Analysis on major factors affected to adsorption time of high rank coal in Qinshui Basin

In order to reach a target to well evaluate the development potential of the coal reservoir, a study was conducted on the seam adsorption time directly rel ated to the fluid movability of the coal reservoir.With the measurements conducted on the coal and rock of No.3seam and No.5 seam in Shouyang Block and Shouyang Block of Qinshui Basin, the paper analyzed the features of the high rank coal adsorption time and discussed the max reflectivity (Rmax) of the vitrinite, coal quality, gas composition and other factors affected to the adsorption time.The study showed that the coal rank (based on the Rmaxas the basis) would be the major factor affected t 0 the adsorption time of the seam, the vitrinite/inertinite ratio and the gas composition φ (CO2) /φ (CH4) and φ (CH4) Iφ (N2) would be the secondary factors and the mo nomaceral (vitrinite and inertinite) and ash content would be less affected to the adsorption time.In the case of the high rank coal, when the Rmaxwas less than 2.9%, t he adsorption time would be increased with the Rmaxincreased.When the Rmaxwas higher than 2.9%, the adsorption time would be decreased with the Rmaxincreased and the adsorption capacity decreased of the coal and rock were caused mainly due to the coal and rock evolution degree increased, the equilibrium moisture content 0 f the coal and rock and the comprehensive role of the specific surface area caused the reductions of the coal and rock porosity, micro pore structure and the specific su rface area.In addition, affected by the adsorption capacity differences of each maceral, the adsorption feature differences of each type gas, the gas concentration differ ence in the seam and other factors.The vitrinite/inertinite, φ (CO2) /φ (CH4) and φ (CH4) /φ (N2) would all have the negative envelope relationship with the adsorption ti me.