Parameters Optimization Of The Hydraulic Fracturing Of Low Permeability Coal

Low permeability is one of the main characteristics of most of our county’s coal seam, which makes our coal seam gas drainage efficiency low, and severely restricts the safety production of coal mine. For low permeability coal seam gas drainage difficult situation of the Tao Yi mine, we proposed hydraulic fracturing gas extraction technology. In this paper, we analyzed initiation pressure, crack extension mechanism and rules of the hydraulic fracturing with the help of theoretical analysis and numerical simulation. Based on the above research and analysis, combined with site industrial test of Tao Yi mine to determine a suitable hydraulic fracturing technology parameters of low permeability coal, it provided a rich theoretical basis and technical support for seam gas drainage.We researched and analyzed the hydraulic fracturing gas extraction technique to clarify the microscopic pore structure of coal seams, failure criterion, cracks spread form and broken coal theory and to reveal the mechanism of hydraulic fracturing gas extraction technology. Using RFPA2D-Flow version simulation software simulated hydraulic fracturing initiation pressure and crack extend law under different lateral pressure coefficients and different firmness coefficients, and also simulated the law of crack extend under different drilling spacing. According to 2# coal mine geological conditions of Tao Yi we selected the site of scene industrial test, put forwarded seam hydraulic fracturing technology program. According to crack initiation theoretical models and numerical simulations, we designed and optimized hydraulic fracturing injection pressure, injection time, injection flow, sealing depth and so on. Finally, through scene industrial test to test whether hydraulic fracturing program reasonable, and examined the effect of coal seam gas drainage.The site industry test results showed that: after fracturing the coal seam gas drainage concentration and flow increased significantly, permeability improved significantly. Finally, combined the theoretical analysis, numerical simulation, site industry test, obtained a reasonable hydraulic fracturing parameters for the Tao Yi mine.