A comprehensive study on the effect of rock corrosion and CO₂ on oil-water interfacial tension during CO₂ injection in heavy oil reservoirs

This study is focused on addressing issues related to the interaction mechanism between reservoir rocks and fluids during CO2 injection in heavy oil reservoirs. The results indicate that the carbonated water formed after high-pressure CO2 injection is causing corrosion in the core structure. Furthermore, the average corrosion rate increases from 0.358% as pressure increases from 8 MPa to 16 MPa to 0.742%. The core slices exhibit corrosion pits and cracks on their surface, as well as surface particles flaking and dissolving. The dynamic IFT between decyl trimethyl ammonium bromide solution and crude oil exhibited slower stabilization and less change without CO2 injection. However, with increasing pressure post CO2 injection, the dynamic IFT decreased at a more rapid rate. Furthermore, positive correlation between equilibrium IFT and temperature was observed with low-pressure CO2. In contrast, the surfactant played a more dominant role in reducing IFT with high-pressure CO2. The findings of this study can help for better understanding of the mechanism of microscopic action on reservoir rock and oil-water interface after CO2 injection, and offer theoretical basis and reference for CO2 injection in heavy oil reservoirs to enhance the recovery rate.