Electric pulse-mechanical composite rock breaking simulation method and device

Abstract

The invention relates to the technical field of petroleum and natural gas drilling, and discloses an electric pulse-mechanical composite rock breaking simulation method and device.The method comprises the steps that an electric pulse drill bit and a mechanical drill bit in an electric pulse-mechanical composite rock breaking drill bit are modeled, and an electric pulse drill bit model and a mechanical drill bit model are obtained; simulating mechanical drill rock breaking according to the rock finite element model and the mechanical drill model; simulating electric pulse rock breaking according to the rock finite element model and an electric pulse drill model; rock related parameters in the mechanical drill bit rock breaking simulation and the electric pulse rock breaking simulation are coupled, and an electric pulse-mechanical composite rock breaking model is obtained; and performing rock breaking simulation according to the electric pulse-mechanical composite rock breaking model. The method provided by the invention can better fit the actual condition of the rock, so that the simulation of rock breaking of the electric pulse-mechanical composite drill bit and the improvement of the drill bit can be better realized.

Description

Technical Field

[0001] The present invention relates to the technical field of oil and gas drilling, and particularly relates to an electric pulse-mechanical compound rock breaking simulation method and device. Background Art

[0002] At present, with the rapid economic development, the energy demands of various countries are increasing continuously. It is estimated that from 2010 to 2040, the global energy demand will increase by 112%, and it is predicted that by 2040, 76% of the global energy consumption will come from fossil energy. As the main body of the energy structure, the demands for oil and gas will inevitably increase significantly. However, the easily accessible shallow oil and gas resources have been gradually exhausted after years of exploitation. In order to meet the growing global energy demand, obtaining oil and gas from deep formations will play an increasingly important role in energy supply. Internationally, formations with a depth of more than 4500m are generally defined as deep formations. In the past decade, deep oil and gas resources have occupied a major position in the newly added global reserves. The proven reserves of oil and gas in formations above 4000m account for 67% and 61% of the newly added proven reserves respectively.

[0003] According to statistics, the deep and ultra-deep oil and gas resources in China reach 67.1×10^8 t of oil equivalent, accounting for 34% of the total oil and gas resources. 39% of the remaining oil and 57% of the remaining natural gas resources are distributed in deep formations. The deep and ultra-deep oil and gas resources in China are mainly concentrated in the Tarim Basin and the Sichuan Basin: the proven oil and gas reserves above 5000m in the Tarim Basin account for about 80% of the total proven reserves, while the geological resource volume of 3500m - 4500m in the Sichuan Basin reaches 12.5×10^12 m 3 ³. The number of ultra-deep wells drilled in China annually exceeds 200. After 2017, the number of ultra-deep well drills in China has exceeded that of the United States. In 2020, 302 ultra-deep wells with a depth of more than 6000m were drilled, and nearly 50 ultra-deep wells with a depth of more than 8000m were completed cumulatively in 5 years.

[0004] The exploration and development of deep and ultra-deep oil and gas resources are the realistic fields and inevitable trends for the important breakthrough of China's petroleum industry, with great development potential. During the drilling process, the impact of the drill bit on the mechanical drilling rate exceeds 30%, which is one of the most important tools for improving the drilling speed. Therefore, advanced drill bit technology can significantly increase the mechanical drilling rate and thus reduce the drilling cost. The electric pulse-mechanical compound rock breaking drill bit combines the advantages of PDC drill bits and electric pulse rock breaking technology and is expected to become a new generation of high-efficiency rock breaking drill bits. However, at present, the research on the rock breaking process of electric pulse-mechanical compound rock breaking drill bits is relatively lacking. Summary of the Invention

[0005] The present invention aims to solve at least one of the technical problems in the above technologies to this end, and proposes an electric pulse-mechanical compound rock breaking simulation method, including:

[0006] Model the electric pulse drill bit and the mechanical drill bit in the electro-mechanical compound rock-breaking drill bit respectively to obtain the electric pulse drill bit model and the mechanical drill bit model;

[0007] Simulate the rock-breaking of the mechanical drill bit according to the rock finite element model and the mechanical drill bit model;

[0008] Simulate the electric pulse rock-breaking according to the rock finite element model and the electric pulse drill bit model;

[0009] Couple the rock-related parameters in the mechanical drill bit rock-breaking simulation and the electric pulse rock-breaking simulation to obtain the electro-mechanical compound rock-breaking model;

[0010] Conduct rock-breaking simulation according to the electro-mechanical compound rock-breaking model.

[0011] Preferably, the construction and mechanical parameter calibration process of the rock finite element model includes:

[0012] Establish a rock finite element model according to the size of the electro-mechanical compound rock-breaking drill bit;

[0013] Perform mesh division on the rock finite element model, and establish a finite element model based on Voronoi subdivision in the area that directly contacts the drill bit during rock-breaking;

[0014] Calibrate the mechanical parameters of the finite element model based on Voronoi subdivision by using uniaxial compression experiments and Brazilian splitting experiments; wherein, the mechanical parameters include: uniaxial compressive strength, tensile strength and Young's modulus.

[0015] Preferably, the establishment process of the finite element model based on Voronoi subdivision includes:

[0016] Construct a geometric model with a three-dimensional Voronoi grain shape;

[0017] Determine the material property of each unit of the three-dimensional Voronoi geometric model based on the material property of the rock in the target formation and the mesh division result of the rock finite element model; wherein,

[0018] The material property of the rock in the target formation is determined by XRD diffraction experiment and / or CT scan experiment; wherein, the material property includes: the composition of minerals, the mass fraction of minerals, the density of different minerals and the particle size range of mineral particles.

[0019] Preferably, the formula used for simulating the electric pulse rock-breaking according to the rock finite element model and the electric pulse drill bit model includes:

[0020]

[0021]

[0022]

[0023] Among them, S R represents the damage condition of the rock during the electro-pulse rock breaking process; t represents time; E e represents the electric field strength inside the rock that changes dynamically with the electrode voltage; a, b 1 , b 2 , c 1 , c 2 are constants fitted according to the experimental data; E S represents the dielectric strength of the rock under quasi-static conditions, and its value is regarded as equal to the ratio of the critical point of electrical breakdown of the rock to L e ; represents the potential difference between the high-voltage electrode and the ground electrode of the electro-pulse drill bit, and L e represents the distance between the high-voltage electrode and the ground electrode; ε r represents the relative permittivity of the rock; ε 0 represents the permittivity of vacuum; E R represents the elastic modulus of the rock; W R represents the volume energy of the rock;

[0024] f and g are logical functions, and their expressions are respectively:

[0025]

[0026]

[0027] Preferably, simulating the electro-pulse rock breaking according to the rock finite element model and the electro-pulse drill bit model includes: obtaining the damage distribution of the rock during electro-pulse rock breaking by applying a high-voltage electric pulse with a specific pulse rise front time and voltage on the electrode drill bit for electro-pulse rock breaking simulation.

[0028] Preferably, simulating the rock breaking according to the electro-pulse-mechanical composite rock breaking model includes:

[0029] simulating the rock breaking under different working conditions according to the electro-pulse-mechanical composite rock breaking model;

[0030] improving the structure of the electro-pulse-mechanical composite rock breaking drill bit according to the comparison results of the rock breaking effects of the electro-pulse-mechanical composite rock breaking drill bit under different working conditions;

[0031] repeating the above method based on the improved electro-pulse-mechanical composite rock breaking drill bit.

[0032] Preferably, the different working conditions include different high-voltage electric pulse parameters and different mechanical drilling parameters.

[0033] The present invention also provides an electro-pulse - mechanical composite rock breaking simulation system, including:

[0034] A drill bit modeling module, configured to model the electro-pulse drill bit and the mechanical drill bit in the electro-pulse - mechanical composite rock breaking drill bit respectively, to obtain an electro-pulse drill bit model and a mechanical drill bit model;

[0035] An independent simulation module, configured to simulate rock breaking by the mechanical drill bit according to the rock finite element model and the mechanical drill bit model; the rock breaking simulation module is further configured to simulate electro-pulse rock breaking according to the rock finite element model and the electro-pulse drill bit model;

[0036] A model coupling module, configured to couple the rock-related parameters in the mechanical drill bit rock breaking simulation and the electro-pulse rock breaking simulation to obtain an electro-pulse - mechanical composite rock breaking model;

[0037] A composite simulation module, configured to perform rock breaking simulation according to the electro-pulse - mechanical composite rock breaking model.

[0038] The present invention also provides an electronic device, including a memory and a processor, wherein a computer program or instruction is stored in the memory, and when the computer program or instruction is executed by the processor, it is at least used to implement the above method.

[0039] The present invention also provides a computer-readable storage medium, characterized in that a computer program or instruction is stored in the computer-readable storage medium, and when the computer program or instruction is executed by a processor, it is at least used to implement the above method.

[0040] Compared with the prior art, the beneficial effects of the present invention are as follows: The present invention establishes a rock finite element model based on Voronoi subdivision according to the mineral composition, mass fraction of minerals, density of different minerals, and particle size range of mineral particles in the drilling formation determined by XRD diffraction experiments and CT scanning experiments, which can better fit the actual situation of the rock, and further better realize the simulation of rock breaking by the electro-pulse - mechanical composite drill bit and the improvement of the drill bit.

[0041] Other features and advantages of the present invention will be described in the following description, and some of them will become obvious from the description, or be understood by implementing the present invention. The objectives and other advantages of the present invention can be achieved and obtained by the structures specifically pointed out in the written description and the drawings.

[0042] The technical solutions of the present invention will be further described in detail below with reference to the drawings and embodiments. Description of the Drawings

[0043] The accompanying drawings are used to provide a further understanding of the present invention, and constitute a part of the specification. Together with the embodiments of the present invention, they are used to explain the present invention, but do not constitute a limitation to the present invention. In the accompanying drawings:

[0044] Figure 1 Schematic diagram of the electro-pulse-mechanical compound rock-breaking simulation method given for the embodiment;

[0045] Figure 2 Flow chart of the electro-pulse-mechanical compound rock-breaking simulation given for the embodiment;

[0046] Figure 3 Schematic diagram of the disassembly modeling of the composite drill bit given for the embodiment;

[0047] Figure 4 Schematic diagram of the process of constructing the finite element model of the rock given for the embodiment;

[0048] Figure 5 Schematic diagram of the electro-pulse rock-breaking simulation process given for the embodiment;

[0049] Figure 6 Schematic diagram of the electro-pulse-mechanical compound rock-breaking simulation given for the embodiment;

[0050] Figure 7 Schematic diagram of the electro-pulse-mechanical compound rock-breaking simulation system given for the embodiment;

[0051] Figure 8 Schematic diagram of the electronic device given for the embodiment;

[0052] Figure 9 Schematic diagram of the computer-readable storage medium given for the embodiment. Detailed implementation manners

[0053] The present invention will be described below with reference to the accompanying drawings. The preferred embodiments described herein are only used to illustrate and explain the present invention, and are not used to limit the present invention.

[0054] Figure 1 The electro-pulse-mechanical compound rock-breaking simulation method given for the present invention includes:

[0055] Model the electro-pulse drill bit and the mechanical drill bit in the electro-pulse-mechanical compound rock-breaking drill bit respectively to obtain the electro-pulse drill bit model and the mechanical drill bit model;

[0056] Simulate the rock-breaking of the mechanical drill bit according to the finite element model of the rock and the mechanical drill bit model;

[0057] Simulate the electro-pulse rock-breaking according to the finite element model of the rock and the electro-pulse drill bit model;

[0058] Couple the rock-related parameters in the mechanical bit rock-breaking simulation and the electric pulse rock-breaking simulation to obtain an electric pulse-mechanical combined rock-breaking model;

[0059] Conduct rock-breaking simulation according to the electric pulse-mechanical combined rock-breaking model.

[0060] According to some embodiments of the present invention, the process of constructing a rock finite element model and calibrating mechanical parameters includes: establishing a rock finite element model according to the size of the electric pulse-mechanical combined rock-breaking bit; performing mesh division on the rock finite element model, and establishing a finite element model based on Voronoi subdivision in the area that directly contacts the bit during rock-breaking; calibrating the mechanical parameters of the finite element model based on Voronoi subdivision by using uniaxial compression experiments and Brazilian splitting experiments; wherein, the mechanical parameters include: uniaxial compressive strength, tensile strength, and Young's modulus.

[0061] According to some embodiments of the present invention, the process of establishing a finite element model based on Voronoi subdivision includes: constructing a geometric model with a three-dimensional Voronoi grain shape; determining the corresponding material properties of each unit in the three-dimensional Voronoi geometric model based on the material properties of the rock in the target formation and the mesh division result of the rock finite element model; wherein, the material properties of the rock in the target formation are determined according to XRD diffraction experiments and / or CT scan experiments; the material properties include: the composition of minerals, the mass fraction of minerals, the density of different minerals, and the particle size range of mineral particles;

[0062] According to some embodiments of the present invention, when simulating electric pulse rock-breaking according to the rock finite element model and the electric pulse bit model, the formulas used include:

[0063]

[0064]

[0065]

[0066] Among them, S R represents the damage situation of the rock during the electric pulse rock-breaking process; t represents time; E e represents the electric field strength that changes dynamically with the electrode voltage; a, b 1 、b 2 、c 1 、c 2 are constants fitted according to experimental data; E S represents the dielectric strength of the rock under quasi-static conditions, and its value is regarded as equal to the ratio of the critical point of the rock's electric breakdown to L e ; represents the potential difference between the high-voltage electrode and the ground electrode of the electric pulse bit, Le represents the distance between the high-voltage electrode and the grounding electrode; ε r represents the relative permittivity of the rock; ε 0 represents the permittivity of vacuum; E R represents the elastic modulus of the rock; W R represents the volumetric energy of the rock; f and g are logical functions, and their expressions are respectively:

[0067]

[0068]

[0069] According to some embodiments of the present invention, by applying a high-voltage electrical pulse with a specific pulse rise front time and voltage to the electrode bit for electrical pulse rock breaking simulation, the damage distribution of the rock during electrical pulse rock breaking is obtained.

[0070] According to some embodiments of the present invention, rock breaking simulation is carried out according to the electrical pulse-mechanical compound rock breaking model, including: carrying out rock breaking simulation under different working conditions (the different working conditions here include different bit structures, different high-voltage electrical pulse parameters and different mechanical drilling parameters) according to the electrical pulse-mechanical compound rock breaking model; improving the structure of the electrical pulse-mechanical compound rock breaking bit according to the comparison results of the rock breaking effects of the electrical pulse-mechanical compound rock breaking bit under different working conditions; repeating the above method based on the improved electrical pulse-mechanical compound rock breaking bit.

[0071] According to some embodiments of the present invention, as Figure 2 shown, the electrical pulse-mechanical compound rock breaking simulation method provided by the present invention includes the following steps:

[0072] Step 1: Use Solidworks to draw a three-dimensional model of the electrical pulse-mechanical compound rock breaking bit, and split it into an electrode bit and a PDC full bit. Figure 3 is a schematic diagram of splitting the compound rock breaking bit into an electrode bit and a PDC full bit.

[0073] Step 2: Establish a rock finite element model with a suitable size according to the maximum outer diameter of the electrical pulse-mechanical compound rock breaking bit; perform mesh division on the rock finite element model, subdivide the mesh of the area where the rock model is in direct contact with the electrical pulse-mechanical compound rock breaking, and establish a finite element model based on Voronoi subdivision in the subdivided area of the rock finite element model.

[0074] Step 3: Calibrate the mechanical parameters of each mineral material for the subdivided regions of the rock finite element model to make the mechanical properties of the subdivided regions consistent with the actual situation of the rock; in some embodiments of the present invention, uniaxial compression experiments and Brazilian splitting experiments are used for mechanical parameter calibration, and the calibrated mechanical parameters include uniaxial compression strength, tensile strength, and Young's modulus. This step and Step 2 are for the construction of the rock finite element model, and the construction process is as Figure 4 shown.

[0075] Step 4: Establish a rock geometric model in COMSOL Multiphysics that is consistent with the outer dimensions and spatial coordinates of the rock finite element model, and at the same time import the geometric model of the electrode drill bit; import the types, distribution, and electrical properties of the minerals in the calibrated finite element model based on Voronoi subdivision into the rock model in COMSOL Multiphysics in the form of interpolation functions, and establish relevant control equations according to the basic theory of rock fragmentation by electric pulses, and establish a dynamic damage model. The construction process is as Figure 5 shown;

[0076] The process of establishing the relevant control equations is as follows:

[0077] During the entire process of the electric pulse damaging the rock, the electric field change in the circuit always conforms to Maxwell's equations and the law of conservation of charge. The equations are as follows:

[0078] J = εE (1)

[0079] D = ε 0 ε r E (2)

[0080]

[0081]

[0082] In the formula, J is the current density; D is the electric displacement; E is the electric field strength (V / m); σ is the conductivity of the medium (rock, insulating liquid, etc.) (S / m); t is the time (s); ε 0 is the permittivity of free space; ε r is the relative permittivity of the medium (rock, insulating liquid, etc.) (F / m); is the electric potential, (V); ρ q is the charge density (C / m 3 );

[0083] The prerequisite for an electric pulse to break rock is that the rock undergoes electric breakdown. According to the solid electric breakdown theory, there is a threshold electric field strength Ec inside the rock during the electric breakdown process. Only when the modulus of the electric field strength formed between the high-voltage electrode and the grounded electrode is greater than |Ec| can the rock be broken down. Generally speaking, it takes a certain amount of time for the rock to undergo electric breakdown, that is, there is a hysteresis effect during the breakdown process. Therefore, when the energy in the circuit is injected into the rock as the plasma channel forms, the dielectric strength and time characteristics of the rock will interact with each other. On this basis, an electric breakdown criterion based on the "incubation time" is proposed, that is

[0084]

[0085] where E S is the dielectric strength of the rock under quasi-static conditions (V / m); ti is the incubation time (s); t 0 is the total time taken for the electric breakdown process (s); E(t) is the electric field strength that varies dynamically with time (V / m);

[0086] Introduce the state variable S R to characterize the damage suffered by the rock during the process of rock breaking by electric pulse. The value of S R is between 0 and 1; the rock in a certain area is approximately an insulator before electric breakdown, that is, S R = 0; S R = 1 indicates that complete electric breakdown has occurred, and at this time the rock is regarded as an ideal conductor; therefore, the state variable S R can also represent the damage caused by the electric pulse to the rock. Combining with the state variable SR of the rock, establish the control equation of the electric field of the breakdown circuit:

[0087]

[0088] where E e is the electric field strength that varies dynamically with the voltage of the electrode (V / m); E P is the local dielectric strength, which refers to the dielectric strength of the part of the rock where electric breakdown is about to occur (V / m), and it is a function related to the spatial distribution inside the rock and related to the properties of the rock itself (such as mineral type, density, etc.); τ is the hysteresis time (s), which refers to the time interval between the voltage peak and the current peak; the expressions of the logical functions f and g are respectively:

[0089]

[0090]

[0091] If the rock is to undergo electric breakdown, it is necessary to determine τ and |E P|. Experiments on electric breakdown show that there is approximately an exponential relationship between the delay time τ and the dielectric strength E of rock under quasi-static conditions. The relationship between the two can be expressed as: S Between them, it is roughly an exponential relationship, and the relationship between the two can be expressed as:

[0092]

[0093] In the formula, the meaning of E S is detailed above. a, b1, b2, c1, and c2 are constants fitted according to experimental data. Es can be directly measured through experiments, and its value is roughly equal to the ratio of the potential difference between the high-voltage electrode and the grounding electrode when the rock just undergoes electric breakdown to the electrode spacing L e , and is equal to the potential on the high-voltage electrode, that is

[0094]

[0095] In the formula, is the potential difference (V) between the high-voltage electrode and the grounding electrode; φH is the potential (V) at the high-voltage electrode end of the electrode bit; L e is the spacing (mm) between the high-voltage electrode and the grounding electrode;

[0096] Regarding the process of electric breakdown occurring inside the rock as a quasi-static process, during the formation of the plasma channel, the energy generated by the electric field includes electrostatic energy and mechanical energy generated due to the change in the electric field. The electrostatic energy density can be expressed as:

[0097]

[0098] In the formula, W q is the electrostatic energy density (J / m 3 ); E pe is the electric field strength (V / m) at the end of the plasma channel;

[0099] The density of the mechanical energy generated due to the change in the electric field can be expressed as:

[0100]

[0101] In the formula, W j is the density of mechanical energy (J / m 3 ); σ m is the Maxwell stress; γ is the strain;

[0102] The calculation formula for the Maxwell stress is:

[0103]

[0104] The relationship between the strain and the Maxwell stress is:

[0105]

[0106] Wherein, E R is the elastic modulus of the rock (GPa);

[0107] The total energy generated by the electric field can be expressed as:

[0108]

[0109] After the plasma channel is formed, to just break the rock, the total energy generated by the electric field must overcome the volume energy of the rock, that is

[0110]

[0111] Wherein, W R is the volume energy density of the rock (J / m 3 );

[0112] Solving Equation (16) gives:

[0113]

[0114] Step 5: Import the PDC bit geometric model into the calibrated rock finite element model based on Voronoi subdivision, set the corresponding boundary conditions, and establish a PDC bit rock-breaking model;

[0115] Step 6: Conduct numerical simulation of electric pulse rock breaking based on the dynamic damage model: Obtain the damage distribution of the rock by applying high-voltage electric pulses with a specific pulse rise front time and voltage on the electrode bit;

[0116] Step 7: Import the damage distribution of the rock into the PDC bit rock-breaking model, and couple the damage with the relevant parameters of the rock in the PDC bit rock-breaking model to establish an electric pulse-mechanical combined rock-breaking model. The construction process is as Figure 6 shown;

[0117] Step 8: Based on the electric pulse-mechanical combined rock-breaking model, conduct numerical simulations under different working conditions; Compare the rock-breaking effects of electric pulse-mechanical combined rock-breaking bits with different structural parameters under the same mechanical drilling parameters, and then optimize the design of the structure of the electric pulse-mechanical combined rock-breaking bit; Repeat steps 1 to 8 to further improve and optimize the structure of the electric pulse-mechanical combined rock-breaking bit.

[0118] Based on the same inventive concept, the present invention provides an electric pulse-mechanical combined rock-breaking simulation system, as Figure 7As shown in the figure, the system includes: a drill bit modeling module 201, which is used to model the electro-pulse drill bit and the mechanical drill bit in the electro-pulse-mechanical composite rock-breaking drill bit respectively to obtain an electro-pulse drill bit model and a mechanical drill bit model; an independent simulation module 202, which is used to simulate the rock-breaking of the mechanical drill bit according to the rock finite element model and the mechanical drill bit model; a rock-breaking simulation module 202, which is also used to simulate the electro-pulse rock-breaking according to the rock finite element model and the electro-pulse drill bit model; a model coupling module 203, which is used to couple the rock-related parameters in the mechanical drill bit rock-breaking simulation and the electro-pulse rock-breaking simulation to obtain an electro-pulse-mechanical composite rock-breaking model; a composite simulation module 204, which is used to simulate the rock-breaking according to the electro-pulse-mechanical composite rock-breaking model.

[0119] In addition, as Figure 8 shown in the figure, the present invention also provides an electronic device 1000, including a memory 1002 and a processor 1001. A computer program or instruction is stored in the memory 1002. When the computer program or instruction is executed by the processor 1001, it is at least used to implement the above method. As Figure 9 shown in the figure, the present invention also provides a computer-readable storage medium 1100. A computer program or instruction is stored in the computer-readable storage medium 1100. When the computer program or instruction is executed by the processor, it is at least used to implement the above method.

[0120] Obviously, those skilled in the art can make various changes and modifications to the present invention without departing from the spirit and scope of the present invention. Thus, if these modifications and variations of the present invention fall within the scope of the claims of the present invention and their equivalent technologies, the present invention also intends to include these changes and modifications.

Claims

1. An electric pulse-mechanical composite rock breaking simulation method, characterized in that: include: The electric pulse drill bit and the mechanical drill bit in the electric pulse-mechanical composite rock breaking drill bit are modeled respectively to obtain an electric pulse drill bit model and a mechanical drill bit model; Simulate rock breaking by mechanical drill bit based on rock finite element model and mechanical drill bit model; Simulating electric pulse rock breaking according to the rock finite element model and the electric pulse drill bit model; The rock-breaking simulation of mechanical drill bit is coupled with the rock-related parameters in the electric pulse rock-breaking simulation to obtain the electric pulse-mechanical composite rock-breaking model; Rock breaking simulation is performed according to the electric pulse-mechanical composite rock breaking model.

2. The method according to claim 1, characterized in that The construction of the rock finite element model and the mechanical parameter calibration process include: Establish a rock finite element model according to the size of the electric pulse-mechanical composite rock breaking drill bit; Meshing the rock finite element model, and establishing a finite element model based on Voronoi subdivision in the area directly contacting the drill bit during rock breaking; The mechanical parameters of the finite element model based on Voronoi subdivision are calibrated by using uniaxial compression test and Brazilian splitting test; wherein the mechanical parameters include: uniaxial compression strength, tensile strength and Young's modulus.

3. The method according to claim 1, characterized in that The process of establishing the finite element model based on Voronoi subdivision includes: Construct a three-dimensional Voronoi geometric model of the grain shape; Based on the material properties of the rock in the target stratum and the meshing results of the rock finite element model, the material properties of each unit of the three-dimensional Voronoi geometric model are determined; The material properties of the rock in the target stratum are determined based on XRD diffraction experiments and / or CT scanning experiments; wherein the material properties include: mineral composition, mineral mass fraction, density of different minerals and particle size range of mineral particles.

4. The method according to claim 1, characterized in that The electric pulse rock breaking is simulated according to the rock finite element model and the electric pulse drill bit model, and the formulas used include: Among them, S R Indicates the damage of rock during the electric pulse rock breaking process; t indicates time; E e represents the electric field strength inside the rock that changes dynamically with the electrode voltage; a, b1, b2, c1, c2 are constants fitted according to experimental data; E S It represents the dielectric strength of rock under quasi-static conditions, and its value is considered to be equal to the critical point of rock electrical breakdown. With L e The ratio of Indicates the potential difference between the high-voltage electrode and the ground electrode of the electric pulse drill, L e Indicates the distance between the high voltage electrode and the grounding electrode; ε r represents the relative permittivity of rock; ε0 represents the permittivity of vacuum; E R Represents the elastic modulus of rock; W R It represents the volume energy of rock; f and g are logical functions, and their expressions are:

5. The method according to claim 4, characterized in that The electric pulse rock breaking is simulated according to the rock finite element model and the electric pulse drill bit model, including: applying a high-voltage electric pulse with a specific pulse rising front time and voltage on the electrode drill bit to simulate the electric pulse rock breaking, and obtaining the rock damage distribution during the electric pulse rock breaking.

6. The method according to claim 1, characterized in that The rock breaking simulation is performed according to the electric pulse-mechanical composite rock breaking model, including: Perform rock breaking simulation under different working conditions according to the electric pulse-mechanical composite rock breaking model; According to the comparison results of the rock breaking effects of the electric pulse-mechanical composite rock breaking drill bit under different working conditions, the structure of the electric pulse-mechanical composite rock breaking drill bit is improved; The above method is repeated based on the improved electric pulse-mechanical composite rock breaking drill bit.

7. The method according to claim 6, characterized in that The different working conditions include different high-voltage electric pulse parameters and different mechanical drilling parameters.

8. An electric pulse-mechanical composite rock breaking simulation system, characterized in that: include: A drill bit modeling module is used to model the electric pulse drill bit and the mechanical drill bit in the electric pulse-mechanical composite rock breaking drill bit, respectively, to obtain an electric pulse drill bit model and a mechanical drill bit model; An independent simulation module is used to simulate rock breaking by a mechanical drill bit according to a rock finite element model and a mechanical drill bit model; the rock breaking simulation module is also used to simulate electric pulse rock breaking according to the rock finite element model and the electric pulse drill bit model; A model coupling module is used to couple the rock-related parameters in the mechanical drill bit rock breaking simulation with the electric pulse rock breaking simulation to obtain an electric pulse-mechanical composite rock breaking model; The composite simulation module is used to perform rock breaking simulation according to the electric pulse-mechanical composite rock breaking model.

9. An electronic device, characterized in that: The method comprises a memory and a processor, wherein the memory stores a computer program or instruction, and when the computer program or instruction is executed by the processor, it is used to implement at least the method described in any one of claims 1 to 8.

10. A computer-readable storage medium, characterized in that: The computer-readable storage medium stores a computer program or instruction, and when the computer program or instruction is executed by a processor, it is used to implement at least the method according to any one of claims 1 to 8.

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