Results

Acknowledgement:

Assignment and Calibration of Relative Permeability by Hydrostratigraphic Units: A Novel Approach for Multiphase Flow Analyses

Case Study: CO2-EOR Operations at the Farnsworth Unit, Texas

NumericalModel

RelativePermeabilityRelationships

AbstractAmongthemostcriticalfactorsforgeologicalCO2 storagesitescreening,selectionandoperationiseffectivesimulationofmultiphaseflow

andtransport.Relativepermeabilityisprobablythegreatestsourceofpotentialuncertaintyinmultiphaseflowsimulation,secondonlytointrinsicpermeabilityheterogeneity.ThespecificrelativepermeabilityrelationshipassignedgreatlyimpactsforecastsofCO2 trappingmechanisms,phasebehavior,andlong-termplumemovement.AprimarygoalofthisstudyistoevaluatetheimpactsandimplicationsonCO2-EORmodelforecastsofdifferentmethodsofassigningrelativepermeabilityrelationships.Weappliedanovelapproachtoassigningrelativepermeabilityrelationshipsinnumericalmodels.Inpreviousresearch,most models

assignrelativepermeabilityfunctionsonthebasisofgeologicformationorrocktype.Inthisstudy,weassignandcalibraterelativepermeabilitybyhydrostratigraphicunits,extendingtheseminalworkofMaxey(1964)tomultiphaseflow.OngoingworkbytheSWPhasidentifieddistinctregionsthatarebelievedtoexhibitsimilarflowcharacteristicsusingtheImprovedHydraulicFlowUnits (IHFU)method.Corefromeachoftheseflowregionswasscannedbymicro-computer-tomography(micro-CT)andMercuryIntrusionCapillaryPressure(MICP)measurementswerecompleted.Specific,constrainedrelativepermeabilityrelationshipswereassignedtoeachhydrostratigraphicunit.Resultsofforwardsimulationswiththenewly-calibratedmodelswillbecomparedtothoseofexistingmodelaswellasawiderangeofdifferentrelativepermeabilityrelationship.ThestudysiteistheFarnsworthUnit(FWU)inthenortheastTexasPanhandle,anactiveCO2-EORoperation.Thetargetformationisthe

Morrow‘B’Sandstone,aclasticformationcomposedofmediumtocoursesands.ThestudywasundertakenaspartoftheSouthwestRegionalPartnershiponCarbonSequestration(SWP)underAwardNo.DE-FC26-05NT42591.

TwoApproaches1. SingleRelativePermeabilitycurveassignedtothewholemodeldomain:[1]MorrowSandstonerelativepermeabilityrelationship,[2]

Linearrelativepermeabilityrelationship,[3-5]eachindividualHydraulicFlowUnit(HFU)curvefromallthreeRegionmodels

HydraulicFlowUnit(HFU)relativepermeabilitycurves• [3]Region1curvesvarythecurveparameterlambdaandthe

saturationend-points• [4]Region2curvesvarythecurveparameterlambda,the

saturationend-points,andtherelativepermeabilityend-points• [5]Regions3curvesvarythecurveparameterlambdaandthe

saturationend-pointsweredeterminedfrommercuryintrusioncapillarypressuremeasurementsforeachoftheHydraulicFlowUnits(HFU)

ModelDomain

Nathan Moodie, William Ampomah, Wei Jia, Brian McPherson

FundingforthisprojectisprovidedbytheU.S.DepartmentofEnergy's(DOE)NationalEnergyTechnologyLaboratory(NETL)throughtheSouthwestRegionalPartnershiponCarbonSequestration(SWP)underAwardNo.DE-FC26-05NT42591

FarnsworthUnit,OchiltreeCounty,TexasMatureoilfieldintheAnadarkoBasin• Primaryproductionstartingin1955• Waterflooding startsinlate1964• CO2-EORstartsinlate2010• EstimatedOOIP~120millionbarrels• Averagepaythicknessis22ft

#13-10AInjectionwell

PetrelE&PSoftwarePlatform• 3-DMeshcreation– 103x95x4(x,y,z)with33,756active

cells• Gridpropertiescreation– permeability&porosity

distribution• Initialconditionsassignment– Watersaturation,Oil

saturation,andPressure- INCONdatafromhistorymatchedwaterfloodmodel

• WaterAlternatingGas(WAG)schedulefor22injectionwells– pureCO2 usedasgasstream

• Bottomholepressurelimits(2400psi)for35productionwells

- Wellsshutwhenwatercutisabove98%

• ThetotalamountofstoredCO2 predictedisbetween3.0milliontonsand3.4milliontonsacrossallofthecurvesstudied• TheRegions3modelpredicts14%moreCO2 asamobilephaseand8%lessdissolvedphasewhencomparedtotheBaseCase• ThethreeHFUregionsmodels(Regions1,2,3)showa26%varianceinfreegasinplaceandonlya3%variationinthetotalgasinplace• Thereisa79%differenceinthevolumeoffreeCO2 predictedacrossallrelativepermeabilitycurvestested• Thereisa49%differenceinthedissolvedgasphaseacrossalltherelativepermeabilitycurvestested

FlowRegions

GasInPlace,freegasanddissolvedgas

HydraulicFlowUnits(HFU)mapoftheentirereservoirshowingthesimulationmodeldomainoutlinedinred.HydraulicFlowUnitswereidentifiedbyD.Ross-Cross,W.Ampomah etal.(2016)(SPE-180375-MS)andusedforthefivegroupedsaturationregionsinthesimulationmodels;HFU1-2,HFU3-4,HFU5,HFU6,HFU7-8.

RelativePermeabilityassignmentbyhydrostratigraphicunits.UniquehydrostratigraphicunitsweredelineatedasHydraulicFlowUnit(HFU)wherethepropertiesthatcontrolfluidflowareinternallyconsistentbutdistinctfromotherrockunits.TheWinland R35methodwasusedtoidentifytheHFUsbyprovidingameansofcorrelatingporositytopermeabilitybyassumingthatwhenasampleis35%saturatedduringaMICPtestcontinuousflowpathsareestablished.Theseflowunitsarethenassignedarelativepermeabilitycurveandforwardsimulationswerecarriedouttoelucidatetheinfluenceofthismethod.

FWUfaultsmodelwithalltheinjectionandproductionwellsusedinthisstudy.Faultsarenotbarrierstoflowinthismodel.

InitialConditionsInitialoilsaturationandwatersaturationwasderivedfromahistorymatchedprimaryproductionandwaterflooding simulation.

OilSaturation WaterSaturation

Permeabilitydistributioninthesimulationmodel.ThisdistributionwasusedtocreatetheHFUrelationshipbytheSWP

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10,000,000

20,000,000

30,000,000

40,000,000

50,000,000

60,000,000

Gas

Vol

ume

[MSC

F]

Date

Gas in place

-5,000,000

10,000,000 15,000,000 20,000,000 25,000,000 30,000,000 35,000,000 40,000,000 45,000,000 50,000,000

Gas

Vol

ume

[MSC

F]

Date

Solution gas in place

-

5,000,000

10,000,000

15,000,000

20,000,000

25,000,000

30,000,000

Gas

Vol

ume

[MSC

F]

Date

Free gas in place

3,000 3,200 3,400 3,600 3,800 4,000 4,200 4,400 4,600 4,800 5,000

Pres

sure

[psi

]

Date

Pressure

Base Model Regions3 Model

Three-phasesaturationmapsattheendofthesimulation(20yearsofCO2-EOR)TheBaseCaseandRegions3modelshadverysimilarpressureprofilesbutdifferentCO2 phasedistribution,oilproduction,andgasproduction.TheyellowandbrownboxeshighlightareasofsignificantvariationbetweentheBaseModelandtheRegions3Model[1].TheCO2 plumesaroundeachoftheinjectionwellsintheRegions3modelshowalotofvariationfromtheBaseCasemodel,withsomewellspredictingfarlessgasphase,especiallyintheSouth-centralportionofthereservoir.Whentheendcasesareevaluated,Region2modelHFU1-2andHFU7-8relativepermeabilitycurves,thedifferenceinphasepredictionsisdrastic[2].

BM

-M2-

Def

3RP

BM

-M2-

StnI

3RP

LM

R1

R1-

HFU

1-2 R

1-H

FU3-

4

R1-

HFU

5

R1-

HFU

6

R1-

HFU

7-8

R2

R2-

HFU

1-2 R2-

HFU

3-4

R2-

HFU

5

R2-

HFU

6

R2-

HFU

7-8

R3

R3-

HFU

1-2

R3-

HFU

3-4

R3-

HFU

5

R3-

HFU

6

R3-

HFU

7-8

-14,000,000

-12,000,000

-10,000,000

-8,000,000

-6,000,000

-4,000,000

-2,000,000

0

2,000,000

4,000,000

6,000,000

8,000,000

10,000,000

12,000,000

Variation in Gas In Place

FGIP

SGIP

TGIP

1 2

3

4 5

BaseModel

1

2

49%

79%