Experimental Investigation of CO₂-Brine Simultaneous and Alternate Injection: Implications for Geomechanics and CO₂ Storage Capacity

To enhance carbon management, the study investigates water-alternating gas (WAG) injection for carbon dioxide (CO2) sequestration in saline aquifers, focusing on its impact on storage capacity.Utilizing core flooding experiments with Gray Berea sandstone and Indiana Limestones at 2500psia confining pressure and CO2 injection at 1100 psi and 100°F to maintain CO2 in a supercritical state, the research compared Continuous CO2 Injection (CCI) and Simultaneous or Alternate Injection of CO2 and Brine (SAI).Findings indicate that CCI and SAI are more favorable regarding increasing storage capacity with SAI, showing a 7.8% porosity increase in sandstone and 11.3% in limestone.However, there is a higher increase in permeability in the case of CCI, which could lead to a higher risk of leakages.SAI demonstrated lower overpressure, suggesting more CO2 can be stored relative to CCI, efficient plume management and enhanced fluid displacement through residual and mineral trapping.This study shows SAI's potential in CO2 sequestration projects, offering insights into brine-assisted strategies for improved storage capacities.