GOOLSBY, STEVEN M., Goolsby Brothers and Associates, Inc., Englewood, CO; DON PIERINI, Pepco, Inc., Denver, CO; and PHIL KRIZ, Evertson Oil Company, Denver, Colorado, USA

Abstract: An Innovative Horizontal Drilling Program Opens a New Exploration Play in Admire (Permian) Reservoirs of the Northern Denver Basin, Nebraska

Often, an innovative approach to oil and gas exploration results in unexpected but beneficial results. Such is the case with a recent horizontal drilling program initiated in the Nebraska Panhandle to exploit the hydrocarbon potential of the lower Wolfcampian Admire "C" of the northern Denver basin.

The zone exhibits relatively uniform thickness and continuity over a large portion of the Alliance basin, reflecting base-level rise and fall symmetrical brining cycles in an intermittently restricted basin affected by glacial-eustatic sea level changes. Reservoir development is variable, with the best reservoirs developed in dolomized packstones associated with shoaling cycles. The reservoir consists of intercrystalline and separate-vug pore types that exhibit permeabilities of less than 25 md. An engineering review of the completion practices in the zone determined that it is a depletion-drive reservoir, and that structural position does not affect water influx. A horizontal program was therefore initiated to increase wellbore permeability-height without regard for structural position.

Although the horizontal drilling venture did not result in economically viable hydrocarbon production, it did demonstrate that a large continuous hydrocarbon accumulation covering an area of up to 5,400 sq mi (13,986 sq km) is present in the Admire "C". With relatively shallow drilling depths of 7500-8500 ft (2286-2592 m), this low permeability pervasively oil-saturated reservoir is currently poised for the development of an innovative technology to recover its extensive oil resources.

AAPG Search and Discovery Article #90921©1999 AAPG Mid-Continent Section Meeting, Wichita, Kansas