针对纹层型页岩油储层纵向非均质性强,水力裂缝起裂与扩展机理不明的问题,采用离散元裂缝模拟和水力压裂物模实验相结合的方法,研究了垂向地应力差、压裂液黏度、泵注流程以及射孔簇间距等因素对纹层型陆相页岩油储层裂缝扩展形态的影响规律。结果表明:层间弱结构面的脱黏滑移是造成纹层型页岩油储层缝高纵向扩展停滞的重要原因,垂向主应力差越小,层理面越易被激活,缝高增长受到抑制;采用高黏度和低黏度压裂液交替泵注有利于实现水力裂缝的纵横向均衡扩展,实现储层的三维立体开发;减小射孔簇间距、增加射孔簇数可显著提高水力裂缝面积,增大油藏泄流面积。该研究结果对于实现纹层型页岩油储层纵向上的深穿透改造,提高单井产量具有重要的指导意义。
In response to the problem of high longitudinal non-homogeneity and unclear mechanism of hydraulic fracture initiation and propagation in grain-type shale oil reservoirs, the combination of discrete element fracture simulation and hydraulic fracturing physical modeling experiments was used to study the influence of factors such as vertical geostress difference, viscosity of fracturing fluid, pumping process, and perforation cluster spacing on the fracture propagation pattern of grain-type terrestrial shale oil reservoirs. The results show that: The de-viscosity and slip of weak structural surfaces between layers is an important reason for the stagnation of longitudinal propagation of fracture height in grain-type shale oil reservoirs, and the smaller the vertical principal stress difference is, the easier the laminar surfaces are activated, and the growth of fracture height is suppressed; the use of alternating pumping of high-viscosity and low-viscosity fracturing fluids is conducive to the realization of balanced longitudinal and transversal propagation of hydraulic fractures, and the realization of 3D development of reservoirs; the reduction of the perforation cluster spacing and the increase in the number of perforation clusters can significantly increase the area of hydraulic fractures and the reservoir drainage area. The study results are of great significance for realizing the deep penetration stimulation of grain-type shale oil reservoirs in the longitudinal direction and increasing the production of a single well.
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