Abstract: Abstract: Use of 3D Reservoir Characterization to Plan and Implement Horizontal Heavy Oil Development of the Tulare Reservoir South Belridge Field, California

FAIRMAN, ROB , Aera Energy LLC, Bakersfield, CA 

In 1997-1998 Mobil Exploration and Producing U.S. Inc. and its successor company in California, Aera Energy LLC., began development of the thinner net pay edges of the Pliocene-Pleistocene Tulare Formation reservoir on the flanks of the South Belridge Field in the San Joaquin Valley of California. The Block VII portion of the development drilled 46 horizontal wells along 7 separate paths, with 5-8 horizontal wells stacked vertically along each path, and separated by rows of primary and secondary injectors. Horizontal laterals averaged 1500 feet in length at an average depth of 1200 feet TVD. The challenge of designing the project and accurately defining horizontal well paths was complicated by the Tulare sands which are fluvial-deltaic deposits that are often channelized and laterally discontinuous, with individual sand bodies commonly less than 10 feet thick and separated by numerous shale barriers. Individual sands can also have separate oil/water contacts, and faulting which made lateral wellbore placement and effective steam injection design difficult. Use of a 3D seismic fault interpretation integrated into a detailed 3D geologic reservoir model was essential to both program design and implementation. This coupled with contractor/operator alliancing allowed the horizontal wells to be drilled with maximum reservoir penetration and wellbore placement while significantly reducing sidetracks. These efficiencies resulted in a substantial cost reduction to drill each horizontal wellbore, and proved the technology to target increasingly thin net pay intervals on the flanks of the field that might not be economic with a conventional vertical well drilling program. A brief history of the Tulare development will be discussed along with a more detailed review of the Block VII reservoir characterization, horizontal well planning, and program implementation.

AAPG Search and Discovery Article #90911©2000 AAPG Pacific Section and Western Region Society of Petroleum Engineers, Long Beach, California