Consol Energy Inc. has proved gas reserves of 3.7 Tcf as of the end of last year, marking an increase of 1.8 Tcf, or 95%, from the 1.9 Tcf reported at year-end 2009. Coalbed methane (CBM) and a “nice jump” in the Marcellus Shale were credited for the growth.

Proved developed reserves (PDP) increased by 86% and proved undeveloped reserves (PUD) increased 107%. Of the 3.7 Tcf of proved reserves, 52% are categorized as proved developed and 48% are classified as proved undeveloped.

The company spent $255.7 million on drilling last year, yielding extensions and discoveries of 621.3 Bcf. The net impacts of revisions yielded another 380 Bcf. The company replaced 486% of its 2010 production through the drill bit.

“We saw solid growth in our coalbed methane reserves and a nice jump in our Marcellus Shale PDP bookings from our 2010 program,” said CEO J. Brett Harvey. “The reserves from our 2010 Marcellus Shale program averaged 5.5 Bcf per well. When you consider that our laterals averaged 3,400 feet, this means that we booked about 1 Bcf of reserves for every 600 feet of lateral.”

The company has total proved, probable and possible reserves of 14.2 Tcf as of Dec. 31, representing an increase of 7.7 Tcf, or 118%, from the 6.5 Tcf reported at year-end 2009, it said.

Last year 24 horizontal wells were drilled in the Marcellus Shale and 13 were turned online. Total well costs averaged $4.1 million. The expected ultimate recovery averaged 5.5 Bcf per well, and the average lateral was 3,400 feet. Total daily production from the Marcellus grew from 14 MMcf/d as of Dec. 31, 2009 to 40 MMcf/d as of Dec. 31, 2010.

More than 99% of Consol’s proved reserves are gas.

Last month Consol management said it was tapering its rig build-up in the Marcellus due to low gas prices (see Shale Daily, Jan. 31).