页岩气高密度固井前置液实验研究及优化

Experimental study and optimization of high-density cementing pre fluid for shale gas

在页岩气固井作业中,通常会采用前置液来解决由于水泥浆与钻井液不相容引起的浆体稳定性差、地层漏失及固井质量差等问题,但是由于前置液加重剂颗粒级配不合理和清洗井壁效果不理想,会导致井内混浆多,水泥与井壁胶结质量差,进而影响前置液防漏堵漏效果和水泥石的强度。因此,室内研究了一种清洗型隔离液(C21L),对高密度加重C21L与水泥浆、泥浆之间的配伍性研究,抗高温性等性能进行了评价。实验结果显示,C21L具有良好的抗温性,在水泥浆和泥浆中加入该前置液有效改善了混浆的流动性,且清洗效果好,为页岩气高密度固井作业奠定了技术基础。

In shale gas cementing operations,pre fluid is usually used to solve problems such as poor slurry stability,formation leakage,and poor cementing quality caused by incompatibility between cement slurry and drilling fluid.However,due to the unreasonable particle size distribution of the pre fluid weighting agent and the unsatisfactory cleaning effect of the wellbore wall,it can lead to more slurry in the well,poor bonding quality between cement and the wellbore wall,which in turn affects the anti leakage and plugging effect of the pre fluid and the strength of the cement stone.Therefore,a cleaning type isolation liquid C21L was studied indoors,and high-density weighted C21L and its compatibility with cement slurry and mud,as well as its high temperature resistance,were evaluated.The experimental results show that C21L has good temperature resistance.Adding this pre liquid to cement slurry and mud effectively improves the fluidity of the mixture,and the cleaning effect is good,laying a technical foundation for high-density shale gas cementing operations.