The discussion on the relationship between macerals and the resource evaluation of coalbed methane

In the course of coalification, large quantities of thermogenic methane accompany the maturation process of coal. There are large internal surface areas of coal which provide an extensive surface for adsorption. Researchers have identified rank, pressure, hydraulic gradients and amount of mineral matter as important parameters for assessing a particular coalbed as methane resource. The authors study the synergism between coal sorptive properties and the macerals sorptive properties, by means of low-temperature nitrogen adsorption to the vitrain-rich sample, the fusain-rich sample and the samples with varying composition, (R{sub o max}=1.052%--1.066%). Moreover, the relationship between the coal and the macerals is analyzed overall. It shows that, the coal sorptive properties don`t decrease significantly with the increasing mineral content, but the mineral content probably influences the permeability of coal. The relationship between the vitrinite sorptive properties and that of inertinite is related to the rank and the maceral composition. The vitrinite sorptive property is higher than that of inertinite in the low-rank bituminous coal stage, but it reverses in the high-rank bituminous coal and anthracite stages. It is closely related to the maceral composition and the characteristics of macerals in the medium-rank bituminous coal stages. There is no the synergism between themore » sorptive properties of vitrinite and that of inertinite.« less