Experiment and Mechanism on Characteristics of Coalbed Methane Adsorption Affected by Water

Abstract

In order to investigate on diversities of existing condition of coalbed methane in same stratum and various moisture content states, raw coking and meager coal have been adopted and a series of experimental equipments for fixed volume adsorption have also been designed. Further dealing with analyses of adsorption velocities, capacities or mechanisms, six different moisture contents of 1# coking and 2# meager cylinder block coal samples have been chosen separately to engage in the typical experiments of coalbed methane adsorption. From the adsorptive experiments, the existing condition of coalbed methane in the real stratum has been illustrated. The results showed that: a) at the same initial gas injection pressure, the adsorption velocities are decreased with the increased of moistures. Gas pressure declines are 22 and 16 times of moisture content 0% than the saturation moistures separately. b) The simulation results of coalbed methane adsorption capacities followed by moistures are linear of 1# and nonlinear of 2# separately. c) At the different moistures, time effect characteristics of adsorption capacity is logarithmic and would not be getting to equilibrium state until undergoing 12 hours or even more. Also simulative constant values are disaffinity in different coal degrees. d) By ways of the analyses in basis of experimental results on adsorptive mechanism between gas and water, the adsorbability of coalbed methane affected by water is related to macro fractures distribution on the surface of coal samples.