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Team completes North Slope hydrate test Successfully used carbon dioxide to extract natural gas from methane hydrate deposit above Prudhoe Bay field; ran test for 30 days Alan Bailey Petroleum News
A team involving the U.S. Department of Energy, ConocoPhillips and the Japan Oil, Gas and Metals National Corp. has successfully completed a test involving the production of natural gas from a methane hydrate deposit above the Prudhoe Bay field on Alaska’s North Slope, Energy Secretary Steven Chu announced May 2. The test succeeded in teasing a flow of natural gas from the hydrates by replacing methane in the hydrate by carbon dioxide injected down a test well. Methane is the main component of natural gas.
Possible gas source Methane hydrate consists of a white crystalline substance that concentrates natural gas by trapping methane molecules inside a lattice of water molecules. There are extensive deposits of the material straddling the base of the permafrost under the North Slope. The hydrates could prove to be a prolific future source of natural gas although the technical and economic feasibility of commercial gas production from the hydrates has yet to be demonstrated.
“The Energy Department’s long term investments in shale gas research during the ’70s and ’80s helped pave the way for today’s boom in domestic natural gas production that is projected to cut the cost of natural gas by 30 percent by 2025 while creating thousands of American jobs,” Chu said. “While this is just the beginning, this (methane hydrate) research could potentially yield significant new supplies of natural gas.”
The use of carbon dioxide to displace methane from hydrates could, in addition to driving natural gas production, bring the added benefit of sequestering carbon dioxide, the bête noire of global warming. The technique has been demonstrated in laboratory experiments but has never before been tried in a field setting.
The team conducted the proof-of-concept field test on the North Slope using the Ignik Sikumi No. 1 well, a well drilled last winter specifically for the test to a depth of 2,597 feet from an ice pad adjacent to the Prudhoe Bay unit L-pad. The well’s name is Inupiaq for “fire in the ice,” a phrase sometimes used to characterize the unusual properties of methane hydrate.
The test was conducted between Feb. 12 and April 10 this year, with the team injecting a mixture of carbon dioxide and nitrogen into the underground formation containing the hydrates and demonstrating that this cocktail of gases would stimulate the release of methane from the hydrate. Data collected during the test will be used to determine the efficiency with which carbon dioxide was simultaneously sequestered in the reservoir.
30 days And a test involving the reduction of the pressure in the underground reservoir rock demonstrated the continuous production of natural gas over a period of 30 days, the Department of Energy says. The longest previous demonstration of sustained gas production from methane hydrate by depressurization, in 2008 in the Mallik well in the Mackenzie River Delta of northern Canada, lasted six days.
In 2007 the Department of Energy was involved with BP, ASRC Energy Services, Ryder Scott Co., the U.S. Geological Survey and university researchers in the drilling and testing of the Mount Elbert methane hydrate stratigraphic test well in the Milne Point unit on the North Slope. That well enabled the collection and analysis of subsurface methane hydrate samples, and the testing of the production characteristic of the methane hydrate in the well.
However, despite success in methane hydrate tests, researchers are still a long way from demonstrating the continuous production of gas from the hydrates on a commercial scale, and from showing that this production can be commercially viable. And then, of course, there is the thorny question of how to ship North Slope gas to market.
Next steps The Department of Energy says that the next steps in its research efforts will be to evaluate gas hydrate production over longer durations, probably through depressurization, with the eventual goal of achieving sustained and commercially viable gas production.
The department announced that it is making $6.5 million available in fiscal year 2012 for research into technologies for characterizing subsea methane hydrate deposits in deepwater settings; into new tools and techniques for determining reservoir response and environmental impacts relating to methane hydrate production; and into the role of methane hydrates in the natural environment, including the response of the material to warming climates.
The department also announced that it will request a further $5 million in research funding in the federal administration’s fiscal year 2013 budget for domestic and international methane hydrate research. That research could include a longer-duration test of methane hydrate production on a North Slope gravel pad that could accommodate year-round operations, the department said, adding that this research would require the involvement of private sector and international partners.
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