Nanoparticles-surfactant foam and crude oil interaction in porous media

Abstract

Nanoparticles and surfactant stabilized foams have versatile applications in enhanced oil recovery process. The synergistic advantages of surface tension reduction by surfactant and nanoparticles adsorption at the foam lamellae can be exploited for producing foam with high foamability and longtime stability in the oil producing reservoir. However, the influence of nanoparticles on the static and the dynamic stability of conventional foam is not yet explicit due to limited studies. Moreover, only few studies have considered the pore-scale mechanisms of the nanoparticles-surfactant foams flow process in porous media and the minimization of surfactant adsorption in presence of nanoparticles. Due to limited research in this area, this study was conducted to understand the influence of silicon dioxide (SiO2) and aluminum oxide (Al2O3) nanoparticles on the surfactant foam bulk and dynamic stability and surfactant adsorption on clay mineral. Four main experimental studies comprising the influence of the nanoparticles on surfactant adsorption on kaolinite, bulk and bubble-scale foam stability evaluation in presence of oil and salts, pore-scale visualization studies in etched glass micromodels, and fluid diversion process experiments were conducted. Results of this study showed that the adsorption of surfactant on clay mineral reduced drastically by 40% and 75% in presence of Al2O3 and SiO2 nanoparticles, respectively. The maximum adsorption of surfactant on the nanoparticles occurred at 0.3 wt % sodium dodecyl sulfate (SDS). The foam bulk and bubble scale stability results indicated that 1 wt % of SiO2 and Al2O3 nanoparticles enhanced the stability of the foam in presence of oil and salts. There was a transition salt concentration beyond which the foam stability increased with increasing salt concentrations. The presence of Al2O3 and SiO2 nanoparticles prevented the entering of emulsified oil into the foam lamellae and decreased the transition salt concentrations. From the results of the pore scale studies, the dominant mechanisms of foam propagation in water-wet system were lamellae division and bubble-to-multiple bubble lamellae division. The dominant mechanisms of residual oil mobilization and displacement by the foam in water-wet media were found to be direct displacement and emulsification of oil. The dominant mechanism of foam propagation and residual oil mobilization in oil-wet system was identified as the generation of pore spanning continuous gas foam. Inter-bubble trapping of oil and water, lamellae detaching and collapsing of SDS-foam were observed in presence of oil in both water-wet and oil-wet systems. Generally, the SiO2- SDS and Al2O3-SDS foams propagated successfully in oil-filled water-wet and oil-wet systems. Bubble coalescence was prevented during film stretching. The results of the fluid diversion process indicated an effective diversion of fluid in layered macroscopic model with permeability ratio of 8:1 in presence of SiO2 and Al2O3 nanoparticles. The outcomes of this research is a major breakthrough in prospective field applications of nanoparticles-surfactant foams in oil-filled water-wet and oil-wet porous media.