Romanak, Katherine

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Geochemical investigation of shallow groundwater over SACROC oilfield    GCCC Digital Publication Series #08-18     K. Romanak                        Cited as:  Romanak, K., 2008, Geochemical investigation of shallow groundwater over SACROC oilfield, prepared for: Southwest Regional Partnership on Carbon Sequestration Phase II Annual Meeting, Albuquerque, New Mexico, October 22-23, 2008. 20 pp. GCCC Digital Publication #08-18. Keywords: Monitoring-groundwater-USDW; Regional study-Permian Basin; Field study-SACROC-Scurry Co-TX Geochemical Investigation of Shallow Groundwater Over SACROC OilfieldPrepared by: Gulf Coast Carbon Center at the Bureau of Economic Geology, Jackson School of Geosciences, The University of Texas at AustinKatherine RomanakScott Tinker, Director; Ian Duncan, Associate DirectorPrepared for: Southwest Regional Partnership on Carbon SequestrationPhase II Annual Meeting, Albuquerque, New Mexico October 22-23, 2008Funded by: Department of Energy, National Environmental Technology Laboratory and Kinder Morgan CO2Significance of Study AreaEngineered InjectionShort time spanArtificially  over-pressured reservoirs~150 MMt CO2injected ~75 MMt CO2recoveredNatural AnaloguesGeologic time spanNaturally over-pressured reservoirTimeCO2Trapped in injection zone?Mobilized outside of injection zone?Research Questions1. Has CO2 from 36 years of EOR at SACROC entered the Dockum aquifer?2. What parameters can be used to detect injected CO2 in shallow aquifers, especially at low concentrations? 3. Has CO2 affected ground water quality above SACROC? Broad ImplicationsPerformance- Can we distinguish leakage through geologic seals from leakage through wells?-Impact from CO2-charged brine movement due to increased pressure?- What factors affect the success of EOR as a method of sequestration?Monitoring- What geochemical parameters will detect CO2 in complex systems?- What are the lowest concentrations of injected CO2that can be detected in complex systems?ApproachConventional SACROC StudyCharacterize background conditions before injectionCompare background with geochemical changes during and after injectionNo opportunity for pre-injection samplingSpatial Inside vs. outside SACROC. Limited capability for spatial background comparison. Due to abundant regional oilfield activity +/- CO2 injection.  Examples: deep storage formation- Frioshallow groundwater - ZERTTemporal Limited TWDB data pre-CO2 injection Long-term samples outside SACROC. Minimal geochemical parameters.ApproachWork in Progress:Compare geochemistry inside versus outside SACROC. Examine temporal trends that link pre and post injection.  Compare geochemistry to EPA drinking water standards.- No definitive evidence of injectate CO2 in Dockum aquifer.- No definitive evidence of degradation of ground water quality due to CO2.Preliminary Results:Potential Influences– Injectate and/or microbial CO2: PCO2, DIC, HCO3-, carbon isotopes, pH– Mineral dissolution: Ca2+, Mg2+, Si, HCO3-, mineral saturation indices, pH– CO2 mobilization of metals: Pb2+, As, Ba2+, Cd, Hg2+, Sb, Se, U and Zn2+– Oilfield brine: Na+, Cl-,  Br-– Underlying Permian evaporites: Ca2+, SO42-Specific Parameters of InterestDissolved inorganic carbon (DIC)  = Ct or total inorganic carbonAlkalinity = concentration of titratable bases HCO3- = one of 3 carbonate species that make up DICGeochemical RelationshipsUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUU UUUUUUUUUUUUUUUUUU UUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUU UUU UUUUUUUUU UUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUU UUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUU UUUUUUUUUUUUUUUUUUUUUUUUUUUUUUU UUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUU UUU UUUUUUUU UUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUU UUUUUUUUUUUU UU U80 60 40 20 20 40 60 8020406080204060802040608020406080Ca Na+K HCO3 ClMg SO4<=Ca + MgCl + SO4=>CCCC CCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCAAAAAAAAAAAAAAAAAAAAAAAAAAA AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA AAA AA AAAAAAAAAAAAAAA AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAIIIIIIIIIIIIIIIBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBB BBBBBB BBBB BBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBB BBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBB BBBBBBBBBBBBBB BBBBBBBBBBBIIIIIIIIIIIIIIIIIIIIIIIIIIACBIBEG and KM DataA Outside SACROC BEGC Inside SACROCB ProducedI PermianUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUU UUUUUUUUUUUUUUUUUU UUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUU UUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUU UUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUU UUUUUUUUUUUUUUUUUUUUUUUUUUUU UUUUUUUU UUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUU UUU UUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUU UUUUUUUUUUUUUUUUUUUUUUUUUUUUUU UUUUUUUUUUUUU UUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUU UUUUUUUUUUU UU UUNo distinction between samples collected inside SACROC and regional Dockum trends.Components of Dockum Water0 1 10 100 1000 10000Cl (mmol/l)0110100SO4 (mmol/l)CCCCCCCCCCCCCCCCCCCCCCCCCCC CCCCCCCCCCCCCCCCCCAAAAAAHHAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAIIHIIIBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBIII III II IIBHCAI PermianB ProducedH Permian-Dockum MixC Inside SACROCA Outside SACROC BEGUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUU UU UU UUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUU UUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUMixing ModelNon-impacted Impacted Dockum Production Calculated Sample(Hint-Herm) Permian (77-9p) Mixture (House)SO4 21.8 1332 750.6 187 188Cl 9.41 172 50532 433 471Br 0.05 1.25 276 2.4 2.2mixing fraction 87.00% 12.20% 0.80%0.0 0.1 1.0 10.0 100.0 1000.0 10000.0log Cl (mmol/l)0.00.11.010.0100.0log SO4 (mmol/l)CCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCAAAAAAHHAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA AAAIIHIIIBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBB BBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBB BBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBUUUUUUUUUUUUUUUUUUUU UUUUUUUUUUUUUUUUUUUUUUUUU UUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUU UUUUUUUUUUUUUUUUUU UU UU UUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUIII III II IACHBIUULeast impactedImpacted SampleModeling assistance from Changbing YangEffects of Mixing on Carbonate GeochemistryBrine infiltration into carbonate aquifer initiates cation exchange.Ca-X2 + 2Na+Ù Ca2+ + 2Na-X Addition of calcium ions drives calcite precipitationCaCO3Ù Ca2+ + CO32-CO2 Controls on Carbonate & Silicate Geochemistry-2.0 -1.5 -1.0 -0.5 0.0log pCO202571012Ca+Mg (mmol/l)CCCC CCCCCCCCCCCCCAAA AAAAAA AAAAAIncreasing CO2-2.0 -1.5 -1.0 -0.5 0.0Log pCO26.06.67.27.88.49.0pHCCCCCCCCCCCC CCC CC AAAAAAAAAAAAAA-2.0 -1.5 -1.0 -0.5 0.0log pCO20.00.20.40.60.81.0Si (mmol/l)CCCCCCCCCCCCCCCCCAAA AAAAAAAAAAA-3.0    -2.5    -2.0    -1.5    -1.0   log PCO2-3.0    -2.5    -2.0    -1.5    -1.0   log PCO2-3.0    -2.5    -2.0    -1.5    -1.0   log PCO2C Inside SACROCA Outside SACROC BEGCarbon IsotopesCollected to date:Injectate CO2(-6.1 to - 0.5 per mil)Dockum ground water(-13.2 to -3.6 per mil)Produced water(1.3 to 9.0 per mil)Plant material(-23.5 to -28.8 per mil)0 22 44 66 88 110DIC (mg/l)-12-10-8-6-4-2013C (per mil)CCCCCCCCCCCCCCCCCCCC CCCCCCAAAAA AAAAAAAAAA AAAAAAAAAAAAC Inside SACROCA Outside SACROC BEGSample impactedby mixingStill needed:Solid phase carbonateIsotope Variations-14 -12 -10 -8 -6 -4 -2 0Carbon Isotope Ratio (per mil)Inside SACROCOutside SACROCJuly ‘08March ‘08Nov ‘07July ‘07Water Quality114 samples, 61 wells, Water is filteredBatch Experiments: CO2 + Dockum SedimentsConclusionsHas CO2 from 36 years of EOR at SACROC entered the Dockum aquifer?Evidence of minimal  CO2 impacts.Currently no source identification.Must understand isotope systematicsHow can we detect injected CO2 in the Dockum, especially at low concentrations?Carbon isotopes Trace metalsDirect/Indirect  measurement of inorganic carbonMajor ElementsNot yet-Need more dataSort out variationsYes to a degree -supports dissolution relationships & indicates mixingCO2 indicators (headspace gas, HCO3, field Alkalinity, DIC, pH)Give the geochemical big pictureDistinguish CO2sourceNot yet but holds promiseIndicate mobilization predicted by experiments and define water qualityYes, very helpful to understanding metal mobilization as a function of CO2ConclusionsHas CO2 affected ground water quality above SACROC? Samples inside SACROC are not geochemically distinct from samples outside SACROC except for TDS and Cl concentrations.Minimal degradation of water quality with respect to EPA standards exists inside SACROC and is comparable to degradation observed outside SACROC.ConclusionsTDS impact in SACROC is volumetrically small and very common in oilfields.Future Work• Model carbon isotopes to determine the source of CO2.• Perform a sensitivity analysis to determine the amount of CO2 that could be detected in this geochemically complex system.• Investigate the source of temporal variation observed in  BEG carbon isotope data.• Relate temporal geochemical trends (TWDB data) to historical CO2 injection.

Geochemical investigation of shallow groundwater over SACROC oilfield

https://repositories.lib.utexas.edu/bitstream/2152/67936/2/GCCCDigPub08-18.pdf

Geochemical investigation of shallow groundwater over SACROC oilfield

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