MEASURING ENGINEERED OIL-RECOVERY

The paper shows that the measurement of engineered-oil-recovery success or failure should begin at and emphasize the production side of the system. Well tests, produced-water mineral composition changes, and any breakthrough of process ingredients, whether they are CO2, alkaline agents, or polymers, need to be detected early and corrected. There is no valid argument for condoning producing well breakthrough of process ingredients designed to improve volumetric sweep. By definition these components are to remain in the formation and allow more oil production rather than be produced from the formation, interfere with oil/water separation, and shorten the economic life of a well. Effective volumetric-sweep improvement is characterized by an increase in the slope of the Hall plot (which reflects a buildup in resistance to flow of injection water) and a straight line or stable in-depth permeability to water from then on.