Exploring the mechanism of cohesive cross-layer fracture in laminated shale

作者：Lei Chen, Haibo Wang, Guangqing Zhang, Fengxia Li, Tong Zhou, Jia Cui, Wei Sun · 发表于：Journal of Rock Mechanics and Geotechnical Engineering · 年份：2025 · DOI：10.1016/j.jrmge.2025.03.048 · 被引用次数：6 · 研究领域：Rock Mechanics and Modeling、Drilling and Well Engineering、Seismic Imaging and Inversion Techniques

The development of geological lamination in shale reservoirs influences fracture propagation during hydraulic stimulation, and the fracture generation mechanism as it propagates through the laminated interface is closely related to fracturing effects. In this paper, the laminated shale was selected to conduct three-point bending experiments using digital image correlation (DIC) and acoustic emission (AE) techniques, which revealed that the propagation path of cross-layer fractures exhibits dislocation features. The cohesive fracture mechanism of cross-layer fractures is investigated from the viewpoint of the fracture process zone (FPZ), which displays the characteristics of intermittence and dislocation during fracture development. A computational criterion for predicting the dislocation of cross-layer fracture at the interface is proposed, which shows that the maximum dislocation range does not exceed 72% of the FPZ length. Considering the mechanical differences between adjacent layers of laminated shale, the cohesive zone model of cross-layer fracture is discussed, from which the constitutive relationship and fracture energy during FPZ development are characterized, and the discontinuous nature of the constitutive relationship is found. This study improves the understanding of the geometry and cohesive fracture mechanism of the cross-layer fracture and provides valuable insights for field fracturing in shale reservoirs.