Quantitative predicting method of coalbed methane relative high permeability region in geo-stress and geothermal field

In order to predict high permeability zone of coalbed methane quantitatively and accurately,based on prediction equation of gas pressure,coal porosity and permeability influenced by stress and temperature,quantitative prediction method of gas permeability was provided in geo-stress and geothermal field.Calculation method of permeability was established considering pore structure,stress and temperature.Corrector method of permeability was given between experiment and actual measurement.Experiments of Kaiser AE stress testing,seepage flow at different temperature and stress,BET surface testing,coal compress testing and heat expansion testing were carried out.The results show that the relationship between permeability and temperature depends on effective stress conditions.Methane permeability in coal decreases with temperature increasing at high effective stress,contrarily,increases with temperature increasing at low.Based on the theory equations and experiments,permeability distribution of Chongqing Libixia mining area in China was predicted quantitatively.Relative high permeability zone was delimited.The quantification problem of high permeability zone prediction was solved;the permeability prediction precision of coalbed methane was improved.