Numerical simulation of interface dip angle on hydraulic fracture propagation path in composite coal rock

Dongjie  Jiang; Fan  Zhang; Rui  Guo; Junjie  Guo; Ji  He; Wei  Han; Yongming  Song; Zidong  Zhao

doi:10.6180/jase.202607_30.032

Numerical simulation of interface dip angle on hydraulic fracture propagation path in composite coal rock

$Numerical simulation of interface dip angle on hydraulic fracture propagation path in composite coal rock$

Dongjie Jiang¹, Fan Zhang¹This email address is being protected from spambots. You need JavaScript enabled to view it., Rui Guo², Junjie Guo¹, Ji He², Wei Han², Yongming Song², and Zidong Zhao¹

¹School of Resources and Safety Engineering, Henan University of Engineering, Zhengzhou 451191, China

²Inner Mongolia Montay Unlian Coal Industry Co., Ltd., Ordos, Inner Mongolia 010303, China

Received: October 2, 2025
Accepted: December 1, 2025
Publication Date: January 19, 2026

Copyright The Author(s). This is an open access article distributed under the terms of the Creative Commons Attribution License (CC BY 4.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are cited.

Download Citation: ||https://doi.org/10.6180/jase.202607_30.032

For deep coalbed methane (CBM) exploitation, it is very important to control hydraulic fractures in coal seam to avoid the decrease of fracturing energy caused by crossing coal-rock interface. To reveal the influence of interface dip angle on hydraulic fracture layer-crossing propagation, the test methods and engineering significance of physical parameters of coal-rock interface were analyzed. Numerical model of “roof-coal seam-floor” was established by RFPA2D-Flow numerical simulation software, hydraulic fracture propagation path and geometrical shape under different interface dip angles were studied. The results show that coal-rock interface involves geometric parameters, mechanical parameters, geological parameters, etc. Their acquisition methods and engineering significance are described. The coal-rock interface parameters and in-situ stress jointly affect hydraulic fracture. As hydraulic fracture passes through coal-rock interface, the proportion of rupture surface increases obviously, which can reflect the relationship of propagating energy, pumping pressure and fractured stage. When interface dip angles are different, hydraulic fractures propagate along coal-rock interface to varying degrees. The smaller interface dip angle makes hydraulic fracture more easily to propagate along coal-rock interface. With the increase of interface dip angle, the breakdown pressure increases, it is more difficult to control whole hydraulic fracture in coal seam. Therefore, directional perforations can be applied to control the initiation direction of hydraulic fracture, so as to avoid hydraulic fracture encountering coal-rock interface in advance and affecting fracturing effect. The research results can provide a basis for improving deep coalbed methane exploitation theory and optimizing field fracturing parameters.

Keywords: Deepcoalbed methane; Coal-rock interface; Interface dip angle; Breakdown pressure; Numerical simulation

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