高温高压环境固井水泥研究进展

Research Advances in Oil Well Cement Subjected to High Temperature and High Pressure Curing Environment

高温高压环境是深井、超深井、地热井、稠油热采井等固井面临的最大挑战之一;水泥石的高温强度衰退现象早在20世纪50年代就得到认识,经过近70年的研究,抗高温油井水泥体系的研究已经取得了很大的进展。该文章对本领域的研究成果进行了梳理与总结,调研了三种抗高温油井水泥体系,即加砂硅酸盐水泥、高铝水泥和磷铝酸盐水泥,分析了各种体系的优点与不足;重点阐述了常用加砂硅酸盐水泥的高温强度衰退机理及其物理力学性能影响因素,从而为油井水泥抗高温性能的进一步研究以及现场的配方优化设计提供参考依据。调研发现在较高温度环境加砂硅酸盐水泥均会出现不同程度的强度衰退现象,而减缓强度衰退的方法主要包括减小硅砂粒径、优化颗粒级配和提高水泥浆中的固相体积分数等。

High temperature and high pressure environment is the biggest challenge faced by cementing deep and ultra-deep wells, geothermal wells, and steam injection wells. The strength retrogression phe-nomenon of cement at high temperature has been identified as early as in the 1950s;after nearly 70 years of research, significant progresses have been made with regard to high-temperature-resistant cement systems, which are reviewed in this paper. Specifically, three temperature-resistant cement systems were investigated, including silica enriched Portland cement (silica-PC) system, high aluminum cement, and phosphoaluminate cement, with each system’s advantages and disadvantages analyzed. The main focus is on the mechanism of strength retrogression as well as influencing factors of physical and mechanical properties of the most commonly used system, i.e. the silica-PC system. Information included in this paper provide references for further research to improve the temperature resistance of oil well cement systems and may be used to guide cement formulation design in the field. The main finding is that the silica-PC system typically experiences various degrees of strength retrogression at relatively high temperature, and the main methods to mitigate such effect are through reduction of silica particle size, optimization of particle packing and increasing volume fraction of solid phase in the mixture.