Temporary Well Plugging for Future CO₂ Storage: CT Analysis of Thermal Sensitive Polymer-Gel Dynamics in Low-Permeability Chalk

Since most oil and gas reservoirs are nearing the end of their productive lifespans, environmental regulations require wells to be securely plugged before they are abandoned to reduce pollution hazards. This study investigates the use of polymer gels for temporary in-situ plugging in chalk formations with low permeability, a challenging environment since high-viscosity fluid injection is problematic. First, a cross-linker and polymer combination with low viscosity are injected into the chalk matrix inside a core holder. Subsequently, when heated this combination forms a gel, significantly raising the viscosity, and effectively blocking the flow channels in the porous medium. Real-time monitoring using computed tomography (CT) analysis is used to verify the plugging procedure and ensure the polymer is injected evenly. Flow tests are performed after gelation to evaluate the level of permeability. The study is expanded to include fractured media to assess how effectively the gel blocks matrix porosity as well as fractures. The findings provide insight on well-plugging methods that support these wells' conversion to CO₂ storage locations, with potential benefits for improving operational sustainability and environmental safety.