加重剂对水基钻井液润滑性能的影响研究

为了定量研究加重剂影响水基钻井液润滑性能的一般规律，采用激光粒度仪测定了重晶石、钛铁矿、保护储层加重剂的粒度分布，考察了3种加重剂将水基钻井液加重到相同密度以及加重到不同密度时滤饼的摩擦系数。研究表明：高密度条件下，3种加重剂均有改善钻井液润滑性能的作用，保护储层加重剂的润滑效果最好；水基钻井液润滑性改善时，重晶石、钛铁矿、保护储层加重剂加重钻井液的临界加重密度分别为1.4、1.6和1.6 g/cm³；钻井液未加润滑剂时，超过此临界密度的一定范围内，钻井液体系的润滑性能均增强。

Study on Influence of Heavyweight Additives on Lubricity of Water-based Drilling Fluids

In order to study the general law of the influence of heavyweight additives on lubricity of water-based drilling fluids quantitatively, the laser granularity instrument is used to measure the particle size distributions of barite, ilmenite and heavyweight additives to protect reservoirs, and the friction coefficients of mud cakes are investigated when water-based drilling fluids are added to same density and different density by the 3 heavyweight additives. The study results show under the conditions of high density, all the 3 heavyweight additives can enhance the lubricity of the drilling fluids. The heavyweight additive to protect reservoirs has the best result. When the lubricity of water-based drilling fluids is improved, the critical densities of drilling fluids added by barite, ilmenite and heavyweight additives to protect reservoirs are 1.4 g/cm3, 1.6 g/cm3, and 1.6 g/cm3 respectively. When no lubricants are added to drilling fluids, the lubricity of the drilling fluids will be improved in a certain range beyond the critical densities.