GEOLOGICAL CHARACTERISTICS OF COALBED METHANE IN Ⅱ₁ COAL IN LOWER PERMIAN SHANXI FORMATION,HENAN PROVINCE

From the aspects such as coal thickness,petrological component,coal rank,coal matrix structure,fracture system,permeabillity,adsorption/desorption features and gas content,which are the main factors having the influences on the exploration and development of coalbed gas,the detailed expound on the geological characteristics of coalbed methane in Ⅱ₁ coal,the main minable coal seam in Henan Province,is conducted.It is indicated that in both coal with original texture and fractured coal,which have higher vitrinite content,more developed cleats and moderately developed fractures,the permeability is best,is the most favorable reservoir;the anthracite with moderately developed fractures is the favorable one;the granulitic coal is the unfavorable one,and the mylonitic coal is the one could not be developed.The first selected area for exploration and development of coalbed methane is the area in where the medium ranks of coal with higher critical desorption pressure and higher gas content are distrbuted.