Study On Gas Occurrence Law And Gas Migration In Mining Area At Kaiping Syncline

Coal is the main energy source in China,which has been exploited on a large scale for more than 40 years since the reform and opening up,and the shallow coal resources have been exploited to the fullest,and most of the coal mines are currently mined at a depth of less than 600 m.However,for the deep coal mines,the complex gas endowment situation makes it very difficult to mine coal safely.For Kailuan mining area in Hebei province,the increasing mining depth,the frequent occurrence of gas gushing from individual mines,and the complex structure of the well field have caused great difficulties for coal mining.To address the above problems,this thesis takes the geological area of Kaiping Slope in Kailuan mine as the research object,fully collects the geological data of Kaiping Slope and the mine gas data in the slope,uses the basic theoretical knowledge of tectonic geology,gas geology and coalfield geology,analyzes the geological background of the research area through data analysis and software simulation,and deeply studies the characteristics of gas distribution,the geological control factors of gas accumulation,and analyzes the gas The study will provide a theoretical basis for mine safety production.The main progress of this study is as follows:(1)It can be seen from the buried hydrocarbon generation history of the strata in the Kaiping syncline mines that there are mainly two buried hydrocarbon generation histories in the Kaiping syncline,namely the Lvjiatuo mine type with one stratigraphic subsidence and two hydrocarbon generation histories and the Tangshan mine type with two subsidences and two hydrocarbon generation histories.From the analysis of the coal seam gas distribution characteristics,it is found that the south east wing mine has low gas content,low gas gush and low gas pressure over the years,while the north west wing mine and the turnaround end mine have high gas content and high gas gush over the years.From the three geological profiles,we can see that the gas content of the north west wing is higher than that of the south east wing of the slope,and the gas content of the mines in different locations is different,and the gas content of the mines in the same structural location is also different,therefore,there are differences in the gas assignment in different parts of the Kaiping syncline.(2)By analyzing the geological control factors of gas in different parts of the mine in Kaiping syncline,it is found that the thickness of coal seams in the south east wing is thin,and there are more positive faults and oblique folds distributed,which is not conducive to the gas distribution,and the distribution of mud sandstone on the top plate of coal seams and the burial depth of coal seams correlate well with the gas content.The north west flank is distributed with more reverse faults and reverse masked folds,the coal thickness varies greatly,and the correlation between lithology and gas content of the coal seam roof is low.For the turning end,it is found that the tectonic variability of the two mines is large,but all of them are unfavorable to the gas fugacity,the coal thickness is around 4 m,and the gas content increases with the increase of the burial depth.This time,the main controlling geological factors for the gas fugacity of different tectonic parts were also derived.(3)This time,FLAC3D 3D modeling software was used to establish the geological model of coal seam 2078E in Qianjiaying,and the simulated mining of coal mining face was carried out,and the maps of vertical stress and horizontal stress distribution,vertical displacement and horizontal displacement distribution,plastic zone damage evolution and fracture change of overburden rock were obtained under different advancement degrees of working face,to analyze the deformation and damage characteristics of overburden rock under different advancement degrees during coal seam excavation Finally,the damage law of overburden movement and fracture change law are analyzed.Finally,we analyzed the kinetic characteristics of gas migration around the mining area under the influence of mining,and derived the pre-mining gas migration pattern diagram,which clarified the fracture development law,gas influx source and gas migration law around the collapsed money of the 2078E mining area,and explained the gas migration law after the collapse of the mining area from the theoretical aspect.There are 99 figures,25 tables and 120 references in the thesis.