Fracability Evaluation Research Of Horizontal Well High Energy Gas Fracturng For Shale Gas Reservoir

High Energy Gas Fracturing technology can overcome the large-scale development of shale gas hydraulic fracturing evils,the scientific fracability evaluation is the basis of fracturing.Based on the shale minerals components classification and mesoscopic mechanical parameters,the mesoscopic numerical model of shale is built.By means of numerical experiments,the mechanism of shale brittle failure is explored,and the effects of different parameters on rock mechanics are studied combined with horizontal well model of High Energy Gas Fracturing,meanwhile,a new evaluation method of fracability is built,and also the best shale reservoir mineral contents distribution for fracturing is defined by analyzing the relationship of mineral component content and mechanical parameters.The result shows:(1)The content of organic matter,diagenesis,rock mechanics properties and mineral content composition are the main factors that affect the fracability of shale.(2)The macroscopic mechanical propertis of shale are effected by mineral composition and content,the stress mutation occurs in different contact surfaces of minerals during the damaging,the shale macro brittle fracture essentially shows that the heterogeneity and anisotropy of rock mechanical property is caused by difference of mineral mechanical.(3)Shale reservoir with higher Young’s modulus starts fracturing early.The velocity of crack propagation is fast and it’s easier to form long and narrow cracks.Shale reservoir with higher Poisson’s ratio starts fracturing and it’s easier to form short and wide cracks.(4)When the reservoir matches these conditions where the Young’s modulus is between 40~60GPa,the Poisson’s ratio is between 0.1~0.25,the TOC content is greater than 2%,Ro is greater than 1.3%,the silica mineral content is between 20%and 60%,carbonate minerals content is between 10% and 30%,and the clay mineral is between 30% and 50%,it is the most suitable for reconstruction in the reservoir.Based on these analysis conclusions,the lower limit of evaluation method is defined.When comprehensive fracability index is greater than 50%,which is the best condition for fracturing.