Advances and Challenges of Integration of Fracturing and Enhanced Oil Recovery in Shale Oil Reservoirs

During the process of fracturing development of shale oil reservoirs, fracturing fluids containing various additives are injected into the reservoir at an injection rate that far exceeds the absorption capacity of the formation, basically completing the mission of one-time injection of fracturing media to benefit the entire life of oil well development. Specifically, two issues are particularly critical: 1) How to create a uniformly distributed fracture network, enhance the contact area between fractures and reservoirs, and improve the fluid flow efficiency? 2) On the basis of forming a fracture network for efficient pressure and mass transfer, how can stored fracturing fluid improve the mobility of crude oil in the reservoir? The integration of fracturing and enhanced oil recovery (EOR) is an important way to solve these problems. Therefore, the connotation of shale oil reservoir fracturing and EOR integration technology was described, and the simulation and experimental techniques for achieving fracturing and EOR integration were summarized; the scientific issue of the fracturing and EOR integration of shale oil reservoir was clarified: balanced stress fracturing forms a uniformly distributed fracture network, improves the efficiency of fluid flow and transmission in the uniformly distributed fracture network, and strengthens the utilization of oil and gas in matrix pores. In addition, the challenges facing the fracturing and EOR integration were pointed out, including clarifying the mechanism of interwell interference caused by non-uniform fracture propagation and establishing control methods, forming the way of high-pressure fluid acting on matrix pores in fracture, and revealing the mechanism of fracturing fluid-reservoir-crude oil interaction to improve the mobility of crude oil. The results show that the formation of a uniformly distributed fracture network is the foundation for controlling fracture-matrix pressure and mass transfer, as well as fluid flow. Utilizing crude oil stored in micro and nano pores by strengthening the interaction among fracturing fluid, reservoir, and crude oil is the core. The application of fracturing and EOR integration in shale oil reservoir development is an effective way to achieve economic maximization. It is of great significance for the efficient development of shale oil reservoirs to implement the idea of fracturing and EOR integration.