Development of Sockeye Field in Offshore California--A Case History

SANKUR, VEGA, Chevron, U.S.A., Inc., La Habra, CA

Sockeye field, discovered in 1970, lies offshore California in the Santa Barbara Channel. The decision to develop the field was made in 1983 based on 1979-1983 exploration drilling. Platform Gail was installed in 1987 and development drilling commenced in June 1988. Currently, there are eleven development wells with plans for two more (two duals and eleven single completions).

This project has taken 20 yr to reach the development stage since the lease sale in 1968. This long time span was partly due to permitting delays encountered in offshore California projects and a Santa Barbara Channel drilling moratorium in the 1970s.

The field produces from five reservoirs: middle and upper Sespe Sands, lower and upper Topanga Sands, and the Monterey Formation. Sespe Sands are fluvial channel deposits with individual sand bodies with limited areal extents. The middle Sespe produces dry sweet gas and the upper Sespe produces sweet 29 degrees API gravity oil. The Topange Sands were deposited in a near shore environment and are more continuous in nature. Lower Topanga Sands contain sweet oil whereas

upper Topanga Sands test a low gravity 18 degrees API sour oil. The Monterey Formation is composed of thin beds of chert, porcellanites, siliceous shales, mudstones, and dolostones. The fractured Lower Monterey produces heavy sour oil, similar to that of the upper Topanga.

To minimize risk, delineation wells were drilled early in the development program to ensure that reserves warranted additional investment in wells and facilities. Nine wells were completed during the first phase of the drilling program. Gas production from these wells was projected to exceed the capacity of the Carpinteria gas plant. The drilling rig was put on standby to evaluate various facilities' modifications to handle production. At the conclusion of the evaluation, drilling was resumed with plans to drill four more wells.

Reservoir information was obtained through an integrated program of formation evaluation, core analysis, production logging, and buildup and interference testing.

AAPG Search and Discovery Article #91009©1991 AAPG-SEPM-SEG-SPWLA Pacific Section Annual Meeting, Bakersfield, California, March 6-8, 1991 (2009)