The invention discloses a method for determining gas contents of
coal beds, and belongs to the field of
coal bed gas exploration and development. The method includes forming theoretical values of
Langmuir volumes corresponding to different
coal rank conditions on the basis of
Langmuir isothermal adsorption theoretical model derivation; applying corresponding conventional
well logging data on the basis of the theoretical values, combining the
well logging data with coal and rock
test analysis and isothermal adsorption experiment data and quantitatively computing and determining the gas contents of the coal beds. The method has the advantages that
Langmuir isothermal adsorption models are improved, relations between the maximum
vitrinite reflectance and the Langmuir volumes are analyzed, a process for solving the maximum
vitrinite reflectance by the aid of conventional
well logging curves is created, and accordingly the gas contents of the coal beds can be determined; the method is continuous in evaluation and
cognition, good
verification effects can be realized, shortcomings of difficulty in experimental sampling and excessively high cost due to the fact that gas contents are measured by the aid of existing experimental technologies at present can be effectively overcome, and reliable reservoir parameters can be provided for developing coal
bed gas in various basins in China.