Study On Coal-bed Gas Seepage Through Thermal Exploiting

The reserve of coal-bed gas in our country is one of the highest in the world. The exploration of coal-bed gas not only can alleviate the shortage of energy effectively, but also can protect the environment and prevent the gas disaster. The characteristic, high reserve and low permeability restrict the development of coal-bed gas industry. The difficulty is how to increase the production of coal-bed gas in low permeability coal seam. Thermal exploitation of coal-bed gas is recognized as the most actual method in academic field, but the yield-increasing mechanism is not clear. Based on the theory of heat transfer, thermodynamics, rock mechanics, elastic mechanics, seepage mechanics, through the method of experiment indoor, the change rule of deposit and flow of coal-bed gas is studied. The change of the temperature field in coal can be simulated by COMSOL, and it proves the yield increasing effect by thermal exploiting. The conclusion is given by experimental study:At the condition of the same temperature and the same axial and confining pressure, with the increase of pore pressure, the permeability of coal sample decreases first and then increases; at the condition of the same temperature and the same pore pressure, with the increase of axial and confining pressure, the permeability of coal sample decreases; at the condition of the same axial and confining pressure and pore pressure, the permeability of coal sample decreases with the increasing temperature. At the condition of the same temperature and the same axial and confining pressure, with the increase of pore pressure, the seepage of coal sample increases exponentially; at the condition of the same temperature and same pore pressure, with the increase of axial and confining pressure, the seepage of coal sample increase. The conclusion is given by numerical simulation:The higher the temperature, the faster the change in pressure. At the condition of the same temperature, the transmission speed slows down with the increasing pressure. The law of temperature on the permeability and desorption of coal-bed gas is studied based on experiment and numerical simulation. We can conclude that:The seepage of coal-bed gas significantly increased with the increasing temperature. The experimental results show that the thermal exploitation of low permeability coal-bed gas is helpful for the production of coal-bed gas.