Gas hydrate extraction methods to be tested in Alaska

Renee Schoof

WASHINGTON -- Will the world be tapping methane hydrates deep in the permafrost and off the edges of continents decades from now? Part of the answer will rest with research in Alaska.

A day after the Department of Energy announced the results of a test at Prudhoe Bay that resulted in a steady flow of natural gas, researchers stressed that this was among many tests to come. The test was the first use of carbon dioxide to extract natural gas. At 30 days, it was also the longest test of methane hydrate extraction.

"There's much more field work that would need to be done. This is the very first attempt to understand the scientific processes and the behavior of these reservoirs," Ray Boswell, the technology manager for gas hydrates at the Energy Department's National Energy Technology Lab, said Thursday.

The recent test focused on just one approach, what industry calls the "huff and puff." The investigators injected nitrogen and carbon dioxide and showed that this mixture could promote the production of natural gas.

Another approach is based primarily on reducing pressure. The research so far suggests that this method would be the most promising way to get a commercially viable flow of natural gas, Boswell said.

But the carbon dioxide method has an important potential advantage: It would be a way to sequester carbon dioxide from fossil fuel use instead of letting it flow into the atmosphere and trap heat, driving climate change. More study of the test data will be needed to see how well the carbon storage worked, the Energy Department said Wednesday when it reported the test.

One of the next steps will be to conduct an extended test of the depressurization method, Boswell said. There's a strong consensus among scientists and industry researchers that a test of 18 months or more will be needed, and additional tests after that, to get a better idea of how promising gas hydrates are.

More tests will give a better idea of how much gas there is, how much investment will be needed to get it and how long it would take to get gas to flow, he said. "There's a lot of opinion and modeling but very little field data to ground-truth it," he said.

Methane hydrates are found in the permafrost and in ocean sediments 1,500 feet or more deep off the coasts of continents. The Arctic is a natural place for testing.

"We refer to Alaska as a natural laboratory because we have a good idea of where the hydrates are and what condition they're in," Boswell said.

The U.S. Geological Survey reported in 2008 that an estimated 85 trillion cubic feet of technically recoverable natural gas was on shore in gas hydrates in northern Alaska.

Japanese researchers similarly tested permafrost hydrates in Arctic Canada in 2008 to learn how to approach hydrates in deep water off Japan, Boswell said.

The Japan Oil, Gas and Metals National Corp. participated in the recent test in Alaska, along with Conoco Phillips.

The Energy Department said additional research in the Arctic would test technologies to find and extract methane hydrates on a larger scale off the U.S. Gulf Coast.

A Massachusetts Institute of Technology study on the future of natural gas released in 2010 said methane hydrates aren't likely to reach global commercial viability for at least 15 to 20 years. It noted that along with the United States and Japan, Canada, China, India and South Korea and other countries have been finding and sampling them.

The study said gas from methane hydrates can be extracted using well-established production methods. The risks are known or "considered manageable," it said.

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