Experiments on CO2 foam seepage characteristics in porous media

Simulative experiments were carried out for CO2 foam flooding process in homogeneous porous media prepared with the sand packing method, and the CO2 foam seepage characteristics in porous media were studied with CT technology. CO2 foam flooding experiments were carried out under different packing sand sizes, different surfactant concentrations and different gas-liquid ratios. CT technology was employed to visualize the displacement process and to obtain the water saturation data along the sample, and the pressure distribution in the sample during the foam seepage process was measured at the same time. Experimental results show that, CO2 foam flooding has higher pressure drop and lower water saturation entrance effect in the porous media with lower average grain sizes; when surfactant concentrations are higher than CMC (Critical Micelle Concentration), the generated foam is stable, without showing obvious difference for the foam displacement efficiency in the sample, and water saturation entrance effect gradually decreases with increase of surfactant concentrations; improving gas-liquid ratio can lead to higher foam seepage pressure drop, but has little effect on residue water saturation after foam displacement. Key words: CO2 flooding, CO2 foam, flooding experiment, seepage characteristics, CT technology, EOR