Continued Development of "Mature" Field: West Cameron Block 45 Field, Gulf of Mexico

Stephen R. Brand, James F. Fox

Initial acreage acquisition and exploration of the West Cameron Block 45 field, located offshore Louisiana, were based on reconnaissance gravity surveys that revealed an anomalous high across the area. Several phases of development drilling activity have been conducted in the field since its discovery in March 1949. Nearly four decades after initial exploration began, an integrated field study incorporating all available geological, geophysical, petrophysical, and engineering data was undertaken to evaluate the remaining potential of the field. As a result of this study, a detailed structural and stratigraphic framework was developed, the controls on reservoir production performance were established, and additional drillable prospects were delineated.

The field consists of two separate geologic features: (1) a rollover anticline on the downthrown side of a major listric growth fault and (2) stratigraphic-structural traps on the upthrown side of the same fault. Natural gas is the primary hydrocarbon found on the upthrown side of the fault, whereas both oil and gas have accumulated on the downthrown side. Production commenced in January 1955, with cumulative production approaching 11.5 million bbl of liquid hydrocarbons and 400 billion ft³ of gas. Results of the integrated study increased estimated recoverable reserves by approximately 2.0 million bbl of liquids and 12 billion ft³ of gas.

Over 30 Miocene sandstones have been productive in this field. These reservoir-quality sandstones were deposited in upper slope submarine channels and delta-front and delta-plain environments. Syndepositional faulting coupled with salt movement resulted in the formation of a complex structural fabric. The differences in hydrocarbon types between the upthrown and downthrown structures suggest that each accumulation has a separate petroleum-generating source and migration pathway. Both water drive and gas expansion systems provide reservoir energy.

The data generated and concepts formulated from the integrated evaluation not only increased the efficiency and economic yield of field development but also refined the geologic knowledge and understanding of the area. Although this field and producing trend are mature, the study provided additional geologic information that justifies continued exploration and development within the field and the prolific offshore lower Miocene trend.

AAPG Search and Discovery Article #91022©1989 AAPG Annual Convention, April 23-26, 1989, San Antonio, Texas.