Distribution characteristics of permeability of depressed coal seam in Lishu Town in Jixi basin

JHCF intelligent core flow test instrument was used to carry out the test of permeability sensibility of the depressed coal seam in Lishu Town in Jixi basin under different effective stress at constant temperature and under constant effective stress at different temperature. Through the analysis and reduction of test data, the variation law of the coal seam permeability with the temperature and the efficient stress was obtained, the increase of the seam permeability with the efficient stress showed exponential decrease, while the variation of the coal seam permeability with the temperature was not evident, so the mathematical physics equations for the relationship among the permeability and ground stress field and temperature field were set up. Using the numerical simulation method, the 3D geological model of coalbed methane reservoir was constructed on the basis of the previous research on the evolution of geological structure and stress field in the depression of Lishu Town, the regional stress filed and temperature field were calculated. In combination with the mathematical physical equation for the relationship among the coal seam permeability, ground stress field and geothermal field, the distribution characteristics of the regional permeability were inverted, providing the guide for the selection of the favorable CBM zone in Jixi area.