US natural gas reserves increased by record 46.1 tcf in 2007

US proved natural gas reserves increased by a record 46.1 tcf in 2007, more than twice the 19.5 tcf actually produced last year, according to the US Energy Information Administration (EIA).
The agency, in a report, said the additions left total gas reserves as of December 31 of 237.7 tcf, 13 % above year-end 2006 and the highest level in the 31 years EIA has published annual reserves data. EIA also said that for the first time in four years, US proved oil reserves rose during 2007, as proved reserve additions of 2 bn barrels exceeded production of 1.7 bn barrels. Year-end proved reserves in 2007 stood at 21.3 bn barrels, nearly 2 % higher than at the end of 2006.

The agency said the natural gas reserve additions mostly reflected the rapid development of unconventional gas resources including shale, coalbed methane, and tight low-permeability formations. Many of these unconventional resources are now economic to develop because of the application of advanced technologies like horizontal drilling with hydraulic fracturing.
Shale proved reserves, in particular, increased 50 % in 2007 and now account for about 9 % of the US total, EIA said.

Texas had the nation's largest increase in year-end proved gas reserves in 2007, amounting to a 17 %, or 10.3 tcf, gain, EIA said. The agency added that "major increases" in year-end proved reserves in the Rocky Mountain states included a 26 %, or 6.2 tcf, increase in Wyoming, a 27 %, or 4.7 tcf, increase in Colorado and a 24 %, or 1.2 tcf, increase in Utah.
Proved reserves declined in two major gas-producing regions -- a 6 %, or 1 tcf, decline in the federal offshore waters of the Gulf of Mexico and a 4 %, or 700,000 mm cf, drop in New Mexico.

EIA said Alaska saw the largest increase of year-end crude oil proved reserves with a 7 %, or 284-mm-barrel, increase over 2006, followed closely by Texas, with a year-end increase in proved reserves of 5 %, or 251 mm barrels. Alaska's increase included 45 mm barrels of new field discoveries, EIA said.
The agency added that because of the rapid development of unconventional oil resources associated with the Bakken Formation, North Dakota had the third largest year-end increase in crude oil proved reserves, up 17 %, or 70 mm barrels, from 2006.

The data was included in an advance summary of EIA's US Crude Oil, Natural Gas and Natural Gas Liquids Reserves 2007 Annual Report.