Structural and Stratigraphic Evaluation of the Southern Belgian Anticline
Area, North Midway-Sunset Field, San Joaquin
Basin, California
Bayer, W. Sebastian1, Shankar Mitra2, Roger Slatt2, Steve
S. Boljen3, Joel S. Pomerene3 (1) The University of
Oklahoma, Houston, TX (2) University of Oklahoma, Norman, OK (3) Berry
Petroleum Company, Bakersfield, CA
The Midway-Sunset field is located in the
West
Side
fold belt in the San Joaquin Basin. The structures in the
area, including the Midway-Sunset, Buena Vista, and Elk Hills
anticlines, were formed during multiple episodes of compressive deformation,
separated by periods of extension, between the Upper Miocene and present. A
regional study of a 250 square mile area was conducted to understand the
structure and stratigraphy within the fields. The
study utilized existing geologic maps and data from over 400 wells to construct
three regional structural and seven stratigraphic
cross sections. One of the structural sections was kinematically
reconstructed through time to understand the tectonic history. The
Midway-Sunset and Buena Vista structures are interpreted as a series of
parallel fault-bounded structures, cored by deeper fault-bend folds. Many of
the larger structures display overturned or steep flanks. Some of the reservoir
units, such as the Stevens and Potter deep water turbidite
sandstones, were deposited in an active tectonic environment, so that the
depositional history is closely related to the structural events. A more
detailed structural-stratigraphic study was conducted
to evaluate an approximately 15 square mile area within the Southern Belgian
anticline. A three-dimensional structural model was constructed using six
closely-spaced balanced structural cross sections constrained by dipmeter logs and surface structural data. This structural
model will provide a tool to evaluate potential bypassed reservoirs in the
Potter sandstone, and new targets in deeper reservoirs.