The Pelican State has another oil and gas shale play in the works. Known as the Lower Smackover Brown Dense, the play spans portions of North Louisiana and southern Arkansas.

The Brown Dense is believed to be a layer of limestone at the base of the Smackover Formation, itself a well known formation that has long been a source for traditionally produced oil and natural gas in North Louisiana.

It joins the Tuscaloosa Marine Shale (TMS) (see Shale Daily, Feb. 28) as the second half of Louisiana's duo of dense-rock plays believed to have the kind of production potential that has made shale plays such as the Haynesville, Barnett and Eagle Ford shales the new norm in energy exploration. The TMS is believed to underlie much of central Louisiana, with potential productive areas currently being explored from Vernon Parish to East Feliciana Parish.

The energy industry is watching the development of the TMS and the Brown Dense closely as both are believed to have the potential to contain oil reserves in addition to natural gas, said Louisiana Department of Natural Resources (DNR) Secretary Scott Angelle.

"We in Louisiana have a long and distinguished history of providing the energy that fuels this nation, and I am bullish on the future of energy production in this state and the role it will play in providing jobs and economic strength," he said. "We are seeing that exploration companies and investors share that optimism and belief in Louisiana's natural resources as they seek new domestic reserves of oil and natural gas."

Initial development of the Brown Dense formation, which is generally believed to underlie northern Claiborne, Union and Morehouse parishes in North Louisiana, has barely begun. Southwestern Energy has drilled its first well in Arkansas and said it will seek a permit to begin drilling for a Brown Dense well in Claiborne Parish before the end of 2011, DNR said.

Southwestern has also said it invested $150 million in leasing mineral rights for 460,000 acres to develop the play (see Shale Daily, Aug. 2). The company recently applied to the Louisiana Office of Conservation for approval of an area of the Lower Smackover formation in Claiborne Parish near the Arkansas border as a designated unit for drilling.

Devon Energy said it has secured 40,000 acres in mineral leases for the Brown Dense and that the company intends to drill a test well for the play. Devon has already received a permit for a well targeting the deeper section of the Smackover in Morehouse Parish, DNR said.

Devon is also active in the TMS, where the company has secured 250,000 acres of mineral leases and is in the process of drilling two wells in the shale (see Shale Daily, Aug. 5). About half a dozen wells targeting the TMS -- long thought to contain substantial reserves, but considered uneconomical to reach through previous methods -- are currently in the process of permitting or drilling.

"New exploration methods have changed the game for development of energy prospects in Louisiana and the nation, as we saw firsthand with the incredible upswing investment and economic activity in North Louisiana in 2008," Angelle said.

"With that exploration of the denser formations will come the need for water for hydraulic fracturing," said state Conservation Commissioner Jim Welsh. Companies drilling into the Brown Dense formation have informed the Office of Conservation that they intend to use surface water and recycled water for their overall project needs, in conformance with guidelines and advisories issued in nearby areas experiencing stressed ground water conditions, Welsh said.

The anticipated Brown Dense area of development in Louisiana underlies the Sparta Aquifer, which is currently experiencing improved water levels after combined state and local efforts to manage ground water use in the area, DNR said.

"We are still discouraging new high-volume users from using ground water in that area, and giving guidance on alternative sources for water," Welsh said.