North Cross Devonian Unit- A Mature Continuous CO2 Flood Beyond 200% HCPV Injection

The North Cross (Devonian) Unit, currently operated by Occidental Oil and Gas, was discovered in 1944. The field was developed using regular 40 acre spacing and produced under primary recovery until 1964. Subsequently, a partial pressure maintenance program was constituted to inject residue gas in an updip location in the field. Large-scale continuous CO2 injection began in April 1972 and was expanded over time to provide CO 2 support throughout the field. The field has been under continuous CO 2 flood for over four decades. Currently, over 200% hydrocarbon pore volume (HCPV) of CO2 has been injected, and over 60% of the latest estimate of its target original-oil-in-place (OOIP) has been recovered. The field continues to perform well with a gross utilization (MCF CO2 injected/bbl oil recovered) of approximately 30 MCF/BO (20 MCF/BOE). North Cross is an excellent example of a successful mature continuous CO2 flood.