Effects of Discontinuous Shales on Multizone Steamflood Performance in the Kern River Field

Abstract

Summary Steamflood performance of the Monte Cristo I lease in the Kern River field was analyzed with a detailed, 18-pattern, heterogeneous model incorporating all reservoir zones. Results were used to improve reservoir management, quantify the impact of discontinuous shales on oil recovery from individual zones, determine interzone gravity drainage, and identify bypassed oil zones for future infill drilling. Results show that detailed modeling provides a more realistic description of actual performance. Furthermore, small pattern-element or single-sand models used in previous steamflood studies are inadequate for such reservoirs. Calculated oil recovery and temperature profiles compare well with field data. Discontinuous shales allow significant oil drainage to occur from the upper to the lower sands. As a result, the upper, unsteamed zones contain less reserve than expected. On the other hand, the lower zones continue to produce long after steam injection into the zone has stopped, giving high apparent recovery. The multipattern, heterogeneous model also may be used to identify bypassed zones for future infill drilling.