The cessation of CO2 injection may be the result of poor reservoir response, low oil prices, or near the end of a CO2 project. The focus of this paper is to describe the effect of CO2 injection curtailment on oil recovery and production in a technically successful CO2 flood of an oil reservoir. The CO2 curtailment is sustained over a significant period of time while water is injected. Following the curtailment, CO2 is again injected.
Early EOR literature covers CO2 and miscible gas injection in the presence of very high water saturation. The key issues are phase behavior, surface tension, viscosity, and oil stripping, which are described in terms of curtailment and the subsequent affect on oil production.
A survey of pertinent literature has been conducted to infer the impact CO2 curtailment has on reservoir performance. Preliminary findings are that the curtailment of CO2 leads to a permanent loss in reserves and production rate. Scenarios that may alleviate these losses such as reduced CO2 injection instead of complete curtailment are addressed.