Reserch On Mechanism Of Hydraulic Fracturing Of The Numerical Simulation In Coal Bed

As China's energy structure adjustment, and coal prices continue to slump, and many other factors, causing a sharp fall in the number of China's coal enterprise economic benefits.Adjust the coal product structure, improving lump coal output is to improve the enterprise economic benefit, one of the effective ways to get rid of economic difficulties, and the best choice of the cleaner production in coal enterprise at present.In this paper, Huanglong Jurassic coalfield of Hongshiyan coal mine as the background,Field measurement, laboratory experiment, theoretical analysis, numerical simulation and other methods are used.Study on the No. 2 coal seam hydraulic fracturing process in the initiation and propagation of law.Through the laboratory experiment of Hongshiyan coal mine no. 2 coal coal sample water has carried on the rational analysis,determination of the physical and mechanical parameters of the coal and rock under different moisture content, the fitting of the no. 2 coal physical mechanics parameters and moisture content between rational expression formula of water.Using the methods of theoretical analysis and field observation, research and analysis of the coal seam pressure caused by main influence factors of crack, and combined with the coal quality of coal seam No. 2,fracture development, analysis the main factors of No. 2 coal seam pressure induced crack of rules.Based on the mechanics analysis, the critical pressure in the process of hydraulic fracturing in coal seam is determined. The effects of the primary fracture and the cutting groove on the initiation pressure, the expansion pressure, the initiation direction and the extension direction of the hydraulic fracturing in the coal seam are studied by numerical simulation.The Study : one is in the hydraulic fracturing initiation process, the existence of preexisting fissures or cutting groove crack of coal seam drilling, with preexisting fissures orcutting groove crack and minimum principal stress and the initiation pressure decreases, but cutting groove hole of coal seam fracturing pressure reduction is more effective, and the crack initiation direction has a certain guiding role; the second is in the expansion process,the presence of native or fissures and grooves are cut with minimum principal stress angle increases and decreases, but cutting groove drilling fracturing, the fracturing effect is better,and the crack propagation direction tends to coal seam drilling cutting groove direction. Third,by preexisting fissures or cutting groove crack of coal seam drilling of horizontal comparison and cut groove seam boreholes in the hydraulic fracturing process, initiation pressure and expansion pressure are relatively lower, and the crack propagation direction guiding role.According to the practical situation of Hongshiyan coal mine No. 2 coal seam, the technological parameters of hydraulic fracturing in coal seam are determined. Based on field effect analysis, The application of hydraulic fracturing in coal seam in Hongshiyan coal mine lump coal production achieved good results, working face lump coal output rate greatly improved.