Experimental Investigation of the Effect of Diffusion of Surface-active Material on Enhanced Oil Recovery Using Surfactant-nanoparticle Stabilized Foam in Sandstone Reservoirs

Injection of nanoparticle-stabilized foam has been considered by the oil industry due to its high stability. In this study, the interaction between nanoparticles and surfactants as well as the hysteresis of the foam injection sequence is investigated. For this purpose, secondary and tertiary core injection experiments were performed on synthetic glass core to investigate the oil recovery behavior of foam stabilized with calcium carbonate nanoparticles and SDS surfactant in sandstone reservoirs. According to the results, the secondary oil recovery by foam stabilized with a mixture of 0.04 wt.% of surfactant and 0.1 wt.%  of nanoparticles is significantly higher than the foam stabilized with counterpart nanoparticle and surfactant. In all cases, tertiary oil recovery was significantly lower than the tertiary mode. This phenomenon was attributed to the diffusion regime governing tertiary recovery compared to the convective regime in the secondary injection. In order to prove this hypothesis, the aging process performed in the core injection experiments was repeated in the contact angle device. In the diffusion regime, the nano fluid could not change the wettability of the glass to more water-wetness. The surfactant solution reduced the glass oil-wetness by only 5 degrees. The mixture of surfactant and nanoparticles brought this change in wettability to 16. The Nano fluid, surfactant solution, and mixture of surfactant and nanoparticles brought the initial wettability of about 150˚ to 76˚, 45˚, and 23, respectively, which it confirms the higher rate of convective regime in the change of wettability. Based on surface tension experiments, the superior behavior of the surfactant and nanoparticle mixture was attributed to the adsorption of surfactant molecules on the nanoparticles and the surface activation of the nanoparticles.