Research On The Mechanism Of Heat Injection And Drainage Of Low Permeability Coal Seam Gas(CBM)

Gas,also known as coal-bed methane,is both a clean energy source and a source of major disasters in underground coal mines.Reasonable gas drainage is of great significance for alleviating my country’s energy dilemma and reducing coal mine accidents.my country has abundant reserves of coalbed methane resources,but the coalfields have many geological types,complex structures,and generally poor coal seam permeability.Therefore,high-efficiency mining of low-permeability coalbed methane will be the focus and difficulty of research.Based on the existing theoretical analysis and combined with experimental data,this paper studies the relationship between temperature and desorption capacity and permeability,the relationship between coal sample fracture development and desorption capacity,and the relationship between desorption capacity and temperature in the coal seam heat injection-driven gas desorption experiment.The relationship and the relationship between desorption amount and gas pressure,using COMSOL Multiphysics numerical simulation software,carried out the rules of the influence of coal seam heat injection on coal seam gas pressure and permeability.The main results of the research are as follows:(1)The effect of temperature on the desorption capacity of raw coal samples is more obvious.The higher the temperature,the greater the desorption capacity,but as the desorption time increases,the increase in desorption capacity becomes slower.The permeability of raw coal samples generally decreases with the increase of temperature.(2)The effect of temperature on the desorption capacity of raw coal samples is more obvious.The higher the temperature,the greater the desorption capacity,but as the desorption time increases,the increase in desorption capacity becomes slower.The permeability of raw coal samples generally decreases with the increase of temperature.(3)During the coal seam heat injection,the temperature between the coal seams appears to gradually decrease with the increase of the distance from the heat injection borehole.The longer the heat injection time,the slower the temperature drop between the coal seams,but the range of temperature influence will be Increase.The higher the heat injection temperature,the greater the range of influence in the coal seam,and the easier the gas desorption and seepage.(4)The coal seam heat injection temperature must be within a certain range.The higher the heat injection temperature,the easier the gas is desorbed from the coal body,the pores and cracks in the coal seam increase,and the coal seam permeability increases.(5)Compared with cross-bed borehole heat injection drainage,the temperature has a larger range of influence on the coal seam,the heat injection effect is better,and the drainage efficiency is higher.