ABSTRACT: Notches Dome Field Development

MEYER, MITCH, Teton Oil & Gas Corporation, Denver, CO, and JOHN STARCK, Pacific Enterprises Oil Company USA, Houston, TX

Notches Dome field, located on the northwestern end of the Casper arch in central Wyoming, was discovered in 1923 by the Midwest Refining Company. Cumulative oil production is 9.9 million bbl, out of the Tensleep Formation, from a total of 29 wells. In early 1988, the field produced from 13 wells at a combined rate of 360 bbl of oil and 30,000 bbl of water per day. Pacific Enterprises Oil Company's development program, initiated in August 1988, resulted in 10 additional wells and increased production to 2200 bbl of oil and 50,000 bbl of water per day.

In 1988 we conducted a detailed review of the aging field and determined that the productive limits had not been defined. Both surface and subsurface mapping, later supplemented by 3.5 mi of proprietary seismic data, depicted a classic trap-door type structure. The primary trapping mechanism consists of over 400 ft of four-way structural closure. This feature is localized on the asymmetrical, southeast-plunging Cottonwood anticline, which has been segregated by left-lateral relative displacement.

The first well was drilled on a nose structurally flat to the lowest producing well in the field. The majority of the new reserves were found along the southwestern side of the reservoir. This area had undergone very little sweeping from water migration through the field. Water movement from the northeast, which trapped the oil along the southwest field edge, was explained by constructing a temperature gradient map using the 13 most recently drilled wells. This project developed 2 million bbl of new oil reserves, split between 10 wells.

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