Improving CO2 storage efficiency in saline aquifers through wettability-optimized nanoparticle foam

The sequestration of CO2 in saline aquifers represents a critical strategy for mitigating the warming effects of greenhouse gases. Nanoparticle foams, known for their superior stability, are instrumental in substantially reducing the CO2 migration rate. This makes their use a promising method for the geological containment of CO2. In this paper, the utilization of nanoparticle foam in the geological storage of CO2 was investigated. By combining nanoparticles with six different wettability characteristics and five types of cationic surfactants, the optimal contact angle range for surfactant compatibility was determined. Additionally, the impact of nanoparticle wettability on foam performance and rheological behavior was evaluated. Ultimately, displacement experiments were conducted to investigate how nanoparticle foams can enhance the CO2 storage capabilities of geological formations. The experimental results show that the primary contact angle of nanoparticles plays a crucial role in determining their compatibility with cationic surfactants. Nanoparticles are found to be most effective within a contact angle range of 37.83°–51.13°. In displacement experiments, foam DDA (ethyl dodecyl dimethyl ammonium chloride) reaches its maximum CO2 geological sequestration capacity at a foam quality of 80%. In contrast, foam produced by surfactant DDA and nanoparticle N20 (DDA+N20) achieved the highest CO2 sequestration capacity at 85% foam quality. Distinctively, compared with traditional foams, foam DDA+N20 exhibits superior capabilities, storing more CO2 while consuming less water. The outcomes of these experiments provide invaluable directions for the application of nanoparticle foams in geological CO2 sequestration endeavors.