Energy Resources and Petroleum Engineering Ph.D. Dissertation

Abstract

The increasing global energy demand, in tandem with climate change concerns, has fueled a growing exploration of pioneering solutions, including CO2 plume geothermal technology (CPG), aimed at meeting the world's energy requirements while simultaneously mitigating carbon emissions. CPG research has been attracting attention for its dual potential: sequestering CO2 and utilizing it as a working fluid in geothermal heat extraction processes. The exceptional thermal expansion properties of supercritical CO2 facilitate the use of medium to low enthalpy porous, permeable aquifers as heat mining reservoirs, enabling the extraction of heat energy. However, these advancements present challenges. In the injection-production setup, optimizing injector and producer well configuration is crucial. Production wells must yield over 95% CO2 mass fraction to avoid liquid loading, ensuring swift CO2 saturation while delaying the occurrence of cool front invasion during the production lifetime. Achieving these conditions demands a comprehensive understanding of phase changes and dynamic fluid properties of CO2 as well as reservoir heterogeneity integrated into the reservoir model. This thesis introduces novel insights into capturing CO2 fluid complexities in simulations, as well as the impact of fault-related or deposition-related heterogeneities, and their combined influence on reservoir performance in CPG studies. We first present an analytical solution for the elastic response of porous rock to long-term slip on strike-slip fault networks within geo-reservoirs, leading to additional heterogeneity. The thesis also delves into the mechanism of thermal recovery in thick, deep saline aquifers by linking the solubility of CO2 with heat exchange, by prescription of mutual solubility, dynamic viscosity, and phase changes of the working fluid enhances our approach. We present a case study of CO2 plume geothermal modeling in the Red Sea's Al Wajh basin, using advanced geostatistical and our novel fluid modeling techniques to assess its geothermal potential. Additionally, we conduct numerical simulations on fractured reservoirs and their associated heterogeneities, exploring how the combined effects of elastic and inelastic deformations due to faults influence CO2 migration as a study case in the Ghawar field's Haradh section. Overall, this research advances our understanding of planning field development in CO2 plume geothermal applications by emphasizing the importance of accurate reservoir and fluid complexity representations to achieve comprehensive insights.