Simulation method for in-crack migration plugging process of temporary plugging agent for deep shale gas fracturing

Abstract

The invention discloses a method for simulating the in-crack migration plugging process of a deep shale gas fracturing temporary plugging agent. The method comprises the following steps: establishing a sand bank distributed crack physical model; the pumping displacement of the temporary plugging agent is converted into the fracture opening flow velocity of the fracture physical model; discretizing the fracturing fluid flow equation by using a finite volume method, and solving the discrete equation to obtain the fracturing fluid flow velocity and pressure in each grid under each time step length; calculating the interaction force between the fracturing fluid and the temporary plugging agent particles; solving the motion equation and the contact equation of the temporary plugging agent particles by using an Euler display difference method to obtain the speed and the position of the temporary plugging agent particles; obtaining plugging time and pressure until the temporary plugging agent forms plugging in the crack or the simulation time is over; and the temporary plugging agent pumping parameters are changed, the plugging time and pressure corresponding to the different pumping parameters are obtained, and the optimal pumping parameter is optimized. According to the device and the method, the migration and plugging process of the temporary plugging agent in the fracture under sand bank distribution is simulated, and a basis is provided for temporary plugging diversion fracturing construction parameter optimization in the deep shale air pressure fracture.

Description

Technical Field

[0001] The invention relates to a method for simulating the migration and plugging process of a temporary plugging agent for deep shale gas fracturing, and belongs to the technical field of oil and gas field production increase and transformation. Background Art

[0002] Hydraulic fracturing technology is a key means to develop unconventional oil and gas resources, especially deep shale gas. Both theoretical research and field practice have shown that the higher the density and volume of the fracture network constructed by hydraulic fracturing, the higher the production capacity of unconventional oil and gas wells. In order to build a high-density and large-volume fracture network, domestic and foreign experts and scholars have proposed the technology of temporary plugging and diversion fracturing in the fracture. This technology pumps a degradable temporary plugging agent into the fracture to block the original extension direction of the fracture, increase the net pressure in the fracture, force the fluid to turn, press open the branch fracture, increase the density of the fracture network, and increase the volume of the fracture network. The key to the success of temporary plugging and diversion fracturing in the fracture lies in the successful plugging of the temporary plugging agent in the fracture, but there is still no relevant theory to guide the design of the pumping parameters of the temporary plugging agent at the fracturing site. Therefore, it is urgent to develop a simulation method for the migration and plugging process of the temporary plugging agent in the fracture to optimize the pumping parameters of the temporary plugging agent and reduce the construction cost.

[0003] At present, some scholars have simulated the migration and plugging process of temporary plugging agents in flat fractures and rough fractures by numerical methods, but the migration process of temporary plugging agents in fractures under the distribution of sand banks has not been studied. In the actual fracturing process, before the temporary plugging agent is pumped, proppant has been pumped into the fracture to form a sand bank, and the sand bank has an important influence on the migration of temporary plugging agents in the fractures.

[0004] In view of this, it is necessary to invent a method for simulating the migration and plugging process of temporary plugging agents in deep shale gas fracturing fractures, so as to simulate the migration and plugging process of temporary plugging agents in fractures under the distribution of sand banks, and provide a basis for optimizing the construction parameters of temporary plugging and fracturing in deep shale gas pressure fractures. Summary of the invention

[0005] The present invention mainly overcomes the deficiencies in the prior art and provides a method for simulating the migration and plugging process of a temporary plugging agent in deep shale gas fracturing fractures. The method solves the problem that the existing numerical model of temporary plugging agent migration and plugging in fractures is not suitable for actual site conditions. The method is used to simulate the migration process of the temporary plugging agent in fractures under the distribution of sand banks, and provides theoretical guidance for optimizing the pumping parameters of temporary plugging and fracturing temporary plugging agents in deep shale gas pressure fractures.

[0006] The technical solution provided by the present invention to solve the above technical problems is: a method for simulating the migration and plugging process of a temporary plugging agent for deep shale gas fracturing, comprising the following steps:

[0007] Step S10, obtaining crack parameters, fracturing fluid parameters, and temporary plugging agent parameters formed by actual hydraulic fracturing, and establishing a crack physical model of sand bank distribution according to a similarity criterion;

[0008] Step S20, converting the temporary plugging agent pumping displacement into the fracture mouth flow rate of the fracture physical model;

[0009] Step S30, meshing the fracture physical model;

[0010] Step S40, using the finite volume method to discretize the fracturing fluid flow equation, and using the SIMPLE algorithm to solve the discrete equation to obtain the fracturing fluid pressure and flow rate in each grid at each time step;

[0011] Step S50, calculating the interaction force between the fracturing fluid and the temporary plugging agent particles according to the fracturing fluid-temporary plugging agent interaction force equation;

[0012] Step S60, using the Euler explicit difference method to solve the motion equation and contact equation of the temporary plugging agent particles to obtain the velocity and position of the temporary plugging agent particles;

[0013] Step S70, repeating steps S40 to S60 until the temporary plugging agent forms a plug in the crack or the simulation time ends, and obtaining the temporary plugging agent migration and plugging process and the plugging time and pressure;

[0014] Step S80, changing the temporary plugging agent pumping parameters, repeating steps S20 to S70, obtaining the plugging time and pressure corresponding to different pumping parameters, and evaluating the plugging effect of the temporary plugging agent in the crack at different pumping parameters based on the crack plugging effect index formula, and selecting the optimal pumping parameters.

[0015] A further technical solution is that the fracture parameters include fracture height, fracture length, fracture width, length and height of sand bank in the fracture formed by hydraulic fracturing;

[0016] The fracturing fluid parameters include fracturing fluid viscosity and fracturing fluid density;

[0017] The temporary plugging agent parameters include temporary plugging agent particle size, temporary plugging agent concentration, temporary plugging agent density, temporary plugging agent Young's modulus, temporary plugging agent Poisson's ratio, temporary plugging agent collision recovery coefficient, temporary plugging agent static friction coefficient, and temporary plugging agent dynamic friction coefficient.

[0018] A further technical solution is that the calculation formula of the slot flow rate in step S20 is:

[0019]

[0020] Where: v s is the simulated inlet velocity, m / s; Q is the on-site construction displacement, m 3 / min; H s is the actual crack height, m; W s is the actual crack width, m.

[0021] A further technical solution is that in step S30, a hexahedral grid is used to draw a structured grid in the fracture physical model and then converted into an unstructured grid.

[0022] A further technical solution is that the fracturing fluid flow equation in step S40 is:

[0023]

[0024] ε f +ε p =1

[0025] Where: ε f is the volume fraction of the fracturing fluid phase, dimensionless; ρ f is the density of fracturing fluid, kg / m 3 ; is the fluid phase velocity of the fracturing fluid, m / s; ε p is the volume fraction of temporary plugging agent particles, dimensionless; p f is the pressure on the fluid microelement, Pa; is the viscous stress on the surface of the fluid microelement, Pa; is the unit mass force of the fluid microelement, m / s 2 ; t is time, s.

[0026] A further technical solution is that the discrete equation in step S40 is:

[0027]

[0028] Where: Δt is the time step, s; V f is the fluid control volume, m 3 ; A f is the interface area of ​​the fluid control volume, m 2 ;p f is the pressure on the fluid microelement, Pa; ε f is the volume fraction of the fracturing fluid phase, dimensionless; ρ f is the density of fracturing fluid, kg / m 3 ; is the velocity of the fracturing fluid phase, m / s; A is the area, m 2 ; t is time, s.

[0029] A further technical solution is that the specific process of using the SIMPLE algorithm to solve the discrete equation in step S40 is: using the SIMPLE algorithm to substitute the relationship between pressure and velocity specified by the discrete form of the momentum equation into the discrete format of the continuous equation, thereby obtaining a pressure correction equation, and obtaining a pressure correction value from the pressure correction equation; based on the corrected pressure field, a new velocity field is obtained; then, based on whether the velocity no longer changes, whether the velocity field converges; if not, using the corrected pressure value as the given pressure field to start the next level of calculation; and repeating this process until a converged solution is obtained.

[0030] A further technical solution is that the calculation formula in step S50 includes:

[0031]

[0032] In the formula, is the flow-particle interaction force, N; is the stable drag force of particle i, N; is the indeterminate drag force, N; is the pressure gradient force, N; is the viscous force caused by the fluid shear stress or deviatoric stress tensor, N; is the lifting force, N; C d is the drag coefficient, dimensionless; Re i is the relative Reynolds number, dimensionless; is the fluid-particle relative velocity, m / s; μ f is the fluid viscosity, Pa·s; ε f is the volume fraction of the fracturing fluid phase, dimensionless; ρ f is the density of fracturing fluid, kg / m 3 ;d i is the particle size of particle i, mm.

[0033] A further technical solution is that the calculation formula in step S60 is:

[0034]

[0035] Where: m p,i is the mass of particle i, kg; is the translational velocity of the center of mass of particle i, m / s; is the center of mass position of particle i, m; CL p,i is the contact set of particle i; is the sum of the particle-particle interaction forces acting on particle i, N; is all fluid-particle interaction forces, N; is all the external forces acting on particle i by uniform or non-uniform external field, N; Ip,i Moment of inertia of particle i, kg·m 2 ; is the rotation speed of particle j, rad / s; is the angular position of particle i, rad; is the torque generated by the particle-particle collision force acting on the contact point, N·m; is the torque generated by rolling friction, N·m.

[0036] A further technical solution is that the formula for the plugging effect index in the seam is:

[0037]

[0038] Where: I P is the sealing effect index in the seam, dimensionless; p P is the plugging pressure, Pa; t P The time for blocking is s.

[0039] The present invention has the following beneficial effects: based on the distribution of sand banks in real fractures, the present invention constructs a fracture physical model under the distribution of sand banks, considers the interaction between fluid and particles, introduces the Di Felice model to characterize the drag of fracturing fluid on temporary plugging agent, uses the CFD-DEM coupling method to establish a simulation method for the migration and plugging process of temporary plugging agent in fractures, and evaluates the plugging effect of temporary plugging agent in fractures under different construction parameter conditions by plugging time and plugging pressure, which can provide a basis for optimizing the pumping parameters of temporary plugging agent for temporary plugging and fracturing in deep shale gas pressure fractures. BRIEF DESCRIPTION OF THE DRAWINGS

[0040] Figure 1 The two-phase flow calculation process of the temporary plugging agent in-slit migration and plugging simulation method established by the present invention;

[0041] Figure 2 It is the shape of sand bank formed by proppant in the fracture;

[0042] Figure 3 A physical model of cracks distributed in a sand bank established for the present invention;

[0043] Figure 4 A schematic diagram of the process of temporary plugging agent migration and plugging cracks provided by the present invention;

[0044] Figure 5 The cloud diagram of particle distribution of temporary plugging agent in the seam under different pumping displacements provided by the present invention;

[0045] Figure 6 A plugging time and plugging pressure curve diagram under different pumping displacements provided by the present invention;

[0046] Figure 7The present invention provides an index curve of the plugging effect in the seam under different pumping displacements. DETAILED DESCRIPTION

[0047] The technical solution of the present invention will be described clearly and completely below in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0048] A method for simulating the migration and plugging process of a temporary plugging agent for deep shale gas fracturing according to the present invention comprises the following steps:

[0049] Step S10, obtaining crack parameters, fracturing fluid parameters, and temporary plugging agent parameters formed by actual hydraulic fracturing, and establishing a crack physical model of sand bank distribution according to a similarity criterion (geometric similarity);

[0050] The fracture parameters include fracture height, fracture length, fracture width, length and height of sand bank in fracture formed by hydraulic fracturing; the fracturing fluid parameters include fracturing fluid viscosity and fracturing fluid density; the temporary plugging agent parameters include temporary plugging agent particle size, temporary plugging agent concentration, temporary plugging agent density, temporary plugging agent Young's modulus, temporary plugging agent Poisson's ratio, temporary plugging agent collision recovery coefficient, temporary plugging agent static friction coefficient, temporary plugging agent dynamic friction coefficient;

[0051] Step S20, converting the temporary plugging agent pumping displacement into the fracture mouth flow rate of the fracture physical model;

[0052] Slit flow velocity calculation equation:

[0053]

[0054] Where: v s is the simulated inlet velocity, m / s; Q is the on-site construction displacement, m 3 / min; H s is the actual crack height, m; W s is the actual crack width, m.

[0055] Step S30, meshing the established fracture physical model, specifically using a hexahedral mesh to draw a structured mesh in the fracture physical model and then converting it into an unstructured mesh;

[0056] Step S40, using the finite volume method to discretize the fracturing fluid flow equation, and using the SIMPLE algorithm to solve the discrete equation to obtain the fracturing fluid flow rate and pressure in each grid at each time step;

[0057] Fracturing fluid flow equation:

[0058]

[0059] ε f +ε p =1 (4)

[0060] Where: ε f is the volume fraction of the fracturing fluid phase, dimensionless; ρ f is the density of fracturing fluid, kg / m 3 ; is the fluid phase velocity of the fracturing fluid, m / s; ε p is the volume fraction of temporary plugging agent particles, dimensionless; p f is the pressure on the fluid microelement, Pa; is the viscous stress on the surface of the fluid microelement, Pa; is the unit mass force of the fluid microelement, m / s 2 ; t is time, s.

[0061] Discrete equations:

[0062]

[0063] Where: Δt is the time step, s; V f is the fluid control volume, m 3 ; A f is the interface area of ​​the fluid control volume, m 2 ;p f is the pressure on the fluid microelement, Pa; ε f is the volume fraction of the fracturing fluid phase, dimensionless; ρ f is the density of fracturing fluid, kg / m 3 ; is the velocity of the fracturing fluid phase, m / s; A is the area, m 2 ; t is time, s.

[0064] The specific process of using SIMPLE algorithm to solve the discrete equation is as follows:

[0065] The SIMPLE algorithm is used to substitute the relationship between pressure and velocity specified by the discrete form of the momentum equation into the discrete format of the continuous equation, thereby obtaining the pressure correction equation, and the pressure correction value is obtained from the pressure correction equation; based on the corrected pressure field, a new velocity field is obtained; then, whether the velocity field converges is checked based on whether the velocity no longer changes; if not, the corrected pressure value is used as the given pressure field to start the next level of calculation; this process is repeated until a converged solution is obtained.

[0066] Step S50, calculating the interaction force between the fracturing fluid and the temporary plugging agent particles according to the fracturing fluid-temporary plugging agent interaction force equation, and realizing the coupling of CFD and DEM;

[0067] Calculation equation for flow-particle interaction force:

[0068]

[0069] Where: is the flow-particle interaction force, N; is the stable drag force of particle i, N; is the indeterminate drag force, N; is the pressure gradient force, N; is the viscous force caused by the fluid shear stress or deviatoric stress tensor, N; is the lifting force, N.

[0070] Di Felice model characterizes the drag force of fracturing fluid on temporary plugging agent:

[0071]

[0072] Where: C d is the drag coefficient, dimensionless; Re i is the relative Reynolds number, dimensionless; is the fluid-particle relative velocity, m / s; μ f is the fluid viscosity, Pa·s; ε f is the volume fraction of the fracturing fluid phase, dimensionless; ρ f is the density of fracturing fluid, kg / m 3 ;d i is the particle size of particle i, mm.

[0073] Step S60, using the Euler explicit difference method to solve the motion equation and contact equation of the temporary plugging agent particles to obtain the velocity and position of the temporary plugging agent particles;

[0074] Control equation of temporary plugging agent particle phase:

[0075]

[0076] Where: m p,i is the mass of particle i, kg; is the translational velocity of the center of mass of particle i, m / s; is the center of mass position of particle i, m; CL p,i is the contact set of particle i; is the sum of the particle-particle interaction forces acting on particle i, N; is all fluid-particle interaction forces, N; is all the external forces acting on particle i by uniform or non-uniform external field, N; I p,i Moment of inertia of particle i, kg·m 2 ; is the rotation speed of particle j, rad / s; is the angular position of particle i, rad; is the torque generated by the particle-particle collision force acting on the contact point, N·m; is the torque generated by rolling friction, N·m.

[0077] Step S70, updating the temporary plugging agent parameters, and repeating steps S40 to S60 until the pressure in the fracture (the pressure at the center of the fracture physical model) rises sharply, the temporary plugging agent forms a plug in the fracture or the simulation time ends, and the temporary plugging agent migration and plugging process and plugging time and pressure are obtained, wherein the pressure in the fracture is the pressure at the center of the fracture physical model;

[0078] Step S80, changing the temporary plugging agent pumping parameters, repeating steps S20 to S70, obtaining the plugging time and pressure corresponding to different pumping parameters, evaluating the plugging effect of the temporary plugging agent in the crack when different pumping parameters are used based on the crack plugging effect index formula, and selecting the optimal pumping parameters;

[0079]

[0080] Where: I P is the sealing effect index in the seam, dimensionless; p P is the plugging pressure, Pa; t P The time for blocking is s.

[0081] Example

[0082] Take a well in Block A for example, where a hydraulic fracture in a deep shale gas pressure fracture is temporarily plugged and diverted for fracturing. The length of a hydraulic fracture in the well is 100m, the height is 30m, and the width is 0.013m. The shape of the sand bank in the fracture is as follows: Figure 2 As shown in the figure, the inlet crack width of the physical model is consistent with the actual crack width, and the crack length and crack height are geometrically similar. A wedge-shaped crack model with an inlet crack width of 13 mm, an outlet crack width of 3 mm, a length of 201 mm, a height of 60 mm, a sand bank height of 30 mm, a lower bottom length of 141 mm, and an upper bottom length of 99 mm is established. Figure 3 As shown;

[0083] In this embodiment, according to the fracture parameters formed by the actual hydraulic fracturing of the fracturing well and the basic parameters of the fracturing fluid and the temporary plugging agent, the numerical simulation input parameters are obtained as shown in Table 1. According to the above steps, different pumping displacements are used to simulate the migration and plugging process of the temporary plugging agent in the fractures distributed in the sand bank.

[0084] Table 1 Numerical simulation input parameters of the embodiment

[0085]

[0086] According to the present invention, combined with the data in Table 1, the total simulation time is set to 6s. Figure 1The flow chart is used to calculate and characterize the migration process of temporary plugging agent, and the following results are obtained: Figure 4 The temporary plugging agent migration and plugging process is shown.

[0087] Figure 5 The cloud diagram of temporary plugging agent particle distribution in the seam when the simulation time reaches 6s or the plugging is formed under different pumping displacements is shown. From the figure, it can be seen that the size of the pumping displacement affects the migration speed of the temporary plugging agent and the quality of the temporary plugging body. According to the simulation results, the temporary plugging agent plugging time and plugging pressure curves under different pumping displacements are drawn as shown in the figure. Figure 6 As shown, the pumping capacity is 3m 3 / min, the plugging time is 6s, and the plugging pressure is less than 5KPa, indicating that the low pumping volume cannot complete the temporary plugging agent pumping construction work within a reasonable construction time. With the increase of pumping volume, the plugging time continues to decrease, indicating that the larger the pumping volume, the faster the plugging. The plugging pressure after crack plugging shows a phenomenon of first decreasing and then increasing with the increase of pumping volume. Figure 5 Analysis shows that this is because at lower pumping rates, the temporary plugging agent migrates stably and the temporary plugging body formed is of high quality; while at higher pumping rates, the temporary plugging body formed is of low quality, with more pores, and it is not easy to form a high plugging pressure; at high pumping rates, there is more fluid in the cracks, resulting in a high plugging pressure, but at high pumping rates, it is very easy to cause a temporary plugging body of poor quality. Figure 5 It also shows that under high pumping rate, part of the temporary plugging body has been destroyed.

[0088] Figure 7 The values ​​of the plugging effect index in the fractures under different pumping rates are shown. From the figure, it can be judged that 4m3 / min should be used as the pumping rate for the temporary plugging agent pumping construction of deep shale gas fracturing.

[0089] The above description is not intended to limit the present invention in any form. Although the present invention has been disclosed through the above embodiments, it is not intended to limit the present invention. Any technician familiar with the profession can make some changes or modifications to equivalent embodiments of equivalent changes using the technical contents disclosed above without departing from the scope of the technical solution of the present invention. However, any simple modification, equivalent changes and modifications made to the above embodiments based on the technical essence of the present invention without departing from the content of the technical solution of the present invention are within the scope of the technical solution of the present invention.

Claims

1. A method for simulating the migration and plugging process of a temporary plugging agent for deep shale gas fracturing, characterized in that: The following steps are involved: Step S10, obtaining crack parameters, fracturing fluid parameters, and temporary plugging agent parameters formed by actual hydraulic fracturing, and establishing a crack physical model of sand bank distribution according to a similarity criterion; Step S20, converting the temporary plugging agent pumping displacement into the fracture mouth flow rate of the fracture physical model; Step S30, meshing the fracture physical model; Step S40, using the finite volume method to discretize the fracturing fluid flow equation, and using the SIMPLE algorithm to solve the discrete equation to obtain the fracturing fluid pressure and flow rate in each grid at each time step; Step S50, calculating the interaction force between the fracturing fluid and the temporary plugging agent particles according to the fracturing fluid-temporary plugging agent interaction force equation; Step S60, using the Euler explicit difference method to solve the motion equation and contact equation of the temporary plugging agent particles to obtain the velocity and position of the temporary plugging agent particles; Step S70, repeating steps S40 to S60 until the temporary plugging agent forms a plug in the crack or the simulation time ends, and obtaining the temporary plugging agent migration and plugging process and the plugging time and pressure; Step S80, changing the temporary plugging agent pumping parameters, repeating steps S20 to S70, obtaining the plugging time and pressure corresponding to different pumping parameters, and evaluating the plugging effect of the temporary plugging agent in the crack at different pumping parameters based on the crack plugging effect index formula, and selecting the optimal pumping parameters.

2. The method for simulating the migration and plugging process of a temporary plugging agent for deep shale gas fracturing according to claim 1 is characterized in that: The fracture parameters include fracture height, fracture length, fracture width, and length and height of sand banks in fractures formed by hydraulic fracturing; The fracturing fluid parameters include fracturing fluid viscosity and fracturing fluid density; The temporary plugging agent parameters include temporary plugging agent particle size, temporary plugging agent concentration, temporary plugging agent density, temporary plugging agent Young's modulus, temporary plugging agent Poisson's ratio, temporary plugging agent collision recovery coefficient, temporary plugging agent static friction coefficient, and temporary plugging agent dynamic friction coefficient.

3. The method for simulating the migration and plugging process of a temporary plugging agent for deep shale gas fracturing according to claim 1, characterized in that: The calculation formula of the slot flow rate in step S20 is: Where: v s is the simulated inlet velocity, m / s; Q is the on-site construction displacement, m 3 / min; H s is the actual crack height, m; W s is the actual crack width, m.

4. The method for simulating the migration and plugging process of a temporary plugging agent for deep shale gas fracturing according to claim 1, characterized in that: In step S30, a hexahedral grid is used to draw a structured grid in the fracture physical model and then converted into an unstructured grid.

5. The method for simulating the migration and plugging process of a temporary plugging agent for deep shale gas fracturing according to claim 1, characterized in that: The fracturing fluid flow equation in step S40 is: e f +e p =1 Where: ε f is the volume fraction of the fracturing fluid phase, dimensionless; ρ f is the density of fracturing fluid, kg / m 3 ; is the fluid phase velocity of the fracturing fluid, m / s; ε p is the volume fraction of temporary plugging agent particles, dimensionless; p f is the pressure on the fluid microelement, Pa; is the viscous stress on the surface of the fluid microelement, Pa; is the unit mass force of the fluid microelement, m / s 2 ; t is time, s.

6. A method for simulating the migration and plugging process of a temporary plugging agent for deep shale gas fracturing according to claim 5, characterized in that: The discrete equation in step S40 is: Where: Δt is the time step, s; V f is the fluid control volume, m 3 ; A f is the interface area of ​​the fluid control volume, m 2 ;p f is the pressure on the fluid microelement, Pa; ε f is the volume fraction of the fracturing fluid phase, dimensionless; ρ f is the density of fracturing fluid, kg / m 3 ; is the velocity of the fracturing fluid phase, m / s; A is the area, m 2 ; t is time, s.

7. A method for simulating the migration and plugging process of a temporary plugging agent for deep shale gas fracturing according to claim 5 or 6, characterized in that: The specific process of using the SIMPLE algorithm to solve the discrete equation in step S40 is: using the SIMPLE algorithm to substitute the relationship between pressure and velocity specified by the discrete form of the momentum equation into the discrete format of the continuous equation, thereby obtaining a pressure correction equation, and obtaining a pressure correction value from the pressure correction equation; according to the corrected pressure field, a new velocity field is obtained; then, whether the velocity field converges is checked according to whether the velocity no longer changes; if not, the corrected pressure value is used as the given pressure field to start the next level of calculation; and this process is repeated until a converged solution is obtained.

8. The method for simulating the migration and plugging process of a temporary plugging agent for deep shale gas fracturing according to claim 1, characterized in that: The calculation formula in step S50 includes: In the formula, is the flow-particle interaction force, N; is the stable drag force of particle i, N; is the indeterminate drag force, N; is the pressure gradient force, N; is the viscous force caused by the fluid shear stress or deviatoric stress tensor, N; is the lifting force, N; C d is the drag coefficient, dimensionless; Re i is the relative Reynolds number, dimensionless; is the fluid-particle relative velocity, m / s; μ f is the fluid viscosity, Pa·s; ε f is the volume fraction of the fracturing fluid phase, dimensionless; ρ f is the density of fracturing fluid, kg / m 3 ;d i is the particle size of particle i, mm.

9. The method for simulating the migration and plugging process of a temporary plugging agent for deep shale gas fracturing according to claim 1, characterized in that: The calculation formula in step S60 is: Where: m p,i is the mass of particle i, kg; is the translational velocity of the center of mass of particle i, m / s; is the center of mass position of particle i, m; CL p,i is the contact set of particle i; is the sum of the particle-particle interaction forces acting on particle i, N; is all fluid-particle interaction forces, N; is all the external forces acting on particle i by uniform or non-uniform external field, N; I p,i Moment of inertia of particle i, kg·m 2 ; is the rotation speed of particle j, rad / s; is the angular position of particle i, rad; is the torque generated by the particle-particle collision force acting on the contact point, N·m; is the torque generated by rolling friction, N·m.

10. The method for simulating the migration and plugging process of a temporary plugging agent for deep shale gas fracturing according to claim 1, characterized in that: The formula for the plugging effect index in the seam is: Where: I P is the sealing effect index in the seam, dimensionless; p P is the plugging pressure, Pa; t P The time for blocking is s.

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