Mowry Shale, Properties and Potential, Big Horn and Powder River Basins, Wyoming

Robert Sterling
Cirque Resources

The Cretaceous Mowry Shale is a prolific source rock for quite a few of the Cretaceous reservoirs in many Rocky Mountain basins, including the Big Horn Basin. A few wells have been completed out of the Mowry Shale as a bailout zone because of the shows seen while drilling through it. In the Powder River Basin there was more production encountered in vertical wells, but once again mainly as a bailout after conventional reservoirs proved nonproductive. The Mowry Shale has been the subject of several concerted exploration programs over the last couple of years in the Powder River and Big Horn Basins. Recent horizontal drilling has had mixed results A better undersanding of what makes the reservoir and the best technological solutions are necessary to advance this play to commerciality . The Mowry is a siliceous shale that ranges in gross thickness across the basins from 120 to over 400 feet. Amorphous silica content ranges from 45% to as high as 70%. There are areas in the basin where very fine grained turbidites are interbedded with siliceous shales in the Mowry. TOC content ranges from 1.1% to as high as 4.0%, but there is a relationship between lower TOC values and higher thermal maturity. There are both type II and type III kerogens present in the Mowry. Data from two recent Mowry Shale cores are presented here. The Mariner Java State 16-1, located in the northern Powder River Basin in 16-T54N-R80W, was cored in the Mowry Shale and recovered 109' of core. The Cirque Federal 1-26H, located in the eastern portion of the Big Horn Basin in 26-T52N-R95W was cored as well in the Mowry Shale and recovered 82' of core. Analysis is presented on these two cores,

AAPG Search and Discovery Article #90169©2013 AAPG Rocky Mountain Section 62^nd Annual Meeting, Salt Lake City, Utah, September 22-24, 2013