油基钻井液润湿剂评价

对于油基钻井液，加重剂颗粒的表面多数为亲水性，如何使其在油包水乳状液中均匀分散不沉降将直接影响钻井液的静态密度；同时，地层中的亲水粘土颗粒侵入油基钻井液时会趋向于与水结合发生颗粒聚集，从而影响钻井液的流变性。为解决以上问题，针对亲水性重晶石、粘土在油基钻井液中聚集导致钻井液稳定性变差的现象进行了分析，并开展了防止聚集的润湿性添加剂选择评价方法的实验研究。研究表明，重晶石粉末在不同润湿剂的油溶液中最终的沉降稳定体积不同。该体积的大小受限于沉降体内毛细孔道的润湿性质，润湿性越强，束缚在重晶石沉降体积中的液相就会越少，使得重晶石的沉降稳定体积就小；反之，重晶石的沉降稳定体积就越大。据此现象归纳出评价润湿剂的一种简单易行的实验研究方法。

Evaluation the Wettability of the Wetting Agent Using in Oil-baseDrilling Fluid

The surface of weighting agent in oil base drilling fluid is often hydrophilic. It disperse in a water-in-oil emulsion，will directly influence the drilling fluid static density. At the same time，the hydrophilic clay particles in the formation tend tocombine with water particles aggregation when penetrating the oil base drilling fluid will. Thereby it will have an effect on therheological properties of drilling fluids. To solve the above problem，we also study the evaluation method of selecting wettingagents that prevent the aggregation. It can be known by analysis that the barite’s sagging volumes are different in several oilphases with different wetting agents. The wettability of large numbers of narrow passages forming inside of barite powderduring sagging will affect the barite’s sagging volumes. If the wetting agents wettability is stronger，the barites sagging volumewill be less because less oil phase is bounded inside barite powder. On the contrary，the barite’s sagging volume will be more.So the barites sagging can evaluate the wetting agent’s wettability，which is handy and convenient for appraising the wettingagent.