ABSTRACT: Optimum Directions for Horizontal Drilling in Fractured Cane Creek Shale, Paradox Basin, Utah

MORGAN, CRAIG D., M. LEE ALLISON, Utah Geological Survey, Salt Lake City, UT, and W. ADOLPH YONKEE, Weber State University, Ogden, UT

The Cane Creek Shale is a fractured, organic-rich, overpressured zone in the Pennsylvanian Paradox Formation of the Paradox basin. Intersecting numerous open fractures appear to be the key to achieving commercial production in the zone with a horizontal well.

Surface fractures are unlikely to extend through the numerous salt layers to the Cane Creek zone, but little data exists on subsurface fracturing. Structural fabric at the surface is dominated by regional northwest-southeast-trending faults and fractures of the Paradox fold and fault belt. A second regional pattern trends northeast-southwest with considerable azimuthal variation. An example of the second trend is the so-called Roberts rift, a long narrow fracture zone that is locally autobrecciated, and which may be a result of explosive fracturing from depth. The Long Canyon 1 well has produced over 900,000 bbl of oil since 1962 from the Cane Creek. It lies on the extension of the Roberts rift fracture. If the Roberts rift feature originally extended to the Cane Creek Shale, it was s bsequently sealed off, possibly by salt movement.

Until the subsurface fracture trends are known, the assumption must be made that the two surface trends reflect fracture directions in the Cane Creek Shale with equal potential for production. Thus, the optimum direction for a horizontal well to intersect the most fractures of both sets would be generally north-south. A secondary direction would be east-west. Local variations of fracture orientation and differences in fracture spacing and aperture will change the recommended directions.

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