Effect of single-step silica nanoparticle on rheological characterization of surfactant based CO2 foam for effective carbon utilization in subsurface applications

Abstract

Foams represent the most viable method of gas mobility control in subsurface reservoirs. However, their wider oilfield application is constrained due to their low stability. In this study, the role of single-step silica nanofluids (size ~30–150 nm) on the rheological behavior of surfactant-based carbon dioxide (CO2) foams was investigated for effective carbon utilization in porous media. Nanofluids, of varying nanoparticle size (36–148 nm) and concentration (0.1–1 wt%), displayed excellent dispersion stability. Pickering CO2 foams of varying sizes (20–40 µm) were developed. CO2 foams were analyzed for foam volume, stability, and rate of liquid drainage. Increasing silica size was found to show a detrimental effect on foam stability while increasing concentration improved foam stability. The foam stability was found to be greatly dependent on test temperature and above 90 °C, Pickering foam exhibited higher foam degradation. For foam, the rheological measurements were conducted at 1 bar as a function of temperature (30–90 °C). Pickering CO2 foams showed non-Newtonian shear thinning behavior where increasing nanoparticle concentration (0.5–1 wt%) yielded a 6–13% increase in foam viscosity. The foams also showed strong viscoelastic nature with the presence of both G′ and G″ over the entire range of investigated strain and amplitude sweep. From the viscoelastic characterization of CO2 foams, it was established that foam behavior was dominated by elastic nature (G′ > G″) at low stress values (10–20 strain %) while increasing stress (>20 strain %) produced liquid-like (G″ > G′) dominance in the behavior of foam. Finally, hysteresis analysis was reported to understand the role of a heterogeneous pore environment (where varying shear conditions usually prevail) on the flow properties of CO2 foams. The addition of silica nanofluid stabilizes CO2 foams and their application is proposed in carbon storage and utilization applications like enhanced oil recovery.