Application Study On Hydraulic Fracturing Permeability Enhanced And Drainage Technology Of A Coal Mine In Chongqing

Focusing on outburst coal seam with low permeability, the combination of theoretical analysis, numerical simulation and field test of the research methods were used in this paper. Study on hydraulic fracturing permeability enhanced and drainage technology were carried out and the economic benefits of research results application were analyzed. The main research contents were as follows:(1)Three fracturing test holes which through coal seam and three along coal seam in Xinglong coal mine were respectively selected, the reasonable model parameters were determined, then RFPA2 D numerical analysis software version- Flow seepage analysis was used to get the stress distribution and acoustic emission of coal or rock under the condition of water injection pressure increasing(The failure process which from micro fracture, gradually expanded, and to large fracture around the hole wall were directly displayed). The water injection pressure and permeability range were finally obtained.(2)The simulation results for test holes which through coal seam and along coal seam were further analyzed, the relation formula between hydraulic fracturing coal injection pressure p, and the consistence coefficient of coal seam f, the permeability range r, the coal seam buried depth h were caculated respectively, which can be the calculation method for fracturing parameters of testing boreholes.(3)The south drainage roadways area at + 200 m level, and the 1601 s working face were selected as the experiment sites, the test borehole spacing and related parameters were designed according to the calculation method for fracturing parameters of testing boreholes, and hydraulic fracturing field test were conducted.Through the coal sample moisture of test bores, the actual fracturing fracture parameters were obtained and had good agreement to the calculation fracturingparameters, which can illustrate the calculation method for fracturing parameters was reasonable and can be the design basis of borehole spacing and related parameters for hydraulic fracturing in coal mine.(4)Compared with the original fracturing technologyof coal mine, after hole spacing increased in two hydraulic fracturing test sites, the gas extraction efficiency were changed little for the drainage segment in coal seam, but the utilization efficiency of fracture holes obviously increased, which showed the original fracturing parameters wasdesign unreasonably. According to the caculation method of fracturing parameters, the fracturing parameters should be optimized, the anti-reflection effect should be kept, the fracturing costs should be reduced, the economic efficiency would increase.(5)A comparative analysis of economic costs for hydraulic fracturing was made between the scheme in experimental area and extension area, the economic benefit of research results application was obtained in this paper.