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SWLGS Luncheon Topics

Updated August 05, 2003

December 2000

Baldpate Field (GB 260): "A Gulf of Mexico Deepwater Challenge"
Ron R. Pressler
and D. Bret Walker, Amerada Hess Corp.


Abstract: The Baldpate Field complex (Garden Banks Block 215/216/259/260) lies within the Gulf of Mexico Plio-Pleistocene Flex Trend, 110 mi offshore, in 1,650 ft of water. In 1991, Amerada Hess and Oryx Energy (now Kerr-McGee) drilled GB 260 Well #1 to test the southwest flank of a tabular salt supported structure. The primary objectives were Upper Pliocene, amplitude-associated events, which had been initially identified on a 1/2-mile 2-D grid from a 1989 time-migrated 3-D seismic volume. The well encountered 180 ft of net vertical Pliocene pay with two major sands, which had 103 ft and 64 ft of net pay. The Baldpate Field complex has reservoir facies which range from Pliocene age turbidite basin floor sheet sands to early Pleistocene age amalgamated channel/levee sands.

Initial Baldpate delineation drilling based on the time-migrated 3-D seismic volume demonstrated significant lateral mis-positioning of the reservoir reflectors which was subsequently demonstrated to be caused by severe local anisotrophy. Using proprietary in-house processing capabilities, the velocity field was dynamically updated during the development drilling, and a series of post-stack depth migrations were generated which were calibrated to the well control. A final migration was selected base on the ties to the pay sands, downdip wet penetrations and the dip salt penetrations and truncations. This migration was used to successfully complete the development drilling phase, including a difficult attic well beneath the salt overhang.

Efforts had previously been initiated to evaluate ocean bottom conditions to delineate and identify the optimum surface location for a potential development. The endeavor included, then state-of-the-art, Deep-Tow Hazard data acquisition which was supported by the integration of 3-D seismic and onsite submersible "ground truthing". This was an extremely critical project phase, as the resulting selected development concept was to be a new innovative "compliant tower" platform structure, which upon installation briefly held the record as the world's tallest freestanding structure.

Understanding of the Baldpate reservoir geometries through integration of conventional core analysis, DST results, petrophysics and reservoir simulation modeling led to better development planning, resulting in significant project cost savings due to a reduced well count and optimally matched production facilities. The appreciation of Baldpate's unique compositional gradient hydrocarbon system and the utilization of state-of-the-art monitoring coupled with rigorous compositional modeling and history matching has allowed AHC to maximize production rates and recoveries. The knowledge base and acquired understanding of seismic migration complexities, geologic structure, reservoir geometries and production performance are routinely incorporated into the evaluation of other developments and prospects.

Biographical Sketch: D. Bret Walker received his Bachelor of Science degree in Physics from Southwestern Oklahoma State University in 1981.  Upon graduation he joined Gulf Oil, where he worked regional exploration in the Michigan and Illinois Basins, and the Texas Gulf Coast.  In 1985 he joined Amoco Production Company, where he was responsible for  HCI/AVO analysis for the Offshore Louisiana Technical Group, performed various field studies in the Offshore Louisiana Exploitation Group, and in 1989 was transferred to the Africa and Middle East Region.  In 1990 he joined Amerada Hess, where he interpreted various projects in the Offshore Gulf of Mexico Exploitation and Development Group.   He is currently the geophysicist assigned to the Amerada Hess Deepwater Production Unit, which is responsible for all deepwater Gulf of Mexico production and development properties.  His recent projects include responsibility for geophysical interpretation and evaluation of AHC's operated Baldpate/ Conger/ Penn State / Northwestern (GB 260/215/216/200) developments, and the Shell operated Enchilada/ Salsa/ Chimichanga developments (GB 128/172/127).