Texas' Permian basin topped North Dakota's Bakken play as contributors to a 9% increase in US crude oil and condensate reserves in 2009 as shale plays drove gas reserves to the highest since 1971.
Wet gas reserves climbed 11% in 2009 to 284 tcf, and oil and condensate reserves hit 22.3 billion bbl, said the US Energy Information Administration.
"Unlike the situation for natural gas," EIA said, "where proved reserves grew robustly despite lower wellhead prices, the rise in proved reserves of crude oil was supported by a 37% increase in the crude oil prices used to estimate reserves."
Louisiana, Arkansas, Texas, Oklahoma, and Pennsylvania were the leading states that added proved reserves of shale gas in 2009, EIA said.
Louisiana led the US in additions of natural gas proved reserves with a net increase of 9.2 tcf or 77%, owing mainly to development of the Haynesville shale. Arkansas with the Fayetteville shale and Pennsylvania with the Marcellus shale nearly doubled their reserves with net increases of 5.2 tcf and 3.4 tcf, respectively.
Shale development in Texas and Oklahoma gave the two states increases of 3.2 tcf and 2.1 tcf, respectively.
The increases occurred despite a 32% decline in the natural gas wellhead prices used to assess economic viability for 2009 reserves as compared to the prices used in reserves reporting for 2008, EIA said.
Proved reserves increased in each of the five largest oil and condensate areas: Texas, the Gulf of Mexico federal offshore, California, Alaska, and North Dakota. Nearly all of Texas' 11% gain of 529 million bbl was in the Permian basin. North Dakota was up 83% or 481 million bbl.
Overall shale gas reserves climbed to 60.6 tcf from 34.4 tcf at the end of 2008. Conventional and tight gas reserves climbed to 283.9 tcf from 255 tcf, with most of the increase occurring in the Lower 48 onshore. Coalbed methane reserves fell to 18.6 tcf from 20.8 tcf.
US crude and condensate reserves in 2009 grew 1.5 billion bbl from discoveries and 2.1 billion bbl from revisions mostly the result of extensions to existing fields. Production was 1.8 billion bbl in 2009.
US lease condensate proved reserves grew 14% to 1.633 billion bbl, primarily from extensions. US natural gas plant liquids reserves were up 5 million bbl to 178 million bbl in 2009. US plant liquids production was up 7% to 714 million bbl in 2009.
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