Assesment of of CO 2 EOR & Sequestration Potential in Gulf Coast Reservoirs Mark H. Holtz, Vanessa Núñez López, and Caroline L. Breton

To develop a comprehensive data base for the Gulf Coast. To apply our screening criteria to determine miscible CO2 EOR resource potential and CO2 sequestration in the Gulf Coast. To determine the geologic distribution of CO2 EOR potential in Gulf Coast oil reservoirs. Objectives Bureau of Economic Geology

Carbonate reservoir (33) Sandstone reservoir (38) Pilots Full floods $ $ $ $ $ $ $ $ $ $ $ $ $ $ $ $ $$ $ $ $ $ $ $ $ $ $ $ $ $ $ $$ $ $ $ $ $ $ $ $ $ Current and Previous CO2 Pilots and Floods Bureau of Economic Geology

Methodology Sources of Data Texas: Atlas of Major Texas Oil Reservoirs, Atlas of Major Texas Gas Reservoirs, Railroad Commission of Texas, others Louisiana and Mississippi: TORIS database, others Alabama: Alabama Geologic Survey, others Bureau of Economic Geology

QAc4748x Cumulative production > 1 MMSTB No Rejected Yes No Minimum miscibility Pressure (depth, temperature, pressure, oil character) Unknown Rejected Oil- reservoir data base Reservoir depth >6000 ft Yes No Rejected No Rejected Does reservoir have water- drive mechanism? Yes Candidate reservoir No Has reservoir been waterflooded? Candidate for secondary recovery Yes Bureau of Economic Geolog y Bureau of Economic Geology Decision Tree for Screening Candidate Reservoirs

Decision Flow Path for Play Determination Postdepositional Physochemical Events Postdepositional diagenesis Tectonic overprint Geologic Province & Sub Province Geologic Stratigraphy Depositional System Geologic Play LithologyTrap Type Hydrocarbon & Drive Type Bureau of Economic Geology

Recovery Efficiency of Sandstone Reservoirs from Enhanced Oil Recovery Projects (1980’s) Frequency Recovery efficiency (percent) Submarine fan Barrier/strandplain Fluvial/deltaic QAc4237c %, Little Creek, MS, Denbury (2004) 14.5 %, Paradis, LA, Texaco Quarantine Bay, LA, Chevron Single well huff ’n’ puff Bureau of Economic Geology

Reservoir Screening for Candidate CO 2 -EOR Flood Potential Texas: –Oil reservoir database developed for Texas: total of 3,266 reservoirs. –Applied screening criteria for 21 Texas Gulf Coast counties and 33 North-Central and East Texas counties. –360 candidates screened in Texas Gulf Coast & 274 candidates screened in North-Central and East Texas counties. Louisiana: –DOE TORIS database utilized to screen 122 candidates. –Continued work with LA Geological Survey as part of DOE SE Regional Partnership. Mississippi: –DOE TORIS database utilized to screen 11 candidates. –Current floods (Little Creek & Mallalieu, West) located. –Continued work with Mississippi as part of DOE SE Regional Partnership. Bureau of Economic Geology

Estimation of Minimum Miscibility Pressure, (MMP) Non-linear Multiple Regression for the Minimum Miscibility Pressure, (MMP) Where: MW = Molecular weight of the C 5 + fraction of the oil T = Reservoir temperature (F) Non-linear regression for the molecular weight of the C 5 + Bureau of Economic Geology Temperature gradient linear regression used for the Frio Plays 5, 6, 7, and 10 Temp = (0.015)*Depth(ft)

Storage Calculations Quick Look (spreadsheet) Storage Potential (Based on Cumulative Production (Np)) Gulf Coast Rules of Thumb CO 2 QLSP (metric tons) = *Np*Boi/Bco 2 Bureau of Economic Geology OOIP = 2Np NCO 2 = OOIP*0.15 Formation Volume factors 50% recovery factor (variable) 15% recovery factor

Areas with Miscible CO 2 EOR Potential Bureau of Economic Geology

Candidate Reservoir Geologic Plays Distribution Bureau of Economic Geology South East Texas

Candidate Reservoir Geologic Plays Distribution Bureau of Economic Geology South East Texas

Miscible CO 2 EOR resource potential in the Gulf Coast Bureau of Economic Geology By State

CO 2 Sequestration capacity in miscible oil reservoirs along the Gulf Coast Bureau of Economic Geology

Summary Screening process identified all current and pilot reservoirs on the Gulf Coast. All sizes of companies are beginning to capitalize on CO 2 EOR. Oil price and cost incentives are merging to form strong market conditions. Pending legislation likely to influence market environment. Bureau of Economic Geology

Thanks to Our GCCC Industry Partners Bureau of Economic Geology

Technical Advances since the 1980’s 3D seismic for delineating fault blocks Directional drilling for placing wells Reservoir characterization for designing flood Improved knowledge of CO2 flooding Bureau of Economic Geology

Outline Objectives Methodology Database Screening Criteria Minimum Miscibility Pressure Storage Calculations Results Summary Bureau of Economic Geology

Methodology Bureau of Economic Geology Oil-reservoir database Has reservoir been waterflooded? Minimum miscibility pressure (depth, temp., pressure, oil character) Does reservoir have water- drive mechanism? No Rejected No Rejected No Rejected No Yes Unknown Yes No Candidate reservoirs Candidate for secondary recovery Reservoir depth > 6000 ft Cumulative production > 1 MMSTB Yes DECISION TREE FOR SCREENING CANDIDATE RESERVOIRS

Function for Obtaining Oil C 5 + Molecular weight Bureau of Economic Geology

Recovery Efficiencies of Gulf Coast Sandstone CO2 EOR Pilots CompanyReservoirFlood type Recovery factor (% of OOIP) TexacoParadisMiscible Gravity Stable15 Gulf/ChevronQuarantine BayWAG17 ChevronTimbalier BayGravity stable23 ShellWeeks Island S ReservoirGravity Stable15 DenburyLittle CreekMiscible CO217 Bureau of Economic Geology

Screening Criteria Temperature gradient linear regression used for the Frio Plays 5, 6, 7, and 10 Non-linear regression for the molecular weight of the C 5 + Temp = (0.015)*Depth(ft) Bureau of Economic Geology

Estimating CO 2 Minimum Miscible Pressure Mole Weight C Bureau of Economic Geology

CO 2 EOR Resource Potential in Texas Bureau of Economic Geology By Depositional System ,000 10,000 Delta sandstone Barrier\Strandplain sandstone Open platform Fan-delta\Braided stream Restricted platform, shoaling cycles, dolomitized Shelf Sandstone Karst overprint Submarine fan sandstone Shelf-edge reefs, drapes Depositional System CO2 EOR (MMSTB)

Sequestration Potential in Texas Bureau of Economic Geology By Depositional System ,000 10, ,000 1,000,000 Delta sandstone Barrier\Strandplain sandstone Open platform Fan-delta\Braided stream Restricted platform, shoaling cycles, dolomitized Karst overprint Shelf Sandstone Submarine fan sandstone Shelf-edge reefs, drapes Depositional System Sequestration (MM Metric Metric Tons)

Usage Potential in the Gulf Coast Bureau of Economic Geology ,000 10, ,000 1,000,000 Delta sandstone Barrier\Strandplain sandstone Open platform Fan-delta\Braided stream Restricted platform, shoaling cycles, dolomitized Karst overprint Shelf Sandstone Submarine fan sandstone Shelf-edge reefs, drapes Depositional System Usage (MM Metric Tons) By Depositional System