Study on flow capacity and percolation behavior of hydraulically induced bedding fracture by different fluids in full-diameter shale cores

Chinaʼs continental shale exhibits favorable geological characteristics and substantial resource potential, yet oil recovery for natural energy extraction remains critically low. Investigating the mechanisms of hydraulically induced bedding fracture to generate complex fracture networks in continental shale, and establishing effective flow systems, is of utmost importance. This study employs laboratory experiments and numerical simulations to investigate the flow capacity and percolation behavior of hydraulically induced bedding fractures by different fluids in full-diameter shale cores. Hydraulic stimulation using different fluids generates bedding plane fracture networks, establishing effective flow systems. Eroded and detached shale fragments support localized fractures, thereby increasing their opening and enhancing flow capacity. Cetyltrimethylammonium bromide (CTAB) solution and SiO₂ solution reduce the hydration of the shale surface, preventing shale fragments from swelling and disintegrating, leading to more stable percolation behavior. Eroded and spalled shale fragments near the injection point are transported to farther locations, where they help support localized fractures. This process differs from conventional hydraulic fracturing. Under a constant injection rate, the velocity in the smaller flow paths near the closure is significantly higher than that in the main flow paths, leading to pronounced bypass flow behavior. This restricts the percolation of fluid during imbibition in shale cores. The results provide valuable insights into the mechanism of hydraulically induced bedding fracture in continental shale, offering guidance for the effective development of shale reservoirs.