CO 2 Sequestration in Gas Shales of Kentucky Brandon C. Nuttall, James A. Drahovzal, Cortland F. Eble, R. Marc Bustin U.S. DOE/NETL DE-FC26-02NT41442 AAPG Calgary June 19-22, 2005
Why Black Shales? Distribution and potential storage volumeDistribution and potential storage volume Known producerKnown producer –Gas adsorbed on kerogen and clay Analogous to CBM?Analogous to CBM?
Basic Research: Feasibility CO 2 sorption capacityCO 2 sorption capacity CH 4 displacement potentialCH 4 displacement potential
Devonian Shale in Kentucky Estimated gas in place: 63 to 112 tcf Present in subsurface >=1000 deep and >=100 thick Producing area
Big Sandy Reservoir Info Completion interval >500Completion interval >500 Average porosity 4.3%Average porosity 4.3% Max. porosity 11%Max. porosity 11% Temperature 84 o FTemperature 84 o F Average pressure 400 psiAverage pressure 400 psi Permeability <0.1 mdPermeability <0.1 md Atlas of Major Appalachian Gas Plays, 1996
Typical Reservoir Conditions for CO 2 Injection Critical Point Saturation Line Melting Line Temp (ºF) Pressure (psia) Solid Liquid Gas
Geologic Column Surface 1,000 2,000 3,000 4,000 Coal measures, mixed sand, shale, and coal. Salt sands Pennington: Sand and shale Big Lime: Carbonate Pennsylvanian Mississippian Devonian Borden: Sand and shale Ohio: Carbonaceous black shale 3,800 +/- of mixed sand, shale, and carbonate provide adequate reservoir seal. Composite thickness data from Knott and Leslie County wells and Dillman and Ettensohn (1980)
Shale Overview Mississippian Borden Cleveland Devonian Ohio Shale Berea Sunbury Three Lick Bed Upper Huron Middle Huron Lower Huron Olentangy 3-component system3-component system –Quartz –Clay –Organic matter 3-component system3-component system –Quartz –Clay –Organic matter } Clastic GR Density
Cross section LAS file AdsorptionBoth Study Area
Average Organic Content Total Organic Carbon
Mean Random Reflectance Upper oil window and wet gas/condensates R 0 random x ~ R 0 max Frequency
Devonian Shale Adsorption Isotherms Standard cubic feet per ton CO 2 CH 4
Adsorption at 400 PSIA Adsorbed gas (standard cubic feet per ton of shale) Average CH 4 : 8.1 scf/ton Average CO 2 : 42.9 scf/ton CO 2 = 5.3 x CH 4 Frequency
CO 2 Adsorption at 400 PSIA r 2 = 0.80 CO 2 scf/ton = 7.9 x TOC
CNR Elk Horn
Cleveland Three Lick Upper Huron Middle Huron Lower Huron Olentangy Sunbury Borden Berea Sidewall cores for adsorption and CH 4 displacement
ECS Shale Analysis Clays BoundWater Kerogen GasSaturation TotalPhi Adsorbed Gas (scf) TotalGas(scf) TOC Cum.Gas(bcf) QFM
Crossplot Lower density & Higher GR = More organic RhoB max gray shale = 2.82 g/cc (g/cc)
Calculate TOC from RhoB Schmoker, 1993, USGS Bull 1909
Shading based on density (RhoB) <2.4 >2.8 More carbonaceous More clastic Cross Section WE 1,600 feet 72 miles
27.6 Billion Tons CO 2 Estimated 40 scf/ton thickness weighted average >3 MM <1 MM Tons/sq km
Future Map TOC from density logsMap TOC from density logs New estimate of CO 2 capacityNew estimate of CO 2 capacity Demonstration projectDemonstration project –CO 2 monitoring Surface soils Produced gas –Reservoir simulation
Conclusion Preliminary analyses indicate the organic-rich Mississippian– Devonian shales of Kentucky have the potential to sequester large volumes of CO 2.