Effects of discontinuous shales on multizone steamflood performance in theKern River field

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, qu antify the impact of discontinuous shales on oil recovery from individual z ones. determine interzone gravity drainage, and identify bypassed oil zones for future infill drilling. Results show that detailed modeling provides a more realistic description o f actual performance. Furthermore, small pattern-element or single-sand mod els used in previous steamflood studies are inadequate for such reservoirs. Calculated oil recovery and temperature profiles compare well with field d ata. Discontinuous shales allow significant oil drainage to occur from the upper to the lower sands. As a result. the upper, unsteamed zones contain l ess reserve than expected. On the other hand, the lower zones continue to p roduce long after steam injection into the zone has stopped. giving high ap parent recovery. The multipattern. heterogeneous model also may be used to identify bypassed zones for future infill drilling.