Well periphery crack propagation simulation method, device and equipment based on phase field method and medium

Abstract

The invention discloses a method, a device and equipment for simulating propagation of cracks around a well based on a phase field method and a storage medium. The method comprises the following steps: dispersing reservoir rock mass around a borehole according to a preset finite element unit, and determining a finite element model of fracture propagation around the borehole; determining an initial value of a phase field damage variable of each finite element unit in the finite element model according to the borehole information and the well periphery perforation information; according to the initial value and water pressure applying information of the target unit, stress field distribution and displacement field distribution around the well are determined; and according to the stress field distribution and the displacement field distribution, determining a well periphery crack propagation simulation result. According to the technical scheme, the problems that an existing hydraulic fracture expansion simulation method is complex, low in accuracy and the like are solved, crack initiation and expansion of the hydraulic fracture along the perforation under the influence of the well periphery stress can be achieved, the expansion and extension characteristics of the hydraulic fracture under the influence of the well periphery stress can be represented, and then optimal design of hydraulic fracture is served.

Description

Technical Field

[0001] The present invention relates to the technical field of hydraulic fracturing, and in particular to a method, device, electronic equipment and storage medium for simulating wellbore fracture extension based on a phase field method. Background Art

[0002] Hydraulic fracturing technology is widely used in the field of oil and gas well production enhancement and transformation. Its action process is complex, involving the initiation and expansion mechanism of hydraulic fractures around the wellbore. During hydraulic fracturing construction, perforating bullets are used to penetrate the wellbore and the surrounding rock of the wellbore wall to form perforations around the wellbore. Under the action of high-flow injection pressure, the perforations around the wellbore often become the initiation points of the fractures, and the hydraulic fractures begin to expand and extend at the initiation points. The wellbore formed by drilling changes the initial ground stress field. Especially in the case of open hole completion, the combined action of the rock stress around the wellbore and the injection pressure makes the expansion morphology of the hydraulic fracture complex. Limited by the size of indoor experimental specimens and the high cost of in-situ field experiments, numerical simulation methods remain one of the main ways to study the expansion of hydraulic fractures around the wellbore.

[0003] Currently, commonly used hydraulic fracture propagation simulation methods can be divided into two categories: one is to "explicitly describe" the fracture using the geometric mesh. The fracture generally propagates along the mesh boundary, such as the zero-thickness interface element method and the discrete element method. The zero-thickness interface element method inserts zero-thickness interface elements at the mesh boundary. There is cohesion between the interface elements, which is used to simulate the tensile and shear stresses on the fracture surface. When the stress on the interface element reaches the fracture criterion, the interface element breaks and fails. Peri-well fractures are subject to complex stresses, and the diversion problem during the fracture propagation process needs to be explained. This type of method is more complicated when dealing with the diversion of fracture propagation, and many models require re-meshing of the geometric mesh. The other type is to "implicitly describe" the fracture morphology. In this type of method, the fracture does not need to propagate along the geometric mesh boundary. Numerical methods can be used to describe the distribution of the fracture within the geometric mesh, such as the extended finite element method and the phase-field fracture method. The extended finite element method adds the displacement discontinuity characteristics of the computational domain to the variational function and test function space by expanding the shape function. The displacement discontinuity of the fracture is implicitly included in the expanded shape function, thereby achieving the characterization of the fracture within the grid. However, the numerical algorithm of this method is relatively cumbersome, especially for three-dimensional hydraulic fracturing problems.

[0004] Therefore, there is an urgent need for a simulation scheme for wellbore fracture propagation with strong reliability, simple algorithm and high accuracy. Summary of the Invention

[0005] The present invention provides a method, device, equipment and storage medium for simulating the expansion of wellbore fractures based on the phase field method to solve the problems of complexity and low accuracy of existing hydraulic fracture expansion simulation methods. It can realize the initiation and expansion of hydraulic fractures along perforations under the influence of wellbore stress, characterize the expansion and extension characteristics of hydraulic fractures under the influence of wellbore stress, and thus serve the optimization design of hydraulic fracturing.

[0006] According to one aspect of the present invention, a method for simulating wellbore fracture propagation based on a phase field method is provided, the method comprising:

[0007] The finite element model of the fracture propagation around the wellbore is determined by discretizing the reservoir rock mass around the wellbore according to the pre-set finite element units;

[0008] Determining the initial value of the phase field damage variable of each finite element unit in the finite element model according to the wellbore information and the perforation information around the well;

[0009] Determine the stress field distribution and displacement field distribution around the well according to the initial value and the water pressure application information of the target unit; wherein the target unit includes the finite element unit associated with the wellbore and the finite element unit associated with the perforation around the well;

[0010] The simulation result of the wellbore perimeter fracture propagation is determined according to the stress field distribution and the displacement field distribution.

[0011] According to another aspect of the present invention, a device for simulating wellbore fracture propagation based on a phase field method is provided, the device comprising:

[0012] A finite element model determination module is used to discretize the reservoir rock mass around the wellbore based on pre-set finite element units to determine the finite element model of the fracture propagation around the wellbore;

[0013] An initial value determination module, configured to determine an initial value of a phase field damage variable of each finite element unit in the finite element model based on wellbore information and wellbore perimeter perforation information;

[0014] a field distribution determination module, configured to determine the stress field distribution and displacement field distribution around the well according to the initial value and the water pressure application information of the target unit; wherein the target unit includes a finite element unit associated with the wellbore and a finite element unit associated with the perforation around the well;

[0015] The simulation result determination module is used to determine the simulation result of the wellbore perimeter fracture expansion according to the stress field distribution and the displacement field distribution.

[0016] According to another aspect of the present invention, an electronic device is provided, comprising:

[0017] at least one processor; and

[0018] a memory communicatively connected to the at least one processor; wherein,

[0019] The memory stores a computer program executable by the at least one processor, and the computer program is executed by the at least one processor so that the at least one processor can execute the method for simulating wellbore fracture propagation based on the phase field method described in any embodiment of the present invention.

[0020] According to another aspect of the present invention, a computer-readable storage medium is provided, wherein the computer-readable storage medium stores computer instructions, and the computer instructions are used to enable a processor to implement the method for simulating wellbore fracture propagation based on the phase field method according to any embodiment of the present invention when executed.

[0021] The technical solution of the embodiment of the present invention discretizes the reservoir rock mass around the wellbore using pre-set finite element units to determine a finite element model for circumferential fracture propagation. Then, based on wellbore information and circumferential perforation information, the initial values ​​of the phase field damage variables of each finite element in the finite element model are determined. The stress and displacement field distributions around the wellbore are then determined based on these initial values ​​and the water pressure application information of the target unit. Finally, the circumferential fracture propagation simulation results are determined based on these stress and displacement field distributions. This technical solution addresses the problems of existing hydraulic fracture propagation simulation methods, such as complexity and low accuracy. It can simulate the initiation and propagation of hydraulic fractures along perforations under the influence of circumferential stress, characterize the propagation and extension characteristics of hydraulic fractures under the influence of circumferential stress, and thus serve to optimize the design of hydraulic fracturing.

[0022] It should be understood that the content described in this section is not intended to identify the key or important features of the embodiments of the present invention, nor is it intended to limit the scope of the present invention. Other features of the present invention will become readily understood through the following description. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the following briefly introduces the drawings required for use in the description of the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0024] Figure 1 This is a flow chart of a method for simulating wellbore fracture propagation based on a phase field method according to the first embodiment of the present invention;

[0025] Figure 2A This is a flow chart of a method for simulating wellbore fracture propagation based on a phase field method according to a second embodiment of the present invention;

[0026] Figure 2B Schematic diagram of the initial value distribution of phase field damage variables of the reservoir rock mass around the well provided by the second embodiment of the present invention.

[0027] Figure 2C Schematic diagram of the trajectory of the wellbore fracture expansion and extension provided by the second embodiment of the present invention.

[0028] Figure 3 2 is a schematic structural diagram of a wellbore fracture propagation simulation device based on a phase field method according to a third embodiment of the present invention;

[0029] Figure 4 It is a structural schematic diagram of an electronic device for implementing the wellbore fracture propagation simulation method based on the phase field method according to an embodiment of the present invention. DETAILED DESCRIPTION

[0030] In order to enable those skilled in the art to better understand the solutions of the present invention, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the embodiments described 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 making creative efforts should fall within the scope of protection of the present invention.

[0031] It should be noted that the terms "first", "second", etc. in the specification and claims of the present invention and the above-mentioned drawings are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that the data used in this way can be interchangeable where appropriate, so that the embodiments of the present invention described herein can be implemented in an order other than those illustrated or described herein. In addition, the terms "including" and "having" and any variations thereof are intended to cover non-exclusive inclusions. For example, a process, method, system, product or device that includes a series of steps or units is not necessarily limited to those steps or units clearly listed, but may include other steps or units that are not clearly listed or inherent to these processes, methods, products or devices. The acquisition, storage, use, processing, etc. of data in the technical solution of this application comply with the relevant provisions of national laws and regulations.

[0032] Example 1

[0033] Figure 1 A flow chart of a method for simulating the propagation of wellbore fractures based on the phase field method is provided for the first embodiment of the present invention. This embodiment is applicable to the simulation of the propagation of wellbore fractures under hydraulic fracturing conditions in oil and gas wells and geothermal wells. The method can be performed by a device for simulating the propagation of wellbore fractures based on the phase field method. The device can be implemented in the form of hardware and / or software, and the device can be configured in an electronic device. Figure 1As shown, the method includes:

[0034] S110 , discretizing the reservoir rock mass around the wellbore according to pre-set finite element units, and determining a finite element model of fracture propagation around the wellbore.

[0035] This solution can be executed by electronic devices such as computers and servers. These devices use a pre-configured finite element mesh to discretize the reservoir rock mass surrounding the wellbore, generating a finite element model of fracture propagation around the wellbore. Each mesh can be a finite element unit. Based on elasticity theory, phase-field fracture methods, and the finite element method, the electronic devices establish force balance governing equations and phase-field damage variable evolution governing equations. Based on each node in the finite element model, the electronic devices can set initial geostress field boundary conditions at the model boundaries.

[0036] S120 , determining an initial value of a phase field damage variable of each finite element unit in the finite element model according to the wellbore information and the perforation information around the wellbore.

[0037] Based on the wellbore information and the peri-well perforation information, the electronic device can determine the wellbore position and the peri-well perforation positions, and then determine the wellbore-associated finite element elements and the peri-well perforation-associated finite element elements in the finite element model based on the wellbore position and the peri-well perforation positions. The electronic device can use the wellbore-associated finite element elements and the peri-well perforation-associated finite element elements as target elements, set the initial value of the phase field damage variable of the target element to a first value, such as 1, and set the initial value of the phase field damage variable of the finite element elements in the finite element model other than the target element to a second value, such as 0.

[0038] S130 , determining the stress field distribution and displacement field distribution around the well according to the initial value and the water pressure application information of the target unit.

[0039] The target units include finite element units associated with the wellbore and finite element units associated with the perforations around the wellbore. It is understood that the electronic device can obtain water pressure application information for the target units, add the nodal integral term for the water pressure acting on the wellbore and perforations to the force balance control equation, and add the phase field integral term for the water pressure acting on the wellbore and perforations to the phase field damage variable evolution control equation. Based on the updated force balance control equation, the updated phase field damage variable evolution control equation, and the stiffness matrix of each finite element unit, the electronic device can generate a set of control equations that match each finite element unit, and then determine the overall control equation set of the finite element model based on the control equation set that matches each finite element unit. Based on the initial values ​​of the phase field damage variables of each finite element unit and the overall control equation set of the finite element model, the electronic device can solve the set of equations to obtain the stress field distribution and displacement field distribution around the wellbore.

[0040] S140 , determining a simulation result of a wellbore perimeter fracture propagation according to the stress field distribution and the displacement field distribution.

[0041] According to the stress field distribution and the displacement field distribution, the electronic device can determine the influence of the initial ground stress field on the propagation mode and propagation trajectory of the fracture around the well in S110.

[0042] The technical solution of the embodiment of the present invention discretizes the reservoir rock mass around the wellbore using pre-set finite element units to determine a finite element model for circumferential fracture propagation. Then, based on wellbore information and circumferential perforation information, the initial values ​​of the phase field damage variables of each finite element in the finite element model are determined. The stress and displacement field distributions around the wellbore are then determined based on these initial values ​​and the water pressure application information of the target unit. Finally, the circumferential fracture propagation simulation results are determined based on these stress and displacement field distributions. This technical solution addresses the problems of existing hydraulic fracture propagation simulation methods, such as complexity and low accuracy. It can simulate the initiation and propagation of hydraulic fractures along perforations under the influence of circumferential stress, characterize the propagation and extension characteristics of hydraulic fractures under the influence of circumferential stress, and thus serve to optimize the design of hydraulic fracturing.

[0043] Example 2

[0044] Figure 2A This is a flow chart of a method for simulating wellbore fracture propagation based on the phase field method provided in the second embodiment of the present invention. This embodiment is based on the above embodiment and is refined. Figure 2A As shown, the method includes:

[0045] S210 , discretizing the reservoir rock mass around the wellbore according to pre-set finite element units, and determining a finite element model of fracture propagation around the wellbore.

[0046] S220: Determine the initial value of the phase field damage variable of each finite element unit in the finite element model based on the wellbore information and the perforation information around the well.

[0047] In this solution, optionally, determining the initial value of the phase field damage variable of each finite element unit in the finite element model based on the wellbore information and the perforation information around the well includes:

[0048] Determining the target unit according to the wellbore information and the perforation information around the well;

[0049] Setting an initial value of a phase field damage variable of a target element in the finite element model to a first value;

[0050] The initial values ​​of the phase field damage variables of the finite element units other than the target unit in the finite element model are set to the second value.

[0051] The first value can be used to indicate that the wellbore and perforation areas are stress-free, i.e., the finite element elements associated with the wellbore and the perforation areas are completely damaged. The second value can be used to indicate that stress exists in the wellbore and perforation areas, i.e., the finite element elements associated with the wellbore and the perforation areas are undamaged.

[0052] In a specific embodiment, the first value may be 1 and the second value may be 0. The electronic device may determine the geometric distribution of the wellbore and the geometric distribution of the perforations around the wellbore based on the wellbore information and the perforation information around the wellbore. Based on the geometric distribution of the wellbore and the geometric distribution of the perforations around the wellbore, the electronic device may determine the finite element elements associated with the wellbore and the finite element elements associated with the perforations around the wellbore in the finite element model. The electronic device may use the finite element elements associated with the wellbore and the finite element elements associated with the perforations around the wellbore as target elements, set the initial value of the phase field damage variable of the target element to 1, and set the initial value of the phase field damage variable of the finite element elements other than the target element in the finite element model to 0.

[0053] S230 , determining a force balance control equation and a phase field damage variable evolution control equation according to the water pressure application information of the target unit and the finite element model.

[0054] In this embodiment, optionally, according to the finite element model, based on the theory of elastic mechanics, an initial force balance control equation is determined, and based on the phase field fracture principle, an initial phase field damage variable evolution control equation is determined;

[0055] According to the water pressure application information of the target unit, the target node force integral term is added to the initial force balance control equation to obtain the force balance control equation, and the phase field integral term is added to the initial phase field damage variable evolution control equation to obtain the phase field damage variable evolution control equation.

[0056] It is easy to understand that the target node force integral term can be the integral term of the water pressure acting on the target unit's associated node, and the phase field integral term can be the phase field integral term of the water pressure acting on the target unit. Specifically, the force balance control equation is:

[0057]

[0058]

[0059] Where i represents the node index in the finite element model, u represents the displacement, represents the unbalanced force generated by the displacement degree of freedom of node i, Ω represents the computational domain, d represents the damage variable, k represents the stability parameter of the numerical model, represents the displacement-deformation matrix of node i, σ0 represents the stress, The shape function representing the displacement degree of freedom of node i, represents the self-weight stress, represents the computational domain boundary, represents the surface force, S represents the integral area of ​​the computational domain boundary, F p represents the target node force integral term, p represents the water pressure, Represents the gradient of the damage variable. The phase field damage variable evolution control equation is:

[0060]

[0061]

[0062] Where i represents the node index in the finite element model, d represents the phase field damage variable, represents the unbalanced force generated by the phase field damage degree of freedom of node i, represents the shape function of the phase field damage degree of freedom of node i, H represents the maximum value of energy history, G c represents the energy release rate, c n represents the damage evolution type, n represents the damage evolution type parameter, l represents the crack width characteristic, represents the damage matrix, F d represents the phase field integral term, Ω represents the computational domain, p represents the water pressure, u represents the displacement vector, represents the gradient of the phase field damage variable.

[0063] S240 , determining a control equation group of each finite element according to the stiffness matrix matched with each finite element, the force balance control equation, and the phase field damage variable evolution control equation.

[0064] It can be understood that the stiffness matrix of the finite element unit can be expressed as:

[0065]

[0066]

[0067] Among them, K uu represents the displacement stiffness matrix, r represents the unbalanced force generated by the displacement freedom, u represents the displacement freedom, K dd represents the damage stiffness matrix, and d represents the phase field damage degree of freedom.

[0068] The electronic device can determine the stiffness matrix of each finite element unit according to the principle of the finite element method, and then determine the control equation group of each finite element unit according to the force balance control equation, the phase field damage variable evolution control equation and the stiffness matrix matched by each finite element unit.

[0069] S250: Determine the stress field distribution and displacement field distribution around the well according to the initial values ​​and the control equation group.

[0070] Based on the governing equations for each finite element, the electronic device determines the overall governing equations for the finite element model. Based on the initial values ​​of the phase field damage variables for each finite element in the finite element model and the overall governing equations, the propagation of the crack around the wellbore is simulated, thereby obtaining the stress and displacement field distributions around the wellbore.

[0071] In a feasible solution, determining the stress field distribution and displacement field distribution around the well based on the initial values ​​and the control equation group includes:

[0072] determining overall degrees of freedom according to each node in the finite element model;

[0073] According to the overall degree of freedom, determine the degree of freedom of each finite element matching;

[0074] Determine the overall stiffness matrix based on the matching degrees of freedom of each finite element unit and the stiffness matrix of each finite element unit;

[0075] Determining an overall control equation group based on the overall stiffness matrix and the control equation group;

[0076] The stress field distribution and displacement field distribution around the well are determined based on the initial values ​​and the overall control equation group.

[0077] As will be readily understood, the electronic device can determine the overall degrees of freedom based on each node in the finite element model. Once the overall degrees of freedom are determined, the electronic device can then determine the matching degrees of freedom for each finite element based on the overall degrees of freedom and the position of each finite element in the finite element model. Based on the matching degrees of freedom for each finite element, the stiffness matrices of each finite element are sequentially added to the overall stiffness matrix, thereby assembling the overall governing equations for the finite element model.

[0078] The electronic device can use the initial values ​​of the phase field damage variables of each finite element in the finite element model to solve the overall control equations and determine the displacement field distribution and phase field damage variable distribution of the finite element model. The displacement field distribution calculation formula can be expressed as:

[0079]

[0080] u (k) =u (k-1) +Δu;

[0081] Where r represents the unbalanced force generated by the displacement degree of freedom, u represents the displacement of the finite element node, k represents the time step, and Δu represents the displacement increment of the finite element node.

[0082] The phase field damage variable distribution can be expressed as:

[0083]

[0084] d (k) =d (k-1) +Δd;

[0085] Where r represents the unbalanced force generated by the phase field damage degree of freedom, d represents the phase field damage variable of the finite element node, k represents the time step, and Δd represents the increment of the phase field damage variable of the finite element node.

[0086] Based on the finite element method, electronic devices can calculate the stress and strain field distributions of finite element models. The formula for calculating the stress field distribution can be expressed as: σ = Dε, where σ represents the stress vector and D represents the strain-stress conversion matrix (constitutive relationship matrix). The formula for calculating the strain field distribution can be expressed as: ε = Au, where ε represents the strain vector and A represents the displacement-strain conversion matrix.

[0087] According to the phase field fracture theory, the phase field damage variables can be used to characterize the initiation and propagation of hydraulic fractures at the perforation. Figure 2B Schematic diagram of the initial value distribution of phase field damage variables of the reservoir rock mass around the well provided by the second embodiment of the present invention. Figure 2C Schematic diagram of the trajectory of the wellbore fracture expansion and extension provided by the second embodiment of the present invention. Figure 2B and Figure 2C The darker the medium gray color, the larger the phase field damage variable value. Figure 2B and Figure 2C , the changes in the distribution of phase-field damage variables during the propagation of the circumferential fracture can be determined. The distribution of mechanical characteristic parameters calculated above can characterize the stress and displacement fields of the reservoir rock mass around the wellbore and perforations, as well as the distribution of phase-field damage variables. Based on the distribution of the stress and displacement fields around the wellbore, electronic equipment can analyze the impact of the initial geostress field on the propagation mode and trajectory of the circumferential hydraulic fracture.

[0088] S260 , determining a simulation result of a wellbore perimeter crack expansion according to the stress field distribution and the displacement field distribution.

[0089] The technical solution of the embodiment of the present invention discretizes the reservoir rock mass around the wellbore using pre-set finite element units to determine a finite element model for circumferential fracture propagation. Then, based on wellbore information and circumferential perforation information, the initial values ​​of the phase field damage variables of each finite element in the finite element model are determined. The stress and displacement field distributions around the wellbore are then determined based on these initial values ​​and the water pressure application information of the target unit. Finally, the circumferential fracture propagation simulation results are determined based on these stress and displacement field distributions. This technical solution addresses the problems of existing hydraulic fracture propagation simulation methods, such as complexity and low accuracy. It can simulate the initiation and propagation of hydraulic fractures along perforations under the influence of circumferential stress, characterize the propagation and extension characteristics of hydraulic fractures under the influence of circumferential stress, and thus serve to optimize the design of hydraulic fracturing.

[0090] Example 3

[0091] Figure 3 This is a schematic diagram of the structure of a wellbore fracture expansion simulation device based on the phase field method provided in the third embodiment of the present invention. Figure 3 As shown, the device includes:

[0092] The finite element model determination module 310 is used to discretize the reservoir rock mass around the wellbore according to the pre-set finite element units to determine the finite element model of the fracture propagation around the wellbore;

[0093] An initial value determination module 320 is used to determine the initial value of the phase field damage variable of each finite element in the finite element model based on the wellbore information and the perforation information around the well;

[0094] A field distribution determination module 330 is configured to determine the stress field distribution and displacement field distribution around the well based on the initial values ​​and the water pressure application information of the target unit, wherein the target unit includes a finite element unit associated with the wellbore and a finite element unit associated with the perforation around the well;

[0095] The simulation result determination module 340 is used to determine the simulation result of the wellbore perimeter fracture propagation according to the stress field distribution and the displacement field distribution.

[0096] In this solution, optionally, the initial value determination module 320 is specifically configured to:

[0097] Determining the target unit according to the wellbore information and the perforation information around the well;

[0098] Setting an initial value of a phase field damage variable of a target element in the finite element model to a first value;

[0099] The initial values ​​of the phase field damage variables of the finite element units other than the target unit in the finite element model are set to the second value.

[0100] In a feasible solution, the field distribution determination module 330 includes:

[0101] a control equation determination unit, configured to determine a force balance control equation and a phase field damage variable evolution control equation based on the water pressure application information of the target unit and the finite element model;

[0102] A unit equation group determination unit is used to determine the control equation group of each finite element according to the stiffness matrix matched with each finite element, the force balance control equation and the phase field damage variable evolution control equation;

[0103] The field distribution determining unit is used to determine the stress field distribution and displacement field distribution around the well according to the initial value and the control equation group.

[0104] Based on the above solution, optionally, the field distribution determining unit is specifically configured to:

[0105] determining overall degrees of freedom according to each node in the finite element model;

[0106] According to the overall degree of freedom, determine the degree of freedom of each finite element matching;

[0107] Determine the overall stiffness matrix based on the matching degrees of freedom of each finite element unit and the stiffness matrix of each finite element unit;

[0108] Determining an overall control equation group based on the overall stiffness matrix and the control equation group;

[0109] The stress field distribution and displacement field distribution around the well are determined based on the initial values ​​and the overall control equation group.

[0110] In a feasible solution, the control equation determination unit is specifically used to:

[0111] According to the finite element model, based on the theory of elastic mechanics, the initial force balance control equation is determined, and based on the phase field fracture principle, the initial phase field damage variable evolution control equation is determined;

[0112] According to the water pressure application information of the target unit, the target node force integral term is added to the initial force balance control equation to obtain the force balance control equation, and the phase field integral term is added to the initial phase field damage variable evolution control equation to obtain the phase field damage variable evolution control equation.

[0113] Based on the above solution, optionally, the force balance control equation is:

[0114]

[0115]

[0116] Where i represents the node index in the finite element model, u represents the displacement, represents the unbalanced force generated by the displacement degree of freedom of node i, Ω represents the computational domain, d represents the damage variable, k represents the stability parameter of the numerical model, represents the displacement-deformation matrix of node i, σ0 represents the stress, The shape function representing the displacement degree of freedom of node i, represents the self-weight stress, represents the computational domain boundary, represents the surface force, S represents the integral area of ​​the computational domain boundary, F p represents the target node force integral term, p represents the water pressure, represents the gradient of the damage variable.

[0117] The phase field damage variable evolution control equation is:

[0118]

[0119]

[0120] Where i represents the node index in the finite element model, d represents the phase field damage variable, represents the unbalanced force generated by the phase field damage degree of freedom of node i, represents the shape function of the phase field damage degree of freedom of node i, H represents the maximum energy history parameter, G c represents the energy release rate, c n represents the damage evolution type, n represents the damage evolution type parameter, l represents the crack width characteristic, represents the damage matrix, F d represents the phase field integral term, Ω represents the computational domain, p represents the water pressure, u represents the displacement vector, represents the gradient of the phase field damage variable.

[0121] The wellbore fracture propagation simulation device based on the phase field method provided in an embodiment of the present invention can execute the wellbore fracture propagation simulation method based on the phase field method provided in any embodiment of the present invention, and has the corresponding functional modules and beneficial effects of the execution method.

[0122] Example 4

[0123] Figure 4A schematic diagram of the structure of an electronic device 410 that can be used to implement an embodiment of the present invention is shown. The electronic device is intended to represent various forms of digital computers, such as laptop computers, desktop computers, workstations, personal digital assistants, servers, blade servers, mainframe computers, and other suitable computers. The electronic device can also represent various forms of mobile devices, such as personal digital processing, cellular phones, smart phones, wearable devices (such as helmets, glasses, watches, etc.) and other similar computing devices. The components shown herein, their connections and relationships, and their functions are merely examples and are not intended to limit the implementation of the present invention described and / or required herein.

[0124] like Figure 4 As shown, the electronic device 410 includes at least one processor 411, and a memory connected to the at least one processor 411, such as a read-only memory (ROM) 412, a random access memory (RAM) 413, etc., wherein the memory stores a computer program that can be executed by the at least one processor, and the processor 411 can perform various appropriate actions and processes according to the computer program stored in the read-only memory (ROM) 412 or the computer program loaded from the storage unit 418 to the random access memory (RAM) 413. Various programs and data required for the operation of the electronic device 410 can also be stored in the RAM 413. The processor 411, ROM 412 and RAM 413 are connected to each other via a bus 414. An input / output (I / O) interface 415 is also connected to the bus 414.

[0125] Multiple components in electronic device 410 are connected to I / O interface 415, including an input unit 416, such as a keyboard, mouse, etc.; an output unit 417, such as various types of displays, speakers, etc.; a storage unit 418, such as a magnetic disk, optical disk, etc.; and a communication unit 419, such as a network card, modem, wireless communication transceiver, etc. The communication unit 419 allows electronic device 410 to exchange information / data with other devices via a computer network such as the Internet and / or various telecommunication networks.

[0126] Processor 411 can be any general-purpose and / or specialized processing component with processing and computing capabilities. Some examples of processor 411 include, but are not limited to, a central processing unit (CPU), a graphics processing unit (GPU), various specialized artificial intelligence (AI) computing chips, various processors running machine learning model algorithms, digital signal processors (DSPs), and any other suitable processors, controllers, microcontrollers, etc. Processor 411 executes the various methods and processes described above, such as the wellbore fracture propagation simulation method based on the phase-field method.

[0127] In some embodiments, the phase-field method-based method for simulating wellbore fracture propagation can be implemented as a computer program tangibly contained in a computer-readable storage medium, such as storage unit 418. In some embodiments, part or all of the computer program can be loaded and / or installed on electronic device 410 via ROM 412 and / or communication unit 419. When the computer program is loaded into RAM 413 and executed by processor 411, one or more steps of the phase-field method-based method for simulating wellbore fracture propagation described above can be performed. Alternatively, in other embodiments, processor 411 can be configured to execute the phase-field method-based method for simulating wellbore fracture propagation using any other appropriate means (e.g., via firmware).

[0128] Various embodiments of the systems and techniques described above can be implemented in digital electronic circuit systems, integrated circuit systems, field programmable gate arrays (FPGAs), application specific integrated circuits (ASICs), application specific standard products (ASSPs), systems on a chip (SOCs), complex programmable logic devices (CPLDs), computer hardware, firmware, software, and / or combinations thereof. These various embodiments can include being implemented in one or more computer programs that are executable and / or interpreted on a programmable system that includes at least one programmable processor, which can be a special purpose or general purpose programmable processor that can receive data and instructions from a storage system, at least one input device, and at least one output device, and transmit data and instructions to the storage system, the at least one input device, and the at least one output device.

[0129] Computer programs for implementing the methods of the present invention can be written in any combination of one or more programming languages. These computer programs can be provided to a processor of a general-purpose computer, a special-purpose computer, or other programmable phase-field-based wellbore fracture propagation simulation device, such that, when executed by the processor, the computer programs implement the functions / operations specified in the flowcharts and / or block diagrams. The computer programs can be executed entirely on the machine, partially on the machine, as a stand-alone software package, partially on the machine and partially on a remote machine, or entirely on a remote machine or server.

[0130] In the context of the present invention, computer-readable storage media can be tangible media that can contain or store a computer program for use with an instruction execution system, device or equipment or used in combination with an instruction execution system, device or equipment. Computer-readable storage media can include but are not limited to electronic, magnetic, optical, electromagnetic, infrared or semiconductor systems, devices or equipment, or any suitable combination of the foregoing. Alternatively, computer-readable storage media can be machine-readable signal media. More specific examples of machine-readable storage media can include electrical connections based on one or more lines, portable computer disks, hard disks, random access memories (RAM), read-only memories (ROM), erasable programmable read-only memories (EPROM or flash memory), optical fibers, portable compact disk read-only memories (CD-ROM), optical storage devices, magnetic storage devices, or any suitable combination of the foregoing.

[0131] To provide interaction with a user, the systems and techniques described herein can be implemented on an electronic device having: a display device (e.g., a CRT (cathode ray tube) or LCD (liquid crystal display) monitor) for displaying information to the user; and a keyboard and pointing device (e.g., a mouse or trackball) through which the user can provide input to the electronic device. Other types of devices can also be used to provide interaction with the user; for example, the feedback provided to the user can be any form of sensory feedback (e.g., visual feedback, auditory feedback, or tactile feedback); and input from the user can be received in any form (including acoustic input, voice input, or tactile input).

[0132] The systems and techniques described herein can be implemented in a computing system that includes back-end components (e.g., as a data server), or a computing system that includes middleware components (e.g., an application server), or a computing system that includes front-end components (e.g., a user computer with a graphical user interface or web browser through which a user can interact with implementations of the systems and techniques described herein), or a computing system that includes any combination of such back-end components, middleware components, or front-end components. The components of the system can be interconnected by any form or medium of digital data communication (e.g., a communication network). Examples of communication networks include: a local area network (LAN), a wide area network (WAN), a blockchain network, and the Internet.

[0133] A computing system may include clients and servers. The clients and servers are typically remote from each other and typically interact via a communication network. This client-server relationship arises through computer programs running on the respective computers, creating a client-server relationship. The server may be a cloud server, also known as a cloud computing server or cloud host. This server is a hosting product within the cloud computing service ecosystem that addresses the management difficulties and limited scalability of traditional physical hosting and VPS services.

[0134] It should be understood that the various forms of the processes shown above can be used to reorder, add, or delete steps. For example, the steps described in the present invention can be performed in parallel, sequentially, or in a different order, as long as the desired results of the technical solution of the present invention can be achieved. This is not limited herein.

[0135] The above specific embodiments do not limit the scope of protection of the present invention. Those skilled in the art will appreciate that various modifications, combinations, sub-combinations, and substitutions may be made based on design requirements and other factors. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention are intended to be included within the scope of protection of the present invention.

Claims

1. A method for simulating wellbore fracture propagation based on phase field method, characterized in that: The method comprises: The finite element model of the fracture propagation around the wellbore is determined by discretizing the reservoir rock mass around the wellbore according to the pre-set finite element units; Determining the initial value of the phase field damage variable of each finite element unit in the finite element model according to the wellbore information and the perforation information around the well; Determine the stress field distribution and displacement field distribution around the well according to the initial value and the water pressure application information of the target unit; wherein the target unit includes the finite element unit associated with the wellbore and the finite element unit associated with the perforation around the well; The simulation result of the wellbore perimeter fracture propagation is determined according to the stress field distribution and the displacement field distribution.

2. The method according to claim 1, characterized in that Determining the initial value of the phase field damage variable of each finite element unit in the finite element model based on the wellbore information and the perforation information around the well includes: Determining the target unit according to the wellbore information and the perforation information around the well; Setting an initial value of a phase field damage variable of a target element in the finite element model to a first value; The initial values ​​of the phase field damage variables of the finite element units other than the target unit in the finite element model are set to the second value.

3. The method according to claim 1, characterized in that Determining the stress field distribution and displacement field distribution around the well according to the initial value and the water pressure application information of the target unit includes: Determining a force balance control equation and a phase field damage variable evolution control equation based on the water pressure application information of the target unit and the finite element model; Determining a control equation group of each finite element according to the stiffness matrix matched with each finite element, the force balance control equation, and the phase field damage variable evolution control equation; The stress field distribution and displacement field distribution around the well are determined based on the initial values ​​and the control equation group.

4. The method according to claim 3, characterized in that Determining the stress field distribution and displacement field distribution around the well based on the initial values ​​and the control equation group includes: determining overall degrees of freedom according to each node in the finite element model; According to the overall degree of freedom, determine the degree of freedom of each finite element matching; Determine the overall stiffness matrix based on the matching degrees of freedom of each finite element unit and the stiffness matrix of each finite element unit; Determining an overall control equation group based on the overall stiffness matrix and the control equation group; The stress field distribution and displacement field distribution around the well are determined based on the initial values ​​and the overall control equation group.

5. The method according to claim 3, characterized in that The determining of the force balance control equation and the phase field damage variable evolution control equation based on the water pressure application information of the target unit and the finite element model includes: According to the finite element model, based on the theory of elastic mechanics, the initial force balance control equation is determined, and based on the phase field fracture principle, the initial phase field damage variable evolution control equation is determined; According to the water pressure application information of the target unit, the target node force integral term is added to the initial force balance control equation to obtain the force balance control equation, and the phase field integral term is added to the initial phase field damage variable evolution control equation to obtain the phase field damage variable evolution control equation.

6. The method according to claim 5, characterized in that The force balance control equation is: Where i represents the node index in the finite element model, u represents the displacement, represents the unbalanced force generated by the displacement degree of freedom of node i, Ω represents the computational domain, d represents the damage variable, k represents the stability parameter of the numerical model, represents the displacement-deformation matrix of node i, σ0 represents the stress, The shape function representing the displacement degree of freedom of node i, represents the self-weight stress, represents the computational domain boundary, represents the surface force, S represents the integral area of ​​the computational domain boundary, F p represents the target node force integral term, p represents the water pressure, represents the gradient of the damage variable.

7. The method according to claim 6, characterized in that The phase field damage variable evolution control equation is: Where i represents the node index in the finite element model, d represents the phase field damage variable, represents the unbalanced force generated by the phase field damage degree of freedom of node i, represents the shape function of the phase field damage degree of freedom of node i, H represents the maximum energy history parameter, G c represents the energy release rate, c n represents the damage evolution type, n represents the damage evolution type parameter, l represents the crack width characteristic, represents the damage matrix, F d represents the phase field integral term, Ω represents the computational domain, p represents the water pressure, u represents the displacement vector, represents the gradient of the phase field damage variable.

8. A device for simulating the propagation of wellbore fractures based on the phase field method, characterized in that: include: A finite element model determination module is used to discretize the reservoir rock mass around the wellbore based on pre-set finite element units to determine the finite element model of the fracture propagation around the wellbore; An initial value determination module, configured to determine an initial value of a phase field damage variable of each finite element unit in the finite element model based on wellbore information and wellbore perimeter perforation information; a field distribution determination module, configured to determine the stress field distribution and displacement field distribution around the well according to the initial value and the water pressure application information of the target unit; wherein the target unit includes a finite element unit associated with the wellbore and a finite element unit associated with the perforation around the well; The simulation result determination module is used to determine the simulation result of the wellbore perimeter fracture expansion according to the stress field distribution and the displacement field distribution.

9. An electronic device, characterized in that: The electronic device comprises: at least one processor; and a memory communicatively connected to the at least one processor; wherein, The memory stores a computer program executable by the at least one processor, and the computer program is executed by the at least one processor to enable the at least one processor to perform the method for simulating wellbore fracture propagation based on the phase field method according to any one of claims 1 to 7.

10. A computer-readable storage medium, characterized in that The computer-readable storage medium stores computer instructions, and the computer instructions are used to enable a processor to implement the wellbore fracture propagation simulation method based on the phase field method according to any one of claims 1 to 7 when executed.

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