Assessment of CO2 Sequestration and ECBM Potential of U.S. Coalbeds
In October, 2000, the U.S. Department of Energy, through contractor Advanced Resources International, launched a multi-year government-industry R&D collaboration called the Coal-Seq project. The Coal-Seq project is investigating the feasibility of CO{sub 2} sequestration in deep, unmineable coalseams, by performing detailed reservoir studies of two enhanced coalbed methane recovery (ECBM) field projects in the San Juan basin. The two sites are the Allison Unit, operated by Burlington Resources, and into which CO{sub 2} is being injected, and the Tiffany Unit, operating by BP America, into which N{sub 2} is being injected (the interest in understanding the N{sub 2}-ECBM process has important implications for CO{sub 2} sequestration via flue-gas injection). The purposes of the field studies are to understand the reservoir mechanisms of CO{sub 2} and N{sub 2} injection into coalseams, demonstrate the practical effectiveness of the ECBM and sequestration processes, an engineering capability to simulate them, and to evaluate sequestration economics. In support of these efforts, laboratory and theoretical studies are also being performed to understand and model multi-component isotherm behavior, and coal permeability changes due to swelling with CO{sub 2} injection. This report describes the results of an important component of the overall project, applying the findings from the San Juan Basin to a national scale to develop a preliminary assessment of the CO{sub 2} sequestration and ECBM recovery potential of U.S. coalbeds. Importantly, this assessment improves upon previous investigations by (1) including a more comprehensive list of U.S. coal basins, (2) adopting technical rationale for setting upper-bound limits on the results, and (3) incorporating new information on CO{sub 2}/CH{sub 4} replacement ratios as a function of coal rank. Based on the results of the assessment, the following conclusions have been drawn: (1) The CO{sub 2} sequestration capacity of U.S. coalbeds is estimated to be about 90 Gt. Of this, about 38 Gt is in Alaska (even after accounting for high costs associated with this province), 14 Gt is in the Powder River basin, 10 Gt is in the San Juan basin, and 8 Gt is in the Greater Green River basin. By comparison, total CO{sub 2} emissions from power generation plants is currently about 2.2 Gt/year. (2) The ECBM recovery potential associated with this sequestration is estimated to be over 150 Tcf. Of this, 47 Tcf is in Alaska (even after accounting for high costs associated with this province), 20 Tcf is in the Powder River basin, 19 Tcf is in the Greater Green River basin, and 16 Tcf is in the San Juan basin. By comparison, total CBM recoverable resources are currently estimated to be about 170 Tcf. (3) Between 25 and 30 Gt of CO{sub 2} can be sequestered at a profit, and 80-85 Gt can be sequestered at costs of less than $5/ton. These estimates do not include any costs associated with CO{sub 2} capture and transportation, and only represent geologic sequestration. (4) Several Rocky Mountain basins, including the San Juan, Raton, Powder River and Uinta appear to hold the most favorable conditions for sequestration economics. The Gulf Coast and the Central Appalachian basin also appear to hold promise as economic sequestration targets, depending upon gas prices. (5) In general, the 'non-commercial' areas (those areas outside the main play area that are not expected to produce primary CBM commercially) appear more favorable for sequestration economics than the 'commercial' areas. This is because there is more in-place methane to recover in these settings (the 'commercial' areas having already been largely depleted of methane).
- Research Organization:
- Advanced Resources International, Incorporated
- Sponsoring Organization:
- USDOE
- DOE Contract Number:
- FC26-00NT40924
- OSTI ID:
- 923256
- Country of Publication:
- United States
- Language:
- English
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