Carbon dioxide (CO2) flooding is a proven process for the improved recovery of oil from oil reservoirs.  Most of the applications to-date has been in West Texas and New Mexico because of the suitability of the reservoirs and the proximity to large supplies of naturally occurring CO₂. Most of these applications have been in reservoirs where a miscible displacement is expected.  CO₂ is not directly miscible with most crude oils.  However, miscibility can be established when the displacement takes place above a pressure level referred to as the minimum miscibility pressure (MMP).  In this case, a bank of rich hydrocarbons is formed by the repeated contact of the injected CO₂ with the reservoir crude oil.  A miscible condition is desirable because of the high displacement efficiency and the corresponding high oil recovery that is achieved.

The application of CO₂ flooding technology has continued to increase in recent years in spite of low oil prices.  The major factors have been improvements in technology, reduced purchase costs, and a reduction of operating costs.  This trend is expected to continue.

DI is especially interested in the application of CO₂ technology in reservoirs where an immiscible displacement condition can lead to significant improvements in oil recovery. The most favorable conditions are reservoirs where (1) the solubilization of CO₂ has an ability to significantly reduce oil viscosity and to increase the oil saturation through swelling, and (2) where the viscosity of the in-place crude oil is at a low-to-moderate level, thereby minimizing the channeling problems that  can occur with extreme contrasts in mobility.  The principal targets are shallow reservoirs where alternative enhanced oil recovery processes have failed to be cost-effective.

DI can assist the client in evaluating the merits of a particular reservoir for CO₂ flooding. Reservoir models are available to assess the potential recovery and the economics of a proposed project.