SCHAMEL, STEVEN¹, MILIND DEO¹, CRAIG FORSTER¹, DOUG SPRINKEL², and KEVEN OLSON^3
1University of Utah Salt Lake City, UT
²Utah Geological Survey, Salt, Lake City, UT
³ARCO Western Energy, Bakersfield, CA

Abstract: Strategies For Steam Flood Optimization In The Midway-Sunset Field, Southern San Joaquin Basin, California

A previously idle portion of the supergiant Midway-Sunset field, the ARCO Western Energy Pru property, has been brought back into commercial production through tight integration of geologic characterization, geostatistical modeling, reservoir simulation and petroleum engineering. This property, shut-in over a decade ago as economically marginal using conventional cyclic steaming, has a 200-300 ft thick oil column in the upper Miocene Monarch Sand. The excellent reservoir properties of this unconsolidated turbidite sand are balanced against a thick water-to-oil transition zone above the oil-water contact and a lack of effective, internal steam barriers. These factors require an innovative approach to steam flood production design to balance optimal total production against economically viable steam-oil ratios and production rates. To develop cost-effective strategies for steam flood optimization in the Midway-Sunset field, a DOE Class III oil technology demonstration is being conducted in an 8 acre pilot at the center of the Pru property. The current approach involves initial steam injection within the upper third of the oil column, where the oil saturation (So) is greater than 60%, so as to avoid undue loss of heat to water. Simulations predict recovery of 23% of original oil in place (OOIP) over a 10 year project cycle following a conventional steam flood strategy alone. However, simulations show that as production proceeds and unrecovered oil drains downward, the injection string can be shifted downward to keep pace with the observed steam chest and the simulated high So interval. After approximately 5 years of production by conventional steam flood through vertical wells, during which time an estimated 16% OOIP will be recovered from the 8 acre pilot, an additional 15% OOIP can be recovered by a pair of appropriately placed horizontal wells.

AAPG Search and Discovery Article #90928©1999 AAPG Annual Convention, San Antonio, Texas