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Abstract: Sub-Lakeview Sandstones, Midway-Sunset Oil Field


The upper Miocene Sub-Lakeview sands of the Monterey Formation were deposited in a tectonically active deep marine setting. Individual sand units were deposited on small fans and in "gully" or channel fill deposits. The 10 to 300 feet thick reservoir units are composed of medium to fine grained arkosic sands. The Sub-Lakeview sands were deposited above the Spellacy/Monarch reservoirs and below the "N" point marker. Oil is generally trapped by the Top Miocene unconformity truncating individual sands on or near anticlinal features.

Production is often commingled with overlying and underlying sands, but individual sands locally form commercial accumulations. The Sub-Lakeview sands produce commercially on primary or with cyclic steam, they have also been steamflooded and fireflooded. The 12 degree to 22 degree API oil is often associated with primary gas caps near the updip edge of individual sand members. Development is on .5 to 2.5 acre spacing with high recoveries due to good gravity drainage.

Individual Sub-Lakeview pools continue to be discovered and developed at Midway-Sunset. Common techniques using old and new data are employed to highgrade prospective targets and reduce the number of dry holes associated with development of the laterally restricted sand accumulations. Driller's logs and old E-logs form the backbone of company data sets and are key to highlighting areas of interest. Wet sands are often difficult to recognize with resistivity logs alone, but porosity logs clearly show sand presence. Berry's use of stratigraphic dipmeter interpretation has significantly reduced the number of dryholes drilled developing these accumulations. Other operators have used 3-D seismic to map several Sub-Lakeview channels that extend eastward from Midway-Sunset toward the center of the San Joaquin Valley.

Search and Discovery Article #90945©1997 AAPG Pacific Section Meeting, Bakersfield, California