Study on Pore Features of Coal Reservoir in Multi Superimposed Independent Gas-Bearing System

Based on analysis on the coal sample from Bide-Santang Basin in the West of Guizhou and the results of scanning electron microscopy experiments and the pressured mercury experiment, the pore features of the coal reservoir in the multiple superimposed independent gas-bearing system were studied.The study showe d that the pore of coal reservoir in the Bide-Santang Basin was developed and the porosity was relative high.The connection of the pore mainly with the small pore and micro pore was good.There was an obvious related relationship between the seam pore rate and the coal metamorphic degree in the study zone.With the coal rank incr eased, the porosity would be firstly increased and then reduced in tendency and would reach the max value when the transmission rate of the max vitrinite was about 3. 00%.In the multi superimposed independent gas-bearing system, in the Shuigonghe syncline and Santang syncline, with the seam depth increased, the pore diameter in each seam would be firstly increased and then reduced, No.16 seam was the variation node and the connection of the pore would be firstly poor and then good.In Zhuz ang syncline, there was less variation in the pore diameter size and pore connection of each seam.Due to some quartz and clay mineral backfilled in the coal samples fr om No. 16 seam, the total pore volume was reduced.