GMX Resources Inc., Oklahoma City, (NYSE: GMXR) has achieved total production of 6 billion cubic feet equivalent (Bcfe) for first-quarter 2011, which is a company record and an achievement of the previously announced guidance.

The 6 Bcfe of production in the first quarter represents a 14% increase over fourth-quarter 2010, and a 89% increase over first-quarter 2010. The company's second-quarter and full-year 2011 guidance is 6.1 Bcfe with an expected range of 25- to 26 Bcfe, respectively, which represents an increase of 42% and 43% to 49% in second-quarter and full-year 2010.

GMXR controls development acreage in two oil-shale resources in the Williston Basin (North Dakota/Montana) targeting the Bakken and Sanish-Three Forks and the DJ Basin (Wyoming), targeting the Niobrara formation. Both plays are 90% oil.

The Bakken properties contain 34 potential operated units (1,280-acre), 136 operated locations (10,000-foot laterals; est. 45-55% working interest), giving the company a seven-year inventory using a two-rig development program. The Niobrara properties contain 133 potential operated units (640-acre), 532 operated locations (5,000-foot laterals; est. 45% working interest), giving the company a five-and-a-half year inventory using a two-rig development program.

The company's natural gas resources are in the East Texas Basin, in the Haynesville/Bossier gas shale and the Cotton Valley sand formation, where the majority of its acreage is contiguous and held by production.

The Haynesville/Bossier and the Cotton Valley sand locations include 257 net Haynesville/Bossier horizontal locations, and 100 to 250 net Cotton Valley sand horizontal locations, representing an estimated 12-year inventory of development utilizing two continuous rigs.