Huge resources of methane gas, trapped in frozen hydrates at thebottom of the oceans, are piquing the interests of researchersworldwide who estimate gas reserves in deep, frigid waters to be asmuch as 500 times larger than conventional gas reserves. With therecent enactment of the Methane Hydrate Act of 2000, passed byCongress and signed last week by President Clinton, more attentionis expected to be focused on these untapped reserves.

The Act, expected to provide up to $47.5 million in funding overfive years, will bolster research already begun in the Gulf ofMexico by the Interior Department’s Minerals Management Service,and the Naval Research Laboratory. A Texas A&M University teamalso is floating a proposal to sample for methane hydrates in theGulf, both in the shallow Garden Banks region, and along the deeperMississippi Canyon.

About three years ago, Texas A&M scientists showed for thefirst time how to create gas hydrates from naturally-occurring gasin the deep ocean. Gas hydrates are made up of natural gas andwater in a crystalline structure that forms at low temperatures andhigh pressures. The hydrates typically are found in sea-floorsediments in water 1,000 feet or deeper, and in the Arctic, methanehydrates have been found in large quantities below the permafrostin about 600 feet of water, according to Edith Allison, manager ofgas hydrates and oil and gas diagnostics and imaging programs forthe Office of Natural Gas and Petroleum Technology at the U.S.Department of Energy.

Scientists believe that these substances serve as markers foroil deposits, and though figures vary widely, the U.S. GeologicSurvey estimates that the United States has 220,000 Tcf of methanein hydrates off its coasts – nearly 220 times the size of itsconventional gas reserves. Worldwide, gas hydrates are estimatedto be 500 times larger than conventional gas reserves.

In 1999, a test well drilled off the coast of Canada found alayer of methane hydrate 500 feet thick, said Allison.And off thecoast of Australia, scientists have discovered an area of methanehydrate that covers 25,000 square kilometers.

Most typically, the dense deposits have been found off of theflanks of faults, seen as bright spots in seismic surveys taken byside-scanning sonar. Caused by the movement of salt within aseabed, they can also be found on salt domes, and near mudvolcanoes. Deposits are not spread evenly over the sea floor, butusually are found in large concentrations.

Two years ago, geologists on board the research vesselResolution were hauling mud-filled pipes up from the seafloor afterdrilling 1,400 feet into ocean sediments when one of the mud-coresamples exploded after reaching the surface. The mud was loadedwith methane, according to the geologists, and the Resolution’screw was the first to measure how much is actually there. AlongBlake Ridge, 250 miles off of the South Carolina’s coast, there areestimated to be 35 billion tons of buried methane, equivalent toU.S. natural gas consumption over 105 years. So far, researchershave found at least 10 different ocean sites with huge amounts ofmethane hydrates, and it is difficult to determine just how muchlies so far beneath the oceans, because as the hydrates are hoistedonto a ship, a drop in pressure lets a lot of the methane escape.

Now, researchers just have to figure out a way to extract thevast energy source, but it won’t be easy, and it is expected tocost a lot of money. A new drilling method may be on the horizon,however. Researchers from James Cook University in Queensland,Australia are using a drilling method whereby a tool grabs a30-foot-long cylinder of sediment and seals it in a pressurizedcontainer. When the container is brought to the ship, thepressurized sediment still contains all of the methane.

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