Economics of CO2 sequestration in coalbed methane reservoirs

Unlike carbon dioxide-enhanced oil recovery processes, carbon dioxide injected during coalbed methane recovery (ECBM) is strongly adsorbed onto the coal, and in a relatively homogeneous reservoir is not expected to break through to the production wells until the bulk of the coalbed methane (CBM) reservoir is swept of methane. This provides a huge carbon dioxide storage potential in coalbeds throughout the world. The likely strategy is dependent upon the cost and credits for sequestration of carbon dioxide and the natural gas sales price. This study is designed to show that the carbon dioxide ECBM process is technically feasible and to show the major effects that carbon dioxide credits would have on the production strategy used for CBM, and on the early use of ECBM. Current indications are that the costs for carbon dioxide capture from concentrated sources are lower than for capture from flue gas, suggesting that these will probably be utilized, assuming that they are available in sufficient quantities. A preliminary economic analysis indicates that flue gas injection into coalbeds may have merit. Studies are currently in progress to determine if there is an optimal mix of carbon dioxide/nitrogen where a balance can be struck between carbon dioxide storage and process economics. 16 refs., 2 tabs., 5 figs