"This potential supply of a clean fossil fuel will remain untapped unless a technically and economically viable means of producing methane from hydrates is found," said David Schoderbek, ConocoPhillips' manager of the hydrate project.

If the procedure works it could also open up a new way of storing CO2 that will be produced when commercial gas production begins on the North Slope, Schoderbek said.

Gas in the Prudhoe Bay field contains about 12.5 percent CO2, which would have to be removed before the gas could be put into a planned large-diameter pipeline. The producing companies, which include ConocoPhillips, are looking for ways to make store or use the CO2 gas.

Schoderbek said injection of the CO2 could lead to a practical way to produce methane locked into gas hydrates on the North Slope. Hydrates are thought to exist across wide areas of Arctic regions where there are petroleum basins, including on the North Slope oil fields.

U.S. Geological Survey studies indicate that large methane resources exist in Arctic hydrates, and DOE is working with several companies on possible technologies to produce the methane.

Schoderbek said ConocoPhillips has tested and patented a procedure for displacement of methane with carbon dioxide in a hydrate in its laboratories in Bartlesville, Okla. The technology was developed in partnership with the University of Bergen in Norway.

"This trial represents the first experiment outside a laboratory of this production technology in which a carbon dioxide molecule is exchanged for a methane molecule locked up in the hydrate's structure. The methane gas is produced and the carbon dioxide is sequestered inside the hydrate structure," a briefing paper prepared by ConocoPhillips on the project said.

Schoderbek said the North Slope test will be the first time the procedure will be tried in the field with a real hydrate. The test injection is expected to cost $16 million with DOE contributing 80 percent, he said.

The agency has other hydrate projects underway on the North Slope, including a long-term production test co-funded with BP.

Schoderbek said his team is currently selecting a location for the test, which will require a well to be drilled into a hydrate on the North Slope. The location for the well should be chosen by March, with drilling and the injection planned for next winter. Testing on the wellsite will take about a month, Schoderbek said.

The plan involves trucking liquid carbon dioxide to the North Slope. There is no local source.

"We expect to produce a small volume of methane during the test because we will be limited by the amount of liquid CO2 we can inject. Our goals, however, are to verify that we can inject CO2 into the hydrate and that the chemical exchange happens," Schoderbek said.

Hydrates are underground lattice structures of ice that form with methane under certain temperature and pressure conditions. They are known to exist in certain offshore regions and government agencies in Japan and India are engaged in hydrates research off their shores.

Most of the U.S. hydrates research is focused in the Arctic, where hydrates are found within and below permafrost. Schoderbek said the permafrost in northern Alaska is typically about 1,500 feet deep and the depth where hydrates occur goes to about 3,000 feet.

The methane that is trapped in the hydrate appears to have migrated up from conventional hydrocarbon sources in deeper rocks, Schoderbek said. That is encouraging because it means the methane in the hydrate may be concentrated in sufficient volumes to be potentially producible, he said.

Producing from an offshore hydrate is much more problematic because the hydrates are believed to be more scattered and occur in deep water.

The North Slope is also an ideal test bed for hydrate technology because hydrates are known to exist in the existing oil and gas fields where there is infrastructure to support the tests, Schoderbek said.

A benefit of the ConocoPhillips test procedure, if it works, is that it will preserve the structure and stability of the hydrate. Other production procedures being researched include thermal and depressurization techniques that would involve warming or reducing pressure so that methane flows out of the hydrate.

A disadvantage of those approaches is that the hydrate could be destabilized. Schoderbek hopes to avoid that by replacing methane molecules with carbon dioxide molecules, thereby preserving the hydrate.

Tim Bradner can be reached at

tim.bradner@alaskajournal.com.