Reassessment of CO₂ sequestration in tight reservoirs and associated formations

CO₂ sequestration and CO₂ enhanced oil recovery (CO₂-EOR) are two major processes that can expose the rock to CO₂. The behavior of a rock when saturated with CO₂ changes over time, affecting both the mechanical and chemical properties of the host rock. CO₂ operation involves the injection and pressurization of reservoirs that usually results in changes to the state of in situ stresses that may initiate fractures. This can lead to slippage along pre-existing fracture and fault systems. CO₂ storage in tight formations, either for EOR or sequestration purposes, is imperative to contribute to the current energy transition and mitigate climate change. Thus, injection of CO₂ may alter the mineralogy, pore structure, mechanics, and other properties and behavior of tight reservoirs, and sometimes may be susceptible to leakage through induced fractures or reactivated faults. Here, we aim to evaluate and reassess studies on CO₂ sequestration in tight reservoirs and associated formations. This report focuses on the changes in properties and behavior of tight rocks (shale and tight carbonate rocks) due to CO₂ exposure through CO₂ sequestration or CO₂-EOR. We highlight the most important findings from available studies to date, and we recommend promising areas of research that can advance the knowledge and development of CO₂ sequestration in tight formations.