Simulation of dual-porosity medium seepage flow in fractured zone

This paper focuses on studying the coalbed water flow and dual-porosity medium permeability before the inter-well interference.Coalbed water flow in dual-porosity medium formed by fracturing coal seams is simulated using COMSOL multi-physics software.The results show that the fissure water pressure in fissure zone is significantly lower than the pore water pressure in the coal after a period of draining.The pressure at the fracture is the lowest and increases gradually toward both sides on any tangential plane. Along the direction of fracture, the pressure at the end of the fracture is the highest while the pressure is the lowest at the wellbore.When draining,coalbed water of fracture firstly enters the wellbore with rapid decrease of head. Due to differential pressure,the coalbed water flows into the fracture continuously, then flows into the wellbore.According to the measuring datas of flow velocity head, the permeability of the dual-porosity medium is 0.013 5 m/s in the x-direction and 8×10-8 m/s in the y-direction.The researeach results can provide the reference for the analysis of the influence of CBM exploitation on the hydrodynamic and storage conditions of ground water.