Analysis of the Devonian Shale in Kentucky for Potential CO 2 Sequestration and Enhanced Natural Gas Production Brandon C. Nuttall, James A. Drahovzal, Cortland F. Eble, R. Marc Bustin U.S. DOE/NETL DE-FC26-02NT41442

Basic Research: Feasibility CO 2 sorption capacityCO 2 sorption capacity CH 4 displacement potentialCH 4 displacement potential

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?

Black Shale Distribution Modified from Ettensohn, 1998, Compressional Tectonic Controls... in Schieber and others, eds., Shales and Mudstones I Antrim Bakken Chattanooga Exshaw New Albany Ohio

Geology of Kentucky

Shale Nomenclature New Albany Chattanooga Ohio Hamilton-Smith, 1993, Gas Exploration in the Devonian Shales of Kentucky: KGS, Ser 10, Bul. 4.

Geologic Column Surface 1,000’ 2,000’ 3,000’ 4,000’ Coal measures, mixed sand, shale, and coal. “Salt” sands Sand and shale Carbonate Pennsylvanian Mississippian Devonian Sand and shale 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)

Devonian Shale Type Log, Eastern Kentucky Lower Huron is thought to have the most sequestration potential. Upper part Lower part

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 >500’Completion 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

Classic Production Decline Cum: 471 MMcf 26 years Eastern Kentucky Devonian Shale Gas Production

Production Incline Suggests Adsorbed Gas Cum: 379 MMcf 40 years Eastern Kentucky Devonian Shale Gas Production

Project Year 1 KGS Well Sample LibraryKGS Well Sample Library –Identified drill cuttings –Petrology –Sorption isotherms –Identified optimum shale facies

Sampling Criteria Minimize sample alterationsMinimize sample alterations –Recent wells –Unwashed samples Geophysical logs availableGeophysical logs available Distributed over shale gas producing areaDistributed over shale gas producing area

Sample locations

Average Organic Content

Average TOC

Mean Random Reflectance Upper oil window and wet gas/condensates R 0 random x ~ R 0 max

Adsorbed Gas

Adsorption Isotherms CO 2 adsorbed (SCF/ton) Ohio Shale (Undif) Upper Ohio Lower Huron Lower Ohio

Calculated Langmuir Volumes CO 2 adsorbed (SCF/ton)

Project Year 2 Cooperative access to new wellCooperative access to new well –Sidewall core –ECS logging suite –Petrology –CO 2 sorption/CH 4 displacement

CNR Elk Horn

Cleveland Three Lick Upper Huron Middle Huron Lower Huron Olentangy Sunbury Borden Berea Sidewall Cores for CH 4 Displacement

ECS Log * * * * Lower Huron SiCaFeSTiGd Sidewall core sample locations in the Lower Huron * Sidewall core sample locations in the Lower Huron

Work Plan: Year 3 Reporting and technology transferReporting and technology transfer –Finish long-term sorption analyses –Implement Web data interface –Final report

Typical Reservoir Conditions for CO 2 Injection Solid Liquid Gas Critical Point Saturation Line Melting Line

27.6 Billion Tons CO 2 Estimated 40 scf/ton thickness weighted average >3 MM <1 MM Tons/sq km

Economic Benefits CO 2 SequestrationCO 2 Sequestration Enhanced natural gas productionEnhanced natural gas production

Future Research Demonstration projectDemonstration project –CO 2 monitoring Surface soils Produced gas –Reservoir simulation

Conclusion The organic-rich Mississippian– Devonian shales of Kentucky have the potential to sequester large volumes of CO 2.