WASHINGTON — U.S. natural gas proved reserves, estimated as “wet” gas, which includes natural gas plant liquids, increased by 11 percent in 2009 to 284 trillion cubic feet, the highest level since 1971, according to the U.S. Energy Information Administration’s Summary: U.S. Crude Oil, Natural Gas, and Natural Gas Liquids Reserves, 2009 , released recently.

“Shale gas development drove an 11 percent increase in U.S. natural gas proved reserves last year, to their highest level since 1971, demonstrating the growing importance of shale gas in meeting both current and projected energy needs,” said Richard Newell, EIA’s administrator.

“Louisiana, Arkansas, Texas, Oklahoma and Pennsylvania were the leading states in adding new proved reserves of shale gas during 2009,” he said.

Leader

Louisiana led the nation in additions of natural gas proved reserves with a net increase of 9.2 Tcf (77 percent) owing primarily to development of the Haynesville Shale. Both Arkansas (Fayetteville Shale) and Pennsylvania (Marcellus Shale) nearly doubled their reserves with net increases of 5.2 Tcf and 3.4 Tcf respectively.

These increases occurred despite a 32 percent 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. Proved reserves of U.S. oil (crude oil plus condensate) also increased in 2009, rising 9 percent to 22.3 billion barrels.

Texas showed the largest increase in reserve volume, while North Dakota had the second largest increase reflecting growth in the Bakken Shale. Unlike the situation for natural gas, where proved reserves grew robustly despite lower wellhead prices, the rise in proved reserves of crude oil was supported by a 37 percent increase in the crude oil prices used to estimate reserves.

Definition

Proved reserves are those volumes of oil and natural gas that geological and engineering data demonstrate with reasonable certainty to be recoverable in future years from known reservoirs under existing economic and operating conditions.

EIA’s estimates of proved reserves are based on an annual survey of about 1,200 domestic oil and gas well operators.

Summary: U.S. Crude Oil, Natural Gas, and Natural Gas Liquids Reserves, 2009 is available at: www.eia.gov/naturalgas/crudeoilnaturalgasreserves.