Research on High-Strength, Tough, and Water-Invasion Resistant Cementing Slurry System

With oil and gas field exploration and development extending to deep, ultra-deep, and geologically complex regions, traditional cementing slurry systems face numerous technical challenges when dealing with high-temperature, high-pressure, and water-invasion prone complex downhole environments. This paper addresses issues such as low cement stone strength, poor toughness, and weak water-invasion resistance by systematically studying the mechanisms of elastoplastic low-density additives, reinforcing fiber materials, water-based epoxy resins, and nano liquid silica, as well as their effects on cement slurry properties. Through this research, a new type of high-strength, tough, and water-invasion resistant cementing slurry system was developed. Results show that the optimized formulation has good fluidity and pumpability, with a thickening time of 141 min, meeting construction requirements. The 7 day compressive strength of the cement stone reaches 41.2 MPa, more than 40% higher than conventional cement slurry. The addition of carbon fiber and epoxy resin significantly improves the toughness of cement stone, with a toughness index of 1.85. The supplementary hydration effect of nano liquid silica reduces cement stone porosity to 22.4% and permeability to 0.18 mD. The penetration depth of the cement slurry into fractured reservoirs is reduced by 65.1% compared to conventional cement slurry, demonstrating excellent reservoir protection performance. Field application results indicate that this system can effectively solve technical challenges in the cementing process, providing new technical support for improving oil and gas well cementing quality.