| dc.description.abstract | The geological storage of hydrogen and carbon dioxide has emerged as a promising solution for mitigating greenhouse gas emissions and facilitating the transition to a low-carbon energy future. However, the success of such storage projects hinges upon the effective containment of hydrogen within subsurface reservoirs, necessitating rigorous assessment of caprock integrity to prevent leakage and ensure long-term storage security. This thesis presents a comprehensive investigation of the Drake FM. caprock integrity assessment for the geological hydrogen storage in the Aurora site using CMG software.
The study begins with a detailed characterization of the Aurora site's geological and aquifer properties, including porosity, permeability, caprock stresses and mechanical properties using data from exploration well NO 31/5-7 (Eos). Barton-Bandis fracture permeability model is constructed to simulate the injection and migration of hydrogen within the reservoir, for 6 months. The model was also used to simulate CO2 sequestration for 50 50-year injection period to assess the caprock integrity.
The primary caprock is the Drake Formation 1 and the storage formations are the Johansen and Cook Formations. Hydrogen is continuously injected at the aroura site for 6 months at a rate of 2075550 m3/day. Simulations reveal that during the initial 3 months of injection, the pressure distribution is relatively higher at the bottom of the aquifer and near the wellbore. This elevated pressure decreases with distance from the wellbore. Throughout the injection period, the caprock and overburden zones maintain significantly lower pressures compared to the aquifer, indicating effective containment by the caprock. Notably, effective stress distribution shows a reduction around the wellbore, particularly below the caprock, due to the increased pore pressure from H2 injection. In the case of CO2 storage, the model indicates a rapid increase in average reservoir pressure during the first year of injection, stabilizing at approximately 28719 KP after one and a half years and maintaining this range until injection ceases. CO2's solubility increases during the entire injection period however the trapping efficiency diminishes after the shut-in period.
Different characteristics are shown by H2 and CO2 when injected into the Aroura site. H2 storage depends more on physical containment inside the pore spaces of the reservoir rock than it does on mechanisms like dissolution, trapping, and mineralization, which are the main ways that CO2 is stored. Furthermore, the pressure build-up of H2 injection is relatively low compared to CO2 injection in the first 6 months. | |
