Investigation of Corrosion-Resistant Grouting Compound Under Conditions of Hydrogen Sulfide Aggression by Express Method

One of the critical challenges in oil and gas well construction and operation is ensuring reliable zonal isolation and maintaining wellbore integrity throughout the well's lifecycle. A major operational issue under harsh downhole conditions is the degradation of cement sheaths due to exposure to aggressive formation fluids containing hydrogen sulfide (H₂S). Under high-temperature, high-pressure (HTHP) conditions, H₂S accelerates corrosion processes, compromising cement strength, inducing microannuli and microcrack formation, and ultimately leading to a loss of integrity. The formation of a competent cement sheath and the subsequent trouble-free operation of the well depend on the composition of the cement slurry, the potential for damage to the sheath during tripping operations and pressure testing, casing centralization, and numerous other factors.This study focuses on developing and evaluating a modified well cement formulation with improved corrosion resistance in H₂S-rich environments. The proposed composition consists of cement clinker, weighting agents, inert fillers, and a suite of technological additives, with calcium polysulfide as the primary functional component at varying concentrations.Experimental cement samples were subjected to accelerated H₂S corrosion testing in a simulated aggressive environment at 90–100 °C. Microstructural and phase composition changes were analyzed using X-ray diffraction (XRD) and scanning electron microscopy (SEM).Results demonstrate that calcium polysulfide interacts with cement hydration products, forming protective compounds within the matrix. This effectively seals micropores and inhibits the ingress of corrosive ions, substantially reducing the corrosion depth and rate, and decreasing the volume of the altered zone. The findings validate the efficacy of this additive in enhancing the durability of cement for wells operating in H₂S-laden oil and gas reservoirs.