Damage evolution of coal reservoirs under cyclic disturbances and optimization suggestions for deep reservoir stimulation

作者：Shida CHEN, Yifan Pu, Zhao Longmei, Xiang Li, Li Huang, Dazhen TANG, Y X Zhang, Song LI, Shu TAO · 发表于：DOAJ (DOAJ: Directory of Open Access Journals) · 年份：2026 · DOI：10.12363/issn.1001-1986.25.10.0750 · 研究领域：Rock Mechanics and Modeling、Coal Properties and Utilization、Hydraulic Fracturing and Reservoir Analysis

Objectives and Methods During volume fracturing or multi-round hydraulic fracturing of deep coal reservoirs, pressure fluctuations induced by the propagation of fracture tips and fluid accumulation within fractures cause cyclic perturbations to surrounding rocks. To clarify both the mechanical responses of coals and the mechanisms behind fracture evolution within coal reservoirs under such cyclic perturbations, this study conducted triaxial cyclic loading-unloading tests on high-rank coals under varying confining pressures, stress amplitudes, and loading modes. In combination with field engineering data, this study proposed strategies for optimizing deep coal reservoir stimulation. Results and ConclusionsThe stress-strain curves of coals under cyclic loading and unloading exhibit pronounced hysteresis loops. Residual stress primarily accumulates during initial loading-unloading cycles, with the stress magnitude controlled by confining pressure, loading mode, and the damage/failure mode. The cyclic process promotes the compaction of coal matrix, as well as the closure of pores and fractures. Consequently, the load-bearing structure of coal reservoirs evolves from a heterogeneous framework providing weak support into a homogeneous skeleton with a high bearing capacity. Accordingly, the elastic modulus generally increases first and then stabilizes with increasing number of cycles. Under the condition of low confining pressure in shallow parts, weak structural constraint and sign...