Study On Gas Geological Law And Gas Geological Unit In Qidong Coal Mine

The tectonic evolution history, burial history and thermal evolution history oncoal seam and gas occurrence were analyzed with regional tectonic evolution theoryand tectonic gradual control theory of gas preservation. Combined with gas andgeological data in Qidong mine, analysis on control action of mine field, roof and floorlithologic characters, burial depth, igneous rock on gas occurrence. Focuses on theanalysis of the impact of igneous rock on gas and coal quality and coal seam, study ongas geological law in Qidong mine. On this foundation, gas geological units weredefined, the favorable rate of gas drainage of each unit were evaluated.The results show that: Qidong mine methane occurrence characteristics strictlycontrolled by structures, in the south of Weimiao fault which was formed duringIndosinian period the gas content was significantly less than the north. EarlyYanshanian, with the Xuzhou-Suzhou arcuate structure was formed, NW trendingreverse fault was builted as well. In the NW trending reverse fault near, The gascontent is higher than the NE trending normal fault which was formed at lateYanshanian. Under the strong compression from the NE trending modern tectonicstress. The gas content is lower near the EW trending tectonic, but higher near theNE-NW trending tectonic.The igneous rock distributed in the upper part of the coal seam with rock sillformation. From NO.32coal seam to NO.10coal seam, magma intrusion activityshowed a scratch and stronger tendency. The coal structure was damaged by igneousrock mainly occurs in the upper and lower of coal seam. In the upper of coal seam, TRand igneous rock interaction arises, tectonic coal is located in the lower coal seam.Tectonic coal distribution from the upper coal seam to lower coal seam show a scratchand more thick trend. The coal quality changes from QM to1/3JM and FM. The coalchemical properties show that: was increased, Hdaf、H/C and Vdafwere decreasedsignificantly, but there was a trend of increase at Cdafand bond index Ymm. In themagma intrusion activity zone, the effect of igneous rock on gas show that the gascontent was significantly higher in igneous roof area than the sand and mudstone roofat the same coal seam. Take the fault as the primary consideration, combined with the distributioncharacteristics of the gas, igneous rock, tectonic coal, coal and gas outburst. Accordingto Weimiao fault and F₁, F₂and F5fault as the boundary, Qidong mine is divided intofive gas geology units. On the basis, combined with each unit coal bed methaneresources and abundance to evaluate Qidong mine gas drainage favorable rate, asfollows: unit Ⅴ, unit Ⅲ, unitⅡ, unit Ⅳ, unit Ⅰ.