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The AAPG/Datapages Combined Publications Database

AAPG Bulletin


Volume: 65 (1981)

Issue: 4. (April)

First Page: 766

Last Page: 766

Title: Washington Ranch Morrow Field: Case History in Frontier Exploration: ABSTRACT

Author(s): Forrest Miller

Article Type: Meeting abstract


The Washington Ranch Morrow gas field is located 35 mi (56 km) southwest of Carlsbad, New Mexico, on the western rim of the Delaware basin 6 mi (10 km) basin-ward from the Capitan reef front.

Late Pennsylvanian orogenic forces created a structural development of such sharp magnitude that most exploration outlook condemned the area as too disturbed for commercial hydrocarbon entrapment. The northwest-southeast-trending fault on the northeast side of the field has a displacement of more than 2,000 ft (610 m), structural contours on the basal Morrow sandstone unit define 600 ft (183 m) of closure against the fault. The crest of the structure has lost 1,700 ft (518 m) of Wolfcampian and Upper Pennsylvanian section through erosion and nondeposition.

Eight deep dry holes had been drilled within an 8 mi (13 km) radius of the drill site for the discovery well. Several of these wells had encountered a significant igneous sill only 400 ft (122 m) below the basal Morrow sandstone. The presence of this sill so close to the main potential reservoir rock further detracted from the prospect. Reefing development of two separate ages in Pennsylvanian sediments caused very rapid lateral facies changes which made well log correlations difficult.

Frontier exploration philosophy and technique were employed to overcome the many negative considerations of the prospect. The discovery well was completed in June 1971 for a calculated absolute open flow potential of 54 MMCFGD natural, through Morrow perforations at 6,795 to 6,806 ft (2,071 to 2,074 m). While drilling was in progress gas flowed at the rate of 22 MMCFGD on a 2-hour and 10-minute drill-stem test from 6,791 to 6,860 ft (2,070 to 2,091 m). Major gas reserves were made available to the pipeline with the drilling of nine development wells.

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