This project aims to develop technologies of aqueous nanobubble (NB) dispersion of CO2 for geological carbon sequestration, primarily for CO2 mineralization in (ultra)mafic rock formations. We aim to substantially reduce the amount of water required to sequester a given amount of CO2 (e.g., by a factor of 2), leading to a reduced cost (capital and operational) of CO2 mineralization. Aqueous nanobubble dispersion also enables supersaturation of brine by CO2 beyond the inherent solubility and enhances the kinetics and extent of mineral dissolution and CO2 mineralization. In addition to fundamental studies of aqueous NB dispersion, we are developing suitable methods of aqueous CO2 NB generation for continuous operation at elevated pressure for CO2 mineralization. Primary collaborators on this topic include “44.01” and “Japan Petroleum Exploration”.

Wettability alteration has been studied as a potential way to enhance oil recovery from tight formations. One of the commonly used wettability modifiers is surfactant, which is expected to make rock surfaces less oil-wet and lower the oil/water interfacial tension (IFT). Shortcomings of using surfactants include i) it unlikely affects fluid flow in tight matrices where the molecular size is greater than pore sizes even as a surfactant monomer, ii) the lowered oil/water IFT tends to reduce the water imbibition, iii) many surfactants are unstable at high-temperature high-salinity conditions (e.g., carbonate reservoirs in the Middle East), and iv) the total cost for an effective surfactant formulation can be high. This project aims to develop ketone EOR technologies for enhanced oil recovery from conventional and unconventional reservoirs. The central hypothesis in this project is that aqueous ketone solution can alter the wettability of rock surfaces to more water-wet by rapidly penetrating matrices through oil and water phases in small pores without affecting the oil/water IFT. We found that 3-pentanone or diethyl ketone is the most effective ketone for EOR in shales and carbonates, as also confirmed by other academic and industrial research groups. The molecular size of 3-pentanone was reported to be 0.4-0.79 nm and stable under high-salinity and high-temperature conditions. The cost is approximately $2/lb. The solubility of 3-pentanone in brine is usually below 3 wt% and decreases with increasing salinity. Primary collaborators on this topic include OXY for shale reservoirs, and INPEX and Cosmo Energy for carbonates.