(498g) Enhancing CO2 Sweep and Storage Efficiency: Development and Evaluation of a Novel Hydrogel for CO2 EOR and Storage Projects

In addressing climate change, carbon capture and sequestration (CCS) is crucial for mitigating emissions from major stationary sources worldwide. The integration of CCS with EOR presents promising prospects, enabling the simultaneous mobilization of oil reserves and sequestration of CO₂ underground. Hydrogel technology offers reliable solutions to key challenges in underground CO₂ storage, such as controlling CO₂ conformance within reservoirs and preventing CO₂ leakage through cap rock integrity maintenance. By strategically utilizing hydrogel, CCS-EOR projects can enhance storage efficiency and comply with environmental standards, significantly contributing to global climate change mitigation efforts. However, traditional polymer gels are not stable at CO₂ acid condition. To solve the problem, we have developed a novel polymer gel that can be utilized as a plugging agent for either improving CO₂ sweep efficiency by controlling the preferential fluid flow problem or used as blocking agent to prevent CO₂ leakage through wellbore or caprocks. This study extends the application of polymer gel systems to the field of CCS, addressing the unique challenges posed by CO₂ injection and storage in underground reservoirs. First, we screen polymers that can be capable to resist CO₂ at reservoir condition. Then the polymer concentration optimization was conducted through bottle tests and core flooding experiments to determine a critical concentration range conducive to stable gel formation in porous media. Subsequently, formula optimization was pursued by assessing the effects of varying polymer concentrations, crosslinker concentrations, and salinity levels, considering the specific conditions encountered in CCS reservoirs. Rheology studies compared static bottle tests with dynamic viscosity measurements under different salinity conditions to simulate the flow state in porous media. Furthermore, the CO₂-resistant properties of the polymer gel were evaluated, encompassing stability assessments and studies on plugging efficiency under simulated CO₂ injection conditions. Through comparison, it was determined that gel modified by polymer AN 125 was the most CO₂-resistant polymer due to the lowest initial viscosity, a lower syneresis degree, and a higher residual resistance factor. Overall, this research provides valuable insights into the development and application of polymer gel systems for sealing CO₂ leakage and enhancing the security and efficiency of CCS operations.