加重剂对水基钻井液润滑性能影响的实验研究

通过粒度分布、扫描电镜、ZETA电位分析，考察了重晶石、活化重晶石、活化铁矿粉3种加重剂及其复配对钻井液加重到不同密度时对滤饼黏滞系数的影响。实验结果表明:高密度条件下，3种加重剂均有改善钻井液润滑性的作用，活化铁矿粉、活化重晶石、重晶石加重钻井液改善润滑性的临界密度分别为1.2、1.4和1.6 g/cm3；超过此密度的一定范围内，钻井液的润滑性均增强。复配加重比单独加重的润滑性效果更好。

Experimental study on the influence of weighting additives on lubricity of water-based drilling fluids

Through the analysis of the particle size distribution, scanning electron microscope, ZETA potential, the friction coefficients of mud cakes are investigated when water-based drilling fluids are added to different densities by three weighting additives of barite, activation barite, activation iron ore powder and their complex combination. The experimental results show that under high density, all the three weighting additives can enhance the lubricity of the drilling fluids. To improve the lubricity of water-based drilling fluids, the critical densities of drilling fluids added by barite, activation barite and activation iron ore powder are 1.6 g/cm3, 1.4 g/cm3 and 1.2 g/cm3, respectively. The lubricity of the drilling fluids will be improved in a certain range beyond the critical density. Complex combination is better than the every single additive.