Exploring epoxy resin sealants for sustained casing pressure mitigation in the wellbore

A significant challenge is sustained casing pressure(SCP) during oil and gas production. This study investigated a solid-free epoxy resin sealant to replace Portland cement. Properties such as sealant viscosity, curing time, compressive strength, and tensile strength were investigated. The sealing and fatigue resistance of cement and epoxy resin were compared. The results indicated that the curing time of epoxy resin was controlled at 3.1 similar to 10.4 h. Adding a 25% viscosity reducer reduced the epoxy resin's viscosity by 97.63%. Remarkably, the epoxy resin surpassed cement in compressive strength, tensile strength, and elongation at break. The breakthrough pressure of the epoxy resin was higher than that of cement, and this advantage was more evident as the length increased. The convergence time of 10 mm epoxy was prolonged by 189.01% over that of cement. The epoxy resin effectively suppressed the rate of pressure increase after gas breakthrough. Under cyclic loading of 20% to 80% breakthrough pressure, the cement seal failed after 12 cycles, while the epoxy maintained seal integrity for 17 processes. The fatigue resistance of epoxy resin was superior to that of cement, ensuring long-term annulus sealing under alternating load perturbations. Epoxy resin sealant can potentially provide a new solution to the SCP problem.