WAG injection in porous media: A microfluidic analysis
Water Alternating Gas (WAG) injection is one of the common methods to displace oil in porous media, which is relevant to many applications including soil remediation or enhanced oil recovery from underground reservoirs. We conducted a comprehensive series of experiments to extend the fundamental understanding of WAG injection in porous media. Three types of porous media were manufactured with a 3D printer in this investigation. The first medium had single permeability (S), the second one was fractured (F), and the third one was a medium with dual permeability (D). The porous media were saturated with silicone oil. Nitrogen and water were used to displace oil under different WAG ratios of 4:1, 2:1, 1:1, 1:2, and 1:4. High-resolution imaging was used to quantify displacement dynamics. The highest oil recovery was observed under WAG ratio of 1:1, i.e., the equal slug size of the water and gas. The obtained results showed that the WAG ratio of 1:1 injection in the S medium recovered 55% of the oil, while in the F and D medium, the recovery efficiency was 36% and 47%, respectively. Our findings offer new insights regarding effects of heterogeneity on WAG injection efficiency in porous media under different boundary conditions.
Immiscible WAG injection