The United States finished 2007 with dry natural gas reserves at a record peak after additions more than doubled production, the US Energy Information Administration reported on Oct. 16.
Total US year-end proved gas reserves reached 237.7 trillion cubic feet, 13% higher than their level at the end of 2006 and the highest level in the 31 years EIA has published annual reserves data, the US Department of Energy forecasting and statistical agency said. The record 46.1 Tcf of additions more than doubled the 19.5 Tcf of production, it indicated.
US crude oil reserves also grew during 2007 for the first time in four years, increasing nearly 2% year-to-year to 21.3 billion bbl as additions of 2 billion bbl exceeded 1.7 billion bbl of production, EIA said.
It said that the dry gas reserve additions mostly reflected development of unconventional gas resources including shale, coalbed methane and tight low-permeability formations. Application of advanced technologies such as horizontal drilling with hydraulic fracturing has made many of these unconventional resources economic to develop, it noted.
Shale proved reserves, in particular, increased 50% in 2007 and now account for about 9% of the US total, according to EIA.
It said that regionally, Texas had the largest year-end proved gas reserves increase last year at 10.3 Tcf, or a 17% year-to-year increase. Major increases in the Rocky Mountain states include 6.2 Tcf (26%) in Wyoming, 4.7 Tcf (27%) in Colorado and 1.2 Tcf (24%) in Utah.
Proved reserves declined during 2007 in two major gas-producing regions, EIA said. The Gulf of Mexico federal offshore area finished 2007 1 Tcf, or 6%, lower while New Mexico's year-end total was 700 billion cubic feet, or 4%, below its total at the end of 2006.
EIA said that the largest increase in US year-end proved crude reserves occurred in Alaska, where the total grew 7% to 284 million bbl from the 2006 year-end figure, followed closely by Texas, which recorded a 251 million bbl, or 5%, year-to-year increase. Alaska's growth included 45 million bbl of new field discoveries, the federal agency said.
"Due to rapid development of unconventional resources associated with the Bakken Formation, North Dakota had the third-largest year-end increased in proved crude oil reserves," it continued. Reserves in the state climbed 17% during the year to 70 million bbl, EIA said.
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