A Review of Studies on Reservoir Responses during CO2, H2, and N2 Storage.

This thesis presents a literature review on underground gas storage in rock formations, with a specific focus on CO2 geological storage. The review highlights the intricate interactions between CO2 and reservoir rocks, caprocks, and clay minerals, emphasizing the complexity involved in predicting and optimizing the performance of CO2 storage projects. The impact of CO2 on rock strength and mechanical properties is a key aspect discussed in the review. Studies demonstrate that CO2-brine activity can decrease strength and elastic moduli while enhancing porosity and permeability. However, further research is needed to fully understand the impact of CO2 on rock strength, necessitating comprehensive rock mechanical laboratory testing. CO2 injection induces various alterations, including cement dissolution, deformations, and changes in transport and elastic properties. These modifications are influenced by site-specific factors such as mineral composition and reactive minerals. Insights from field-scale tests, laboratory studies, natural analogue sites, and numerical models help understand these complex interactions and geomechanical responses. Numerical simulations contribute to the comprehension of coupling phenomena. The impact of CO2 injection on chemically altered carbonates in storage projects is explored, focusing on reservoir and caprock integrity. Altered samples typically exhibit reduced failure strength and elastic moduli. However, understanding the chemical alteration processes remains challenging, necessitating advanced models that consider formation characteristics. Studying the dissolution of CO2 in pore fluids and its mechano-chemical interactions with rock minerals reveals changes in porosity, permeability, elastic moduli, and strength characteristics. Laboratory experiments provide valuable insights, but accurate assessments require accounting for site-specific conditions and reservoir-scale heterogeneities. The containment's integrity relies on undamaged caprocks and sealed faults, emphasizing their crucial role. Cyclic stress loading and unloading on sandstone permeability for underground gas storage is investigated, showing reduced permeability at higher stress levels due to pore space compression. Geomechanical processes, including stress-and-strain changes, microseismic events, and mechanical changes at high pressure, highlight the complexity involved in CO2 storage projects. Numerical simulators and monitoring techniques aid in analyzing and predicting geomechanical issues. The importance of considering hydrogeological, geochemical, and geomechanical processes in accurate predictions for CO2 sequestration models is emphasized. Particle flow models and exploration of different rock formations enhance understanding of fracture propagation and fluid-solid mechanical effects. Computational analyses and dynamic models are necessary to improve accuracy in geoenvironmental systems impacted by CO2 sequestration. Interactions between CO2 and clay minerals play a significant role in caprock effectiveness and well sealing for CO2 storage. The sorption and swelling behaviors of CO2 in clays are investigated, highlighting advantages of adsorption over bulk phase storage. Molecular dynamics simulations and experimental studies provide insights into CO2/clay interactions and their impact on CO2 trapping, diffusion, and storage safety.