The term “Granite Wash” is used in many different areas of the play to describe different kinds of rocks, says Dr. Randy Keller, director of the Oklahoma Geological Survey, in the webinar titled “Granite Wash: The Hot Play’s Prospectiveness & Production Results” hosted recently by OilandGasInvestor.com and UGcenter.com and now available for viewing on demand.

“Major tectonic inversion that involved thrusting and strike-slip created the structures that were the source of the Granite Wash,” says Keller, who is also McCollough Chair, ConocoPhillips School of Geology and Geophysics, for the University of Oklahoma. “Better understanding of those structures should help our efforts to exploit the Granite Wash and perhaps even find some new fields.”

The gas- and oil-rich play in Oklahoma and the Texas Panhandle is eroded off the Wichita and Amarillo uplifts to the south, producing an inverse set of layers where carbonate rock has uplifted about 30,000 feet in Pennsylvanian time, followed by fine grains and then arkose sandstones called Granite Wash. Citing Answers.com, Keller defines the Granite Wash as “material eroded from granites and re-deposited, forming a rock with the same major mineral constituents as the original rock.”

From a larger picture, sediments eroded off a large uplifted structure. The extreme size and amount of material eroded since Pennsylvanian time is significant. Structures from Cambrian cut across Precambrian creating uplifts producing granite washes.

The Ancestral Rocky Mountain uplifts occur throughout the continent and are essentially Pennsylvanian uplifts that over time form granite wash-like stories. The Amarillo uplift is a continuation of the Wichita uplift, where a dead vertical fault affects how far the play extends. The Granite Wash in Oklahoma occurs mostly in four counties: Roger Mills, Beckham, Custer and Washita.

John Brooks, vice president for Penn Virginia Corp. and regional manager of its Penn Virginia MC Energy LLC unit based in Tulsa, says the company’s Granite Wash play in Oklahoma began in 2006 with vertical drilling. An AMI with Chesapeake Energy Corp. as well as Penn-operated areas of the play has expanded with horizontal drilling. Brooks says the play is attractive because the “drilling economics are robust, repeatable, low risk with proved reserves.”

The company’s South Clinton wells come on strong with rapid recovery and include oil. Plug-and-perf completions help make this a robust play for Penn, he adds.

J.C. Ridens, executive vice president and chief operating officer for Forest Oil Corp., describes the company’s work in the Greater Buffalo Wallow area in Wheeler County, Texas. With 135,000 gross acres, it is one of the largest operators in the play. The play is 140 miles long (50 miles in Texas), 30 miles wide, at depths from 13,000 to 17,000 feet, with thicknesses of 1,500 to 3,500 feet and eight pay zones, Ridens says.

The play began in the 1960s. Forest has 400 vertical wells providing a wealth of data. Horizontal drilling, hydraulic fracturing and tighter well spacing all help create a prolific and economic play where Forest has seen a 100% success rate, he adds.

The company plans to use four horizontal rigs in 2010, where it sees better economics with 7.2 billion cubic feet equivalent compared with 1.7 billion equivalent in its vertical wells. Horizontal costs are approximately $5.5 million compared with $2.3 million for vertical wells. The low-risk play has good infrastructure and take-away capacity, plus provides expansion into the Atoka and Morrow, he says.

Kamil Tazi, vice president, engineering and planning, for Cordillera Energy Partners (III), joining the company’s previous iteration, Cordillera II, in 2006, before it was sold to Forest Oil, cites Cordillera’s approximately 98,000 gross acres in the play. It plans 25 to 30 vertical and five to 10 horizontal wells in 2010.

Tazi likes the play for its excellent infrastructure, good community acceptance and play diversification. The 38,000-square-mile play has up to nine productive benches and 170 trillion cubic feet equivalent in recoverable reserves. There are currently 30 active rigs, and 150 producing horizontal wells with estimated ultimate recoveries of between 5- and 15 billion cubic feet in the play.

Cordillera averages 5.5 billion cubic feet equivalent with well costs of $4.8- to $7 million. Tazi compared vertical and horizontal statistics and Granite Wash with shale economics, concluding that the Granite Wash has “bigger reserves and better economics than shales” and that vertical and horizontal drilling can co-exist.

Their remarks and slides are available now for viewing on demand at “Granite Wash: The Hot Play’s Prospectiveness & Production Results.” The webinar Includes a PDF of UGcenter.com’s 31-page January 2010 special report, “Granite Wash: Texas, Oklahoma,” including details on 26 Granite Wash wells.

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