Assessment of carbon dioxide storage potential in saline formations and shale gas reservoirs with enhanced gas recovery in the Midwest regions, U.S.A

Geological CO2 storage has been increasingly regarded as a promising option for mitigating climate change. This dissertation presents three investigations of CO2 storage in two targeted hosts: deep saline formations and shale gas reservoirs with potential enhanced gas recovery. A combination of modeling and experimental methods was used. The primary goal is to verify the storage effectiveness and security by identifying the key processes associated with the CO2 injection and storage and to quantifying the fate of the injected CO2 related to various trapping mechanisms in these formations.;Deep saline formations provide by far the largest estimated storage capacity for geological carbon sequestration. I performed multi-phase reactive flow and transport modeling to investigate the dynamics of CO2 injection and storage in the Mt. Simon sandstone, a major candidate saline formation for carbon sequestration in the Midwest region. The long-term contribution and variation of four major trapping mechanisms were evaluated, i.e., hydrodynamic, solubility, residual, and mineral trapping. Additionally, I studied the caprock integrity/security issue under the CO2 intrusion. Reactivity experiments were conducted using the Eau Claire Shale (the caprock overlying the Mt. Simon sandstone) samples exposed to CO2 and brine at high temperature and pressure. Relevant experimental and modeling studies, as well as field observations, were also reviewed in this study.;The recent proliferation of shale gas production provides a unique opportunity for evaluating the potential of CO2 storage in shale gas reservoirs which is the third part of my Ph.D. work. In theory, the injected CO2 may be preferentially adsorbed onto the organic matter in shales and simultaneously replace CH4 leading to enhanced gas recovery (EGR). Reservoir simulations were performed to evaluate this hypothesis using the New Albany Shale in the Illinois Basin as a case study. CO2 trapping mechanisms are fundamentally different in shales with gas adsorption playing a primary role. Due to the intensive development and wide distribution of shale gas formations, successful implementation of CO 2 storage in shales may have a major impact on regional and national plans for carbon sequestration and shale gas production strategies.