Abstract: In order to study the effects of moisture content on adsorption capability of high rank coal reservoir, we conducted experimental investigations on eight representative coal samples collected from the YangquanShouyang block. Vitrinite reflectance, maceral composition and porosity measurements, combined with mercury injection, nuclear magnetic resonance (NMR) and methane isothermal adsorption experiments, were carried out to investigate pore size distribution, NMR T2 spectrum response, NMR porosity and adsorption capability of coal reservoir. Moisture contents in the water saturated coal samples were quantitatively characterized, and their impacts on methane adsorption capability were studied. The results showed that micropores dominate the pore structure in high rank coal; the bound water is the main source of moisture in micropores; and the bound water content shows a positive correlation with Ro,m. Moreover, among the factors affecting methane adsorption capacity, moisture content, especially bound water in micropores, plays a key role as higher bound water content corresponds to poorer methane adsorption capability.

Key words: YangquanShouyang block, moisture content, adsorption capacity, nuclear magnetic resonance, bound water