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Reversing the Gas Crisis: The Methane Hydrate Solution

 

Commercialization of methane recovery from coastal deposits of methane hydrates could head off an impending gas shortage.

Fortnightly Magazine - January 2005

National Research Council), and numerous other studies are under way. The Gulf of Mexico Hydrate Research Consortium includes six private organizations and 17 universities organized in 1999 by the Center for Marine Resources and Environmental Technology at the University of Mississippi (CMRET), which has developed and installed a remote seafloor observatory within the hydrate stability zone of the continental slope of the Northern Gulf of Mexico. Funding for this consortium initially was obtained from the Department of Interior's Minerals Management Service and then from the cognizant agencies of DOE and the Department of Commerce [9]. Japan's Ministry of International Trade and Industry (MITI) and the Japan National Oil Corp. (JNOC) also have mounted a large research, development, and demonstration (R,D&D) effort. As noted before, a major focus of the Japanese effort is the Nankai Trough southeast of the main island of Honshu, which has yielded promising geophysical data [10].

Blake Ridge, about 250 miles east of Charleston, S.C., a sedimentary deposit at roughly 6,500 to 16,000 feet of water depth and 310 miles long, may be a good U.S. site for a demonstration of the feasibility of methane recovery from methane hydrates using the pressure reduction technique. Occurrence of methane hydrates in the United States has been studied there for about 30 years, and it is believed to contain large amounts of methane trapped both within the hydrate layer and as free gas below it. A recent (2000) estimate by Collett of the total gas content is 57 trillion m 3 or 2013 Tcf (more than 10 times U.S. proved reserves), although it is distributed over an area of 10,000 square miles. Of this 34 percent is free gas and 66 percent comes from methane hydrates in the overlying sediment [4]. Other estimates place the total gas content as high as 70 trillion m 3 (2,470 Tcf) [4]. Similarly, the hydrate-bearing sediments in the Nankai Trough, southeast of Japan's main island of Honshu, contain as much as 60 trillion cubic meters (2,119 Tcf) of gas and range in porosity from about 36 to 39 percent [10].

The Impending Shortage of Natural Gas

On the problems of U.S. natural gas supply and price stability, there are two critical areas in which R,D&D can make relatively near-term contributions, including more aggressive development of still sizeable lower-48 conventional and unconventional natural gas reserves and resources. There are also much higher imports of plentiful and relatively low-cost LNG from large stranded reserves of natural gas in many parts of the world (Trinidad, North Africa, Nigeria, the Persian Gulf region, Indonesia, etc.) But the most promising long-term solution would be the commercialization of methane production from a relatively small percentage of the enormous U.S. coastal resources of methane hydrates.

The recovery of coalbed methane, of which there were proved U.S. reserves of 18.491 Tcf on Dec. 31, 2002 [11] and the total potential resource is about 169 Tcf (see Table 1), is another opportunity for R,D&D to increase the production from 1.6 Tcf in 2002 [11] to only 2 Tcf projected for 2025 [12]. The same is