabilityPermeability  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 PermeabilityPermeability Water Saturation Gas Saturation Liquid Saturation
Saturation Effects on RelativeSaturation Effects on Relative PermeabilityPermeability  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  Refers to residual oil saturation in theRefers to residual oil saturation in the swept pattern at the time ofswept pattern at the time of MaximumMaximum EconomicEconomic water cutwater cut INJ PROD
Ultimate (True) SorUltimate (True) Sor  Refers to residual oil saturation in theRefers to residual oil saturation in the 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
Waterflooding in DifferingWaterflooding in Differing Wettability ReservoirsWettability Reservoirs Cumulative Pore Volumes of Injection PercentRecoveryOOIP
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) Water Saturation – Fraction of Pore Space RelativePermeability 0 1.0 0 1.0 WATER OIL
Example – Primary Imbitition –Example – Primary Imbitition – (Waterflood)(Waterflood) Water Saturation – Fraction of Pore Space RelativePermeability 0 1.0 0 1.0 WATER OIL
Example –Secondary Drainage –Example –Secondary Drainage – (ie Gas flood)(ie Gas flood) Water Saturation – Fraction of Pore Space RelativePermeability 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 PermeabilityPermeability  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 PermeabilityPermeability Gas or Water Saturation - Fraction RelativePermeability
‘‘Classic’ IFT Effects on RelativeClassic’ IFT Effects on Relative PermeabilityPermeability Gas or Water Saturation - Fraction RelativePermeability
‘‘Classic’ IFT Effects on RelativeClassic’ IFT Effects on Relative PermeabilityPermeability Gas or Water Saturation - Fraction RelativePermeability
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 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
Example – Presence of TrappedExample – Presence of Trapped Initial Gas SaturationInitial Gas SaturationRelativePermeability Water Saturation
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) RelativePermeability Water Saturation Sample at Initial Conditions of Water (Irreducible) and Oil (Maximum) Saturation
The Steady State DeterminationThe Steady State Determination Method for Relative Permeability (2Method for Relative Permeability (2 Phase)Phase) RelativePermeability Water Saturation Commence Injection of 100% Oil at Swi, Measure Ko at Swi
The Steady State DeterminationThe Steady State Determination Method for Relative Permeability (2Method for Relative Permeability (2 Phase)Phase) RelativePermeability Water Saturation Commence Injection of 90% Oil and 10% water, Measure Ko And Kw at New Stabilized Higher Sw
The Steady State DeterminationThe Steady State Determination Method for Relative Permeability (2Method for Relative Permeability (2 Phase)Phase) RelativePermeability Water Saturation Commence Injection of 70% Oil and 30% water, Measure Ko And Kw at New Stabilized Higher Sw
The Steady State DeterminationThe Steady State Determination Method for Relative Permeability (2Method for Relative Permeability (2 Phase)Phase) RelativePermeability Water Saturation Commence Injection of 30% Oil and 70% water, Measure Ko And Kw at New Stabilized Higher Sw
The Steady State DeterminationThe Steady State Determination Method for Relative Permeability (2Method for Relative Permeability (2 Phase)Phase) RelativePermeability Water Saturation Commence Injection of 10% Oil and 90% water, Measure Ko And Kw at New Stabilized Higher Sw
The Steady State DeterminationThe Steady State Determination Method for Relative Permeability (2Method for Relative Permeability (2 Phase)Phase) RelativePermeability Water Saturation Commence Injection of 0% Oil and 100% water, Measure Kw at Sorw
The Steady State DeterminationThe Steady State Determination Method for Relative Permeability (2Method for Relative Permeability (2 Phase)Phase) RelativePermeability 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) RelativePermeability 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) RelativePermeability Water Saturation Commence Injection of 100% Oil at Swi, Measure Ko at Swi
Unsteady Steady State Method forUnsteady Steady State Method for Relative Permeability (2 Phase)Relative Permeability (2 Phase) RelativePermeability 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
Transient Pressure and ProductionTransient Pressure and Production HistoryHistory ProductionRate Cumulative Run Time Breakthrough Point
Transient Pressure and ProductionTransient Pressure and Production HistoryHistory ProductionVolume Cumulative Run Time Breakthrough Point
The Unsteady State DeterminationThe Unsteady State Determination Method for Relative Permeability (2Method for Relative Permeability (2 Phase)Phase) RelativePermeability 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 RelativePermeability Results in Highly Compressed Saturation Range
Requirement for Two Phase FlowRequirement for Two Phase Flow Fw Average Sw Water Saturation RelativePermeability
Requirement for Two Phase FlowRequirement for Two Phase Flow Fw Average Sw Water Saturation RelativePermeability Results in a More Dispersed Saturation Range
Requirement for Two Phase FlowRequirement for Two Phase Flow Fw Average Sw Water Saturation RelativePermeability
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 DifferentialPressure RelativePermeability Step 1 – Pick Functional Form For Rel Perm Curve Step 2 – Pick Initial ‘Guess’ For Rel Perm Curve Configuration
Time Time Saturation CumulativeProduction DifferentialPressure RelativePermeability
Time Time Saturation CumulativeProduction DifferentialPressure RelativePermeability
Time Time Saturation CumulativeProduction DifferentialPressure RelativePermeability
Time Time Saturation CumulativeProduction DifferentialPressure RelativePermeability
Time Time Saturation CumulativeProduction DifferentialPressure RelativePermeability
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
Time Time Saturation CumulativeProduction DifferentialPressure RelativePermeability
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 RelativePermeability
Constant IFT FloodConstant IFT Flood Reservoir Dominated byReservoir Dominated by MobilityMobility Gas Saturation - Fraction RelativePermeability
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
Thank you!Thank you!

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Relative permeability presentation

  • 1.
    Relative Permeability DisplayVersionRelative Permeability Display Version RelativeRelative PermeabilityPermeability April 2005April 2005
  • 2.
    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
  • 3.
    Common Uses ofRelativeCommon 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
  • 4.
    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
  • 5.
    Darcy’s Law forSINGLE 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
  • 6.
    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
  • 7.
    Relative Permeability DefinitionRelativePermeability 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
  • 8.
    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
  • 9.
    ‘‘Normalized’ Relative PermeabilityNormalized’Relative Permeability 1.0 0.0 0.0 1.0SATURATION KRO @ Swi = 1.00
  • 10.
    ‘‘Absolute’ Relative PermBasisAbsolute’ Relative Perm Basis 1.0 0.0 0.0 1.0SATURATION KRO @ Swi = Ko Kabs
  • 11.
    Which Method ofRepresentation 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)
  • 12.
    Saturation ConceptsSaturation Concepts SinitScrit 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
  • 13.
    Major Factors ImpactingRelativeMajor Factors Impacting Relative PermeabilityPermeability  Fluid SaturationsFluid Saturations  Rock PropertiesRock Properties  WettabilityWettability  Saturation HistorySaturation History
  • 14.
    Other Factors WhichAlso 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
  • 15.
    Saturation Effects onRelativeSaturation Effects on Relative PermeabilityPermeability Water Saturation Gas Saturation Liquid Saturation
  • 16.
    Saturation Effects onRelativeSaturation Effects on Relative PermeabilityPermeability  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
  • 17.
    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
  • 18.
    Example of RelPerm Curves for aExample of Rel Perm Curves for a System Dominated bySystem Dominated by Macroporosity (e.g. – fractures)Macroporosity (e.g. – fractures)
  • 19.
    More Uniform Intergranular/MatrixMoreUniform Intergranular/Matrix Type Porosity SystemType Porosity System
  • 20.
    Macroporous Flow SystemWithMacroporous Flow System With MicroporosityMicroporosity
  • 21.
  • 22.
    Flow Parallel toBedding PlanesFlow Parallel to Bedding Planes
  • 23.
    Flow Perpendicular toBeddingFlow Perpendicular to Bedding PlanesPlanes
  • 24.
    WettabilityWettability The fluid thatcoats the rock pores Also describes the wettability Nature of that reservoir
  • 25.
    Wettability TypesWettability Types Water WetWater Wet  Oil WetOil Wet  Neutral WetNeutral Wet  Mixed WetMixed Wet  Spotted/Dalmation WetSpotted/Dalmation Wet
  • 26.
    Relative PermeabilityRelative Permeability WaterSaturation - Fraction RelativePermeability-Fraction Swi 10% Crossover 22% Sw Krw = 0.88 Swi approx 25% Crossover approx 68% Krw = 0.08
  • 27.
    Typical RelativeTypical Relative PermeabilityCurvePermeability Curve Configurations for OtherConfigurations for Other Wettability TypesWettability Types
  • 28.
    Neutral Wet FormationsNeutralWet Formations Swi 10-20% Crossover around 50% Krw = 0.45
  • 29.
    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
  • 30.
    Typical Mixed WettabilityRelativeTypical Mixed Wettability Relative Permeability CurvesPermeability Curves Swi = 40% Crossover approx 55% Krw = 0.70
  • 31.
  • 32.
  • 33.
    Concept of ‘MobilityRatio’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
  • 34.
    Factors Improving MobilityFactorsImproving Mobility M = µο x Krw µ w x K r o Low Oil ViscosityLow Krw/Krg Value High Displacing Phase Viscosity High Kro Value
  • 35.
    Example – Waterfloodin aExample – Waterflood in a Favorable Mobility System (M=0.5)Favorable Mobility System (M=0.5)
  • 36.
    Example – Waterfloodin aExample – Waterflood in a Unfavorable Mobility SystemUnfavorable Mobility System (M=20)(M=20)
  • 37.
    Residual Oil SaturationsinResidual Oil Saturations in WaterfloodsWaterfloods  BREAKTHROUGHBREAKTHROUGH SorSor  ECONOMICECONOMIC SorSor  ULTIMATEULTIMATE SorSor
  • 38.
    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
  • 39.
    Economic SorEconomic 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 MaximumMaximum EconomicEconomic water cutwater cut INJ PROD
  • 40.
    Ultimate (True) SorUltimate(True) Sor  Refers to residual oil saturation in theRefers to residual oil saturation in the 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
  • 41.
    Lab Measurements ofSorLab 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)
  • 42.
    Waterflooding in DifferingWaterfloodingin Differing Wettability ReservoirsWettability Reservoirs Cumulative Pore Volumes of Injection PercentRecoveryOOIP Breakthrough Sor Economic Sor Ultimate Sor
  • 43.
    Waterflooding in DifferingWaterfloodingin Differing Wettability ReservoirsWettability Reservoirs Cumulative Pore Volumes of Injection PercentRecoveryOOIP
  • 44.
    Waterflooding in DifferingWaterfloodingin Differing Wettability ReservoirsWettability Reservoirs Cumulative Pore Volumes of Injection PercentRecoveryOOIP
  • 45.
    Waterflooding in DifferingWaterfloodingin Differing Wettability ReservoirsWettability Reservoirs Cumulative Pore Volumes of Injection PercentRecoveryOOIP
  • 46.
    Relative Permeability HysteresisRelativePermeability 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
  • 47.
    Example – PrimaryDrainage –Example – Primary Drainage – Initial Reservoir SaturationInitial Reservoir Saturation Water Saturation – Fraction of Pore Space RelativePermeability 0 1.0 0 1.0 WATER OIL
  • 48.
    Example – PrimaryImbitition –Example – Primary Imbitition – (Waterflood)(Waterflood) Water Saturation – Fraction of Pore Space RelativePermeability 0 1.0 0 1.0 WATER OIL
  • 49.
    Example – PrimaryImbitition –Example – Primary Imbitition – (Waterflood)(Waterflood) Water Saturation – Fraction of Pore Space RelativePermeability 0 1.0 0 1.0 WATER OIL
  • 50.
    Example –Secondary Drainage–Example –Secondary Drainage – (ie Gas flood)(ie Gas flood) Water Saturation – Fraction of Pore Space RelativePermeability 0 1.0 0 1.0 WATER OIL
  • 51.
    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
  • 52.
    Effect of Temperatureon RelativeEffect of Temperature on Relative PermeabilityPermeability  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
  • 53.
    Effect of InterfacialTension (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
  • 54.
    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
  • 55.
    Effect of IFTon 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
  • 56.
    ‘‘Classic’ IFT Effectson RelativeClassic’ IFT Effects on Relative PermeabilityPermeability Gas or Water Saturation - Fraction RelativePermeability
  • 57.
    ‘‘Classic’ IFT Effectson RelativeClassic’ IFT Effects on Relative PermeabilityPermeability Gas or Water Saturation - Fraction RelativePermeability
  • 58.
    ‘‘Classic’ IFT Effectson RelativeClassic’ IFT Effects on Relative PermeabilityPermeability Gas or Water Saturation - Fraction RelativePermeability
  • 59.
    Using Proper IFTUsingProper 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
  • 60.
  • 61.
  • 62.
    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
  • 63.
    Favorable Viscosity Ratio(Favorable Viscosity Ratio (µµdd >>>>µµinsitu)insitu)RelativePermeability Water Saturation
  • 64.
    Unit Viscosity Ratio(Unit Viscosity Ratio (µµd =d = µµinsitu)insitu)RelativePermeability Water Saturation
  • 65.
    Unfavorable Viscosity Ratio(Unfavorable Viscosity Ratio (µµdd <<<<µµinsitu)insitu)RelativePermeability Water Saturation
  • 66.
    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
  • 67.
    Example – Effectof Swi on Ko/KgExample – Effect of Swi on Ko/KgRelativePermeability Water Saturation
  • 68.
    Example – Effectof Swi on RelExample – Effect of Swi on Rel Perm Curve ConfigurationPerm Curve ConfigurationRelativePermeability Water Saturation
  • 69.
    Presence of aMobile 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
  • 70.
    Example – Presenceof TrappedExample – Presence of Trapped Initial Gas SaturationInitial Gas SaturationRelativePermeability Water Saturation
  • 71.
    Example – Presenceof TrappedExample – Presence of Trapped Initial Gas SaturationInitial Gas SaturationRelativePermeability Water Saturation
  • 72.
    Example – Presenceof TrappedExample – Presence of Trapped Initial Gas SaturationInitial Gas SaturationRelativePermeability Water Saturation
  • 73.
    Capillary End EffectsCapillaryEnd 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
  • 74.
    Consequences of anEnd EffectConsequences of an End Effect Commence Water Injection Delayed Production of Water & Dp due to End Effect
  • 75.
    Consequences of anEnd 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
  • 76.
    Mitigation of EndEffectsMitigation 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
  • 77.
  • 78.
    Common Determination MethodsCommonDetermination Methods  Steady StateSteady State  Unsteady StateUnsteady State  CentrifugeCentrifuge  Ambient vs. Reservoir Condition TestingAmbient vs. Reservoir Condition Testing
  • 79.
    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
  • 80.
  • 81.
    The Steady StateDeterminationThe Steady State Determination Method for Relative Permeability (2Method for Relative Permeability (2 Phase)Phase) RelativePermeability Water Saturation Sample at Initial Conditions of Water (Irreducible) and Oil (Maximum) Saturation
  • 82.
    The Steady StateDeterminationThe Steady State Determination Method for Relative Permeability (2Method for Relative Permeability (2 Phase)Phase) RelativePermeability Water Saturation Commence Injection of 100% Oil at Swi, Measure Ko at Swi
  • 83.
    The Steady StateDeterminationThe Steady State Determination Method for Relative Permeability (2Method for Relative Permeability (2 Phase)Phase) RelativePermeability Water Saturation Commence Injection of 90% Oil and 10% water, Measure Ko And Kw at New Stabilized Higher Sw
  • 84.
    The Steady StateDeterminationThe Steady State Determination Method for Relative Permeability (2Method for Relative Permeability (2 Phase)Phase) RelativePermeability Water Saturation Commence Injection of 70% Oil and 30% water, Measure Ko And Kw at New Stabilized Higher Sw
  • 85.
    The Steady StateDeterminationThe Steady State Determination Method for Relative Permeability (2Method for Relative Permeability (2 Phase)Phase) RelativePermeability Water Saturation Commence Injection of 30% Oil and 70% water, Measure Ko And Kw at New Stabilized Higher Sw
  • 86.
    The Steady StateDeterminationThe Steady State Determination Method for Relative Permeability (2Method for Relative Permeability (2 Phase)Phase) RelativePermeability Water Saturation Commence Injection of 10% Oil and 90% water, Measure Ko And Kw at New Stabilized Higher Sw
  • 87.
    The Steady StateDeterminationThe Steady State Determination Method for Relative Permeability (2Method for Relative Permeability (2 Phase)Phase) RelativePermeability Water Saturation Commence Injection of 0% Oil and 100% water, Measure Kw at Sorw
  • 88.
    The Steady StateDeterminationThe Steady State Determination Method for Relative Permeability (2Method for Relative Permeability (2 Phase)Phase) RelativePermeability Water Saturation
  • 89.
    Advantages of theSteady 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
  • 90.
    Disadvantages of theSteady 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
  • 91.
    Typical Steady StateApparatusTypical Steady State Apparatus Capillary Contact Paper Inlet Section Outlet Section
  • 92.
    Typical Steady StateApparatusTypical Steady State Apparatus Pressure Taps External Core Sleeve Flow Head Flow Head
  • 93.
    Steady State ApparatusSteadyState 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
  • 94.
    Common In-situ SaturationCommonIn-situ Saturation Determination MethodsDetermination Methods  GravimetricGravimetric  Electrical resistivityElectrical resistivity  X-rayX-ray  MRIMRI  Gamma rayGamma ray  Microwave attenuationMicrowave attenuation
  • 95.
    X-Ray SaturationX-Ray Saturation MannvilleSamples 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
  • 96.
    Typical Steady StateLabTypical Steady State Lab ApparatusApparatus
  • 97.
  • 98.
  • 99.
    Unsteady State Methodfor RelativeUnsteady State Method for Relative Permeability (2 Phase)Permeability (2 Phase) RelativePermeability Water Saturation Sample at Initial Conditions of Water (Irreducible) and Oil (Maximum) Saturation
  • 100.
    Unsteady Steady StateMethod forUnsteady Steady State Method for Relative Permeability (2 Phase)Relative Permeability (2 Phase) RelativePermeability Water Saturation Commence Injection of 100% Oil at Swi, Measure Ko at Swi
  • 101.
    Unsteady Steady StateMethod forUnsteady Steady State Method for Relative Permeability (2 Phase)Relative Permeability (2 Phase) RelativePermeability Water Saturation Switch to Injection of 100% Water at Swi, Measure Transient Pressure and Production History
  • 102.
    Transient Pressure andProductionTransient Pressure and Production HistoryHistory DifferentialPressure Cumulative Run Time Breakthrough Point
  • 103.
    Transient Pressure andProductionTransient Pressure and Production HistoryHistory ProductionRate Cumulative Run Time Breakthrough Point
  • 104.
    Transient Pressure andProductionTransient Pressure and Production HistoryHistory ProductionVolume Cumulative Run Time Breakthrough Point
  • 105.
    The Unsteady StateDeterminationThe Unsteady State Determination Method for Relative Permeability (2Method for Relative Permeability (2 Phase)Phase) RelativePermeability Water Saturation
  • 106.
    Advantages of theUnsteady 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
  • 107.
    Disadvantages of theUnsteadyDisadvantages 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
  • 108.
    Typical Unsteady StateApparatusTypical Unsteady State Apparatus Injection Pump Coreholder Three Phase Separator BPR Piston Cylinders Pressure Transducers Core Sample OVEN
  • 109.
    Typical Unsteady StateApparatusTypical Unsteady State Apparatus
  • 110.
    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
  • 111.
    What is theBest Method to Use?What is the Best Method to Use?
  • 112.
    What is theBest 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
  • 113.
    Requirement for TwoPhase FlowRequirement for Two Phase Flow Fw Average Sw Water Saturation RelativePermeability Results in Highly Compressed Saturation Range
  • 114.
    Requirement for TwoPhase FlowRequirement for Two Phase Flow Fw Average Sw Water Saturation RelativePermeability
  • 115.
    Requirement for TwoPhase FlowRequirement for Two Phase Flow Fw Average Sw Water Saturation RelativePermeability Results in a More Dispersed Saturation Range
  • 116.
    Requirement for TwoPhase FlowRequirement for Two Phase Flow Fw Average Sw Water Saturation RelativePermeability
  • 117.
    Common Techniques Usedin 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
  • 118.
    Overcoming TheseOvercoming These DeficienciesUsingDeficiencies Using Modern SimulationModern Simulation MethodsMethods
  • 119.
    Simulation or ‘HistoryMatching’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
  • 120.
    History Matching TechniqueHistoryMatching 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
  • 121.
    Typical History MatchModelTypical 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
  • 122.
  • 123.
    Time Time Saturation CumulativeProduction DifferentialPressure RelativePermeability Step1 – Pick Functional Form For Rel Perm Curve Step 2 – Pick Initial ‘Guess’ For Rel Perm Curve Configuration
  • 124.
  • 125.
  • 126.
  • 127.
  • 128.
  • 129.
    History Matching ProcessHistoryMatching 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
  • 130.
  • 131.
    Conventional Relative PermeabilityConventionalRelative 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
  • 132.
    Specialty Rel PermExperimentsSpecialty 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
  • 133.
    Critical condensate floodsCriticalcondensate 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
  • 134.
    Typical critical condensateTypicalcritical condensate apparatusapparatus
  • 135.
    Constant IFT FloodsConstantIFT 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…
  • 136.
    Vaporizing MiscibilityVaporizing Miscibility FluidPreparationFluid Preparation Rich Gas Lean Gas Low IFT Oil High IFT Oil Flood #1 Made From: Flood #2 Made From:
  • 137.
    Condensing MiscibilityCondensing Miscibility FluidPreparationFluid Preparation Leaner GasRich Gas High IFT Oil Low IFT Oil Flood #1 Made from: Flood #2 Made From:
  • 138.
    Constant IFT FloodConstantIFT Flood Reservoir Dominated byReservoir Dominated by IFTIFT Gas Saturation - Fraction RelativePermeability
  • 139.
    Constant IFT FloodConstantIFT Flood Reservoir Dominated byReservoir Dominated by MobilityMobility Gas Saturation - Fraction RelativePermeability
  • 140.
    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
  • 141.