Coalbed methane (CBM) production has spread to several countries since its meager beginnings in the US.
The US nearly replaced the 1.76 tcf of CBM it produced in 2006, the Energy Information Administration reported.
CBM reserves fell 1.4% to 19.62 tcf at the end of 2006. The reserves-to-production ratio was 9 at year’s end, and CBM production was reported in 16 states.
It was 1977 when geologists Ed Dolly and the late Fred Meissner authored a paper on their “recognition of the generation and potential production of gas from coalbeds and carbonaceous shales,” the AAPG Explorer noted in its November 2007 issue.
OGJ has ridden along the whole way. A 1977 article by Frank Getz, NEEG Inc., Dusseldorf, is titled, “Molecular nitrogen: clue in coal-derived-methane hunt” (OGJ, Apr. 25, 1977, p. 221).
US CBM reserves
After rising nearly every year since 1989, US CBM reserves fell slightly in 2 of the last 3 years, EIA reported.
At yearend 2006, Colorado had the largest CBM reserves, 6.3 tcf, followed by New Mexico at 4.9 tcf, Wyoming at 2.4 tcf, and Alabama at 2.1 tcf. Virginia, which EIA reported separately for the first time in 2006, had 1.8 tcf.
Colorado has been producing 451-520 bcf/year of CBM the past 7 years, and its 2006 CBM reserve figure is within 350 bcf of the state’s all-time high reserves of 6.7 tcf in 2002.
Overall, EIA reported CBM reserves at the end of 2006 in 16 states: Alabama, Arkansas, Colorado, Illinois, Indiana, Kansas, Louisiana, Montana, New Mexico, Ohio, Oklahoma, Pennsylvania, Utah, Virginia, West Virginia, and Wyoming.
EIA tallied a total of 1 tcf of reserves in 2006 for Arkansas, Kansas, Louisiana, Montana, and Oklahoma combined.
Drilling-production
EIA figures show 2006 as the peak year of CBM production in the US.
The 1.76 tcf of 2006 output was up slightly from 1.73 tcf in 2005 and 1.72 tcf in 2004.
The three largest CBM-producing states are in the Rockies. New Mexico led in 2006 with 510 bcf produced, followed by 477 bcf in Colorado and 378 bcf in Wyoming.
Wyoming’s Powder River basin is the leader in that state, which has CBM production from several basins (see map, OGJ, Oct. 1, 2007, p. 50).
Alabama produced 114 bcf of CBM in 2006. Its output had been as high as 123 bcf in 1998 and 121 bcf in 2004.
US production of unconventional gas peaked at 24 bcfd in 2006, up from 14 bcfd 1 decade ago, and CBM’s share was nearly 5 bcfd.
Producers added more than 20,000 new unconventional gas wells in each of the past 2 years, of which 4,000 wells/year were for CBM and 4,000 wells/year were for gas from shales.
Other trends
US tax credits helped launch economic CBM production in the 1980s, and output in other countries was slow to follow.
The emphasis for CBM exploitation in the US seems to have shifted to deeper coals, lower rank coals, and the opportunity to develop existing plays more intensively, said Advanced Resources International Inc., Arlington, Va., in a six-part series in OGJ on unconventional gas that concluded last month (OGJ, Sept. 24, 2007, p. 51).
For example, 85% of the 314-tcf CBM resource in the Green River basin occurs below 6,000 ft. And as much as 4-8 tcf or more of gas is judged to be in place in Gulf Coast Tertiary coals between Texas and Florida, with 3.4 tcf possibly recoverable.
Other countries are hosting CBM development. In July, Santos Ltd. said it hopes to make a final investment decision by the end of 2009 on a 3-4 million tonne/year LNG plant in Gladstone, Queensland, to be fed by CBM (OGJ Online, July 19, 2007).
That move followed a similar proposal from Arrow Energy Ltd., Brisbane, last May to supply CBM to a planned 1 million tonne facility, also in Gladstone.
Santos, which has more than 4.65 tcf of CBM reserves and contingent resources, said its Surat and Bowen basin permits would supply 158-205 bcf of CBM starting in early 2014.
CBM drilling in Alberta had been rising since 2002. It peaked at nearly 3,400 wells in 2005 and may have relaxed in 2006-07 after gas prices softened, said the Canadian Society for Unconventional Gas.
Great Eastern Energy Corp., London, made India’s first CBM sale earlier this year (OGJ Online, July 16, 2007). China is only beginning to exploit CBM in its vast coal reserves. And Indonesia is estimated to have a CBM resource of as much as 337 tcf (OGJ, Oct. 22, 2001, p. 40).
