SHI Leiting, ZHAO Qiming, REN Zhenyu, et al. Numerical simulation study on the influence of coal rock fracture morphology on seepage capacity[J]. Petroleum Reservoir Evaluation and Development, 2023, 13(4): 424-432. DOI: 10.13809/j.cnki.cn32-1825/te.2023.04.003.
The fracture network developed in coal rock serves as the primary channel for gas migration
significantly influencing the seepage capacity of coal reservoir. The geometric characteristics of fracture plays a crucial role on determining the flow characteristics of coal-bed methane. To study this
a two-dimensional fracture network model of coal rock was established using COMSOL Multiphysics simulation software
focusing on the coal samples of Baode block as the research subject. The effects of fracture length
density
opening degree and angle on production were investigated
providing valuable theoretical guidance for enhancing coal-bed methane production. The results indicate that fracture length
density
and opening degree have a positive correlation with the seepage capacity of coal rock
while the angle with the flow direction negatively impacts it. However
with the increase of length
density and opening degree
the improvement in flow rate slows down
and the effect of increasing single factor to improve coal-bed methane mining can be neglected
making it difficult to control the cost-benefit ratio. Among the factors influencing outlet
angle and density exert a more significant effect than length and opening degree. Considering the surface directional well plus the high pressure hydraulic cutting method
we can enhance the efficiency of coalbed methane development. This approach connects the natural fracture system using directional borehole and hydraulic slot
fully utilizing the permeability advantage of parallel surface cutting direction. The high-pressure hydraulic cutting process induces cracks in the coal seam
increasing the number and connectivity of diversion channels
thereby bolstering the production of coal-bed methane.