Once dubbed an energy pipe dream, the prospect of extracting significant quantities of natural gas from frosty hydrate deposits just got a major boost. Scientists have demonstrated for the first time that they can produce natural gas from an existing gas hydrate deposit in nature. An international consortium of researchers and gas industry experts met in December in Tokyo to discuss results from an experimental drilling project conducted at the hydrate-rich well site known as Mallik, in the Mackenzie Delta of northern Canada.Hydrate forms when gas, usually methane, mixes with water under just the right temperature and pressure conditions. A lattice-work of frozen water molecules encases each molecule of the gas, creating a flammable, ice-like substance. When it was first discovered in the 1950s, hydrate was considered a nuisance, often clogging pipelines at drill sites. Hydrates were a “gold-plated pain in the rear,” says gas industry veteran Robert Maddox, an emeritus professor of chemical engineering at Oklahoma State University.
In the past few decades, however, interest in hydrate has soared. The biggest reason for hydrate’s appeal is the sheer volume of deposits buried beneath marine sediment and permafrost regions of the globe. Keith Kvenvolden, senior scientist (emeritus) at the U.S Geological Survey, estimates that the world’s total supply of hydrate is more than double the amount of all other known fossil fuel deposits combined. If we could produce gas from only 1 percent of all the hydrates in the world, says USGS researcher Tim Collett, we would have enough natural gas to last more than 170,000 years at the present U.S. consumption rate of 23 trillion cubic feet annually.
As a source for natural gas, hydrate today is about where coal bed methane was 15 years ago, says Michael Max, a hydrate expert formerly with the Naval Research Laboratory in Washington, D.C. “Coal bed methane was a classic, unconventional gas play,” with more than a few doubters, Max says. “Now it supplies around eight percent of the U.S natural gas supply. We think hydrate has a similar trajectory.”
Yet hydrate’s evolution has, until the December announcement, hinged on the giant “if” of technical feasibility. Engineers and geoscientists worked for years studying how changes in temperature and pressure affect hydrates in deposit. Reduce pressure or increase temperature just enough, and hydrate will melt. When that happens, the gas and water molecules go their separate ways and the gas, everyone assumed, could then be captured much like gas from conventional deposits. Computer models had predicted the resulting release of gas, but the idea had never been tested, making the successful melting and recapture of natural gas at Mallik a milestone for energy science.