Coal Structure Affected to Coalbed Methane Development in Qinnan Region

In order to study the coal structure affected to coalbed methane development, an information comparison was conducted on the dilling, fracturing and dr ainage mining to different coal structure of primary coal, fragmented coal, fine coal and mylonite coal from No.3seam in Qinnan Region, and underground observation a nd analysis were conducted in some mines.The study showed the coal structure was more broken, the stability of well wall would be poorer and the diameter of well and drilling cuttings from the gas drainage mining borehole would be higher.Meanwhile, the reservoir polluted scope and the well diameters would be in a positive relationsh ip.At fine coal and mylonite coal developed area, thick cement rings formed around well wall and at the initial hydraulic fracturing operation, the pressure would be rapid ly increased and the cement ring could be broken.Meanwhile, great amount fracturing liquid lost would reduce the expansion scope of the fractured cracks and even ca use sand jammed and other engineering problems.During the gas drainage mining process, the coalbed water and coalbed methane would both have the ability to carry coal powder and thus the gas drainage mining channel would be jammed, the gas well production would be rapidly reduced, the crack closure could be easily caused a nd gas desorption scope would be reduced.The more broken the coal structure was, the higher production of the coal powder would be and the more serious crack clos ure would be.