The Levelland 12-acre (4.8 ha.) pilot was drilled during the latter part of 1972 on a double five-spot pattern, and underwent waterflooding from March 1973 until August 1979. On August 3, 1979, carbon dioxide flooding was initiated.

The purpose of this study was to define a stratigraphic zonation for the San Andres Formation (Permian) in and around the pilot, to obtain an accurate, quantitative, reservoir description to aid engineers achieve a historical match of the waterflood, and to evaluate the tertiary recovery efficiency of carbon dioxide flooding.

Excellent core control demonstrated that sedimentary deposition had occurred in an arid coastal carbonate-evaporite province similar to that which exists today on the Trucial Coast, Persian Gulf. Stratigraphic zonation was made using core data in conjunction with log data. A quantitative reservoir description was achieved by the following steps: (1) porosity calibration of the gamma ray-neutron logs; (2) permeability calculation from the calibrated porosity using available core data; (3) determination of the permeability cutoff for net pay; (4) determination of connate-water saturation from applicable native state cores; (5) determination of the reservoir zonation, and (6) computer generation of ^phgrH, KH, and H maps for individual reservoir zones and combinations of reservoir zones. /P>

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