基于低凝固点柴油的高密度油基钻井液体系构建及性能

Construction and Performance of High Density and Low Freezing Point Oil-based Drilling Fluid

为了解决准噶尔盆地南缘低温环境钻井液的配制困难的问题,以现场用钻井液材料及配方为基础,采用低凝固点(-38℃)的-35^(#)柴油为基油,通过调整乳化剂、提切剂、润湿剂及有机土等的加量,构建了适应低温环境的高密度油基钻井液体系,并评价了体系在低温(-10~-2℃)和高温(180℃)条件下的流变性及体系的抗污染、封堵性能。研究结果表明,该体系不仅能满足温度低至-10℃条件下的配制且能满足在复杂地层条件下(温度180℃、密度2.5 g/cm^(3))的流变性能要求,乳化性能稳定(破乳电压1000 V以上)且抗污染性能强;同时具有良好的封堵性能,模拟缝宽0.5 mm时的封堵承压为7.0 MPa。该钻井液可在准噶尔南缘低温地面环境下顺利配制且能满足地层条件下的性能要求。

To overcome the inadequacies of drilling fluid in low temperature environment in the southern margin of Junggar basin,a drilling fluid system was formulated using-35^(#) diesel oil,freezing point being of-38℃,as a continuous phase.Through regulating the dosage of emulsifier,viscosifier,wetting agent,and organophilic clay,a high-density oil-based drilling fluid suitable for low temperature environments was prepared,and the fluid performance was evaluated at both low temperature(-10-2℃)and high temperature(180℃)with respect to rheology,resistance to contaminants,and plugging performance.The results revealed that the fluid could not only meet the requirements of the preparation at the temperature as low as-10℃,but also meet satisfactorily rheological requirements under complex underground conditions that the temperature was 180℃and density was 2.5 g/cm^(3).The drilling fluid possessed stable emulsifying properties,demulsification breaking voltage being above 1000 V,and strong tolerance to contaminants.Moreover,the drilling fluid had good plugging performance,the plugging pressure was 7.0 MPa when the slit width was 0.5 mm.The drilling fluid can be successfully prepared at low temperature environmental condition in the southern margin of Junggar basin and can meet the performance requirements of the underground conditions.