Scaled Experimental and Simulation Study of Segregation in Water-Above-Gas Injection

Abstract

Summary The water-above-gas injection has been introduced as a modified injection strategy for simultaneous or alternating water/gas injection to improve the recovery factor. This can be achieved through maximizing the size of the mixed zone and extending the complete-segregation distance. Verifying this approach in the laboratory needs special experimental design in which the effect of capillary force is eliminated or strongly reduced, and viscous and gravity forces are active. In this study, an experimental setup has been prepared and implemented to verify the advantages of the water-above-gas injection. Key parameters in this experiment have been scaled to reservoir conditions. This was possible through choosing correct porous media and fluid system. The porous media should have high porosity and permeability, and the fluid system should have very low interfacial tension (IFT) between phases. Supplementary experiments have been conducted to prove the reliability of the model before the main experiment. In addition to the investigation of different injection rates and water/gas injection ratios in this process, the effect of stepwise injection also has been investigated to verify the practical approach, which results in maximized sweep efficiency. Finally, a simulation study has been conducted, and by comparing its results to experimental results, the applicability of numerical simulation in designing reservoir-scale water-above-gas injection is confirmed.