钻井法凿井壁后充填大比重水泥浆研制及其耐久性能

Development and durability performance of high density cementslurry filled with drilling method for shaft sinking

为提升西部地区深大钻井井筒第一段高壁后充填置换效果,提出采用大比重水泥浆作为新型壁后充填材料。首先,通过对比试验,优选重晶石粉作为加重剂、硅酸镁铝为悬浮剂。然后,采用正交试验和极差分析法,分析了水灰比、重晶石粉、硅酸镁铝和膨胀剂掺量对大比重水泥浆的密度、初凝时间、流动度、3 d及28 d抗压强度的影响,采用综合平衡法确定了大比重壁后充填材料的最优配合比为水泥∶水∶重晶石粉∶硅酸镁铝∶膨胀剂∶减水剂=1∶0.55∶0.5∶0.03∶0.025∶0.015。硫酸盐溶液侵蚀对比试验表明,与常用的水泥浆充填材料相比,大比重水泥浆充填材料具有可靠的耐久性能。最后,通过XRD和SEM分析了优选组加重水泥浆在3 d和28 d的水化产物和微观结构,揭示其优异抗渗性和耐久性能的机理。研究结果可为西部地区深大钻井井筒壁后充填提供大比重、高强度、低渗透以及耐久性好的新型壁后充填材料。

In order to improve the filling and replacement effect of the first section of high wall in deep and large drilling shafts in western China,it was proposed to use high density cement slurry as a new type of wall filling material.Firstly,through comparative experiments,barite powder was selected as the weighting agent and magnesium aluminum silicate as the suspension agent.Then,orthogonal experiments and range analysis were used to analyze the effects of water cement ratio,barite powder,magnesium aluminum silicate,and expansion agent dosage on the density,initial setting time,flowability,and compressive strength at 3 and 28 days of high density cement slurry.The optimal mix ratio of high density wall filling material was determined using the comprehensive balance method as cement:water:barite powder:magnesium aluminum silicate∶expansion agent∶water reducing agent=1∶0.55∶0.5∶0.03∶0.025∶0.015.Through comparative experiments with sulfate solution erosion of commonly used cement slurry filling materials,it is shown that high density cement slurry filling materials have reliable durability performance.Finally,the hydration products and microstructure of the optimized weighted cement slurry at 3 d and 28 d were analyzed by XRD and SEM,revealing its superior impermeability and durability mechanism.The research results provide a new type of cement slurry material with high density,high strength,low permeability,and good durability for the back wall filling of deep and large shaft drilling in western China.