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July 29, 2009

Unconventional Natural Gas Reserves

The Potential Gas Committee, a group of academics and industry specialists supported by the Colorado School of Mines, reports the largest increase in natural-gas reserves in its 44-year history. Estimated reserves rose to 2,074 trillion cubic feet (Tcf) in 2008 from 1,532 Tcf in its 2006 report.

UPDATE: Robert Rapier made a calculation that if the potential gas committee estimates of 2,074 tcf is correct then converting all cars to natural gas in the USA would provide 43 years worth of oil imports for the USA.

Most of this increase resulted from development of a technique known as “hydraulic fracturing” where water is injected via special “wells” to shatter underground shale formations and release trapped gas.

Not included in the committee’s “reserves” are the discoveries in “unconventional resources” that are becoming technologically practical to tap. One of these is the presence of “geopressurized zones” with gas at depths on the order of 25,000 feet found on the Gulf Coast of the United States. Experts put these reserves at 5,000 to 49,000 Tcf. Beyond that are the methane hydrates on the seafloor, which if not banned to the United States by a Law of the Sea Treaty, could provide an estimated at 7,000 to 73,000 Tcf.


More details from the Potential gas committee report is at the Colorado School of Mines.

Multistage fracturing success has been previously reported here

Three years ago, Packers could insert a half-dozen or so "stages" into a single well. As horizontal wells got longer, that number has grown to 22, and Themig says new advancements will allow virtually "unlimited" stages in a single well. That, in turn, has resulted in an order-of-magnitude higher production for a basic well that costs only about twice as much to drill.

The average conventional gas well in Western Canada produces about 250,000 cubic feet of gas a day. EnCana Corp. CEO Randy Eresman said in releasing the company's second-quarter results this week that its latest Horn River wells that use the multistage technology are coming on at initial rates of up to 11 million cubic feet per day.


A new estimate for the producable yield of Marcellus shale is 500 trillion cubic feet (tcf).



Unconventional gas resources are discussed at this dedicated ugresources website.

Canadian unconventional gas potential is huge with resource estimates are over 2,000 Tcf, excluding hydrates.











































Unconventional Gas Resource Estimates for the USA are
Tight Sand: 1200+ Tcf
Coalbed Methane: 1200+ Tcf
Shale Gas: 1100+ Tcf

FURTHER READING

New Energy and Fuel reports on a different new fracturing method by Exxon for accessing unconventional natural gas.

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