Perforation well completion bursting pressure prediction method, system and equipment and storage medium

Abstract

The embodiment of the invention relates to the technical field of petroleum engineering fracturing, and discloses a perforation well completion fracture pressure prediction method, system and device and a storage medium, and the method comprises the steps: building a fluid-solid coupling phase field mathematical model; acquiring a stratum ground stress parameter, a rock mechanics parameter, a natural fracture parameter and a perforation parameter; based on the fluid-solid coupling phase field mathematical model, applying the stratum ground stress parameter, the rock mechanics parameter, the natural fracture parameter and the perforation parameter, considering that a perforation hole penetrates through a natural fracture, and establishing a perforation well completion fracture pressure prediction finite element model; and sequentially iteratively solving a displacement field, a phase field and a fluid pressure field of the perforation completion fracture pressure prediction finite element model by utilizing an interlacing algorithm to form an eyelet tip phase field cloud picture and a fluid pressure curve. The embodiment of the invention is proposed based on the principle of the phase field method, and has the advantages of the phase field method, that is, the expansion path of the crack can be obtained without a fracture judgment criterion and a reconstruction grid technology.

Description

Technical Field

[0001] The disclosed embodiments relate to the technical field of petroleum engineering fracturing, and in particular to a method, system, device and storage medium for predicting fracture pressure of perforation completion. Background Art

[0002] In the process of oil and gas development, especially in the process of increasing the production of fractured reservoirs, accurately predicting the fracture pressure of the formation at the perforation during fracturing is of great significance for optimizing the fracturing construction parameters.

[0003] Currently, most methods for predicting the fracture pressure of perforating fracturing require the combination of fracture criteria and do not consider the influence of natural fractures. In the actual fracturing process, the perforation holes may pass through natural fractures. In this case, a solution is urgently needed to predict the fracture pressure. Summary of the invention

[0004] The embodiments of the present disclosure provide a method, system, device and storage medium for predicting fracture pressure of a perforation completion well, so as to solve or alleviate one or more of the above technical problems in the prior art.

[0005] According to one aspect of the present disclosure, a method for predicting fracture pressure of a perforation completion is provided, comprising:

[0006] Establish a fluid-solid coupling phase field mathematical model;

[0007] Obtain formation in-situ stress parameters, rock mechanics parameters, natural fracture parameters and perforation parameters;

[0008] Based on the fluid-solid coupling phase field mathematical model, the formation in-situ stress parameters, rock mechanics parameters, natural fracture parameters and perforation parameters are applied, and a finite element model for predicting the fracture pressure of perforation completion is established by considering that the perforation holes pass through the natural fractures;

[0009] The displacement field, phase field and fluid pressure field of the perforation completion fracture pressure prediction finite element model are solved iteratively in sequence by using a staggered algorithm to form a perforation tip phase field cloud diagram and a fluid pressure curve;

[0010] The perforation completion fracture pressure is read according to the phase field cloud diagram at the hole tip and the fluid pressure curve.

[0011] In a possible implementation, establishing a fluid-solid coupling phase field mathematical model includes:

[0012] Establish a fluid-solid coupling mathematical model based on Biot's poroelasticity theory;

[0013] Phase field variables, fluid pressure and effective stress are introduced to jointly drive the evolution of phase field;

[0014] Introducing historical constant functions;

[0015] The phase field evolution equation is obtained according to the variational principle;

[0016] Based on the phase field evolution equation, a fluid-solid coupling phase field mathematical model is established to characterize the flow field in the hydraulic fractures of the formation, the formation pressure distribution and stress state, and the initiation and expansion morphology of the hydraulic fractures.

[0017] In a possible implementation, the expression of the fluid-solid coupling phase field mathematical model is:

[0018]

[0019] In the formula, d is the phase field, u is the displacement, p is the fluid pressure, ε is the strain, and k is a parameter to enhance numerical stability, which is 10 -6 , are the elastic energies of the tensile and compressive parts, respectively, l 0 is the internal length dimension, α is the Biot coefficient, G c is the critical energy release rate, b i ,t i represent body force and surface force respectively, λ,μ represent Lame constants respectively, σ is total stress, σ eff is the effective stress of the rock skeleton, H is the history field function, ψ is the total energy functional, Ω is the entire solid domain, and u i is the displacement component, S is the action boundary, tr is the trace function, t is a certain moment, T is the maximum solution time, and x is a certain position.

[0020] In a possible implementation, the obtaining of formation in-situ stress parameters, rock mechanics parameters, natural fracture parameters and perforation parameters includes:

[0021] The three-dimensional geostress parameters and formation pore pressure values ​​are obtained based on the well logging interpretation data;

[0022] Obtain the mechanical parameters of formation rocks based on core mechanics experimental tests or logging interpretation data;

[0023] The perforation parameters are obtained according to the perforation method and perforating gun bullet model during fracturing construction;

[0024] Obtain formation rock porosity and permeability based on core porosity test, permeability test or logging interpretation data;

[0025] The porosity and permeability parameters of natural fractures, as well as the degree of development, are obtained based on microseismic monitoring data or well logging interpretation data.

[0026] In a possible implementation, based on the fluid-solid coupling phase field mathematical model, applying the formation in-situ stress parameters, rock mechanics parameters, natural fracture parameters and perforation parameters, considering that the perforation holes pass through the natural fractures, establishing a perforation completion fracture pressure prediction finite element model includes:

[0027] Establish a finite element geometric model for predicting the fracture pressure of perforation completion;

[0028] Assigning values ​​of material parameters corresponding to the formation, perforation holes, and natural fractures to the perforation completion fracture pressure prediction finite element geometric model;

[0029] The ground stress parameters, construction displacement parameters and the phase field at the hole are added as boundary conditions to the assigned perforation completion fracture pressure prediction finite element geometric model to form the perforation completion fracture pressure prediction finite element model.

[0030] In a possible implementation, adding the ground stress parameter, the construction displacement parameter and the phase field at the hole as boundary conditions to the assigned perforation completion fracture pressure prediction finite element geometric model includes:

[0031] The phase field at the perforation hole is used as the first type boundary condition of the finite element geometric model for perforation completion fracture pressure prediction after assignment, and the initial value of the phase field at the perforation hole is set to 1;

[0032] The target reservoir in-situ stress parameters and construction displacement parameters are applied to the corresponding boundary conditions as the second type of boundary conditions of the finite element geometric model for perforation completion fracture pressure prediction after assignment.

[0033] In a possible implementation, the iteratively solving the displacement field, phase field and fluid pressure field of the perforation completion fracture pressure prediction finite element model in sequence by using the staggered algorithm includes:

[0034] Introduce shape function matrix and shape function derivative matrix;

[0035] The displacement field, phase field and fluid pressure field are discretized respectively using the shape function matrix and its shape function derivative matrix;

[0036] The residual expressions of the displacement field, phase field and fluid pressure field are calculated iteratively in sequence until the residual is less than the residual setting value, or the number of iterations exceeds the iteration number setting value.

[0037] In a possible implementation, the displacement field, phase field and fluid pressure field of the perforation completion fracture pressure prediction finite element model are solved iteratively in sequence using a staggered algorithm. The expressions are:

[0038]

[0039] Among them, Ru ,R d ,R p are the residuals of displacement field, phase field and fluid pressure field respectively, are the external forces of displacement field and phase field, respectively, is the external flux of the fluid pressure field, K u ,K d are the stiffness matrices of the displacement field and phase field, respectively, S p is the compression coefficient matrix, H p is the permeability matrix, N u 、N d and N p are the shape function matrices of displacement field, phase field and fluid pressure field, respectively, and B u ,B d ,B p are the derivatives of the shape function matrices of the displacement field, phase field and fluid pressure field, respectively; ρ is the density of the fracturing fluid; K is the formation permeability; μ is the viscosity of the fracturing fluid; k is a parameter to enhance numerical stability and is taken as 10 -6 , d is the phase field, u is the displacement, p is the fluid pressure, G c is the critical energy release rate, H is the history field function, D e is the stiffness matrix, N d The transpose of N p , S is the action boundary.

[0040] According to one aspect of the present disclosure, a perforation completion fracture pressure prediction system is provided, comprising:

[0041] Establishing a unit for establishing a fluid-solid coupling phase field mathematical model;

[0042] An acquisition unit, used to acquire formation in-situ stress parameters, rock mechanics parameters, natural fracture parameters and perforation parameters;

[0043] A construction unit is used to establish a finite element model for predicting the fracture pressure of perforation completion based on the fluid-solid coupling phase field mathematical model, applying the formation in-situ stress parameters, rock mechanics parameters, natural fracture parameters and perforation parameters, and considering that the perforation holes pass through the natural fractures;

[0044] A solving unit, used for iteratively solving the displacement field, phase field and fluid pressure field of the perforation completion fracture pressure prediction finite element model in sequence by using a staggered algorithm, to form a perforation tip phase field cloud diagram and a fluid pressure curve;

[0045] The reading unit is used to read the perforation completion fracture pressure according to the phase field cloud diagram at the hole tip and the fluid pressure curve.

[0046] In a possible implementation, the establishing unit includes:

[0047] The first building module is used to establish a fluid-solid coupling mathematical model based on Biot's poroelasticity theory;

[0048] The first introduction module is used to introduce phase field variables, fluid pressure and effective stress to jointly drive the evolution of the phase field;

[0049] The second introduction module is used to introduce the historical constant function;

[0050] An acquisition module, used to obtain the phase field evolution equation according to the variational principle;

[0051] The construction module is used to establish a fluid-solid coupling phase field mathematical model based on the phase field evolution equation to characterize the flow field in the hydraulic fracture of the formation, the formation pressure distribution and stress state, and the initiation and expansion morphology of the hydraulic fracture.

[0052] In a possible implementation, the expression of the fluid-solid coupling phase field mathematical model is:

[0053]

[0054] In the formula, d is the phase field, u is the displacement, p is the fluid pressure, ε is the strain, and k is a parameter to enhance numerical stability, which is 10 -6 , are the elastic energies of the tensile and compressive parts, respectively, l 0 is the internal length dimension, α is the Biot coefficient, G c is the critical energy release rate, b i ,t i represent body force and surface force respectively, λ,μ represent Lame constants respectively, σ is total stress, σ eff is the effective stress of the rock skeleton, H is the history field function, ψ is the total energy functional, Ω is the entire solid domain, and u i is the displacement component, S is the action boundary, tr is the trace function, t is a certain moment, T is the maximum solution time, and x is a certain position.

[0055] In a possible implementation, the acquiring unit includes:

[0056] The first acquisition module is used to obtain three-dimensional geostress parameters and formation pore pressure values ​​according to the logging interpretation data;

[0057] The second acquisition module is used to obtain mechanical parameters of formation rocks according to core mechanical experimental tests or logging interpretation data;

[0058] The third acquisition module is used to obtain perforation parameters according to the perforation method and perforating gun bullet model during fracturing construction;

[0059] The fourth acquisition module is used to obtain the porosity and permeability of the formation rock according to the core porosity test, permeability test or logging interpretation data;

[0060] The fifth acquisition module is used to obtain the porosity and permeability parameters and the development degree of natural fractures based on microseismic monitoring data or logging interpretation data.

[0061] In a possible implementation, the construction unit includes:

[0062] The second building module is to build a finite element geometric model for predicting the fracture pressure of perforation completion;

[0063] An assignment module, used for assigning values ​​of material parameters corresponding to formations, perforation holes, and natural fractures to the finite element geometric model for predicting the fracture pressure of perforation completion;

[0064] A module is formed, which is used to add the ground stress parameters, the construction displacement parameters and the phase field at the hole as boundary conditions to the assigned perforation completion fracture pressure prediction finite element geometric model to form the perforation completion fracture pressure prediction finite element model.

[0065] In a possible implementation, the assignment module is used to:

[0066] The phase field at the perforation hole is used as the first type boundary condition of the finite element geometric model for perforation completion fracture pressure prediction after assignment, and the initial value of the phase field at the perforation hole is set to 1;

[0067] The target reservoir in-situ stress parameters and construction displacement parameters are applied to the corresponding boundary conditions as the second type of boundary conditions of the finite element geometric model for perforation completion fracture pressure prediction after assignment.

[0068] In a possible implementation, the solving unit includes:

[0069] The third introduction module is used to introduce the shape function matrix and the shape function derivative matrix;

[0070] A discretization module is used to discretize the displacement field, phase field and fluid pressure field respectively using the shape function matrix and its shape function derivative matrix;

[0071] The calculation module is used to iteratively calculate the residual expressions of the displacement field, phase field and fluid pressure field in sequence until the residual is less than the residual setting value 0.001, or the number of iterations exceeds the number of iterations setting value 100.

[0072] In a possible implementation, the expression of the solution unit is:

[0073]

[0074] Among them, R u ,R d ,R p are the residuals of displacement field, phase field and fluid pressure field respectively, are the external forces of displacement field and phase field, respectively, is the external flux of the fluid pressure field, K u ,K d are the stiffness matrices of the displacement field and phase field, respectively, S p is the compression coefficient matrix, H p is the permeability matrix, N u , N d ,N p are the shape function matrices of displacement field, phase field and fluid pressure field, respectively, and B u ,B d ,B p are the derivatives of the shape function matrices of the displacement field, phase field and fluid pressure field, respectively; ρ is the density of the fracturing fluid; K is the formation permeability; μ is the viscosity of the fracturing fluid; k is a parameter to enhance numerical stability and is taken as 10 -6 , d is the phase field, u is the displacement, p is the fluid pressure, G c is the critical energy release rate, H is the history field function, D e is the stiffness matrix, N d The transpose of N p is the transpose of , and S is the action boundary.

[0075] According to one aspect of the present disclosure, a perforation completion fracture pressure prediction device is provided, comprising:

[0076] Processor and memory;

[0077] The memory is used to store a computer program, and the processor calls the computer program stored in the memory to execute any of the above-mentioned perforation completion fracture pressure prediction methods.

[0078] According to one aspect of the present disclosure, a computer-readable storage medium is provided, wherein a computer program is stored in the computer-readable storage medium. When the computer program is executed by a processor, the processor is enabled to execute any of the above-mentioned methods for predicting fracture pressure of perforation completion.

[0079] The exemplary embodiments of the present disclosure have the following beneficial effects:

[0080] (1) The exemplary embodiments of the present disclosure are proposed based on the principle of phase field method, and therefore have the advantages of phase field method, that is, the propagation path of the crack can be obtained without fracture judgment criteria and grid reconstruction technology.

[0081] (2) The exemplary embodiment of the present disclosure obtains the rupture pressure by reading the curve of the fluid pressure at the end of the hole over time. The fluid pressure rises to a peak point and then gradually decreases. The peak value of the fluid pressure is the rupture pressure.

[0082] (3) The exemplary embodiments of the present disclosure are also applicable to reservoirs with developed natural fractures, taking into account the impact of natural fractures on the expansion of hydraulic fractures, and are capable of calculating the impact of natural fractures of different orientations on the fracturing pressure.

[0083] The details of one or more embodiments of the present application are presented in the following drawings and descriptions. Other features and advantages of the present application will become apparent from the accompanying drawings. It should be understood that the above general description and the detailed descriptions below are only exemplary and explanatory and cannot limit the present disclosure. BRIEF DESCRIPTION OF THE DRAWINGS

[0084] The accompanying drawings herein are incorporated into the specification and constitute a part of the specification, illustrate embodiments consistent with the present disclosure, and together with the specification are used to explain the principles of the present disclosure. Obviously, the accompanying drawings described below are only some embodiments of the present disclosure, and for ordinary technicians in this field, other accompanying drawings can be obtained based on these accompanying drawings without creative work.

[0085] Figure 1 is a flow chart of a method for predicting fracture pressure of a perforation completion according to the exemplary embodiment;

[0086] Figure 2 is a flow chart of the exemplary embodiment for calculating a prediction of a perforated completion fracture pressure;

[0087] Figure 3 This exemplary embodiment Figure 2 The specific flow chart of step S110 is shown;

[0088] Figure 4 This exemplary embodiment Figure 2 The specific flow chart of step S120 is shown;

[0089] Figure 5 This exemplary embodiment Figure 2 The specific flow chart of step S130 is shown;

[0090] Figure 6 is a flow chart of the exemplary embodiment of using the staggered algorithm to sequentially iteratively solve the displacement field, the phase field and the fluid pressure field;

[0091] Figure 7 is a schematic diagram of a wellbore-perforation hole-formation finite element geometric model and its boundary conditions of the exemplary embodiment;

[0092] Figure 8 is a pore fluid pressure distribution cloud diagram obtained by solving the model of this exemplary embodiment;

[0093] Fig. 9 is a hydraulic fracture phase field cloud diagram obtained by solving the model of this exemplary embodiment;

[0094] Fig.10 is a schematic diagram of a curve of fluid pressure variation over time at the ends of holes in different directions obtained by solving the model of this exemplary embodiment;

[0095] Fig.11 is a block diagram of a perforation completion fracture pressure prediction system of the exemplary embodiment;

[0096] Fig.12 It is a schematic structural diagram of a perforation completion fracture pressure prediction device according to the exemplary embodiment of the present invention. DETAILED DESCRIPTION

[0097] Example embodiments will now be described more fully with reference to the accompanying drawings. However, example embodiments can be implemented in a variety of forms and should not be construed as being limited to the examples set forth herein; on the contrary, these embodiments are provided so that the present disclosure will be more comprehensive and complete, and the concepts of the example embodiments are fully conveyed to those skilled in the art. The described features, structures, or characteristics may be combined in one or more embodiments in any suitable manner. In the following description, many specific details are provided to provide a full understanding of the embodiments of the present disclosure. However, those skilled in the art will appreciate that the technical solutions of the present disclosure may be practiced while omitting one or more of the specific details, or other methods, components, devices, steps, etc. may be adopted. In other cases, known technical solutions are not shown or described in detail to avoid obscuring various aspects of the present disclosure.

[0098] In addition, the accompanying drawings are only schematic illustrations of the present disclosure and are not necessarily drawn to scale. The same reference numerals in the figures represent the same or similar parts, and thus their repeated description will be omitted. Some of the block diagrams shown in the accompanying drawings are functional entities and do not necessarily correspond to physically or logically independent entities. These functional entities can be implemented in software form, or implemented in one or more hardware units or integrated circuits, or implemented in different networks and / or processor devices and / or microcontroller devices.

[0099] The flowcharts shown in the accompanying drawings are only exemplary and do not necessarily include all the steps. For example, some steps may be decomposed, while some steps may be combined or partially combined, so the actual execution order may change according to the actual situation.

[0100] The terms "first", "second", etc. in the specification and claims of the present application 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 terms used in this way can be interchanged where appropriate, so that the embodiments of the present application described herein can be implemented in an order other than those illustrated or described herein, for example.

[0101] In addition, the terms "include" and "have" and any variations thereof are intended to cover non-exclusive inclusions. For example, a process, method, system, product, or apparatus comprising a series of steps or sub-modules is not necessarily limited to those steps or sub-modules explicitly listed, but may include other steps or sub-modules not explicitly listed or inherent to these processes, methods, products, or apparatuses.

[0102] The main purpose of the present invention is to provide a new method for calculating the fracture pressure of perforation completion, which does not need to be combined with fracture criteria and can take into account the influence of natural fractures. The proposed method can accurately predict the fracture pressure of perforation fracturing in natural fracture reservoirs, and provide help for optimizing fracturing construction parameters.

[0103] Figure 1 is a flow chart of a method for predicting fracture pressure of a perforation completion according to an exemplary embodiment of the present invention. Figure 1 As shown, an exemplary embodiment of the present disclosure provides a method for predicting fracture pressure of a perforation completion, comprising:

[0104] S1 Establish a mathematical model of fluid-solid coupling phase field;

[0105] S2 obtains formation in-situ stress parameters, rock mechanics parameters, natural fracture parameters and perforation parameters;

[0106] S3, based on the fluid-solid coupling phase field mathematical model, applying the formation in-situ stress parameters, rock mechanics parameters, natural fracture parameters and perforation parameters, considering that the perforation holes pass through the natural fractures, a finite element model for predicting the fracture pressure of the perforation completion is established;

[0107] S4 uses a staggered algorithm to iteratively solve the displacement field, phase field and fluid pressure field of the perforation completion fracture pressure prediction finite element model in sequence to form a perforation tip phase field cloud diagram and a fluid pressure curve;

[0108] S5: reading the perforation completion fracture pressure according to the phase field cloud diagram at the hole tip and the fluid pressure curve.

[0109] The present embodiment provides a method for predicting the fracture pressure of perforation completion based on the phase field method, including: establishing a fluid-solid coupling phase field mathematical model based on the linear elastic mechanics theory, the Darcy seepage theory of porous media and the phase field method, the mathematical model is used to characterize the flow field in the hydraulic fractures of the formation, the formation pressure distribution and stress state, and the initiation and expansion morphology of the hydraulic fractures; applying the above mathematical model to establish a finite element model for predicting the fracture pressure of perforation completion, the parameters required for model establishment include: formation ground stress parameters, rock mechanics parameters, natural fracture parameters and perforation parameters; using a shape function matrix and shape function derivatives to discretize the displacement field, phase field and fluid pressure field, and then using a separation algorithm to iteratively solve the three field variables in sequence; after the calculation is completed, a curve of the change of the pressure in the fracture with time during the hydraulic fracturing process is obtained, and the fracture pressure of the formation is read according to the curve.

[0110] The process of establishing the perforation completion fracture pressure prediction finite element model includes: collecting parameters required for modeling according to the well logging interpretation data and seismic interpretation data of the target reservoir; applying the ground stress parameters and construction displacement parameters of the target reservoir to the corresponding boundary conditions as the second type of boundary conditions of the model, and directly setting the initial value of the phase field at the perforation hole as the first type of boundary condition to be 1; using the interlaced algorithm to iteratively solve the displacement field, phase field and fluid pressure field in sequence; after the solution is completed, reading the perforation completion fracture pressure according to the phase field cloud map at the hole tip and the fluid pressure curve.

[0111] The above fluid-solid coupling phase field mathematical model is expressed by the following expression:

[0112]

[0113] Where d is the phase field, u is the displacement, p is the fluid pressure, ε is the strain, and k is a parameter to enhance numerical stability, which is 10 -6 , are the elastic energies of the tensile and compressive parts, respectively, l 0 is the internal length dimension, α is the Biot coefficient, G c is the critical energy release rate, b i ,t i represent body force and surface force respectively, λ,μ represent Lame constants respectively, σ is total stress, σ eff is the effective stress of rock skeleton, and H is the historical field function.

[0114] After establishing the above mathematical model, the shape function matrix and shape function derivative matrix are introduced to discretize, and the expressions of displacement field, phase field and fluid pressure field are solved iteratively in sequence using the staggered algorithm as follows:

[0115]

[0116] Among them, R u ,Rd ,R p are the residuals of displacement field, phase field and fluid pressure field respectively, are the external forces of displacement field and phase field, respectively, is the external flux of the fluid pressure field, K u ,K d are the stiffness matrices of the displacement field and phase field, respectively, S p is the compression coefficient matrix, H p is the permeability matrix, N u , N d ,N p are the shape function matrices of displacement field, phase field and fluid pressure field, respectively, and B u ,B d ,B p are the derivatives of the shape function matrices of the displacement field, phase field and fluid pressure field, respectively; ρ is the density of the fracturing fluid; K is the formation permeability; and μ is the viscosity of the fracturing fluid.

[0117] Other functions of the above-mentioned perforation completion fracture pressure prediction finite element model include: optimizing the input fracturing construction parameters and perforation parameters by modifying them; and predicting the hydraulic fracture expansion mode.

[0118] like Figure 2 As shown in Figure 1, the process of perforating completion fracture pressure prediction includes the following steps:

[0119] S110 established a fluid-solid coupling mathematical model and introduced the phase field method to describe the morphology of hydraulic fractures;

[0120] S120 obtains formation in-situ stress parameters, rock mechanics parameters, natural fracture parameters and perforation parameters;

[0121] S130 considers that the perforation holes pass through natural fractures and establishes a finite element model for predicting the fracture pressure of perforation completion;

[0122] S140 uses an interleaved algorithm to iteratively solve the displacement field, phase field and fluid pressure field in sequence;

[0123] S150 reads the perforation completion fracture pressure based on the phase field cloud diagram at the hole tip and the fluid pressure curve.

[0124] Specifically, Figure 3 As shown, S110 establishes the fluid-solid coupling phase field mathematical model including:

[0125] S111 Establish a fluid-solid coupling mathematical model based on Biot's poroelasticity theory;

[0126] S112 introduces phase field variables, fluid pressure and effective stress to jointly drive the evolution of the phase field;

[0127] S113 In order to prevent the closure of opened cracks, a historical constant function is introduced;

[0128] S114 obtains the phase field evolution equation according to the variational principle.

[0129] Specifically, the expression of the fluid-solid coupling phase field mathematical model is:

[0130]

[0131] In the formula, d is the phase field, u is the displacement, p is the fluid pressure, ε is the strain, and k is a parameter to enhance numerical stability, which is 10 -6 , are the elastic energies of the tensile and compressive parts, respectively, l 0 is the internal length dimension, α is the Biot coefficient, G c is the critical energy release rate, b i ,t i represent body force and surface force respectively, λ,μ represent Lame constants respectively, σ is total stress, σ eff is the effective stress of the rock skeleton, H is the history field function, is the total energy functional, Ω is the entire solid domain, u i is the displacement component, S is the action boundary, tr is the trace function, t is a certain moment, T is the maximum solution time, and x is a certain position.

[0132] Specifically, Figure 4 The step S120 acquires formation in-situ stress parameters, rock mechanics parameters, natural fracture parameters and perforation parameters; including:

[0133] S121 obtains three-dimensional geostress parameters and formation pore pressure values ​​based on logging interpretation data;

[0134] S122 obtains mechanical parameters of formation rocks based on core mechanical experimental tests or logging interpretation data;

[0135] S123 obtains perforation parameters according to the perforation method and perforating gun bullet model during fracturing construction;

[0136] S124 obtains formation rock porosity and permeability based on core porosity test, permeability test or logging interpretation data;

[0137] S125 obtains the porosity and permeability parameters and development degree of natural fractures based on microseismic monitoring data or logging interpretation data.

[0138] Specifically, Figure 5 As shown, the S130 considers that the perforation holes pass through natural fractures, and establishes a finite element model for predicting the fracture pressure of perforation completion, including:

[0139] S131 Establish a finite element geometric model for predicting the fracture pressure of perforated completion;

[0140] S132 assigns corresponding material parameters to formations, perforations, and natural fractures;

[0141] S133 applies the ground stress parameters, construction displacement parameters and the phase field at the hole as boundary conditions to the model;

[0142] S134 Establish a finite element network model and solve it.

[0143] Specifically, adding the ground stress parameter, the construction displacement parameter and the phase field at the hole as boundary conditions to the assigned perforation completion fracture pressure prediction finite element geometric model includes:

[0144] The phase field at the perforation hole is used as the first type boundary condition of the finite element geometric model for perforation completion fracture pressure prediction after assignment, and the initial value of the phase field at the perforation hole is set to 1;

[0145] The target reservoir in-situ stress parameters and construction displacement parameters are applied to the corresponding boundary conditions as the second type of boundary conditions of the finite element geometric model for perforation completion fracture pressure prediction after assignment.

[0146] Specifically, Figure 6 As shown, the S140 uses the staggered algorithm to iteratively solve the displacement field, the phase field and the fluid pressure field in sequence, including:

[0147] S141 introduces shape function matrix and shape function derivative matrix;

[0148] S142 discretizes the displacement field, phase field and fluid pressure field respectively using the shape function matrix and its shape function derivative matrix;

[0149] S143 iteratively calculates the residual expressions of the displacement field, phase field and fluid pressure field in sequence until the residual is less than a residual setting value, or the number of iterations exceeds a set number of iterations.

[0150] If the S144 residual is less than the set value, it will enter the next time step; if the number of iterations exceeds the set value, the calculation will stop.

[0151] Specifically, the expressions of displacement field, phase field and fluid pressure field of the perforation completion fracture pressure prediction finite element model are solved iteratively in sequence using the staggered algorithm:

[0152]

[0153] Among them, R u ,R d ,R p are the residuals of displacement field, phase field and fluid pressure field respectively, are the external forces of displacement field and phase field, respectively, is the external flux of the fluid pressure field, K u ,K d are the stiffness matrices of the displacement field and phase field, respectively, S p is the compression coefficient matrix, H p is the permeability matrix, N u , N d ,N p are the shape function matrices of displacement field, phase field and fluid pressure field, respectively, and B u ,B d ,B p are the derivatives of the shape function matrices of the displacement field, phase field and fluid pressure field, respectively; ρ is the density of the fracturing fluid; K is the formation permeability; μ is the viscosity of the fracturing fluid; k is a parameter to enhance numerical stability and is taken as 10 -6 , d is the phase field, u is the displacement, p is the fluid pressure, G c is the critical energy release rate, H is the history field function, D e is the stiffness matrix, N d The transpose of N p is the transpose of , and S is the action boundary.

[0154] The present invention provides a specific application example of the above-mentioned perforation completion fracture pressure calculation method. The model parameters used in the calculation of this embodiment are shown in Table 1 (main model parameter table of the embodiment).

[0155] Table 1

[0156] parameter data Maximum horizontal principal stress / MPa 50 Minimum horizontal principal stress / MPa 40 Reservoir Young's modulus / GPa 45 Reservoir Poisson's ratio 0.3 Rock critical energy release rate / N / m 2024 Internal length / mm 10 Biot coefficient 0.7 Reservoir matrix permeability / mD 0.32 Hydraulic fracture and natural fracture permeability / mD 10000 <![CDATA[Reservoir rock density / g / cm 3 > 2.54 Reservoir porosity 0.058 Perforation phase angle / ° 60 Perforation penetration / mm 200 Perforation aperture / mm 13 Wellbore diameter / mm 152.7 Fluid viscosity / mPa·s 1

[0157] The geometric model of the embodiment can be found in Figure 7 , where the side length of the square formation is 2m, the wellbore is located in the center of the formation, and the positions of the two natural fractures in the formation are shown in the figure, one of which passes through the perforation hole.

[0158] Substitute the model parameters in Table 1 into the perforation completion finite element model. Figure 6 The flow chart of the interleaved algorithm solves the displacement field, fluid pressure field and phase field in sequence. The maximum number of iterations is set to 100 times. When the residuals of the displacement field, phase field and fluid pressure field are less than 0.001, the results of the time step are output and the next time step is automatically calculated.

[0159] After the calculation is completed, the fluid pressure distribution cloud map can be output ( Figure 8 ), hydraulic fracture phase field cloud diagram ( Fig. 9 ) and the time variation curves of fluid pressure at the ends of holes in different directions ( Fig.10), the fracture pressure of the target reservoir can be obtained by analyzing the cloud map and the curve. The above curves and cloud maps are only output data necessary for obtaining the fracture pressure as an embodiment, and do not represent all output results of the present invention. The output results of the present invention also include: displacement distribution cloud map, flow velocity size distribution cloud map, formation stress / strain distribution cloud map, displacement change curve over time, bottom hole pressure change curve over time, etc.

[0160] pass Fig.10 The bursting pressure read was 76.5 MPa, and the bursting pressure obtained through the pump pressure curve during on-site construction was 79 MPa, with a relative error of 3.3%, which proved the accuracy of the present invention.

[0161] pass Fig.10 The fluid pressure curve can also be used to obtain the extension pressure of the hydraulic fracture in different directions. The value when the fluid pressure tends to be stable with time is the hydraulic fracture extension pressure. In the embodiment, the hydraulic fracture extension pressure of the target reservoir is 56.5 MPa.

[0162] Fig.10 It can also be used to analyze the effect of natural fractures on fracture pressure. Fig.10 As shown in the figure, the influence of natural fractures on holes in different directions is specifically manifested as follows: hole 1, due to the leakage of injected fluid along the natural fracture, the initiation of hydraulic fracture is delayed, but the magnitude of the fracture pressure does not change significantly due to the existence of natural fractures, and the fracture extension pressure in this direction is the smallest; hole 2, the fluid in hole 1 is lost along the natural fracture to the formation near hole 2, resulting in a smaller fracture pressure in hole 2 than in hole 3, but the fracture extension pressure of hole 2 is not much different from that of hole 3; hole 3 is symmetrical with hole 2 in position, but because it is far away from the natural fracture, the stress field near hole 2 is not affected by the natural fracture, its fracture pressure is greater than that of hole 2, and its fracture time is slower than that of hole 3; hole 4 is in the same direction as hole 1, but because there is a certain distance between the natural fracture and hole 4, the fracture time and fracture pressure of hole 4 are not affected by the natural fracture. When the hydraulic fracture intersects with the natural fracture, the curve drops sharply and then begins to hold pressure. After the fluid pressure reaches the fracture pressure level, the hydraulic fracture passes through the natural fracture, and the fracture extension pressure of hole 4 is the largest.

[0163] In addition, in addition to the influence of the above-mentioned natural fracture factors on the fracture pressure, the perforation completion fracture pressure calculation method described in the embodiment of the present invention can also be used to analyze the influence of factors such as horizontal stress difference, perforation azimuth, perforation penetration, perforation aperture, rock mechanical properties, fluid properties, etc. on the fracture pressure and extension pressure, thereby conducting a more in-depth analysis of the fracture initiation and expansion laws of the target reservoir.

[0164] Fig.11 is a block diagram of a perforation completion fracture pressure prediction system of the exemplary embodiment of the present invention. Fig.11 As shown, an exemplary embodiment of the present disclosure provides a perforation completion fracture pressure prediction system, comprising:

[0165] Establishing unit 10, for establishing a fluid-solid coupling phase field mathematical model;

[0166] An acquisition unit 20 is used to acquire formation in-situ stress parameters, rock mechanics parameters, natural fracture parameters and perforation parameters;

[0167] A construction unit 30 is used to establish a finite element model for predicting the fracture pressure of perforation completion based on the fluid-solid coupling phase field mathematical model, applying the formation in-situ stress parameters, rock mechanics parameters, natural fracture parameters and perforation parameters, and considering that the perforation holes pass through the natural fractures;

[0168] A solving unit 40 is used to iteratively solve the displacement field, phase field and fluid pressure field of the perforation completion fracture pressure prediction finite element model in sequence by using a staggered algorithm to form a perforation tip phase field cloud diagram and a fluid pressure curve;

[0169] The reading unit 50 is used to read the perforation completion fracture pressure according to the phase field cloud diagram at the hole tip and the fluid pressure curve.

[0170] Specifically, the establishment unit includes:

[0171] The first building module is used to establish a fluid-solid coupling mathematical model based on Biot's poroelasticity theory;

[0172] The first introduction module is used to introduce phase field variables, fluid pressure and effective stress to jointly drive the evolution of the phase field;

[0173] The second introduction module is used to introduce the historical constant function;

[0174] An acquisition module, used to obtain the phase field evolution equation according to the variational principle;

[0175] The construction module is used to establish a fluid-solid coupling phase field mathematical model based on the phase field evolution equation to characterize the flow field in the hydraulic fracture of the formation, the formation pressure distribution and stress state, and the initiation and expansion morphology of the hydraulic fracture.

[0176] Specifically, the expression of the fluid-solid coupling phase field mathematical model is:

[0177]

[0178] In the formula, d is the phase field, u is the displacement, p is the fluid pressure, ε is the strain, and k is a parameter to enhance numerical stability, which is 10 -6 , are the elastic energies of the tensile and compressive parts, respectively, l 0is the internal length dimension, α is the Biot coefficient, G c is the critical energy release rate, b i ,t i represent body force and surface force respectively, λ,μ represent Lame constants respectively, σ is total stress, σ eff is the effective stress of the rock skeleton, H is the history field function, ψ is the total energy functional, Ω is the entire solid domain, and u i is the displacement component, S is the action boundary, tr is the trace function, t is a certain moment, T is the maximum solution time, and x is a certain position.

[0179] Specifically, the acquisition unit includes:

[0180] The first acquisition module is used to obtain three-dimensional geostress parameters and formation pore pressure values ​​according to the well logging interpretation data;

[0181] The second acquisition module is used to obtain mechanical parameters of formation rocks according to core mechanical experimental tests or logging interpretation data;

[0182] The third acquisition module is used to obtain perforation parameters according to the perforation method and perforating gun bullet model during fracturing construction;

[0183] The fourth acquisition module is used to obtain the porosity and permeability of the formation rock according to the core porosity test, permeability test or logging interpretation data;

[0184] The fifth acquisition module is used to obtain the porosity and permeability parameters and the development degree of natural fractures based on microseismic monitoring data or logging interpretation data.

[0185] Specifically, the construction unit includes:

[0186] The second building module is to build a finite element geometric model for predicting the fracture pressure of perforation completion;

[0187] An assignment module, used for assigning values ​​of material parameters corresponding to formations, perforation holes, and natural fractures to the finite element geometric model for predicting the fracture pressure of perforation completion;

[0188] A module is formed, which is used to add the ground stress parameters, the construction displacement parameters and the phase field at the hole as boundary conditions to the assigned perforation completion fracture pressure prediction finite element geometric model to form the perforation completion fracture pressure prediction finite element model.

[0189] Specifically, the assignment module is used to:

[0190] The phase field at the perforation hole is used as the first type boundary condition of the finite element geometric model for perforation completion fracture pressure prediction after assignment, and the initial value of the phase field at the perforation hole is set to 1;

[0191] The target reservoir in-situ stress parameters and construction displacement parameters are applied to the corresponding boundary conditions as the second type of boundary conditions of the finite element geometric model for perforation completion fracture pressure prediction after assignment.

[0192] Specifically, the solving unit includes:

[0193] The third introduction module is used to introduce the shape function matrix and the shape function derivative matrix;

[0194] A discretization module is used to discretize the displacement field, phase field and fluid pressure field respectively using the shape function matrix and its shape function derivative matrix;

[0195] The calculation module is used to iteratively calculate the residual expressions of the displacement field, the phase field and the fluid pressure field in sequence until the residual is less than a residual setting value, or the number of iterations exceeds a setting value of the number of iterations.

[0196] Specifically, the expression of the solution unit is:

[0197]

[0198] Among them, R u ,R d ,R p are the residuals of displacement field, phase field and fluid pressure field respectively, are the external forces of displacement field and phase field, respectively, is the external flux of the fluid pressure field, K u ,K d are the stiffness matrices of the displacement field and phase field, respectively, S p is the compression coefficient matrix, H p is the permeability matrix, N u , N d ,N p are the shape function matrices of displacement field, phase field and fluid pressure field, respectively, and B u ,B d ,B p are the derivatives of the shape function matrices of the displacement field, phase field and fluid pressure field, respectively; ρ is the density of the fracturing fluid; K is the formation permeability; μ is the viscosity of the fracturing fluid; k is a parameter to enhance numerical stability and is taken as 10 -6 , d is the phase field, u is the displacement, p is the fluid pressure, G c is the critical energy release rate, H is the history field function, D e is the stiffness matrix, N d The transpose of N p is the transpose of , and S is the action boundary.

[0199] Fig.12FIG. 1 is a schematic diagram of a perforation completion fracture pressure prediction device according to an exemplary embodiment of the present invention. Fig.12 As shown, corresponding to the perforation completion fracture pressure prediction method provided above, the present invention also provides a perforation completion fracture pressure prediction device. Since the embodiment of the device is similar to the above method embodiment, the description is relatively simple. For relevant parts, please refer to the description of the above method embodiment part. The device described below is only schematic. The device may include: a processor (processor) 1, a memory (memory) 2 and a communication bus (i.e., the above device bus) and a search engine, wherein the processor 1 and the memory 2 communicate with each other through the communication bus and communicate with the outside through the communication interface. The processor 1 can call the logic instructions in the memory 2 to execute the perforation completion fracture pressure prediction method.

[0200] In addition, the logic instructions in the above-mentioned memory 2 can be implemented in the form of a software functional unit and can be stored in a computer-readable storage medium when it is sold or used as an independent product. Based on such an understanding, the technical solution of the present invention is essentially or the part that contributes to the prior art or the part of the technical solution can be embodied in the form of a software product, and the computer software product is stored in a storage medium, including a number of instructions to enable a computer device (which can be a personal computer, a server, or a network device, etc.) to perform all or part of the steps of the methods of each embodiment of the present invention. The aforementioned storage medium includes: a storage chip, a U disk, a mobile hard disk, a read-only memory (ROM, Read-Only Memory), a random access memory (RAM, Random Access Memory), a disk or an optical disk, and other media that can store program codes.

[0201] On the other hand, an embodiment of the present invention further provides a processor-readable storage medium, on which a computer program 3 is stored. When the computer program 3 is executed by the processor 1, the perforation completion fracture pressure prediction method provided in the above embodiments is implemented.

[0202] The processor-readable storage medium can be any available medium or data storage device that can be accessed by the processor 1, including but not limited to magnetic storage (such as floppy disks, hard disks, magnetic tapes, magneto-optical disks (MO), etc.), optical storage (such as CD, DVD, BD, HVD, etc.), and semiconductor storage (such as ROM, EPROM, EEPROM, non-volatile memory (NANDFLASH), solid-state drive (SSD)), etc.

[0203] The above are only preferred implementations of the present disclosure, and the protection scope of the present disclosure is not limited to the above embodiments. All technical solutions under the concept of the present disclosure belong to the protection scope of the present disclosure. It should be pointed out that for ordinary technicians in this technical field, some improvements and modifications without departing from the principle of the present disclosure should be regarded as the protection scope of the present disclosure.

Claims

1. A method for predicting fracture pressure of perforation completion, characterized in that: include: Establish a fluid-solid coupling phase field mathematical model; Obtain formation in-situ stress parameters, rock mechanics parameters, natural fracture parameters and perforation parameters; Based on the fluid-solid coupling phase field mathematical model, the formation in-situ stress parameters, rock mechanics parameters, natural fracture parameters and perforation parameters are applied, and a finite element model for predicting the fracture pressure of perforation completion is established by considering that the perforation holes pass through the natural fractures; The displacement field, phase field and fluid pressure field of the perforation completion fracture pressure prediction finite element model are solved iteratively in sequence by using a staggered algorithm to form a perforation tip phase field cloud diagram and a fluid pressure curve; The perforation completion fracture pressure is read according to the phase field cloud diagram at the hole tip and the fluid pressure curve.

2. The method for predicting fracture pressure of perforation completion according to claim 1, characterized in that: The establishment of the fluid-solid coupling phase field mathematical model includes: Establish a fluid-solid coupling mathematical model based on Biot's poroelasticity theory; Phase field variables, fluid pressure and effective stress are introduced to jointly drive the evolution of phase field; Introduce historical constant function; The phase field evolution equation is obtained according to the variational principle; Based on the phase field evolution equation, a fluid-solid coupling phase field mathematical model is established to characterize the flow field in the hydraulic fractures of the formation, the formation pressure distribution and stress state, and the initiation and expansion morphology of the hydraulic fractures.

3. The method for predicting fracture pressure of perforation completion according to claim 2, characterized in that: The expression of the fluid-solid coupling phase field mathematical model is: In the formula, d is the phase field, u is the displacement, p is the fluid pressure, ε is the strain, and k is a parameter to enhance numerical stability, which is 10 -6 , denote the elastic energy of the tensile and compressive parts, respectively, l0 is the internal length dimension, α is the Biot coefficient, G c is the critical energy release rate, b i ,t i represent body force and surface force respectively, λ,μ represent Lame constants respectively, σ is total stress, σ eff is the effective stress of the rock skeleton, H is the history field function, ψ is the total energy functional, Ω is the entire solid domain, and u i is the displacement component, S is the action boundary, tr is the trace function, t is a certain moment, T is the maximum solution time, and x is a certain position.

4. The method for predicting fracture pressure of perforation completion according to claim 1, characterized in that: The acquisition of formation in-situ stress parameters, rock mechanics parameters, natural fracture parameters and perforation parameters includes: The three-dimensional geostress parameters and formation pore pressure values ​​are obtained based on the well logging interpretation data; Obtain the mechanical parameters of formation rocks based on core mechanics experimental tests or logging interpretation data; The perforation parameters are obtained according to the perforation method and perforating gun bullet model during fracturing construction; Obtain formation rock porosity and permeability based on core porosity test, permeability test or logging interpretation data; The porosity and permeability parameters of natural fractures, as well as the degree of development, are obtained based on microseismic monitoring data or well logging interpretation data.

5. The method for predicting fracture pressure of perforation completion according to claim 1, characterized in that: The method of establishing a finite element model for predicting the fracture pressure of a well perforation completion based on the fluid-solid coupling phase field mathematical model, applying the formation in-situ stress parameters, rock mechanics parameters, natural fracture parameters and perforation parameters, and considering that the perforation holes pass through the natural fractures, comprises: Establish a finite element geometric model for predicting the fracture pressure of perforation completion; Assigning values ​​of material parameters corresponding to the formation, perforation holes, and natural fractures to the perforation completion fracture pressure prediction finite element geometric model; The ground stress parameters, construction displacement parameters and the phase field at the hole are added as boundary conditions to the assigned perforation completion fracture pressure prediction finite element geometric model to form the perforation completion fracture pressure prediction finite element model.

6. The method for predicting fracture pressure of perforation completion according to claim 5, characterized in that: The adding of the ground stress parameter, the construction displacement parameter and the phase field at the hole as boundary conditions to the perforation completion fracture pressure prediction finite element geometric model after the assignment includes: The phase field at the perforation hole is used as the first type boundary condition of the finite element geometric model for perforation completion fracture pressure prediction after assignment, and the initial value of the phase field at the perforation hole is set to 1; The target reservoir in-situ stress parameters and construction displacement parameters are applied to the corresponding boundary conditions as the second type of boundary conditions of the finite element geometric model for perforation completion fracture pressure prediction after assignment.

7. The method for predicting fracture pressure of perforation completion according to claim 1, characterized in that: The method of iteratively solving the displacement field, phase field and fluid pressure field of the perforation completion fracture pressure prediction finite element model in sequence by using the staggered algorithm includes: Introduce shape function matrix and shape function derivative matrix; The displacement field, phase field and fluid pressure field are discretized respectively using the shape function matrix and its shape function derivative matrix; The residual expressions of the displacement field, phase field and fluid pressure field are calculated iteratively in sequence until the residual is less than the residual setting value, or the number of iterations exceeds the iteration number setting value.

8. The method for predicting fracture pressure of perforation completion according to claim 7, characterized in that: The expressions of displacement field, phase field and fluid pressure field of the perforation completion fracture pressure prediction finite element model are solved iteratively in sequence using the staggered algorithm: Among them, R u ,R d ,R p are the residuals of displacement field, phase field and fluid pressure field respectively, are the external forces of displacement field and phase field, respectively, is the external flux of the fluid pressure field, K u ,K d are the stiffness matrices of the displacement field and phase field, respectively, S p is the compression coefficient matrix, H p is the permeability matrix, N u 、N d and N p are the shape function matrices of displacement field, phase field and fluid pressure field, respectively, and B u ,B d ,B p are the derivatives of the shape function matrices of the displacement field, phase field and fluid pressure field, respectively; ρ is the density of the fracturing fluid; K is the formation permeability; μ is the viscosity of the fracturing fluid; k is a parameter to enhance numerical stability and is taken as 10 -6 , d is the phase field, u is the displacement, p is the fluid pressure, G c is the critical energy release rate, H is the history field function, D e is the stiffness matrix, N d The transpose of N p is the transpose of , and S is the action boundary.

9. A perforation completion fracture pressure prediction system, characterized in that: include: Establishing a unit for establishing a fluid-solid coupling phase field mathematical model; An acquisition unit, used to acquire formation in-situ stress parameters, rock mechanics parameters, natural fracture parameters and perforation parameters; A construction unit is used to establish a finite element model for predicting the fracture pressure of perforation completion based on the fluid-solid coupling phase field mathematical model, applying the formation in-situ stress parameters, rock mechanics parameters, natural fracture parameters and perforation parameters, and considering that the perforation holes pass through the natural fractures; A solving unit, used for iteratively solving the displacement field, phase field and fluid pressure field of the perforation completion fracture pressure prediction finite element model in sequence by using a staggered algorithm, to form a perforation tip phase field cloud diagram and a fluid pressure curve; The reading unit is used to read the perforation completion fracture pressure according to the phase field cloud diagram at the hole tip and the fluid pressure curve.

10. The perforation completion fracture pressure prediction system according to claim 9, characterized in that: The building blocks include: The first building module is used to establish a fluid-solid coupling mathematical model based on Biot's poroelasticity theory; The first introduction module is used to introduce phase field variables, fluid pressure and effective stress to jointly drive the evolution of the phase field; The second introduction module is used to introduce the historical constant function; An acquisition module, used to obtain the phase field evolution equation according to the variational principle; The construction module is used to establish a fluid-solid coupling phase field mathematical model based on the phase field evolution equation to characterize the flow field in the hydraulic fracture of the formation, the formation pressure distribution and stress state, and the initiation and expansion morphology of the hydraulic fracture.

11. The perforation completion fracture pressure prediction system according to claim 10, characterized in that: The expression of the fluid-solid coupling phase field mathematical model is: In the formula, d is the phase field, u is the displacement, p is the fluid pressure, ε is the strain, and k is a parameter to enhance numerical stability, which is 10 -6 , denote the elastic energy of the tensile and compressive parts, respectively, l0 is the internal length dimension, α is the Biot coefficient, G c is the critical energy release rate, b i ,t i represent body force and surface force respectively, λ,μ represent Lame constants respectively, σ is total stress, σ eff is the effective stress of the rock skeleton, H is the history field function, ψ is the total energy functional, Ω is the entire solid domain, and u i is the displacement component, S is the action boundary, tr is the trace function, t is a certain moment, T is the maximum solution time, and x is a certain position.

12. The perforation completion fracture pressure prediction system according to claim 9, characterized in that: The acquisition unit comprises: The first acquisition module is used to obtain three-dimensional geostress parameters and formation pore pressure values ​​according to the well logging interpretation data; The second acquisition module is used to obtain mechanical parameters of formation rocks according to core mechanical experimental tests or logging interpretation data; The third acquisition module is used to obtain perforation parameters according to the perforation method and perforating gun bullet model during fracturing construction; The fourth acquisition module is used to obtain the porosity and permeability of the formation rock according to the core porosity test, permeability test or logging interpretation data; The fifth acquisition module is used to obtain the porosity and permeability parameters and the development degree of natural fractures based on microseismic monitoring data or logging interpretation data.

13. The perforation completion fracture pressure prediction system according to claim 9, characterized in that: The building block comprises: The second building module is to build a finite element geometric model for predicting the fracture pressure of perforation completion; An assignment module, used for assigning values ​​of material parameters corresponding to formations, perforation holes, and natural fractures to the finite element geometric model for predicting the fracture pressure of perforation completion; A module is formed, which is used to add the ground stress parameters, the construction displacement parameters and the phase field at the hole as boundary conditions to the assigned perforation completion fracture pressure prediction finite element geometric model to form the perforation completion fracture pressure prediction finite element model.

14. The perforation completion fracture pressure prediction system according to claim 13, characterized in that: The assignment module is used to: The phase field at the perforation hole is used as the first type boundary condition of the finite element geometric model for perforation completion fracture pressure prediction after assignment, and the initial value of the phase field at the perforation hole is set to 1; The target reservoir in-situ stress parameters and construction displacement parameters are applied to the corresponding boundary conditions as the second type of boundary conditions of the finite element geometric model for perforation completion fracture pressure prediction after assignment.

15. The perforation completion fracture pressure prediction system according to claim 9, characterized in that: The solution unit comprises: The third introduction module is used to introduce the shape function matrix and the shape function derivative matrix; A discretization module is used to discretize the displacement field, phase field and fluid pressure field respectively using the shape function matrix and its shape function derivative matrix; The calculation module is used to iteratively calculate the residual expressions of the displacement field, phase field and fluid pressure field in sequence until the residual is less than the residual setting value 0.001, or the number of iterations exceeds the number of iterations setting value 100.

16. The perforation completion fracture pressure prediction system according to claim 15, characterized in that: The expression of the solution unit is: Among them, R u ,R d ,R p are the residuals of displacement field, phase field and fluid pressure field respectively, are the external forces of displacement field and phase field, respectively, is the external flux of the fluid pressure field, K u ,K d are the stiffness matrices of the displacement field and phase field, respectively, S p is the compression coefficient matrix, H p is the permeability matrix, N u , N d ,N p are the shape function matrices of displacement field, phase field and fluid pressure field, respectively, and B u ,B d ,B p are the derivatives of the shape function matrices of the displacement field, phase field and fluid pressure field, respectively; ρ is the density of the fracturing fluid; K is the formation permeability; μ is the viscosity of the fracturing fluid; k is a parameter to enhance numerical stability and is taken as 10 -6 , d is the phase field, u is the displacement, p is the fluid pressure, G c is the critical energy release rate, H is the history field function, D e is the stiffness matrix, N d The transpose of N p is the transpose of , and S is the action boundary.

17. A perforation completion fracture pressure prediction device, characterized in that: include: Processor and memory; The memory is used to store a computer program, and the processor calls the computer program stored in the memory to execute the method for predicting the fracture pressure of perforation completion according to any one of claims 1 to 8.

18. A computer-readable storage medium, characterized in that: The computer-readable storage medium stores a computer program, and when the computer program is executed by a processor, the processor is enabled to execute the method for predicting the fracture pressure of the perforation completion according to any one of claims 1 to 8.

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