Field Development, Depositional Model and Production Performance of the Turbiditic "J" Sands at Prospect Bullwinkle, Green Canyon 65 Field Outer-Shelf Gulf of Mexico

William E. Holman, Stephen S. Robertson

The Green Canyon 65 Field (GC 65) is located approximately 150 miles southwest of New Orleans, Louisiana in the Gulf of Mexico. The field was developed between 1989 and 1990 from a single 60-slot conventional platform in 1,353 feet of water. GC 65 is expected to produce in excess of 90 MMBO and 170 BCF, 90% of which is contained within the prolific "J" sand sequence. The field's daily production consistently exceeded 50,000 BO and 90 MMCFG from 19 producing wells during its first two years of full scale production. The field is currently 70% depleted and has entered a steep decline.

The field lies along the margin of a Plio-Pleistocene salt-withdrawal basin. Salt had some influence on "J" sand deposition; however, the primary trap is stratigraphic onlap against a broad lowstand valley. The "J" package consists of numerous interconnected turbidite sheet and channel sands. Grain size and bedding style indicate depositional energy increased upward within the package; the upper surface of the package is defined by multiple erosional unconformities, reflecting sediment bypass as the basin filled.

Integration of multiple 3D seismic surveys, well control, evolving geologic models, produce while drilling data and reservoir simulations optimized the development of Bullwinkle, one of the Gulf of Mexico's premier oil reservoirs.

Our understanding of the "J" sand reservoirs continues to evolve as production data are incorporated into the subsurface model, reservoir simulator, and compared with seismic/well control. Production has confirmed extensive lateral continuity within individual sands and intercommunication between sand members. Aquifer/pressure support is greater than anticipated. Understanding the reservoir architecture of both the "J" sand package as well as its individual members is considered fundamental in developing an effective reservoir management scheme.

AAPG Search and Discovery Article #91020©1995 AAPG Annual Convention, Houston, Texas, May 5-8, 1995