Shale Natural Gas Plays Expanding in State

The spread of shale prospects into new areas across Oklahoma has resulted in cutting-edge geology and geochemistry as challenges in shale gas plays force operators into innovative approaches.
“They’re finding out that mineralogy is very important,” said Brian Cardott, an organic petrologist and coal geologist at the Oklahoma Geological Survey in Norman, during a presentation of “History and Status of Coalbed methane and the Woodford Gas-Shale Plays of Oklahoma.”
The story about gas shales could hardly be any bigger.
By current estimates, the 19 shale gas basins resource in the U.S. could total 500 to 700 trillion cubic feet of gas.
There’s plenty of area left to roam in Oklahoma, he said.
Recent discoveries include the Woodford Shale in southeast Oklahoma, where Newfield Exploration is the largest operator.
At an average cost of $3 million to $4 million per well, more than 1,500 wells have already been drilled in the Woodford with more to come.
First, drilling companies sink vertical wells. Then, they drill horizontally with fracturing techniques, which involves fracturing the shale rock deposits with high pressured water. This releases the trapped gas. The sweet spots in the Woodford Shale are McIntosh County to Hughes, Coal, Pittsburg and Atoka counties. Landowners often get up to 15 percent royalties on the natural gas found in the Woodford Shale.
Also in Oklahoma, the Caney Field is another shale gas play that is part of the Woodford Shale. The Cana Field is a shale formation deep in Blaine, Caddo and Canadian Counties west of Oklahoma City. That field is attracting the attention of Oklahoma City-based Devon Energy. Marathon Oil also announced, earlier this year, it would begin drilling in Canadian County. Other major shale plays in this region and in eastern parts of the U.S. include the Fayetteville Shale in northwest Arkansas; the Haynesville Shale in Louisiana; Marcellus Shale in the Appalachian Basin and the Utica Shale in New York.
The first shale gas well was 188 years ago. But the first gas production in this era came from the Barnett Shale in the Fort Worth Basin in 1981. Until the success of the Barnett Shale, it was thought that natural fractures needed to be present in gas shales. Because the gas would not flow from the dense shale, plays were viewed as technological plays and ignored. Then, advances in horizontal drilling, fracture stimulation and the application of 3-D seismic contributed to the success of gas-shale wells, Cardott said.
“It’s one of the more interesting unconventional plays because it’s so undefined,” he said.



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