一种低密度钻井液体系研究

Study on a Low DensityDrilling Fluid System

为了防止钻井液漏失以及保护油气藏,以丙烯腈(AN)、甲基丙烯酸甲酯(MMA)、苯乙烯(St)为原料制备一种高性能可膨胀聚合物微球,并作为减轻剂应用于水基钻井液中。实验表明:室内制备的可膨胀聚合物微球具有良好的抗压性能,其外观上未出现聚合物碎屑,直径较为集中,其粒径在30~40μm。通过优选增黏剂、降滤失剂和润湿分散剂形成一套低密度钻井液体系,使可膨胀聚合物微球稳定地分散在钻井液中,该体系长时间静置后或热滚后仍具有良好的流变性且滤失量低,避免低密度钻井液井底当量循环密度(ECD值)增大,有效控制钻井过程中井漏的发生,有利于储层保护。

In order to prevent drilling fluid leakage and protect oil and gas reservoirs,a high-performance expandable polymer microsphere was prepared with acrylonitrile(AN),methyl methacrylate(MMA)and styrene(St)as raw materials,and used as a reducer in water-based drilling fluid.The results showed that the expandable polymer microspheres prepared in the laboratory hadgood compressive properties,there was no polymer debris on the appearance,the diameter was relatively concentrated,and the particle sizes were 30~40μm.A set of low-density drilling fluid system was formed by optimizing viscosifier,fluid loss reducer and wetting dispersant,so that the expellable polymer microsphere was stably dispersed in the drilling fluid.The system still had good rheological properties and low filtration loss after long standing or hot rolling,so as to avoid the increase of equivalent circulating density(ECD)of low-density drilling fluid and effectively control the occurrence of leakage during drilling,which was beneficial to reservoir protection.