First Results from the Maljamar Carbon Dioxide Pilot

Abstract

SUMMARY Continuous carbon dioxide injection in the Grayburg/San Andres formations of the MCA unit has been completed; follow-up brine injection began in December 1983. Incremental oil production began in mid-1983 from the Grayburg zone and six months later from the San Andres. Special features of the inverted five-spot pilot include (a) separate completions in the Grayburg and San Andres zones; (b) fiberglass-cased logging observation wells for in situ monitoring of oil, brine, and carbon dioxide movement; and (c) gamma-ray emitting tracers for improved vertical resolution of flow zones. The a priori prediction of the flow behavior in the Grayburg reservoir, developed from core and log data from seven closely spaced wells, was not consistent with pressure interference data, nor with the arrival times of tracers at the logging and production wells. At least three different reservoir descriptions match the Grayburg data; the most likely explanation is a change in the effective location of the injection well due to a hydraulic fracture.