页岩储层压裂物理模拟技术进展及发展趋势

Status and Tendency of Physical Simulation Technology for Hydraulic Fracturing of Shale Reservoirs

传统压裂物理模拟难以仿真深部储层高温高压、复杂地应力和工况环境,在模拟分段细分射孔工艺和实时监测裂缝扩展路径等方面存在一定挑战。系统调研了真三轴压裂物理模拟试验的试样制备、压裂井型和射孔组合、装置原理、相似准则和裂缝监测方式等,探究变排量、交替注液作用模式,穿层压裂缝高延伸机制,缝群压裂竞争扩展和暂堵转向模式;研究厘清了变排量和交替注液在提升缝网改造规模上的差异性,归纳了层状页岩储层水力裂缝缝高穿层主控因素排序,揭示了密切割多段多簇施工模式下裂缝群竞争扩展下的非平面、非对称和非均衡等扩展特征,总结了暂堵后裂缝转向扩展形态,指出“井工厂”立体压裂物理模拟、智能化和数字化为未来研究趋势。采取调整压裂时机、改变射孔参数和优化压裂液性能等措施可以有效控制裂缝扩展路径,能大幅度开启多尺度弱面,增大页岩储层压裂造缝规模。研究结果对深层和超深层页岩储层优化压裂施工参数、提升压裂改造效果具有一定的借鉴作用。

Traditional hydraulic fracturing physical simulations face challenges such as simulating high temperature and high pressure,complex in-situ stress and working conditions,staged and subdivided perforation technologies,and real-time monitoring of fracture propagation.The sample preparation,well type and perforation combinations,device principles,similarity criteria,and fracture monitoring methods in true triaxial fracturing physical simulation experiment were systematically investigated.The variable displacement,alternating fluid injection modes,vertical fracture propagation mechanisms,competitive propagation among fracture groups,and fracture turning modes after temporary plugging were explored.The differences between variable displacement and alternating fluid injection in improving the scale of fracture network stimulation were clarified,and the ranking of the main controlling factors for hydraulic fractures and vertical fracture propagation in layered shale reservoirs was summarized.The non-planar,asymmetric,and unbalanced propagation characteristics of fracture groups in competitive propagation under dense cutting and multistage/multi-cluster fracturing were revealed,and the fracture propagation pattern after temporary plugging was summarized.Three-dimensional fracturing physical simulation,intelligence,and digitization of well plants were pointed out as future research trends.Adjusting the fracturing timing,modifying perforation parameters,and optimizing fracturing fluid properties could effectively control fracture propagation,significantly open multi-scale weak surfaces,and increase stimulation scale for shale reservoirs.This overview can serve as a reference for optimizing fracturing operation parameters and improving the effectiveness of fracturing stimulation for deep and ultra-deep shale reservoirs.