--> Abstract: Shale Gas Potential of the Mowry Shale in Wyoming Laramide Basins; #90063 (2007)

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Shale Gas Potential of the Mowry Shale in Wyoming Laramide Basins

 

Surdam, Ronald1, Zunsheng Jiao1, Ramsey Bentley1, Rodney DeBruin1 (1) Wyoming State Geological Survey, Laramie, WY

 

The siliceous Mowry Shale in Wyoming is an outstanding source rock and should be considered a potential shale-gas target. Total organic carbon (TOC) from the Cretaceous Mowry Shale in Wyoming basins ranges from 0.7% to 5.1%. The TOC content of the Mowry Shale generally increases from northwest to southeast; and, conversely it thins from about 600 feet in the northwest to about 250 feet in the southeast. T-max for samples ranges from 411o C to 455o C. Vitrinite reflectance ranges to 1.7 at depths greater than 10,000 feet. Displacement pressures range from 300 psi at 5500 feet to over 2000 psi at 13,000 feet. The 13C nuclear resonance spectra indicate that the aliphatic carbon peak of the Mowry Shale is almost greatly diminished at 13,000 feet. Therefore, at this depth remaining kerogen in the formation has very little capacity to generate liquid or gaseous hydrocarbons. Thermal maturation modeling suggests that for each gram of TOC in the Mowry Shale, about 80 milligrams (mg) of gas was generated, 18 mg of gas was expelled, and 62 mg of gas remains (i.e., stored in shale). Sonic and seismic interval velocities show a pronounced slowdown where significant quantities of natural gas remain in the Mowry Shale. The Mowry attributes described above suggest that it has significant potential as a shale-gas prospect. This suggestion is supported by conventional Mowry production in Wyoming. With new drilling and completion techniques, the recovery of remaining natural gas in the Mowry could be substantial.

 

AAPG Search and Discover Article #90063©2007 AAPG Annual Convention, Long Beach, California