Numerical Simulation And Experimental Study Of Hydraulic Fracturing In Granite Based On Particle Flow Code

Hydraulic fracturing technology is an important technical measure as an increase in oil and gas production and the use of hot dry rock geothermal resources.Since the invention,after a long period of practical and theoretical research,recognized by relevant scholars at home and abroad.It has been widely used and has achieved great practical benefits.Exploring the law of fracture propagation in reservoir during fracturing can improve the efficiency of hydraulic fracturing and provide reference value for practical projects.Granite is a relatively common reservoir rock in hydraulic fracturing engineering.There are several researches on large-scale hydraulic fracturing of granite at home and abroad.Therefore,it is of great theoretical value and engineering value to hydraulic fracturing test with granite as the research object.Particle flow code as a new numerical simulation method can better describe the meso-mechanical deformation results of rock and better fit for hydraulic fracturing simulations.This paper makes use of granite samples from the dry hot rock target area as the research object to carry out numerical simulation and experimental study of hydraulic fracturing in granite based on particle flow code.According to scanning electron microscopy and pore penetration tests,the micro-characteristics and pore-permeability characteristics of granite were obtained respectively.In this way,two large-scale indoor hydraulic fracturing tests are conducted.And according to the results of fracturing and acoustic emission monitoring,the fracturing pressure and crack propagation law of the sample are obtained.The modulus of elasticity,Poisson’s ratio and uniaxial compressive strength are obtained from the wave velocity test and uniaxial compression test of granite.Utilizing the uniaxial compression numerical simulation in the PFC program to perform the mesoscopic parameter calibration of the particle flow model and establish a numerical simulation model of particle flow hydraulic fracturing.The simulation results are consistent with the large-scale indoor hydraulic fracturing test results and the fracture propagation law of granite hydraulic fracturing is proposed.On the basis of verifying the accuracy of the model,the influences of the parameters such as the porosity of the granite,the water pressure,the single pre-pitched fracture and the two intersecting pre-defined fractures on the crack propagation law were analyzed,and the relevant fracture propagation was obtained.