页岩油储层压裂–提采一体化研究进展与面临的挑战

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

  • 摘要: 页岩油储层压裂开发中,以远超地层吸收能力的注入速率向储层注入包含各类添加剂的工作液,基本完成了压裂介质一次注入、油井开发全生命周期受益的使命。其中,2个问题尤为关键:1)如何形成均匀展布的裂缝网络,增大裂缝和储层的接触面积、提高液体流动效率?2)在形成高效传压传质缝网的基础上,存地压裂液如何提高储层中原油的可动性?压裂和提采一体化是解决上述问题的重要思路。为此,阐述了页岩油储层压裂–提采一体化的内涵,归纳了实现压裂–提采一体化的模拟和试验技术;明确了页岩油储层压裂–提采一体化的科学问题:均衡应力压裂形成均匀展布的缝网,提高均布缝网中流体流动与传输的效率,强化基质孔隙中油气的动用。同时,指出了压裂–提采一体化面临的挑战:明确裂缝非均匀扩展导致的压裂井间干扰机理并建立控制方法,形成裂缝中高压流体高效作用于基质孔隙的途径,揭示压裂液–储层–原油相互作用提高原油可动性机理。研究结果表明:形成均布的裂缝网络是控制裂缝–基质传压传质及流体流动的基础,通过强化压裂液–储层–原油之间的相互作用动用赋存于微–纳米孔隙中的原油是核心,将压裂–提采一体化应用于页岩油储层开发是实现经济最大化的有效途径。贯彻和落实压裂–提采一体化的理念,对页岩油储层的高效开发具有重要意义。

     

    Abstract: 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.

     

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