Onshore gas hydrate reserves close to recovery

The Mackenzie delta in Arctic Canada has been an area of conventional hydrocarbon exploration for decades.  In 1972 methane-ice mixtures in the permanently frozen ground were discovered in one well at a depth of about a kilometre during exploratory drilling.  They are rich, with up to 90% of the pore spaces in alluvial gravels being full of the white gas hydrate.  Being associated with conventional gas at greater depths, there is a good chance that combined production could make the considerable reserves economic.  On their own, gas hydrates are not yet economic, even onshore, since they would need heating to break down the peculiar compound, and natural gas prices are currently at a low level.  Economics also depend on a conventional gas pipeline being extended to the area  Tests and computer simulations suggest that production of deeper conventional gas can lower the pressure on the gas hydrate inducing it to break down and add to the flow from a well.  In maybe 10 to 20 years production could begin.  The likely origin of the Canadian reserves and those in the North Slope of Alaska is from methane leaking from deeper reserves to “freeze” in the colder conditions at shallow depths.

Arctic North America could eventually produce up to one sixth of current US natural gas consumption from onshore gas hydrate.  Of course, vastly greater gas-hydrate potential exists offshore – between 10 000 to 42 000 trillion cubic metres (tcm) world-wide, compared with 370 tcm of estimated conventional gas reserves.  Methane (CH4) burns to produce less carbon dioxide per unit of heat energy than more carbonic natural gas, so is a means of easing “greenhouse” gas emissions.  Potentially it could be feedstock for CO2-free hydrogen production.  Pressures on the economy of Japan, which has very few natural energy resources, have prompted Japanese researchers to begin exploratory offshore drilling into the Nankai trough offshore of SE Japan, where there are potentially rich reserves of gas hydrate in sands.  This may produce commercially in 10 to 15 years.  The thorniest problem with many gas hydrate deposits is that they are in “tight”, fine-grained sediments.

Source:  Kerr, R.A. 2004.  Gas hydrate resource: smaller but sooner.  Science, v. 303, p. 946-947

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