Study on the gradient distribution of coal seam stress and the mechanism of hydraulic fracture damage propagation
Year: 2026
Type: article
Abstract: In-situ stress gradient distribution significantly influences the effectiveness of permeability enhancement via hydraulic fracturing in coal seams. To investigate the coupling mechanism between in-situ stress gradient distribution and dynamic hydraulic fracture propagation, a coal mine in Guizhou Province was selected as the study site, and research was conducted using physical experiments and numerical simulations. Results demonstrate that the fracturing zone in coal seams under in-situ stress gradients generally exhibits a "dumbbell-shaped" geometry. The breakdown pressure increases exponentially with vertical in-situ stress, while fracture width is inversely proportional to vertical in-situ stress. When i < 1, the pore opening displacement and fracture aperture in the coal matrix decrease with increasing vertical stress, thereby hindering forward fracture propagation. As the horizontal stress difference gradient increases from 1.0 MPa to 7.0 MPa, the breakdown pressure decreases from 21.6 MPa to 17.0 MPa (a 21.3% reduction), following an exponential function. This stress gradient amplifies fracture deflection angles, favoring the formation of simple, regular bi-wing planar fractures with negligible impact on fracture width. When fractures propagate toward regions with lower horizontal stress difference coefficients, both the effective fluid velocity in pores and the stress driving fracture propagation increase. In-situ stress gradient distribution affects hydraulic fracture geometry and complexity, thereby influencing water-methane contact, methane displacement efficiency, and water retention capacity. These findings elucidate the influence mechanism of in-situ stress gradient characteristics on hydraulic fracture propagation and provide a theoretical foundation for efficient coalbed methane extraction.
Source: Results in Engineering
Authors: Dongbin Huang, Xiangtao Kang, Zuhao XU, Ping Cao
Institution: Guizhou University
Language: English
Subfield: Mechanical Engineering
Field: Engineering
Domain: Physical Sciences
Open Access status: gold
Estimated APC paid: $1,940
Award: G7738862240
OpenAlex ID: W7127050065