Reservoir Characterization of the Uteland Butte Formation in the Uinta Basin

Jason Anderson and Daniel Pritchard
1099 18th Street, Suite 2300, Denver, CO

Following recent success of horizontal drilling, the Uteland Butte Member has received much attention as a horizontal target. The Uteland Butte is known as the basal carbonate of the Green River Formation. The Uteland Butte Member covers a majority of the Uinta Basin. The Uteland Butte, is correlative, has good reservoir properties and is located in an established oil and gas field. Under Bill Barrett Corporation's (BBG) acreage, the main target is a dolomite comprised of 10% quartz, 25% calcite, 63% dolomite and 2% total clay. The dolomite has an average porosity of 20% and the permeability averages 0.076 md based on core samples. The interval ranges in thickness from 3' to 8' across the basin being the thickest towards the center of the basin. The over and underlying rock is comprised mostly of highly fractured limestone, which contains oil and gas as well. The fracture count in surrounding rock can be as high as 14 fractures per 3'. This fracture network in combination with the reservoir properties has made the Uteland Butte an attractive target to operators in the basin. BBG, Newfield Exploration (NFX), LINN Energy (LINE) and QEP Resources (QEP) are the most active in the basin. Like other unconventional horizontal targets the Uteland Butte member has 'sweet spots'. Areas with thicker dolomite and higher temperature and pressure regimes tend to be the most successful. A few operators in the basin have applied for 1280 acre drilling units which will enhance the exploitation of the resource.

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