Petrohawk declaredd estimated proved oil and gas reserves at December 31, 2010 of approximately 3.4 trillion cubic feet of natural gas equivalent (Tcfe). Of total estimated proved reserves, 2.35 Tcfe were in the Haynesville Shale, 736 Bcfe were in the Eagle Ford Shale, 12 Bcfe in the Lower Bossier Shale, and 294 Bcfe were in other areas.

Pro forma for the sale of approximately 500 Bcfe of proved reserves during 2010, the Company replaced 647% of production and reported a net increase in proved reserves of 1.13 Tcfe over year-end 2009, a growth rate of 50% year over year. Petrohawk's estimated proved reserves at December 31, 2010 were prepared by the independent reserve engineering firm Netherland, Sewell and Associates, Inc. in accordance with Securities and Exchange Commission ("SEC") guidelines, which include a requirement that proved undeveloped reserves be part of a five-year development plan. The Company estimates that without the application of the five-year rule, estimated proved reserves would have been 4.46 Tcfe.

Through active drilling programs in the Haynesville Shale and Eagle Ford Shale during 2010, the Company increased its proved developed reserves by approximately 92% on a pro forma basis, to a total of 1.2 Tcfe. Proved reserves are 35% proved developed. In 2010, organic finding and development costs, excluding land and seismic costs, were $1.35 per Mcfe, with $1.8 billion in capital expenditures, on a pro forma basis.

Of Petrohawk's 3.4 Tcfe of proved reserves (92% natural gas), approximately 1.4 Tcfe were added through the drillbit in 2010 (net of revisions) comprised of 973 Bcfe in the Haynesville Shale, 14 Bcfe in the Bossier Shale and 467 Bcfe in the Eagle Ford Shale. Proved undeveloped reserves in Elm Grove Field were reduced by 112 Bcfe due to the five year rule. Additions net of revisions on other areas totaled 40 Bcfe.

Tags: Petrohawk Energy Corporation