After drilling each section of a well, cement is placed in the annulus of the casing and the formation. The cement integrity must be ensured during the life cycle of the well or after abandonment. If for any reason, the cement lost its integrity, the consequences could be severe for personnel, equipment, and the environment. When the cement fail, leakages may occur through the cement pathways and sealant materials are used to plug these pathways. This study investigates a temperature activated epoxy resin sealant to evaluate the potential use of this sealant as an alternative to Portland cement in oil and gas wells. This study focuses on analyzing the rheological behavior of the sealant, the effect of temperature on the rheology and the curing time of the sealant, the penetrability of the sealant into small voids, and the blocking efficiency of the sealant. Experimental tests were conducted to evaluate the epoxy resin sealant including rheological measurements, density, injectivity, blocking efficiency, and mechanical properties. The findings of this study show that this sealant has low viscosity and Newtonian rheological behavior, low density as low as water, high injectivity and penetrability even in small gaps, ability to resist differential pressure higher 1000 psi, and extremely high compressive strength. This work demonstrates that epoxy resin sealant can be used effectively and safely in sealing cement voids.