Coal structure and gas controlling effect of seam No.3 in Anze block of Qinshui basin

Anze block of Qinshui basin has experienced several tectonic events since coal-forming period, resulting in the destruction of coal structure at different degrees, the exploitation of coal bed methane(CBM) in Anze block of QinShui basin has been restricted by the undefined distribution of the coal structure. Based on the above-mentioned fact, coal-bed structure of 3# seam in single well is classified into three coal structure types, namelyⅠ,Ⅱand Ⅲ, and the correlations among the spatial distributions, CBM content and burial depth of coal seams of different coal structures are analyzed comparatively by using logging data in the area and putting forward the method to recognize coal structures by logging data. The results showed that the cataclastic-ranulitic structural coal are more universal than undeformed coal and mylonitic structural coal in Anze block.In the south the cataclastic-granulitic structural coal is thick and in the north the mylonitic structural coal is thin. The CBM content increases significantly with the burial depth and is greatly influenced by the distribution of the coal structure at certain buried depth. The high content of CBM is present in the south because of a larger adsorptive capacity in the thick cataclastic-granulitic structural coal in this area.