基于微流控方法提高致密油渗吸采出程度

致密储层成藏机理复杂、孔喉细小等特点,使得这类储层的开发极具挑战.自发渗吸是致密储层开采过程中的一个重要机理,值得重点关注.根据实际岩心的孔隙结构,利用聚二甲基硅氧烷(polydimethylsiloxane,PDMS)和玻璃薄片设计制作了模拟芯片,结合微流控泵以及高清晰显微镜,对捕捉的图片利用ImageJ软件进行数据处理,可以直接观察到渗吸过程的油水分布,并计算出渗吸采出程度.基于设计的两种孔径分布不同的芯片以及裂缝结构,研究了不同类型的表面活性剂对渗吸采出程度的影响.研究表明:平均孔喉半径越大的芯片,渗吸采出程度越高;裂缝的存在提高了渗吸效果;表面活性剂降低了流体的界面张力,减小黏附功和附加阻力,从而提高渗吸采出程度.

Research on Improving Imbibition Recovery Efficiency in Tight Oil Reservoir Based on Microfluidic Method

Due to complicated reservoir accumulation mechanisms and tiny size of pore and throat, to develop tight reservoirs is very challenging. Spontaneous imbibition is an important mechanism in developing tight oil reservoir and deserves special attention. In this study, based on pore structure of real rock, simulation chips were designed and manufactured by using PDMS materials and glass sheets. Combined with a microfluidic pump and a microscope, the fluid distribution during and after imbibition is observed and the recovery efficiency is calculated by ImageJ program for image data process. Two kinds of chips with different pore radius distribution were designed with or without fracture structure. Using designed chips, the effects of different types of surfactants on imbibition recovery factor were studied. It is found that the imbibition recovery factor is higher when the physical property of the chip sample is better. The imbibition recovery efficiency can be obviously improved when fracture exists. Surfactants reduce the interfacial tension, adhesion work and additional resistance during fluid seepage, thus promoting imbibition recovery efficiency.