养护环境对漂珠微硅类低密度水泥石抗压强度的影响

Effect of curing environment on compressive strength of low density set cement mixed with floating potential and microsilica

应用漂珠微硅类低密度水泥体系固井是解决低压易漏层段和长封固段固井作业难题的主要手段,但是对其高温高压强度发展规律尚缺乏系统的理论分析和实验评价。在分析颗粒级配原理、利用激光粒度测试仪及配伍性实验方法优化低密度水泥体系配方的基础上,利用抗压强度实验方法研究了不同养护环境对漂珠微硅类低密度水泥石试件强度的影响规律,并与嘉华G级水泥基浆水泥石高温强度进行了对比。最后从化学成分、颗粒级配及搅拌方法等角度对实验结果进行了原因探析。结果表明:养护环境对低密度体系抗压强度的影响规律明显不同于基浆,漂珠微硅类水泥体系具有一定的抗高温强度衰退特性,良好的紧密堆积效应使养护压力对体系强度影响程度较小。

Application of floating potential and microsilica typed low -density cement system is one of the major solutions for cementing low - pressure lost circulation sections and long well intervals. Its strength development under high temperature and high pressure, however, has not been well systematically analyzed and experimentally evaluated. Based on the analysis of particle size distribution and the optimization of low density cement system formulation using laser grain size test and related compatibility experiments, the effect of different curing environment on the strength of cement samples is analyzed by conducting the compressive strength test. Meanwhile, experimental results are compared with the high - temperature strength of base slurry of Jiahua class - G cement. Finally, experimental results are discussed from the perspectives of chemical composition, particle size distribution and agitation method. Results show that the effect of curing environment on the compressive strength of low density system is apparently different with that of base slurry. The cement system with floating potential and microsilica has favorable durothermic properties to inhibit the decline of high - temperature strength. The close packing effect allows less influence of curing pressure on the compressive strength of set cement.