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

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.