--> Abstract: Understanding the Complex Geometry of Extensional Faulting in a Compressional Laramide Structure: Teapot Dome, Wyoming, by Black, Brian J.and Mark Milliken; #90071 (2007)

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Understanding the Complex Geometry of Extensional Faulting in a Compressional Laramide Structure: Teapot Dome, Wyoming

Black, Brian J. and Mark Milliken
Rocky Mountain Oilfield Testing Center, Casper, WY

     Teapot Dome is a doubly plunging anticline, formed during the Laramide orogeny. It is one of several structures aligned along a northwest to southeast trend in the southern end of the Powder River Basin. The structure consists of an asymmetric fold with a steep flank on the west, bounded by a deep seated blind reverse fault. Over 1300 wells have been drilled into the structure providing an extensive database to work from. Previous work at Teapot Dome identified a series of normal faults in the shallow units that cross the structure almost perpendicular to the axis of the anticline. Recent surficial mapping, fault trenching, and subsurface log interpretation, have provided new understanding the faulting geometry. This work has shown that there is a very complicated network of normal faulting and fracturing that significantly influences oil production. In many cases, the faults do not line up in a sub-parallel array as interpreted previously. Instead, many of the larger normal faults cross the field in a curvilinear manner. Also, some faults are aligned parallel to the axis of the structure, rather than perpendicular to it. The normal faults seen in shallower units of the anticline appear to be related to older normal faults that are seated in the basement. These deeper faults existed prior to Laramide deformation and may have been active during deposition of the lower Cretaceous units. These pre-existing deeper faults may have contributed to a distinct change in the trend of the anticlinal axis that formed during Laramide deformation.

 

AAPG Search and Discovery Article #90071 © 2007 AAPG Rocky Mountain Meeting, Snowbird, Utah