“It is the world’s first offshore experiment producing gas from methane hydrate,” an official from Japan’s Economy, Trade and Industry Ministry said. The test field is about 30 miles from Japan’s main island, where offshore reserves could contain more than 38 trillion cubic feet (tcf) of frozen methane hydrate, according to a Japanese study. If Japan’s government can foster practical methane hydrate technology — a task officials say will take about five years — the nation could lessen its reliance on natural gas imports to meet climbing domestic demand.

Methane hydrate forms where methane, formed by shallow subsurface bacteria or leaking from deep thermogenic hydrocarbon deposits, contacts water at high pressures and cold temperatures.

The U.S. has huge methane hydrate resources off the coasts of Alaska and the lower-48 states, and onshore in the Alaska North Slope. The Alaska North Slope technically recoverable resources is estimated at 85 tcf.

The U.S. methane hydrate research program is led by the U.S. Department of Energy (DOE) with the assistance of industry and other government research programs including the U.S. Geological Survey. The program includes laboratory experiments, field studies and production experiments.

A field experiment on the North Slope of Alaska during the winter of 2011-2012 was conducted by ConocoPhillips, Japan Oil, Gas and Metals National Corporation (JOGMEC) and the DOE. The experimental well injected carbon dioxide, which can replace the methane molecules inside the hydrate structure, to successfully produce methane from subsurface methane hydrates.

The U.S. program also works to develop tools and knowledge needed to understand and control the impact of methane hydrate on seafloor stability and to develop a greater understanding of the role methane hydrate plays in geohazards and in global environmental processes.