There were more than 14,000 oil and gas field operators in the United States last year, but the largest 100 of them as determined by total operated reserves accounted for nearly 90% of proved oil and gas reserves and included shale giant Chesapeake Energy Corp. and other companies active in the nation’s shale plays, according to a U.S. Energy Information Administration (EIA) report.

The top 10 operators in 2009 accounted for 48% of proved wet natural gas reserves and 54% of proved crude oil plus lease condensate reserves, EIA said.

The top operators ranked by 2009 natural gas proved reserves is a list of familiar names: BP plc (15.2 Tcf), Chesapeake Operating Inc. (13.5 Tcf), XTO Energy Inc. (12.5 Tcf), ExxonMobil Corp. (11.7 Tcf), ConocoPhillips (10.7 Tcf), Devon Energy Corp. (8.5 Tcf), Anadarko Petroleum Corp. (7.8 Tcf), EOG Resources Inc. (6.4 Tcf), Encana Oil & Gas Inc. (5.7 Tcf) and The Williams Companies Inc. (4.3 Tcf).

BP also headed the list of 2009’s largest companies as determined by production numbers: BP (907 Bcf), XTO (855 Bcf), ConocoPhillips (850 Bcf), Chesapeake (835 Bcf), Anadarko (817 Bcf), Devon (743 Bcf), Encana Oil & Gas (590 Bcf), Chevron Corp. (511 Bcf), Williams (435 Bcf) and EOG (422 Bcf).

Those rankings are likely to change when EIA rolls out its 2010 survey next year. Late in 2009 ExxonMobil agreed to pay $41 billion to acquire XTO, a move which would add around 45 Tcfe to ExxonMobil’s resource base and lift its gas weighting to 45% (see Daily GPI, Dec. 15, 2009). And Chesapeake recently added 500,000 net acres to the its million-plus-acre leasehold in the Marcellus Shale (see Shale Daily, Nov. 5).

In addition, Chevron, one of the few major oil companies without a visible presence in the North American shale plays, last month announced a deal to buy Atlas Energy Inc. for an estimated $4.3 billion (see Shale Daily, Nov. 10). Pittsburgh-based Atlas has close to 486,000 net acres in the Marcellus Shale. It also holds an estimated 623,000 acres in the Utica Shale, as well as close to 370,000 acres in Michigan in the Antrim Shale and the Collingwood/Utica play (see Daily GPI, May 10). In addition, Atlas has about 120,000 acres in the Chattanooga Shale of Tennessee and 123,000 acres in the New Albany Shale.

U.S. natural gas proved reserves, estimated as wet gas (including natural gas plant liquids) increased by 11% in 2009 to 284 Tcf — the highest level since 1971 — according to EIA (see Shale Daily, Dec. 1). The increase demonstrates “the growing importance of shale gas in meeting both current and projected energy needs,” said Richard Newell, EIA administrator.

The Barnett accounted for 9% of the country’s proved reserves at the end of last year, followed by the Haynesville/Bossier at 4%; the Fayetteville, 3%; the Woodford, 2%; the Marcellus, 2%; the Antrim, 1%; and other shales accounting for less than 1%, EIA said (see Shale Daily, Dec. 3). Combined, the shale plays accounted for 21% of the country’s proved reserves of 284 Tcf.