Structural Development of Billings and McKenzie Counties, Southwestern North Dakota

CRASHELL, JOHN J., University of North Dakota, Grand Forks, ND

Billings and southern McKenzie counties contain about 40 active oil and gas fields. In the same area, two major structural highs and several minor ones can be recognized. The Billings anticline extends approximately 60 km (18 mi) along a north-south line in central Billings County and is composed of two parallel folds. A second major structure, the Rough Rider anticline, lies west of the Billings anticline and also extends about 60 km (18 mi) along a north-south line from north-central Billings County into southern McKenzie County. Both of these structures are fault bounded on their eastern sides and are sites of significant hydrocarbon accumulation.

Episodes of tectonic activity within the area were identified by study of isopach patterns derived from wireline log picks and by subsidence analysis. Although the subsidence of the Williston basin was the principal regional tectonic activity, the structural features in Billings and McKenzie counties were intermittently decoupled from the larger scale basin movement, producing local highs. The two major positive features, as well as several minor ones, have behaved independently of each other through time. Most of the development of these structures took place during the Devonian and Mississippian.

AAPG Search and Discovery Article #91010©1991 AAPG Rocky Mountain Section Meeting, Billings, Montana, July 28-31, 1991 (2009)