Abstract

The overall goal of this project is to improve the efficiency of miscible CO₂ floods and enhance the prospects for flooding heterogeneous reservoirs. This objective is being accomplished by extending experimental research in three task areas:

1. foams for selective mobility control in heterogeneous reservoirs,
2. reduction of the amount of CO₂ required in CO₂ floods, and
3. miscible CO₂ flooding in fractured reservoirs.

This report provides results of the first year of the three-year project for each of the three task areas. A desirable characteristic of CO₂-foam called Selective Mobility Reduction (SMR) promises an improvement in displacement efficiency by reducing the effects of reservoir heterogeneity. Laboratory measurements of the mobility in single cores have been expanded by pumping the high-pressure CO₂-foam through two cores in series and measuring the pressure drop across each during the same test. This, along with a second experimental innovation using a withdrawal pump to maintain pressure, enables direct comparison of the mobilities of high and low permeability cores. The system has been used to extend results, showing that a greater SMR effect takes place at low flow velocities rather than at high rates of flow.