Enhancing CO2 hydrate formation, stability and storage potential in sub-seafloor saline sediments using nanoparticle-assisted surfactant/ polymer formulations: Exploring molecular interaction to field application

There has been some success with nanoparticles (NPs), surfactants, and polymers used to enhance CO2 hydrate formation, stability, and storage in sub-seafloor saline sediments. However, their long-term stability is compromised in harsh conditions of sediment heterogeneity, overly high pressure and temperature, fluctuation in salinity, and sediment interactions. Incorporating NPs into polymers and surfactants yields a nanofluid revealing increased stability, enhanced rheological behaviors, improved wettability, enhanced CO2 adsorption, reduced induction time, increased water-to-hydrate conversion rate, boosted CO2 hydrate storage capacity, ultimately leading to CO2 hydrate storage efficiency, all attributable to the synergistic effects of their components. In this work, the performance of NP-assisted surfactant/polymer formulations and the factors that impair their effectiveness were highlighted. Numerous NP-assisted surfactant/polymer formulations adsorption mechanisms, such as electrostatic interactions, specific chemical affinity, hydrogen bonding, and hydrophobic interactions, on the hydrate-forming surface were illustrated. The synergistic interaction of NP-assisted surfactant or polymer to the interfacial tension (IFT) reduction, enhanced CO2 uptake efficiency, increased CO2 gas consumption rate, and enhanced CO2 adsorption tendencies for enhancing CO2 hydrate formation, stability, and storage capacity were also presented. Additionally, the review emphasized the existing challenges, research gaps and proposed potential interventions.