HR: 1330h
AN: GC32A-0202    [PDF]
TI: Carbon Dioxide Sequestration and ECBM in the Powder River Basin
AU: * Colmenares, L B
EM: LBCF@pangea.stanford.edu
AF: Stanford University, 397 Panama Mall, Department of Geophysics, Stanford, CA 94305-2215 United States
AU: Zoback, M D
EM: zoback@pangea.stanford.edu
AF: Stanford University, 397 Panama Mall, Department of Geophysics, Stanford, CA 94305-2215 United States
AB: Coal seams are both a source of coal bed methane (CBM) and a potential carbon dioxide sink. For sub-bituminous coals like those in the Powder River Basin (PRB), the CO2/CH4 adsorption ratio is approximately 10:1, which indicates the significant potential for sequestering carbon dioxide. In addition, injected carbon dioxide would also enhance the production of methane from the coal seam because of its higher adsorption capacity. This means that the injection of carbon dioxide in coal beds may have the dual benefit of sequestering carbon dioxide and enhancing CBM production. Moreover, if carbon dioxide injection efficiently displaces the adsorbed methane, it may reduce the amount of water produced from CBM wells as part of the depressurization process. Our work in the Powder River Basin indicates that drilling and completion operations result in hydraulic fracturing of the coal and possibly the adjacent strata. This would result in both excess CBM water production and inefficient depressurization of coals. We have been able to collect water-enhancement tests data in coals to obtain the magnitude of the least principal stress in the coal seam. The preliminary data we have analyzed indicates that the hydrofracs are horizontal in some areas because the least principal stress corresponds to the overburden. It is interesting to speculate that one could use horizontal hydrofracs near the bottom of the coal seam for carbon dioxide injection and a horizontal hydrofrac near the upper part of the coal seam for methane production.
DE: 1694 Instruments and techniques
DE: 1699 General or miscellaneous
SC: Global Climate Change [GC]
MN: 2003 Fall Meeting