Oil and gas exploration and production companies operating in the US added nearly 3.8 billion bbl in proved reserves of crude oil and lease condensate in 2011, according to a recent report released by the US Energy Information Administration. EIA reported that US proved reserves at yearend 2011 totaled 29 billion bbl, up 15% year-on-year and the greatest volume increase since EIA began publishing proved reserves estimates in 1977.
Proved reserves of US wet natural gas, meanwhile, increased to 348.8 tcf at yearend 2011 from 317.6 tcf at yearend 2010. EIA said, “Though this increase was lower than the 33.8 tcf added in 2010, it was only the second year since 1977 that natural gas net reserves additions surpassed 30 tcf.”
EIA noted that proved reserves of crude oil and lease condensate increased in 2011 in each of the five largest crude oil and lease condensate areas, namely Texas, the Gulf of Mexico federal offshore, Alaska, California, and North Dakota.
Texas has the largest increase, up by 1.8 billion bbl, mostly from continuing development in the Permian and Western gulf basins. North Dakota had the second-largest increase, up by 771 million bbl, driven by development activity in the Williston basin. North Dakota and Texas combined accounted for two thirds of the net increase in total US proved oil reserves in 2011, EIA said.
Proved wet natural gas reserves increased in 2011 in each of the five largest gas producing states: Texas, Wyoming, Louisiana, Oklahoma, and Pennsylvania, EIA said. Texas and Pennsylvania accounted for a combined 73% net increase in proved wet natural gas reserves in 2011. Proved reserves in shale gas plays accounted for 38%, or 131.6 tcf, of total proved reserves in 2011.
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