Enhancing CO₂ storage capacity and containment security of basaltic formation using silica nanofluids

The affinity of the basalt surfaces towards CO₂, quantified as wettability functions, is one of the most important driving factors for CO₂ trapping capacity and containment security. SiO₂ is a minor constituent, often found in traces in the seawater and formation brine injected or reinjected into the sub-surface formations. This work, thus, evaluates the effect of nano-sized SiO₂ (100, 1000, and 2000 mg. L⁻¹) on the wettability of the basalt rock surface in the pressure range of 5-20 MPa. The results from brine/CO₂/rock wettability measurements show that SiO₂ nanoparticles turn the CO₂-wet basalt surface to weakly water-wet upon aging with nanofluids. About 40% reduction in the measured brine contact angle takes place upon treatment of the rock sample with 1000 mg. L⁻¹ nanoparticles. We hypothesize that this change in wettability may facilitate enhanced capillary or residual trapping of CO₂ in the basalt formation having adequate porosity and permeability to enhance the basalt CO₂ trapping capacity.