The Mathematical Models Of Coupled Thermal-hydrological-mechanical And Numerical Simulation Of Coal Bed Methane With Heat Inject

Over along period of time, the exploration and development of CBM were mostly focused on the high rank of coal. However, the exploration and develpomnet of low rank coal and the corresponding reseaerh still were the blank in our eounty.In order to obtain seepage rules and production of coal-bed methane in the process of heat injection exploitation, a coupled thermal-fluid-solid mathematical models of coal-bed mathane was established based on the expermental results that permeability, porosity of coal increases with temperature, stress and thermal conductivity, coefficient of gas, Young’s modulus, Poisson’s ratio as a function of the temperature, combined with seepage mechanics,rock mechanics,heat transfer and so on. Multi-well exploitation way was used to simulate seepage rules during extracting methane in low-permeability coal bed by heat injection after three fields were discreted.The numerical simulation results show that after10d heat injection and100d extracting, the average velocity of heat transfer is66.25mm/h in coal bed under the action of conductivity of coal bed and convection of coal-bed methane, and pressure drop of reservoir cauesd by heat injection is2.45times without heat injection, and production of coal-bed methane under the conditons of heat injection is2.2time without heat injection. It is a effective way for production improvement of low permeability coal-bed methane.Summary the adsorption-desoprtion isotherm experiment, the heat injection exploitation of coal bed methane engineering research, the thermal economic analysis The research indieated that:(1) low-rank coal desorption quantity as the temperature increased, but when the temperature exceeds100degrees after the desorption temperature increased slowly;(2)when the temperature is lower than the critical desorption temperature, temperature increase will not make desorption quantity changes (3) heat injection exploitation of the maximum heat efficiency for60%, the energy efficiency up to a maximum of9.2.