--> Abstract: Velocity Study of Abnormally Pressured Zones in the Powder River Basin of Wyoming, by D. Maucione, V. Serebryakov, P. Valasek, W. Yue, and S. Smithson; #91017 (1992).

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ABSTRACT: Velocity Study of Abnormally Pressured Zones in the Powder River Basin of Wyoming.

MAUCIONE, DEBRA, VLADIMIR SEREBRYAKOV, PAUL VALASEK, WANG YUE, and SCOTT SMITHSON, University of Wyoming, Department of Geology and Geophysics, Laramie, WY

The abnormally pressured Cretaceous section of the Powder River basin in eastern Wyoming is a prolific source of hydrocarbons. Identifying and delineating abnormally pressured reservoirs with surface seismic methods would greatly enhance hydrocarbon discovery. This well log velocity study illustrates that the application of surface seismic methods may be useful in this regard. Velocity profiles, pressure profiles, and abnormal pressure gradient calculations all indicate that Cretaceous shales in the Powder River basin of Wyoming are overpressured throughout the basin, whereas sandstones exhibit all pressure characteristics (i.e., over, under, and normal pressure). Profiles in different parts of the basin, (T46N, R69-76W, Hilight field area; T51N, R69-77W, Amos Draw-Kitty field area; T 1N, R69-76W, north of Powell field area) show the top of the basin-wide overpressured zone occurs within the Steele shale, and the bottom seal is the Fuson shale. Synthetic seismograms were generated from the velocity model developed from the well-log data. The synthetic data were then compared with seismic data analyzed by an unique application of existing processing techniques. These techniques, which delineate abnormally pressured regions with surface seismic data, may significantly reduce the risk involved in exploring for subtle hydrocarbon traps associated with abnormally pressured zones when applied to the Powder River and other basins.

 

AAPG Search and Discovery Article #91017©1992 AAPG Rocky Mountain Section Meeting, Casper, Wyoming, September 13-16, 1992 (2009)