超高温固井水泥添加剂研选及工程性能评价

Development and Engineering Performance Evaluation of Additives for Ultra-high Temperature Cement Slurry

随着浅层油气资源的不断开发和不断增长的油气需求,油气勘探开发开始向高温、超高温等极端环境迈进,给固井水泥体系带来巨大的挑战。针对超高温环境下水泥石强度衰退的固井难题,通过研选硅砂、高温增强材料、缓凝剂、降失水剂及高温稳定剂,进行了超高温水泥浆体系的研究。研究结果表明,超高温水泥浆体系具有优异的工程性能,在210℃高温环境下,体系高温失水量小于100 mL,密度差小于0.02 g/cm^(3),稠化时间可调;在250℃环境下水泥石抗压强度大于50 MPa且不衰退。非晶态高温增强材料能提高水泥石高温力学性能并抑制强度的衰退,并可作为硅粉的替代物,减少高温水泥中硅粉的用量。通过XRD和SEM分析发现高温增强材料有效地阻止了高温水化产物托勃莫来石(C_(5)S_(6)H_(5))转变为硬硅钙石(C_(6)S_(6)H)。文章的研究成果对解决深井、超深井固井水泥石强度衰退问题具有重要意义。

With the continuous development of shallow oil and gas resources and the growing demand for oil and gas,oil and gas exploration and development have begun to move towards extreme environments such as high temperature and ultra-high temperature,which brought great challenges to cementing cement system.Aiming at the problem of cement strength decline in ultra-high temperature environment,the ultra-high temperature cement slurry system was studied by selecting silica sand,high temperature reinforcement materials,retarders,filtrate reducers and high temperature stabilizers.The results show that the ultra-high temperature cement slurry system has excellent engineering performance,and the high temperature water loss of the system is less than 100 mL,the high temperature stability is less than 0.02 g/cm^(3),and the thickening time can be adjusted at 210℃.At 250℃,the compressive strength of the cement stone is greater than 50 MPa and does not decline.Amorphous high temperature reinforced material can improve the high temperature mechanical properties of cement stone and restrain the decline of strength,which can be used as a substitute for silica powder to reduce the amount of silica powder in high temperature cement.Through XRD and SEM analysis,it was found that the high-temperature reinforcing material effectively prevented the high temperature hydration product tobermorite(C_(5)S_(6)H_(5))from transforming into xonotlite(C_(6)S_(6)H).The research results of this article are of great significance in solving the problem of cement stone strength decline in deep and ultra deep well cementing.