Analysis on Physical Property Features of Different Coal Rank Coal Reservoirs in Western Guizhou and Eastern Yunnan Area

In order to analyze the control role of the coal rank to the physical properties of coal reservoir, taking the samples from western Guizhou and eastern Yu nnan area as examples, many different experiment methods were applied to discuss the pore and crack structure, adsorption and desorption capacity and pore permea bility features of the different coal rank coal samples.The results showed that when the reflection rate of vitrinite was less than 2.5%, with the coal rank improved, the C ompaction degree of the coal and rock would be continuously increased, the gas content of the adsorption pores in seam would be steadily increased, the BET specific surface area and BJH total pore volume would be steadily increased.Thus the adsorption capacity of the coal and rock would be steadily enhanced, the content of the s eepage pores would be relatively reduced, the crack structure of the seepage pore would be getting poor, the seepage capacity of the coal and rock would be reduced a nd the permeability would be reduced with the coal rank increased.When the reflection rate of vitrinite was higher than 2.5%, with the coal rank improved, the gas conte nt of the adsorption pores in seam would be reduced, the BET specific surface area and BJH total pore volume would be in a reducing tendency and the adsorption cap acity would be reduced.However, regenerated cracks occurred in the late evolution process of the coal and rock would make the content of the seepage pores in the Co al and rock increased, the structure would be better, the total cracks of the pore would be increased and the seepage capacity would be improved.