Study On Coalbed Gas Geology Of The Xuehu Coal Mine And Its Application

This dissertation takes the Xuehu Coal Mine（No.2₂coal seam）of the Henan Shenhuo Coal and Electricity Co.,Ltd.as the study object,systematically studied its coal gas occreeence and its geological control;a gas geological comprehensive evalution was conducted;gas emission and outburst of the coal mine were predicted and estimated.The achievements are as following.（1）The gas content of No.2₂coal seam is between 0.03 m³/t～19.71m³/t and the average value is 9.00 m³/t,while the gas is composed of methane in majority and little other gases,and the gas weathering zone is above the-450m level.The gas content increases with the increasing of the coal seam burial depth,the thickness of overburden rock and the elevation of coal seam floor,and their relationships are in a certain linear form.And the close degree of gas content and coal seam depth,overburden rock thickness and coal seam floor elevation in I₂geological unit is more significant than that in I₁geological unit.In the two gas geological units,the elevation of coal seam floor is the main control factor affecting the distribution of gas content in I₁and I₂gas geological units of No.2₂coal seam.（2）Based on geological structure characteristics,coal structure characteristics and gas occurrence characteristics,GCI（gas geological comprehensive index）was quantitatively characterised.The GCI in the Xuehu coal mine is generally above 0.3,showing a trend of gradual increase from shallow to deep.the overall GCI is small（below 0.3）in natural coke area due to not considering the influence of gas factors,and belongs to the simple type of gas geology;The GCI of lean coal and anthracite is generally between 0.3 and 0.6,which belongs to the medium type of gas geology,and some areas is above 0.6,which belongs to the complex type.（3）Based on the main control factors of gas occurrence geological control in Xuehu Mine,the gas emission of working face under different production rates was predicted to be 5.0–15.0 m³/min by using the source-dividing prediction method of gas emission.Based on the gas geological comprehensive index（GCI）grade range,the 2306 air roadway and 2306 machine roadway in the gas geological complex area of the second 2 coal seam are selected as the study area.Predicting the outburst results of heading face is that the sensitivity of cuttings desorption index is poor,the initial velocity of gas emission is in the middle,and the cuttings quantity index is the most sensitive.The reasonable selection of prediction indexes and the critical value of outburst prediction were determined,namely,the drilling cuttings amount S was5.4 kg/m,and the initial velocity index q of borehole gas emission was 3.6 L/min.The safety and reliability of the critical value of corresponding prediction indexes were tested based on the“four rate method”.The gas control system of outburst prediction based on GCI can provide scientific basis for prevention and control of outburst disasters in mining operations.There are 23 pictures,28 tables and 78 references in this dissertation.