MEAR, CHARLES E., and JOHN O'REAR, Cross Timbers Oil Company, Fort Worth, TX

ABSTRACT: Developing New Oil Reserves in the N.E. IAB Unit, Coke County, Texas: An Abandoned Waterflood Project

Located in north-central Coke County, Texas, the 3115-ac N.E. IAB Unit produces oil from the Wolfcampian Menielle sandstone (5150-ft Penn). When formed in 1966, the unit contained 38 well bores that originally were in the IAB, N.E., and Sanco Canyon fields. Water injection in the unit was stopped in 1982, after 12 million bbl of water had been injected into 11 wells, and about 721,000 bbl of water had been produced. Cumulative production through 1989 totaled 2.6 million bbl of oil, of which an estimated 2.28 million bbl were primary. At the time Cross Timbers acquired operations, the unit had four active wells that produced a total of 35 BOPD, 30 MCFGD, and 40 BWPD; and water injection had ceased.

After conducting a joint geological and engineering study of the unit pay zone, it was concluded that significant additional reserves could be developed through step-out and infill drilling. Cross Timbers then drilled its 3310 and 3309 wells in the south part of the unit. Both wells were completed as very economically attractive oil wells, with the 3309 flowing at a rate greater than its allowable. At least three, and perhaps five, additional locations were proved by these wells.

The reservoir in the N.E. IAB unit consists of six discrete, fine-grained quartzose sandstone units that were deposited in constructional distributary channels at the eastern edge of the Midland basin. Source for the sand was the Eastern shelf, located to the east of the unit.

AAPG Search and Discovery Article #90994©1993 AAPG Southwest Section Meeting, Fort Worth, Texas, February 21-23, 1993.