The North Cross (Devonian) Unit CO2 flood, Shell's first, began in 1972. While fairly small by West Texas standards, the project provides an example of a successful, mature CO2 flood. Seventy-eight billion cubic feet (BCF) of pipeline CO2 have been injected into the reservoir. Recycled produced gas has augmented this to bring cumulative CO2 injection to 128 BCF- or nearly 70% of the hydrocarbon pore volume. Production performance has been excellent. Unit oil production increased from approximately 1400 barrels per day (BOPD) when CO2 injection began to its peak of over 2600 BOPD in late 1978 before declining gradually to approximately 1900 BOPD by the end of 1991. An estimated 11 million barrels of enhanced oil have been recovered through 1991 and ultimate EOR is expected to double to over 22 million barrels.

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