Published: 2005
Total Pages: 444
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The Marshall County Project was undertaken by CONSOL Energy Inc. (CONSOL) with partial funding from the U.S. Department of Energy's (DOE) Carbon Storage Program (CSP). The project, initiated in October 2001, was conducted to evaluate opportunities for carbon dioxide CO2 sequestration in an unmineable coal seam in the Northern Appalachian Basin with simultaneous enhanced coal bed methane recovery. This report details the final results from the project that established a pilot test in Marshall County, West Virginia, USA, where a series of coal bed methane (CBM) production wells were developed in an unmineable coal seam (Upper Freeport (UF)) and the overlying mineable Pittsburgh (PIT) seam. The initial wells were drilled beginning in 2003, using slant-hole drilling procedures with a single production leg, in a down-dip orientation that provided limited success. Improved well design, implemented in the remaining wells, allowed for greater CBM production. The nearly-square-shaped project area was bounded by the perimeter production wells in the UF and PIT seams encompassing an area of 206 acres. Two CBM wells were drilled into the UF at the center of the project site, and these were later converted to serve as CO2 injection wells through which, 20,000 short tons of CO2 were planned to be injected at a maximum rate of 27 tons per day. A CO2 injection system comprised of a 50-ton liquid CO2 storage tank, a cryogenic pump, and vaporization system was installed in the center of the site and, after obtaining a Class II underground injection permit (UIC) permit from the West Virginia Department of Environmental Protection (WVDEP), CO2 injection, through the two center wells, into the UF was initiated in September 2009. Numerous complications limited CO2 injection continuity, but CO2 was injected until breakthrough was encountered in September 2013, at which point the project had achieved an injection total of 4,968 tons of CO2. During the injection and post-injection periods, the observed daily CBM production rates increased by more than 17% over pre-injection period production rates. An extensive multi-pronged monitoring program conducted by researchers from West Virginia University (WVU), the DOE National Energy Technology Laboratory (NETL), and CONSOL confirmed the absence of any reliable evidence of vertical migration of the injected CO2. The breakthrough event was the only evidence of horizontal migration, and there was no evidence of migration outside of the area of review (AOR). Current environmental regulatory conditions in the U.S. do not provide a need for CO2 sequestration, and the currently depressed natural gas market further detracts from any economic success that could be realized from CBM production enhancements at this time; however this report does offer details on alternative scenarios that could provide for limited economic viability of this concept.