Reassessment of CO2 sequestration in tight reservoirs and associated formations

Abstract

CO 2 sequestration and CO 2 enhanced oil recovery (CO 2 -EOR) are two major processes that can expose the rock to CO 2 . The behavior of a rock when saturated with CO 2 changes over time, affecting both the mechanical and chemical properties of the host rock. CO 2 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. CO 2 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 CO 2 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 CO 2 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 CO 2 exposure through CO 2 sequestration or CO 2 -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 CO 2 sequestration in tight formations.