Natural Gas Hydrates

In addition to the petroleum and free natural gas found on Alaska's North Slope, there is the possibility there of another large and, as yet, untapped energy source. This resource is the substance called natural gas hydrates.

Natural gas hydrates are crystalline solids resembling snow that form from mixtures of water and natural gas under certain conditions. Unless natural gas has any associated water removed from it before being fed into a pipeline, gas hydrates may form and plug up the pipeline. The hydrates sometimes have plugged up the fittings placed at the heads of gas wells.

Low pressures and temperatures favor the formation of the natural gas hydrates. Consequently, they are likely to be found beneath the 2,000-foot thick layer of permafrost that covers Alaska's North Slope down to depths perhaps near 4,000 feet. The hydrates may also occur in the upper reaches of offshore gas fields. In 1970, Soviet scientists announced the discovery of huge deposits of natural gas hydrates beneath permafrost in the Soviet Union. Other deposits have been discovered in the seafloor off the coasts of Africa and Central America.

As yet, it is not known how large the natural gas hydrate resource might be in Alaska and nearby Canada. Nor is enough known about the characteristics of the hydrates to be certain that they can be extracted economically. However, it is likely, according to the University of Alaska's Christine Ehlig-Economides, writing in a recent issue of The Northern Engineer, that methods involving reduction of the gas pressure within the deposits or injection of methyl alcohol into the formation will enable profitable extraction.