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Southwestern to probe Smackover Brown Dense lime

Southwestern Energy Co., Houston, said it has accumulated 460,000 net acres prospective for oil in Upper Jurassic Lower Smackover Brown Dense limestone along the Arkansas-Louisiana state line.

The unconventional play is the first the company has revealed publicly of several new ventures it has been pursuing the last 1-2 years and in which it holds a combined 835,000 net acres. The formation’s commerciality is still to be determined, Southwestern said.

Southwestern plans to spud its first horizontal well in the play, in Columbia County, Ark., just southwest of Atlanta and east of Dorcheat-Macedonia oil field, late in the third quarter of 2011. It is to have a 3,500-ft lateral at 8,900 ft true vertical depth.

The company wants to spud a second well later this year in Claiborne Parish, La., that would have a 6,000-ft lateral at 10,700 ft TVD.

The Brown Dense formation is 300-550 ft thick at 8,000-11,000 ft over a large area, said Southwestern, which has invested $150 million in undeveloped acreage. The leases have an average 82% net revenue interest and 4-year average primary lease term with 4-year extensions.

Southwestern said, “We extensively reviewed the Brown Dense across the region and have indications that the right mix of reservoir depth, thickness, porosity, matrix permeability, sealing formations, thermal maturity, and oil characteristics are found in the area of southern Arkansas and northern Louisiana.

“This region of Arkansas and Louisiana has produced oil and gas from the Upper Smackover since the 1920s. The Brown Dense formation is the source rock for these Upper Smackover fields. It has the critical properties necessary to be a successful play and compares favorably to other productive oil plays in the United States. However, it has never been exploited with horizontal drilling technology until now.”

Southwestern aims to drill as many as 10 more wells to test the geological concept in 2012 and if successful could greatly ramp up activity after that.

Southwestern didn’t disclose a map of its lease position, but the Brown Dense play appears to have little or no overlap with the Jurassic Haynesville play now prevalent in North Louisiana and Northeast Texas.


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