Changes brought yearend 2007 reserves to 21.3 billion bbl of oil and 237.7 tcf of gas
The US replaced more oil reserves than the country used in 2007 and added more than twice the amount of gas used that year, the US Energy Information Administration said Oct. 17.
The oil additions were the first in 4 years, and the gas additions set a record, the agency said. Operators added 2 billion bbl of proved oil reserves in 2007, a year in which the country produced 1.7 billion bbl. They added 46.1 tcf of proved dry gas reserves while producing 19.5 tcf.
The changes brought yearend 2007 reserves to 21.3 billion bbl of oil and 237.7 tcf of gas. That left the country with 13% more proved gas reserves and nearly 2% more proved oil reserves than yearend 2006.
"The dry natural gas reserve additions mostly reflected the rapid development of unconventional gas resources including shale, coalbed methane, and tight low-permeability formations," EIA said.
It said shale proved reserves rose 50% in 2007 and now account for 9% of the US total.
Texas had the nation's largest year-to-year increase in dry gas reserves, adding 10.3 tcf or 17%. Wyoming added 6.2 tcf or 26%, Colorado grew 4.7 tcf or 27%, and Utah climbed 1.2 tcf or 24%. The Gulf of Mexico federal region fell 1 tcf or 6%, and New Mexico was off .7 tcf or 4%.
Alaska's year-to-year proved oil reserves were up 284 million bbl or 7%, including 45 million bbl in new field discoveries. Texas was up 251 million bbl or 5%. North Dakota had the third largest gain, 70 million bbl or 17%, due to rapid development of unconventional oil in the Bakken formation.
The US produced 76 billion bbl of oil in 1977-2007, more than twice the proved reserves estimated in 1977, EIA noted.
Coalbed gas reserves grew 11.5% in 2007 to 21.8 tcf and account for 9% of US dry gas reserves.
Natural gas liquids reserves, which represented 30% of total liquid hydrocarbon proved reserves in 2007, climbed 8% to 9.1 billion bbl in 2007. NGL reserves include condensate.