Steeply Dipping Reservoir Research Articles

The Use of Balanced Cross Sections to Design the Cymric/McKittrick Area Tulare Steamfloods

Recently developed techniques of cross section balancing by the kink method are being used to precisely define the structure of the Tulare Formation fold belt in one area of the Cymric/McKittrick Oil field, San joaquin Valley, California. The Tulare fold belt is a series of northeast-verging, fault-propagation folds that are detached near the base of the Tulare Formation. Good sand continuity and a detailed understanding of the reservoir structural geometry is necessary for successful steamflooding, requiring a rigorous method of structural interpretation to precisely define this highly-folded area. Because of reservoir depletion over the crest of anticlines in Cymric, experience has shown that the most successful steamflood configuration is a staggered line drive with both the producers and injectors located as close to the synclinal axes as possible. This promotes maximum heating and drainage of the reservoir. This configuration is most effective in steeply-dipping reservoirs, although producers downdip of injectors produce the most oil and experience the least amount of steam break-through even in fairly moderately dipping (20{degree}) reservoirs.

Steamflood Strategies for a Steeply Dipping Reservoir

Summary A computer simulation study was conducted to determine the best steamflood strategy for a steeply dipping (20° [0.35-rad]) reservoir. A compositional steamflood simulator was used with both two-dimensional (2D cross section) and three-dimensional (3D) models of the reservoir. The study showed that gravity drainage of the heated oil is the main production mechanism in steamflooding steeply dipping reservoirs. Consequently, oil production is strongly affected by injector and producer locations. The best steamflood strategy for this type of reservoir, therefore, involves judicious selection of injector and producer locations, reducing steam injection rate and shutting in wells selectively at appropriate times, and injecting a noncondensable gas to prevent steam cycling in the depleted updip portion of the reservoir. This paper compares oil production performances and steamflood efficiencies for nine different operating strategies and recommends the best strategy for a steeply dipping reservoir.