蓄能缝网压裂开发中表面活性剂作用研究

Study on the surfactant in the development of energy storage net fracturing

水平井蓄能体积压裂结合焖井渗吸是提高非常规油藏油井产量的主要方式。通过渗吸动力解析计算和多介质油藏温度常压静态可视平行渗吸实验定量比较渗吸液驱油效率,认识到表面活性剂在非常规油藏开发和渗吸置换中的作用是双向的:正向作用是改善储层表面润湿性、降低残余油饱和度,但是作用深度和程度十分有限。表面活性剂降低界面张力大幅度减小渗吸动力,常态下难以进入微纳米孔缝,进而难以改变非常规油藏细粒沉积岩作为原油主要赋存空间的微纳米岩石的润湿性。表面活性剂在非常规油藏开发中的负向作用是降低油水界面张力、减小毛细管力、减小渗吸动力,大幅度降低了油水渗吸置换效率,而且表面活性剂浓度越高,渗吸排油效率越低。为发挥表面活性剂在非常规油藏中的作用,需要以纳米粒子等为载体,以改善润湿性为主要目的。该成果认识对于致密油、页岩油开发中注入介质和方式的选择具有借鉴作用。

Horizontal well energy storage volume fracturing combined with soak imbibition is the main way to improve the production of unconventional reservoir.Quantitative comparison of oil displacement efficiency of imbibition fluid through analytical calculation of imbibition dynamics and static visual imbibition experiment of multi-media reservoir at normal temperature and pressure,recognizing that surfactant play a two-way role in unconventional reservoir development and imbibition displacement.The positive role is to improve surface wettability and reduce residual oil saturation,but the effect is limited in depth and extent.The surfactant reduces the interfacial tension and greatly reduces the imbibition force,therefore,it is difficult to change the wettability of fine-grained sedimentary rocks in unconventional reservoirs as micro-and nano-rocks in which crude oil is mainly distributed.The negative effect of surfactant on the development of unconventional reservoirs is to reduce the oil-water interface tension,reduce the capillary force,reduce the imbibition power,and greatly reduce the imbibition and displacement efficiency of oil-water,and the higher the concentration of surfactant,the lower the efficiency of oil absorption and drainage.In order to play the role of surfactant in unconventional reservoirs,it is necessary to use nanoparticles as carriers to improve wettability and maintain a certain interfacial tension.The results can be used as a reference for the selection of injection media and methods in the development of tight oil and shale oil.