Study On Influence Factors Of Fracturing Initation Mode In Horizontal Shale Wells

According to American experience in shale gas exploitation,if shale gas is to be exploited on a large scale in China,it is indispensable to study the advanced technology of shale gas.According to the experimental result,shale is low porosity and permeability.Therefore explorate the shale gas need to use some measures to increase production and special drilling and well completion method,choose horizontal well drilling to exploitate the shale gas.an important technology of the shale gas development is the hydraulic fracturing and horizontal well production technology,the application of these two technologies can effectively improve the exploitation of shale gas rate,and the ability to make single well ultimate recovery,The current study of hydraulic fracturing of shale is obtained through the indoor experiment means more rock mechanics parameters of the shale or through gathering larger shale outcrop,hydraulic fracturing was used for indoor simulation or by means of numerical simulation to simulate the hydraulic fracturing of stratum in the condition of situation,the research method of this paper is through the indoor rock mechanics experiment,found influence the influence factors of shale fracture crack model,and establish the indoor rock mechanics experiments and the connection between the numerical simulation of hydraulic fracturing.Therefore,(1)This article selects the shale from yongchuan,weiyuan and songliao basin,in the light of the problem of the influence factor of shale fracture mode,using the triaxial rock mechanics experiment was carried out on the shale statistics after the experiment the method of shale fracture mode,the mineral of brittleness index,the method of rock mechanics method to calculate the brittleness index,bedding direction and confining pressure of these four factors will affect the shale fracture mode of understanding;(2)According to the reliability of the numerical simulation,choose PFC2D established the software triaxial rock mechanics experimental numerical simulation model,and the indoor experiment results as macro parameters,fitting to mesoscopic parameters by fitting formula,as input parameters,inputting to the model,the triaxial rock mechanics numerical simulation results are obtained,and compared with the indoor experiment results,and further explore the brittleness index and confining pressure effect on the shale fracture mode,and validate the reliability of the numerical simulation method,considering the brittleness index,the factors of the simulation results,the fracture number and types of basic consistent with the experimental results,In exploring the numerical simulation results of confining pressure on shale fracture mode,the following conclusions are obtained:the lower the confining pressure is,the more significant the fracture characteristics of the rock will be;the splitting failure will become the dominant one,and the shear slip trend will be gradually reflected as the confining pressure increases.(3)Aiming at indoor rock mechanics test has not been established in previous studies and the actual hydraulic fracturing problem of the connection between the fracture failure mode,and taking the parameters obtained from the experimental fitting after input as numerical simulation method of mesoscopic parameters,hydraulic fracturing horizontal Wells in the shale fracture crack and extension of numerical simulation,through the single factor analysis method,research on in-situ stress,displacement,perforation length and hole diameter on shale horizontal well fracturing fracture crack mode and the influence of the fracture pressure.