Abstract
The Jordan (San Andres) reservoir is composed of approximately 400 ft of upward-shoaling subtidal to peritidal carbonate strata that are thoroughly dolomitized and partly cemented by sulfate minerals. The reservoir is divided into four flow units on the basis of depositional facies and subsequent diagenetic alteration. Delineation of these flow units is based on the relationship between open-hole wireline log response and rock mineralogy.
Cumulative production is 68 MMSTB of 218 MMSTB original oil in place, which is a recovery efficiency of 31 percent. Forty-seven MMSTB of remaining mobile oil occurs as bypassed oil in the contacted upper part of the reservoir, which has been penetrated by well bores, and 12 MMSTB of mobile oil is in the uncontacted lower part, which has not been penetrated by well bores. The most prospective areas for increased production by waterflood profile modification in the contacted part of the reservoir are the southwest corner of the field, in low-permeability Flow Unit B, which is incompletely swept, and the eastern central part of the field, where heterogeneous permeability in Flow Unit D has resulted in an incomplete sweep. The most prospective areas for increased production through well bore deepening into the uncontacted part of the reservoir are the southeast corner of the field, where high-permeability Flow Unit C is uncontacted, and the central part of the field, where high-permeability Flow Unit A is uncontacted.
This reservoir contains 113 MMSTB of oil residual to waterflood, and reservoir properties meet preliminary screening criteria for effective carbon dioxide flooding. Thus, this reservoir is a candidate for enhanced oil recovery operations.
