Peridynamic Simulation Of Rock Formation Fracturing Process

So far,in the face of the decreasing of conventional energy sources,the development of unconventional natural gas has been highly valued by various countries.In order to facilitate the exploitation of unconventional natural gas,it is necessary to fracture the gas storage layer to obtain a network of cracks with high permeability,which is favorable for the precipitation of natural gas.Therefore,in order to improve the mining efficiency of unconventional natural gas,it is necessary to study the initiation and propagation of cracks in gas reservoirs.Peridynamics(PD)is a nonlocal theory,and it employs integral operator to describe the equation of motion of matter,which has a natural advantage for solving non-continuous problems such as crack propagation.In this paper,peridynamics method is adopted to study the rock formation fracturing process.The main research work is as follows:1.Introduce the basic ideas of peridynamics theory,and summarize the research status of rock formation fracturing and peridynamics theory at home and abroad.Introduce the PMB model and damage model of peridynamics theory.2.The numerical discrete methods of peridynamics theory are summarized,including spatial discrete and time integral methods.The peridynamics equation with damping is introduced.The correctness of the PD model is verified by two example.3.The peridynamics model of the rock material failure process is established.The numerical examples show that the PD model can effectively analyze the crack propagation and bifurcation of rock materials under load.The influence of different material parameters and load conditions on crack propagation and bifurcation is analyzed,which lays a foundation for simulating the fracture process of rock formation.4.The tracking method of crack surface is proposed.Based on the hydraulic fracturing of rock formation,a PD model for simulating rock formation fracturing process is proposed.The fracturing process of the horizontal well in the cross section is simulated.For the longitudinal section of horizontal well,the fracturing process with single perforation and three perforations is studied and the influences of distances between perforations on crack propagation is analyzed.Further,the fracturing process of rock formation,which has natural cracks,is simulated.The above work shows that using PD theory to establish the failure model of rock materials can effectively analyze the crack propagation and bifurcation of materials.By establishing an effective rock formation fracturing model,the crack propagation and tracking can be realized,and the crack propagation mechanism can be clarified,which provides analytical tools for the exploitation of unconventional natural gas in rock formations.