Gas Occurrence Law and Division of Gas Geological Unit in 11-2 Coal Seam of Dingji Mine

In order to reveal the gas (CBM) occurrence distribution laws in 11-2 coal seam of Dingji Mine, Huainan Coal Field, six gas geological units were divided mainly according to the distribution of the geological structures in mine in this article. The gas occurrence distribution laws and the unbalanced distribution were revealed by using the theory of tectonic-level-control of coalmine gas occurrence. The results show that geological structures in different forms and burial depths of coalbed are the main controlling factors that influence the gas content in each unit; Huainan Coal Field was denudated during the period from the middle period of the E. Cretaceous to the early period of the Miocene which led to the desorption and dissipation of much gas in coalbed and the gas content in study area is low in general and significantly unbalanced. On the basis of the study above, CBM drainage should focus in unit Ⅱand Ⅴ which are the favorable blocks and research on ground stress should be strengthened for better coal and gas outburst prevention.