FACT SHEET
ANALYSIS
AND
The Emission Reduction Benefits of Carbon
Capture Utilization and Storage using CO2
Enhanced Oil Recovery
Oil Recovery
ABOUT THE AUTHORS
Deepika Nagabhushan is a
CCS Policy Associate at
CATF
You can reach Deepika at
[email protected] or
847-505-4149.
Kurt Waltzer is the Managing
Director at CATF
You can reach Kurt at
[email protected] or
617-624-0234, ext. 292
Enhanced Oil Recovery (EOR) using industrial CO2 provides
an important way to stimulate the development of the
infrastructure needed to capture and store large amounts of
CO2 consistent with decarbonizing the energy system.
According to the International Energy Agency (IEA), utilizing
industrial CO2 Enhanced Oil Recovery for the purposes of
Carbon Capture Utilization and Storage (CCUS) results in a
net CO2 emissions reduction.
Based on IEA’s analysis CCUS-EOR using industrial CO2 can
result in a 63% net reduction in CO2 emissions for every barrel
of oil produced.
If we do not take advantage of CO2 EOR, the oil may be
produced by other technologies that do not reduce emissions.
AccordingtotheIEA,thereisapotentialtostore140billiontonsofCO2inoilreservoirsaround
theworldthroughCO2EOR1-resultinginanetemissionsreductionby88billiontonsofCO2.
Thisismorethan40timesthecurrentU.S.powersectoremissions.Thus,undertheright
economicconditionstherewouldbealargemarket-basedopportunitytoreduceman-made
CO2emissions.Asaresult,enhancedoilrecoveryactivityusingcapturedanthropogenicCO2,
couldsignificantlydrivethedeploymentofCCUStechnology&infrastructure,andhelplower
technologycostsaroundtheglobe.
CanCO2EORprovideanetreductioninCO2emissions?
Yes.CCUScombinedwithEORinvolvestheincidentalgeologictrappingorstorageofCO2that
occursaspartoftheoilrecoveryprocess.CO2isinjectedintomaturereservoirs,whereitmixes
withtheremainingoil,enablingittobemoreeasilyproduced,andasaresultofwhicha
portionoftheCO2(usuallyaboutone-thirdtoahalf)isgeologicallytrapped,permanently.The
CO2thatisnottrappedisproducedwiththeoil,recaptured,andreinjected–andtheprocess
continuesuntilalloftheCO2ispermanentlysequestered.
Overthelifeoftheproject,almostalloftheCO2deliveredtothefieldisstoredinthegeologic
formation.ButbecauseEORproducesoil,whichwhenprocessedorusedproducesemissions,
thestoredvolumeofCO2cannotentirelybecountedasanemissionsreduction.Whenthe
volumeofCO2storedundergroundisgreaterthanthoseemittedbytheexcessemissions
causedbyEORactivity,thenthedifferencemustbecountedasanetemissionsreduction
benefit.
ThemostrecentandcomprehensiveassessmentofnetstoragefromCO2EORwasdeveloped
bytheIEAin2015.2ThestudyindicatesthatforagivenvolumeofCO2deliveredtoanoilfield
orstoragesite,EORcanprovidea63%netemissionsreductionbenefit,underthereasonable
assumptionsoutlinedbelow.
2
Figure1:NetReductionsinCO2EmissionsthroughEnhancedOilRecovery(metrictons) Figure1showsthebenefitsofCO2EORintermsofCO2emissionsreduction.Theproduction
andconsumptionofatypicalbarrelresultsinabouthalfametrictonofCO2beingemittedto
theatmosphere.
But,doesn’tEORresultingreateroverallCO2emissionsduetooilproduction?
No.ProducingabarrelofoilfromCO2EORisslightlymoreenergyintensivethanaconventional
barrelofoil,withemissionsof0.54metrictonsand0.51metrictonsofCO2respectively.But
CO2EORhasthebenefitofstoringthe0.30metrictonsofCO2thatwasneededtoproduce1
barrelofoil.Afteraccountingforthisbenefit,theproductionandconsumptionofabarrelofoil
fromEORcontributesanetof0.24metrictonsofCO2totheatmosphere.
IfanEORbarrelreplacedabarrelofconventionallyproducedoilinthemarket,thenthere
wouldanemissionsreductionof0.27metrictonsofCO2perbarrel(thedifferencebetween
conventionaloilemissionsandEORbarrelemissions).Inrealitythough,allelsebeingequal,this
1to1displacementdoesnotoccur.Thenewoilsupplywilllowerthemarketpriceofoiland
thusincreasethedemandforoil.TheIEAestimatesthatforevery10barrelsofoilproduced
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throughCO2EOR,only8barrelsofexistingoilaredisplacedand2barrelsareadditional.The
displacementofthe8barrels(or80%ofexistingsupply)providesanemissionsreduction
benefitof0.23tonsperEORbarrel.3But,theincreaseinconsumptionoftheadditional2EOR
barrels(20%ofexistingsupply)increasesemissionsby0.04tonsperEORbarrel.4Thesemarket
effectsresultinanetemissionsreductionbenefitto0.19metrictonsofCO2perEORbarrel,on
average.
ConsideringtheCO2usedforEORisanthropogenic,i.e.capturedfromthepowerorindustrial
sectorsandwhichwouldotherwisebereleasedintotheatmosphere,thenetreductionofCO2
is63%perbarrelofoilproducedorper0.3tonsinjected(or,peranyothervolumeofCO2
injected).
ThetypeofoilproductionthatisassumedtobereplacedbyEORisalsoakeyfactorin
determiningthenetreductioninemissions.TheIEAanalysisfoundthatnetemissionreductions
couldrangefrom47%to150%dependingonthecarboncontentoftheoilthatisassumedto
beoffset.5Whilea20%increaseinoilconsumptiondrivenbyCO2EORoilproductiondelivers
netemissionsreduction,eveniftheconsumptionincreasedby50%ofabarrel,therewouldstill
beanetemissionsreductionbenefit.
ArethereanyotheremissionsthatmightaffectEOR'sbenefit?
Yes,emissionsupstreamfromtheCO2EORprocesscanalsoaffecttheCO2emissionsreduction
benefitsfromusinganthropogenicCO2.But,itisimportanttonotethattheupstreamemissions
affectanysequestrationmethodthesameexactway.Inotherwords,upstreamemissions
affectbothEORandstorageindeepsalinegeologicreservoirsequally.Hence,itisonly
downstreamemissionsthatprovidethecrucial“applestoapples”netemissionsreductions
benefitcomparison.
Upstreamemissionsincludethosefromcoalandnaturalgasproduction,transportationoffuel,
combustionandtransportationofcapturedCO2.But,thekeyemissionsimpactisdrivenby
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capturetechnologyandconfiguration(new/retrofit/fullorpartialcapture)usedattheemitting
source.Forexample,ifweweretoincludeinourupstreamcalculationsa90%capturefroma
retrofitonanexistingcoalplantusingcurrentconventionalcapturetechnology,thenitwould
reducetheemissionsreductionbenefitfromCO2EORby25%,duetoprocessenergypenalties
andcapturerates.6Alternatively,ifweweretoconsideranadvancedcarboncapture
technologysuchasonebasedontheAllamCycle,whichcouldreach100%capturelevels,
bringingtheenergypenaltytominimallevels,thenthereductioninthebenefitfrom
downstreamCO2EORwouldbeminimal.7
WouldtheoilfromdepletedoilfieldsbeproducedanywaywithoutCO2EOR?
Likely.ThesameoilthatistargetedforCO2EOR,canbeproducedbyothertechnologiesand
willonlyresultinincreasedemissions.Oilfromdepletedwellswillberecoveredusingthebest
availablemethod,evenifitisnotCO2injection,iftheoilpricessodictate.CO2EORiseffectively
incompetitionwithotherEORoptionsoutlinedbelow.Theseoptionsdonotprovideany
climatebenefit,butinsteadonlypermitandleadtoincreasedCO2emissions.
Geologically-sourcedCO2hasbeeninuseforseveraldecadesforCO2EOR.75%oftheCO2
currentlyusedforEORisproducedfromnaturalgeologicdeposits.NationalEnergyTechnology
Laboratory(NETL)estimatesthatthereareanadditional3.9billionmetrictonsofgeologicallysourcedCO2intheUSthatcouldbeproducedeconomicallyforuseinEOR.8Becausethe
natural-sourcedCO2wasalreadygeologicallytrapped,itdoesnotdeliveraclimatebenefit
whenusedforCO2EOR,unlikeindustrial-sourcedCO2.
Theuseofsurfactants,polymers,anddetergentsforchemicalfloodinginreservoirsisanother
formofenhancedoilrecovery.Advancesindrillingsuchasinfielddrilling,horizontaldrilling
andfrackingcouldalsobeusedtoextracttheoilfromreservoirs,whichwouldotherwisebe
targetsforCO2injection.
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MethanereactsinoilfieldsinamannersimilartoCO2.TheNorwegianoilcompanyStatoilhas
beeninjectingmethaneintotheNorthSeaforoilrecovery(64millionmetrictons/year)in
amountsthataresimilartothoseofCO2injectedintothePermianBasininTexasforEOR.9
MethaneisalsoregularlyinjectedintotheNorthSlopeformationalsoforEOR.AlthoughEORis
typicallynotthewaytoextractthemosteconomicvalueoutofmethane,itisstillusedinsome
regionswhereeitherCO2isnotavailableoroil-gaspricearbitragedrivesapreferencefor
methaneinjectiontoproduceadditionaloil.
Conclusion
EnhancedOilRecoveryusingcapturedindustrialCO2canprovideanetCO2emissionsreduction
of63%relativetotheCO2stored,takingintoaccountemissionsfromoilconsumption.The
combinationoftheexistingandprojecteddemandforEORandtheavailabilityofindustrialCO2
offersthepotentialfordevelopingtheneededinfrastructuretomorewidelydeployCCUS
technologyatasignificantscaleandtostorelargeamountsofCO2.WithoutCO2EORusing
capturedindustrial(anthropogenic)CO2,theoilwilllikelybeproducedanyway,usingother
methodsofextractionthatdonotprovideemissionsreductionbenefits.
1
IEA Greenhouse Gas R&D Programme (IEA, GHG), “CO2 Storage in Depleted Oilfields: Global Application Criteria
for Carbon Dioxide Enhanced Oil Recovery, 2009/12, December 2009.”
2
International Energy Agency, “Storing CO2 through Enhanced Oil Recovery, combining EOR with CO2 storage
(EOR+) for profit,” 2015.
3
The more precise IEA displacement estimate is 84%. Multiplying that with the difference between conventional oil
and EOR oil (0.27 metric tons per bbl) results in a net benefit of 0.23 metric tons per bbl.
4
The more precise IEA displacement estimate is 16%. Multiplying that with the emissions from one barrel of EOR oil
(0.24 metric tons per bbl) results in a net increase of 0.04 metric tons per bbl.
5
International Energy Agency, “Storing CO2 through Enhanced Oil Recovery, combining EOR with CO2 storage
(EOR+) for profit,” 2015.
6
Calculated from spreadsheet model developed for Azzolina, et al., “How green is my oil? A detailed look at
greenhouse gas accounting for CO2-enhanced oil recovery (CO2-EOR) sites.” International Journal of Greenhouse
Gas Control 51 (2016) pp. 369-379. Considering coal plant retrofit with 90% capture level, 30% energy penalty and
make up power from NGCC without carbon capture (no displacement of electricity grid mix).
7
NETPower briefing to USEA, May 25, 2016.
8
National Energy Technology Laboratory, “Subsurface Sources of CO2 in the Contiguous United States Volume 1:
Discovered Reservoirs,” March 4, 2015, DOE/NETL-2014/1637.
9
Cavanagh, Ringrose, Statoil, ASA “Improving oil recovery and enabling CCS: a comparison of offshore gasrecycling in Europe to CCUS in North America”, GHGT-12, Energy Procedia 63 (2014) 7677 – 7684.
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