INSIGHT: US reaches key milestone for gas hydrate

22 February 2007 15:24  [Source: ICIS news]

US is fishing for natgas in arctic permafrostBy Joe Kamalick


WASHINGTON (ICIS news)--The US Energy Department says it has reached a key research milestone that could lead within ten years to commercial production of vast new natural gas resources from methane hydrates beneath arctic ice and in deep sea reservoirs.


The department said that in co-operation with BP it had completed a test well in the Prudhoe Bay region of the Alaskan North Slope that has successfully demonstrated the ability to identify methane hydrate reservoirs in arctic permafrost.


“This is both a major milestone and another step on the way toward what we hope will be commercial production from gas hydrates,” said Ray Boswell, the department’s technology manager for methane hydrates.


The payoff could deliver an energy breakthrough for the US, and not least for US chemicals manufacturers who are almost wholly dependent on natural gas for feedstock.


Methane hydrate is an open, solid lattice of water molecules that encloses, without chemical bonding, molecules of methane. 


According to Boswell, methane hydrates are stable at varying levels of pressure and temperature, even up to 50° Fahrenheit, although generally they are found at low but not necessarily freezing temperatures. When heated, the hydrate releases its methane, the principal component of natural gas.


There is an awful lot of it around.


Citing data from the US Geological Survey, the Energy Department says “the size of the global gas hydrate resource is staggering, holding more energy potential than all other fossil fuels combined”.


In the US and its offshore regions, gas hydrate deposits and reservoirs are estimated to contain 200,000trn cubic feet (tcf) of natural gas, more than 100 times greater than known US reserves of recoverable natgas of some 1,500 tcf. 


Of course it is by no means certain that even a substantial portion of that 200,000 tcf in gas hydrate can be technically and economically recovered. 


However, the department notes that if just 1% of US methane hydrates can be developed commercially, it would double the country’s natgas resource base.


The US consumes about 23 tcf of gas annually.  If as much as 10% of the country’s methane hydrate resources could be developed, it would be sufficient to meet US gas demand for some 800 years.


The test well at Prudhoe Bay was significant, said Boswell, for two reasons.


First, it proved that geologists can accurately predict where subsurface gas hydrates are concentrated. 


“We drilled in an area that had not previously been drilled and for which we had geophysical data only,” Boswell said.


“We were looking for and we expected to find hydrate reservoirs at the site at certain levels, at two levels, and in specific depth ranges and volumes,” he said.  “This test well showed those interpretations to be correct.”


“We now have confidence in our ability to characterize hydrate deposits in areas that have not been drilled yet,” Boswell said.


The Prudhoe Bay hydrates test well also recovered a wealth of core samples, providing the first modern data on hydrates as they exist in substrates.


This data, said Boswell, along with the now proven seismic means of predicting worthwhile methane hydrate deposits, leaves the Energy Department and BP poised for the next step: drilling the first hydrates production test well.


Boswell said a methane production test well could start drilling within 12 months. That well will test various means of liberating the methane from its hydrate home and bringing the gas to the surface.


The tests likely will include heating the substrate and possible injections of carbon dioxide and other chemical triggers.


That production test well will move research much further along to the goal. “We hope to learn by 2015 what portions of known in-place gas hydrate resources can be technically and economically recovered,” said Boswell.


“We believe and we are hopeful that we can produce commercial volumes by then,” he said.

By: Joe Kamalick
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