Baldpate Field Exploration History, Garden Banks 260, Gulf of Mexico
Baldpate Field (GB 260) is located in the offshore Gulf of Mexico approximately 195 miles (122 km) southwest of New Orleans, Louisiana, in 1650 feet (503m) of water. The prospect was identified on 2-D seismic as a pair of stacked amplitude anomalies which were regionally tied to Shell’s Auger discovery, and in 1991 Amerada Hess and partner Oryx Energy (now Kerr-McGee) drilled the Baldpate discovery well. Proved and probable reserves of 128 MMBOE are present in four Plio-Pleistocene turbidite reservoirs covering portions of Garden Banks 259, 260, 216, and the south half of 215.
Delineation drilling based on time-migrated 3-D seismic data demonstrated significant lateral mispositioning of the reservoirs. Detailed evaluation showed that seismic velocities were too fast as a result of severe local anisotropy, resulting in over-migration of the reservoir anomalies. Using proprietary in-house processing capabilities, the velocity field was dynamically updated during the development phase, and a post-stack depth migration was generated which was calibrated to the well control. This migration was used to successfully complete the development drilling.
Baldpate Field reservoirs range from Pliocene turbidite sheet sands (Big sand, Twin sands) to early Pleistocene amalgamated channel and sheet sands (BL-3 sands). The primary reservoirs in the field are the turbidite sheet sands that are characterized by high porosity and permeability and exhibit excellent lateral continuity. These reservoirs contain under-saturated volatile fluid; a significant compositional gradient is trapped on the southwest flank of a subhorizontal salt feature.
Understanding of the Baldpate reservoir geometries through integration of conventional core analysis, DST results, petrophysics, and reservoir simulation modeling has led to better development planning, resulting in significant cost savings due to a reduced well count and subsequently smaller production facilities.
Amerada Hess, operator of the field and 50% partner Kerr-McGee chose a compliant tower to develop Baldpate field. Production began in September 1998, at a peak rate of 59,000 BOPD and 234 MMCFGPD. Cumulative production through July, 2000 was 26.5 MMBO and 97.6 BCF.