Wellbore thermal coupling simulation method, device and equipment based on fractional order model

Abstract

The application relates to the technical field of enhanced geothermal system, and discloses a wellbore thermal coupling simulation method, device and equipment based on a fractional order model; the method comprises the following steps: assigning values to a geological geometry model of a thermal reservoir work area, setting initial conditions and boundary conditions of the geological geometry model, and constructing a thermal coupling model of the thermal reservoir work area; based on the thermal coupling model of the thermal reservoir work area, extracting a temperature field and a stress field around a target wellbore; setting outer boundary conditions for a geometry model of the target wellbore based on the temperature field and the stress field around the target wellbore, setting initial conditions and inner boundary conditions, and constructing a wellbore thermal coupling model; introducing a fractional order heat transfer model and a fractional order plasticity model into the wellbore thermal coupling model, performing wellbore thermal coupling simulation, and obtaining a temperature field and a stress field of the target wellbore evolving over time. The application realizes cross-scale thermal coupling analysis from a thermal reservoir well group to a single wellbore, and more accurately depicts temperature and stress responses of the wellbore under complex working conditions.

Description

TECHNICAL FIELD

[0001] The present disclosure relates to the technical field of enhanced geothermal system, in particular, to a wellbore thermal coupling simulation method, device and equipment based on a fractional order model. BACKGROUND

[0002] As the only channel between the ground and the deep thermal reservoir, the wellbore of the enhanced geothermal system is in a complex coupling environment for a long time, and bears the combined action of temperature gradient, water pressure and ground stress disturbance. With the extension of the operation period, the wellbore structure may have risks such as casing strength attenuation, thermal cracks in the cement sheath, or a decrease in wellbore sealing integrity, which are closely related to the coupling evolution of the temperature field and the stress field at each part of the wellbore. Therefore, it is necessary to propose a simulation method for the thermal coupling analysis of the wellbore of the enhanced geothermal system to provide a reliable basis for the safe operation and management of the enhanced geothermal system.

[0003] In the existing analysis and research of the wellbore of the enhanced geothermal system, the control equation of the numerical model is still limited to the integer order thermoelastic-plastic theory framework, and the long-time history dependence of the thermal coupling effect of the wellbore is not considered, which leads to a deviation between the prediction result and the actual operation condition. In addition, the existing researches are mostly focused on the thermal coupling analysis of a single wellbore scale, and the overall response of the well group in the whole enhanced geothermal system thermal reservoir development block (i.e. the injection-production coupling effect between multiple injection wells and production wells) is not considered, which makes it difficult to fully reveal the thermal evolution law of the single well under the interaction between the well groups, and leads to the inability to meet the requirements of simulation accuracy and reliability in actual engineering. SUMMARY

[0004] In view of the above, the embodiments of the present application provide a wellbore thermal coupling simulation method and device based on a fractional order model, which aims to solve the above problems or at least partially solve the above problems.

[0005] In a first aspect, the embodiments of the present application provide a wellbore thermal coupling simulation method based on a fractional order model, which comprises:

[0006] The physical property parameters of the rock and the wellbore in the thermal reservoir work area are assigned to the geological geometry model of the thermal reservoir work area, the initial conditions of the geological geometry model of the thermal reservoir work area are set based on the temperature field and the stress field of the thermal reservoir work area, and the boundary conditions of the geological geometry model of the thermal reservoir work area are set, so as to construct a thermal coupling model of the thermal reservoir work area;

[0007] Based on the thermal coupling model of the thermal reservoir work area, the temperature field and the stress field around the target wellbore are extracted;

[0008] set an outer boundary condition for the geometric model of the target wellbore based on the temperature field and the stress field around the target wellbore, set an initial condition and an inner boundary condition for the geometric model of the target wellbore, and construct a thermal-mechanical coupling model of the wellbore;

[0009] introduce a fractional order heat transfer model and a fractional order plasticity model into the thermal-mechanical coupling model of the wellbore, perform thermal-mechanical coupling simulation of the wellbore, and obtain the temperature field and the stress field of the target wellbore evolving over time.

[0010] In a second aspect, the embodiments of the present application further provide a wellbore thermal-mechanical coupling simulation device based on a fractional order model, and the device comprises:

[0011] The establishing module is configured to assign values to a geological geometry model of a thermal reservoir work area based on physical property parameters of rocks and wellbores in the thermal reservoir work area, set an initial condition of the geological geometry model of the thermal reservoir work area based on a temperature field and a stress field of the thermal reservoir work area, and set a boundary condition for the geological geometry model of the thermal reservoir work area, so as to construct a thermal-mechanical coupling model of the thermal reservoir work area.

[0012] The extracting module is configured to extract a temperature field and a stress field around a target wellbore based on the thermal-mechanical coupling model.

[0013] The establishing module is further configured to set an outer boundary condition for a geometric model of the target wellbore based on the temperature field and the stress field around the target wellbore, set an initial condition and an inner boundary condition for the geometric model of the target wellbore, and construct a thermal-mechanical coupling model of the wellbore.

[0014] The simulation module is configured to introduce a fractional order heat transfer model and a fractional order plasticity model into the thermal-mechanical coupling model of the wellbore, perform thermal-mechanical coupling simulation of the wellbore, and obtain the temperature field and the stress field of the target wellbore evolving over time.

[0015] In a third aspect, the embodiments of the present application further provide an electronic device, which comprises a processor and a memory arranged to store computer executable instructions, the computer executable instructions, when executed, causing the processor to perform the steps of the first aspect.

[0016] In a fourth aspect, the embodiments of the present application further provide a computer readable storage medium storing one or more programs, the one or more programs, when executed by an electronic device comprising a plurality of application programs, causing the electronic device to perform the steps of the first aspect.

[0017] The at least one technical solution adopted by the embodiments of the present application can achieve the following beneficial effects: the temperature field and the stress field around the target wellbore are extracted by establishing the thermal coupling model of the thermal reservoir work area, and then the wellbore thermal coupling model is established based on the temperature field and the stress field around the target wellbore, so as to realize the cross-scale thermal coupling analysis from the thermal reservoir well group to the single wellbore. Further, the fractional order heat transfer model and the fractional order plastic model are introduced in the wellbore thermal coupling model. Since the fractional order model has memory effect and path dependence, the limitations of the traditional Fourier heat transfer model and the integer order plastic model are broken through, and the temperature and stress response of the wellbore under complex working conditions is more accurately described. BRIEF DESCRIPTION OF DRAWINGS

[0018] The accompanying drawings, which are included to provide a further understanding of the present application, constitute a part of the present application and illustrate the illustrative embodiments of the present application and their description serve to explain the present application, and do not constitute improper limitations on the present application. In the drawings:

[0019] Figure 1 A flowchart of the wellbore thermal coupling simulation method based on the fractional order model provided by the embodiments of the present application is shown;

[0020] Figure 2 A flowchart of the wellbore thermal coupling simulation method based on the fractional order model provided by another embodiment of the present application is shown;

[0021] Figure 3 A system architecture diagram of the wellbore thermal coupling simulation method based on the fractional order model provided by the embodiments of the present application is shown;

[0022] Figure 4 A structural diagram of the wellbore thermal coupling simulation device based on the fractional order model provided by the embodiments of the present application is shown;

[0023] Figure 5 A structural diagram of an electronic device provided by the embodiments of the present application is shown. DETAILED DESCRIPTION

[0024] To make the objectives, technical solutions and advantages of the present application clearer, the technical solutions of the present application will be described clearly and completely below in conjunction with the embodiments of the present application and the corresponding drawings. Obviously, the described embodiments are only some of the embodiments of the present application, but not all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without making any creative efforts fall within the scope of protection of the present application.

[0025] It should be noted that the terms "first", "second", etc. in the specification and claims of the present application and in the above drawings are used to distinguish similar objects, and do not necessarily have to be used to describe a specific order or sequence. It should be understood that such use can be interchanged under appropriate circumstances, so that the embodiments of the present application described herein can be implemented in an order other than that illustrated or described herein. In addition, the term "comprising" and its variants are to be interpreted as meaning "including but not limited to" an open term.

[0026] Figure 1 A flowchart of the wellbore thermal coupling simulation method based on the fractional order model provided by the embodiments of the present application is shown, from Figure 1 It can be seen that the present application at least includes steps S101-S104:

[0027] Step S101: Based on the physical parameters of the rock and wellbore of the thermal reservoir work area, the geological geometry model of the thermal reservoir work area is valued, the initial conditions of the geological geometry model of the thermal reservoir work area are set based on the temperature field and stress field of the thermal reservoir work area, and the boundary conditions of the geological geometry model of the thermal reservoir work area are set, to construct the thermal coupling model of the thermal reservoir work area.

[0028] Step S102: Based on the thermal coupling model of the thermal reservoir work area, the temperature field and stress field around the target wellbore are extracted.

[0029] Step S103: Based on the temperature field and stress field around the target wellbore, the outer boundary conditions of the geometric model of the target wellbore are set, and the initial conditions and inner boundary conditions of the geometric model of the target wellbore are set, to construct the wellbore thermal coupling model.

[0030] Step S104: Introducing the fractional order heat transfer model and the fractional order plasticity model in the wellbore thermal coupling model, performing wellbore thermal coupling simulation, and obtaining the temperature field and stress field of the target wellbore evolving with time.

[0031] From Figure 1 As shown in the method, the present application combines the thermal coupling model of the thermal reservoir work area with the refined thermal coupling model of the wellbore, realizes the cross-scale thermal coupling analysis from the thermal reservoir well group to the single wellbore, and further introduces the fractional order heat transfer model and the fractional order plasticity model, breaks through the limitations of the traditional Fourier heat transfer model and the integer order plasticity model, and more accurately describes the temperature and stress response of the wellbore under complex working conditions.

[0032] In some embodiments of the present application, in the above method, step S101 specifically establishes the thermal reservoir work area based on the following manner, such as Figure 2 As shown, it includes steps S1011-S1014:

[0033] S1011: Establish a geological geometry model of the thermal reservoir work area based on the three-dimensional seismic survey results and the wellbore structure data.

[0034] The three-dimensional seismic survey results include fault plane, horizon plane, thickness distribution and other data; the wellbore structure data includes drilling columnar chart and the like. Specifically, structural interpretation is performed, main faults and layer system distribution are identified, a fault-layer system framework is established, and a continuous three-dimensional geological body is generated by using thickness constraint; a hexahedral grid is used to generate a grid required for numerical simulation, and local encryption is performed in the fault zone and wellbore area. Finally, a thermal reservoir work area geometry model is generated, which contains information about the influence of faults on reservoir connectivity and heat conduction path, as well as a corresponding high-quality grid file.

[0035] S1012: Obtain the temperature field of the thermal reservoir work area by using spatial interpolation method based on drilling temperature measurement data, geothermal exploration data and well temperature monitoring data.

[0036] Specifically, the in-situ temperature data of different wellheads and well sections are time and space registered, a spatial interpolation method is used to construct a continuous temperature distribution field in the work area, local correction is added in the fracture zone or heat conduction abnormal area to reflect the non-uniform heat conduction characteristics, and a continuous three-dimensional temperature field of the work area scale is constructed as an important input for subsequent thermal coupling modeling.

[0037] S1013: Obtain the stress field of the thermal reservoir work area based on acoustic logging data, core mechanical experiment data and seismic wave velocity inversion data.

[0038] Specifically, based on acoustic logging data, the ground stress parameters around the wellbore are inverted combined with the difference between P-wave and S-wave velocity; the results of core mechanical experiments (uniaxial compression, triaxial compression, Brazilian splitting, etc.) are used to calibrate rock elastic modulus, Poisson's ratio and other parameters to provide input for stress inversion; a large-scale three-dimensional ground stress distribution field is constructed by using seismic wave velocity inversion method; the inversion results are constrained combined with regional geomechanical background to obtain the size, direction and depth variation of the principal stress; local tectonic stress correction is introduced in the fracture development zone or tectonic abnormal area to reflect the disturbance effect of the fracture on the stress field, so as to ensure the authenticity and reliability of the stress field model. Finally, a three-dimensional work area ground stress field model is constructed as an important input for the subsequent thermal reservoir work area thermal coupling model.

[0039] S1014: Assign values to the geological geometry model based on the physical parameters of the rock and wellbore of the thermal reservoir work area, set the initial conditions of the geological geometry model based on the temperature field and stress field of the thermal reservoir work area, and set the boundary conditions of the geological geometry model to construct a thermal coupling model of the thermal reservoir work area.

[0040] The physical property parameters of the rock and the wellbore are determined based on rock physical property experiments (thermal conductivity, specific heat, density), rock mechanics experiments (elastic modulus, Poisson's ratio), acoustic logging and density logging data inversion results, and material parameters of the casing and cement sheath in the database. Specifically, the thermal conductivity, specific heat capacity, and density of the rock sample are tested in the laboratory, and the core samples at different depths are compared; the porosity is inversed by acoustic logging and density logging, and is corrected with the measured core experiment data; the thermal and mechanical parameters of the casing and cement sheath materials are obtained by consulting relevant databases.

[0041] The boundary conditions of the geological geometry model include temperature boundary conditions, stress boundary conditions, and displacement boundary conditions. Specifically, the temperature boundary conditions of the thermal reservoir work area thermal coupling model are set as adiabatic boundaries except for the surface, and no heat exchange occurs with the external environment; the temperature boundary conditions at the wellbore are set according to the mathematical model fitted from the temperature monitoring data of the enhanced geothermal system before exploitation; the stress boundary conditions of the thermal reservoir work area thermal coupling model are the gradient geostress model around the model obtained from geological exploration in the database; the stress boundary conditions at the wellbore are set according to the mathematical model fitted from the stress monitoring data of the enhanced geothermal system before exploitation; and the displacement boundary conditions of the thermal reservoir work area thermal coupling model are fixed at the bottom, and no deformation and displacement occur.

[0042] In some embodiments of the present application, in the above method, the extraction of the temperature field and the stress field around the target wellbore based on the thermal coupling model in step S102 can be specifically implemented as follows: modifying the temperature and stress boundary conditions inside the wellbore, simulating the thermal response of the thermal reservoir work area under injection-production conditions, and extracting the temperature field and the stress field of the unit nodes around the target wellbore.

[0043] Specifically, based on the established thermodynamic coupling model of the geothermal reservoir area, the temperature and stress boundary conditions inside the wellbore in the thermodynamic coupling model are modified according to the injection and production scheme (such as injection flow rate, injection water temperature, production water temperature, circulation cycle, etc.). For example, the boundary conditions inside the injection wellbore are modified to correspond to the temperature and hydraulic pressure of low-temperature injection water. These modifications transform the thermodynamic coupling model of the geothermal reservoir area from an initial "unexploited" state to a dynamic "injection and operation" state. Furthermore, the finite element method is used to solve the modified boundary condition model of the reservoir area, simulating the entire process of temperature and stress field evolution over time under the drive of injection and production operations. After the simulation, each element and node in the reservoir area model stores complete historical data from the start to the end of the simulation, including temperature and stress values ​​at each time step. Finally, data around the target wellbore is extracted from the calculation results of the reservoir area model. For example, in post-processing software or through scripts, all elements and nodes within a specific range around the target wellbore are identified and selected based on its coordinates and trajectory. For all element nodes in the selected region, the temperature and stress results at each time step are exported and converted into a continuous spatial field distribution that evolves over time.

[0044] In some embodiments of this application, in the above method, step S103 establishes a wellbore thermo-coupling model based on the temperature field and stress field around the target wellbore. Specifically, this can be implemented as follows: a geometric model of the casing-cement sheath-formation combination is established based on the structure of the target wellbore. A local meshing method is used in the radial section area of ​​the wellbore, and a sparser meshing method is used in the longitudinal section of the wellbore. Initial conditions and boundary conditions are set for the geometric model to obtain the wellbore thermo-coupling model. The initial temperature conditions of the geometric model are set based on the well monitoring data and the temperature field of the thermal reservoir area. The initial stress conditions of the geometric model are set based on the measured data in the well and the stress field of the thermal reservoir area. The outer boundary conditions of the geometric model are set based on the temperature field and stress field around the target wellbore. The inner boundary conditions of the geometric model are set based on the injection and production method.

[0045] Specifically, based on the wellbore structural design data, including casing dimensions, number of layers, wall thickness, cement sheath thickness, and well diameter, a combined system model of "casing-cement sheath-formation" is established to realistically reflect the multi-layered structure inside the wellbore, serving as the basis for subsequent analysis of heat transfer and stress distribution. In the radial section of the wellbore, due to significant temperature gradients and stress concentration effects, a locally refined fine mesh is required to capture these key changes. In the longitudinal direction of the wellbore, a relatively sparse mesh can be used, ensuring accuracy while considering overall computational efficiency, ultimately resulting in a geometric model and its corresponding mesh file that accurately reflects the wellbore structure.

[0046] Further initial and boundary conditions were set for the model. Initial conditions included: casing and cement sheath temperatures fitted from monitoring data; formation temperature provided by the temperature field of the reservoir area; initial stresses of the casing and cement sheath given by downhole monitoring data; and initial formation stresses provided by the stress field of the work area. Boundary conditions: the outer boundary was set based on the temperature and stress fields around the target wellbore, while the inner boundary was determined by the actual injection-production scheme. Parameters such as the flow rate, temperature, and pressure of the injected working fluid were compared and fitted with corresponding historical injection-production monitoring data to derive the temperature and stress boundary conditions at the wellbore.

[0047] Finally, different structures in the model, such as casing, cement sheath, and formation, are assigned corresponding thermophysical parameters (density, specific heat capacity, thermal conductivity, etc.) and mechanical parameters (elastic modulus, Poisson's ratio, yield strength, etc.).

[0048] In some embodiments of this application, in the above method, the fractional-order heat transfer model in step S104 is implemented by introducing the fractional-order heat transfer constitutive model into the heat transfer equations in the classical thermo-coupling equation set.

[0049] Among them, the fractional heat transfer constitutive model is Introducing the fractional-order heat transfer constitutive model into the heat transfer equations of the classical thermo-coupling equations, we obtain the following fractional-order heat transfer model:

[0050]

[0051] The fractional-order plasticity model in step S104 introduces the fractional-order plasticity constitutive model into the stress balance equations of the classical thermo-mechanical coupling equation set, resulting in the following fractional-order stress balance governing equations (fractional-order plasticity model):

[0052]

[0053] In the above embodiments, fractional derivative The abbreviation for fractional derivative; there are multiple definitions of fractional derivative, but the one used in this implementation plan is the fractional derivative defined by Grünwald–Letnikov (GL), which has the following specific form:

[0054]

[0055] in, For temperature; It is the fractional order thermal conductivity coefficient; Density; Specific heat capacity; Thermal relaxation time; For time; For volumetric strain; Let be the yield function; It is the thermal expansion factor; For reference temperature; For stress; Equivalent stress; The yield stress; In response Plastic strain; The yield stress; The viscosity coefficient; The coefficient of thermal expansion; It is the elasticity matrix; These are the volume forces in each direction; , It is a fractional order and belongs to (0,1); This is the initial time; Let be the variable to be differentiated; greater than The smallest positive integer.

[0056] Furthermore, to implement fractional-order heat transfer and fractional-order plasticity in ABAQUS, corresponding models were developed based on the user subroutine interface. Specifically, the UMATHT subroutine file (fractional-order heat transfer constitutive model) and the UMAT subroutine file (fractional-order plasticity constitutive model) were written in Fortran. Since the Fortran built-in mathematical library lacks definitions for fractional-order derivatives, numerical methods were used for approximate calculations.

[0057] For any variable At a time step of In this case, its The fractional derivative of GL of order at time 1 The approximation is as follows:

[0058]

[0059] Among them, the weight function The definition is as follows:

[0060]

[0061] To calculate the historical accumulation term in the above approximation, it is necessary to access the state variables of all time steps. This application provides two methods: 1) Common area storage: Define a multidimensional array in the compilation file to store the historical state variables in the ABAQUS internal storage according to the time step and cell integration point number, and call them as needed. Advantages: Fast model calculation speed; Disadvantages: The size of the Common area is limited by 2GB of memory, which is not suitable for large 3D models with long time spans and many mesh cells / integration points. 2) External file storage: At the end of each time step, the required state variables are written to a TXT file, and all recorded state variables are read in during the next calculation. Advantages: Overcomes memory limitations and is convenient for long-term / multi-grid calculations; Disadvantages: The model calculation speed is relatively slow. This application takes external file storage as an example, writing the state variables calculated in the current time step to a file, and reading all the state variables written in the file when calculating the result of the next time step.

[0062] Defined in subroutine code Based on the relations of the fractional-order heat transfer constitutive model, the relationship between heat flux (FLUX) and temperature gradient (DTEMDX) is defined as follows:

[0063]

[0064] The letter i can be 1, 2, or 3, representing the x, y, and z directions of the 3D model, respectively, and DTIME represents the time step size.

[0065] Furthermore, by defining in the subroutine The stress update formula is defined. When updating the stress, an elastic trial is performed; if the equivalent stress is less than the yield stress, it is in the elastic range, and the stress is updated based on the preset stress update formula; if the equivalent stress is greater than or equal to the yield stress, it is in the plastic range, and the stress is updated based on the fractional-order plasticity model.

[0066] Specifically, strain decomposition:

[0067] Elasticity calculation: ,in accordance with Solve .

[0068] Judgment and correction:

[0069] 1) If ≤0: Elastic range, stress update formula is as follows

[0070]

[0071] 2) If >0, plastic range, stress update formula as follows

[0072]

[0073] In the coupled equation system, the heat source term of the heat transfer equation is defined using the RPL variable in the UMAT subroutine:

[0074]

[0075] in, Plasticity matrix; DSTRANi is the principal strain increment.

[0076] Finally, during thermo-mechanical coupling, in the ABAQUS material properties, select material density and enable "User Material"; select "Thermo-mechanical" as the user material type; compile the UMATHT and UMAT program codes in the same Fortran source file and import the Fortran source file into the Job module; select the temperature-displacement coupling (transient) analysis step, and use a fixed increment step for time progression; use the C3D8T element type; solve for the evolution of the wellbore temperature field and stress field over time to obtain the results of the changes in the multi-layer structure temperature field and stress field of the wellbore during the injection and production cycle, including: circumferential stress and its corresponding time, maximum temperature drop and gradient distribution, cement shear stress and plastic accumulation, etc., for subsequent integrity assessment, risk determination and operating condition optimization.

[0077] The following is combined with Figure 3 The diagram shown below illustrates the architecture of a wellbore thermo-coupling simulation system based on a fractional-order model, serving as a representation of the aforementioned method.

[0078] Part 1: Thermodynamic coupling model of geothermal reservoir area, which simulates the thermodynamic response of the entire geothermal reservoir during the injection and production process, and provides realistic boundary conditions for wellbore analysis.

[0079] Basic data includes geological structural information obtained through 3D seismic exploration, well logging data, and laboratory rock mechanics test results. Using this data, an initial temperature and stress field at the work area scale is established. With clearly defined injection and production parameters (such as flow rate and temperature), and integrating geological information and wellbore data, a 3D geological geometric model of the reservoir area is constructed. Using the initial field and injection-production scheme as input, a thermo-mechanical coupling model of the reservoir area is run for numerical simulation. The simulation results yield the temperature and stress fields around the wellbore.

[0080] Part Two: Wellbore Thermodynamic Coupled Model. Driven by the macroscopic environmental background, this part accurately analyzes the thermodynamic behavior of the wellbore's own structure (casing, cement sheath, formation) and assesses its integrity.

[0081] The temperature and stress fields around the wellbore output in the first part are the most important inputs to the wellbore model, serving as its external boundary conditions. Wellbore data includes injection and production schemes (injection temperature, pressure, etc.), wellbore structural design data (casing dimensions, cement sheath thickness, etc.), and material parameters (thermal and mechanical properties of casing steel and cement). Based on the wellbore structural design, a wellbore geometric model is established to characterize the multi-layered structure of the casing, cement sheath, and formation in detail. The boundary conditions provided by the macroscopic model and the wellbore data are input into the wellbore model. This model innovatively introduces a fractional-order heat transfer model and a fractional-order plasticity model to more accurately describe the complex behavior of materials under cyclic loading.

[0082] The calculations yielded a refined result on the stress field and temperature field of the well shaft structure, showing their evolution over time.

[0083] In some embodiments of this application, a wellbore thermal coupling simulation device based on a fractional-order model is provided, which corresponds one-to-one with the wellbore thermal coupling simulation method based on a fractional-order model described in the above embodiments. For example... Figure 4 As shown, the wellbore thermo-coupling simulation based on the fractional-order model includes a setup module 101, an extraction module 102, and a simulation module 103.

[0084] Module 101 is established to assign values ​​to the geological geometric model of the geothermal reservoir area based on the physical property parameters of the rock and wellbore in the geothermal reservoir area, set the initial conditions of the geological geometric model of the geothermal reservoir area based on the temperature field and stress field of the geothermal reservoir area, and set the boundary conditions for the geological geometric model of the geothermal reservoir area to construct the thermo-mechanical coupling model of the geothermal reservoir area.

[0085] Extraction module 102 is used to extract the temperature field and stress field around the target wellbore based on the thermo-mechanical coupling model of the thermal reservoir area;

[0086] The module 101 is also used to set the outer boundary conditions for the geometric model of the target wellbore based on the temperature field and stress field around the target wellbore, and to set the initial conditions and inner boundary conditions for the geometric model of the target wellbore, thereby constructing a thermo-mechanical coupling model of the wellbore.

[0087] The simulation module 103 is used to introduce a fractional-order heat transfer model and a fractional-order plasticity model into the wellbore thermo-coupling model to perform wellbore thermo-coupling simulation and obtain the temperature field and stress field of the target wellbore evolving over time.

[0088] In some embodiments of this application, in the above-mentioned apparatus, the geological geometric model of the geothermal reservoir area is established based on three-dimensional seismic survey results and wellbore structure data; the temperature field of the geothermal reservoir area is obtained by spatial interpolation based on drilling temperature measurement data, geothermal exploration data and well temperature monitoring data; the stress field of the geothermal reservoir area is obtained based on sonic logging data, core mechanics experimental data and seismic wave velocity inversion data.

[0089] In some embodiments of this application, in the above-mentioned device, the extraction module 102 is specifically used to modify the temperature and stress boundary conditions around the wellbore, simulate the thermal response of the thermal reservoir under injection and production conditions, and extract the temperature field and stress field of the unit nodes around the target wellbore.

[0090] In some embodiments of this application, in the above-described apparatus, the geometric model of the target wellbore is a geometric model of the casing-cement sheath-formation combination established based on the structure of the target wellbore, with a local densification method in the radial cross-sectional area of ​​the wellbore and a sparser grid division method in the longitudinal direction of the wellbore;

[0091] The initial temperature conditions of the geometric model of the target wellbore are set based on the monitoring data inside the well and the temperature field of the thermal reservoir area; the initial stress conditions of the geometric model are set based on the measured data inside the well and the stress field of the thermal reservoir area; the outer boundary conditions of the geometric model are set based on the temperature field and stress field around the target wellbore; and the inner boundary conditions of the geometric model are set based on the injection and production method.

[0092] In some embodiments of this application, in the above-described apparatus, the fractional-order heat transfer model is implemented by introducing a fractional-order heat transfer constitutive model into the heat transfer equations of the thermodynamic coupling equation set:

[0093]

[0094] in, For density, For specific heat capacity, For temperature, For time; It is the fractional order thermal conductivity. For fractional derivative operators, The thermal expansion factor, For reference temperature, For volumetric strain.

[0095] In some embodiments of this application, in the above-described apparatus, the fractional-order plasticity model is implemented by introducing a fractional-order plasticity constitutive model into the stress balance equations of the classical thermo-mechanical coupling equation set:

[0096]

[0097] in, For stress, For the elasticity matrix, In response For plastic strain, The viscosity coefficient, For fractional derivative operators, For yield stress, Let be the yield function. For equivalent stress, For yield stress, The coefficient of thermal expansion is These are the volume forces in each direction.

[0098] In some embodiments of this application, in the above-described apparatus, the fractional derivative is the GL fractional derivative, and is approximated using a numerical method:

[0099]

[0100] in, For fractional derivative operators, Let be the variable to be differentiated. For the weight function, For fractional order, Initial time For time.

[0101] In some embodiments of this application, in the above-described apparatus, the simulation module 103 is specifically used to perform temperature and stress-strain calculations related to the fractional-order model. Specifically, during stress updates, an elastic trial calculation is performed; if the equivalent stress is less than the yield stress, it is within the elastic range, and the stress is updated based on a preset stress update formula; if the equivalent stress is greater than or equal to the yield stress, it is within the plastic range, and the stress is updated based on a fractional-order plastic model.

[0102] It should be noted that any of the above-mentioned wellbore thermo-coupling simulation devices based on fractional-order models can be used to implement the aforementioned wellbore thermo-coupling simulation method based on fractional-order models, which will not be elaborated here.

[0103] Figure 5 A schematic diagram of the structure of an electronic device provided in an embodiment of this application is shown. Figure 5 As shown, at the hardware level, this electronic device includes a processor, and optionally also includes an internal bus, a network interface, and memory. The memory may include main memory, such as high-speed random-access memory (RAM), or it may include non-volatile memory, such as at least one disk drive. Of course, this electronic device may also include other hardware required for other business operations.

[0104] The processor, network interface, and memory can be interconnected via an internal bus, which can be an ISA (Industry Standard Architecture) bus, a PCI (Peripheral Component Interconnect) bus, or an EISA (Extended Industry Standard Architecture) bus, etc. The bus can be divided into address bus, data bus, control bus, etc. For ease of representation, Figure 5 The symbol is represented by a single double-headed arrow, but this does not mean that there is only one bus or one type of bus.

[0105] Memory is used to store programs. Specifically, programs may include program code, which includes computer operation instructions. Memory may include main memory and non-volatile memory, and provides instructions and data to the processor.

[0106] The processor reads the corresponding computer program from non-volatile memory into main memory and then runs it, forming a wellbore thermal coupling simulation device based on a fractional-order model at the logical level. The processor executes the program stored in memory and specifically performs the aforementioned methods.

[0107] The processor may be an integrated circuit chip with signal processing capabilities. In implementation, each step of the above method can be completed by integrated logic circuits in the processor's hardware or by instructions in software form. The processor can be a general-purpose processor, including a Central Processing Unit (CPU), a Network Processor (NP), etc.; it can also be a Digital Signal Processor (DSP), an Application Specific Integrated Circuit (ASIC), a Field-Programmable Gate Array (FPGA), or other programmable logic devices, discrete gate or transistor logic devices, or discrete hardware components. It can implement or execute the methods, steps, and logic block diagrams disclosed in the embodiments of this application. The general-purpose processor can be a microprocessor or any conventional processor. The steps of the methods disclosed in the embodiments of this application can be directly embodied in the execution of a hardware decoding processor, or executed by a combination of hardware and software modules in the decoding processor. The software modules can reside in random access memory, flash memory, read-only memory, programmable read-only memory, electrically erasable programmable memory, registers, or other mature storage media in the art. The storage medium is located in the memory, and the processor reads the information in the memory and, in conjunction with its hardware, completes the steps of the above method.

[0108] This electronic device can execute the wellbore thermal coupling simulation method based on a fractional-order model provided in several embodiments of this application, and is implemented as a wellbore thermal coupling simulation device based on a fractional-order model. Figure 4 The functions of the embodiments shown are not described in detail here.

[0109] This application also proposes a computer-readable storage medium that stores one or more programs, the programs including instructions that, when executed by an electronic device including multiple applications, enable the electronic device to perform the wellbore thermal coupling simulation method based on a fractional-order model provided in several embodiments of this application.

[0110] Those skilled in the art will understand that embodiments of this application can be provided as methods, systems, or computer program products. Therefore, this application can take the form of a completely hardware embodiment, a completely software embodiment, or an embodiment combining software and hardware aspects. Furthermore, this application can take the form of a computer program product embodied on one or more computer-usable storage media (including, but not limited to, disk storage, CD-ROM, optical storage, etc.) containing computer-usable program code.

[0111] This application is described with reference to flowchart illustrations and / or block diagrams of methods, apparatus (systems), and computer program products according to embodiments of this application. It will be understood that each block of the flowchart illustrations and / or block diagrams, and combinations of blocks in the flowchart illustrations and / or block diagrams, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, special-purpose computer, embedded processor, or other programmable data processing apparatus to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing apparatus, generate instructions for implementing the flowchart... Figure 1 One or more processes and / or boxes Figure 1 A device that provides the functions specified in one or more boxes.

[0112] These computer program instructions may also be stored in a computer-readable storage medium that can direct a computer or other programmable data processing device to function in a particular manner, such that the instructions stored in the computer-readable storage medium produce an article of manufacture including instruction means, which are implemented in a process Figure 1 One or more processes and / or boxes Figure 1 The function specified in one or more boxes.

[0113] These computer program instructions may also be loaded onto a computer or other programmable data processing equipment to cause a series of operational steps to be performed on the computer or other programmable equipment to produce a computer-implemented process, thereby providing instructions that execute on the computer or other programmable equipment for implementing the process. Figure 1 One or more processes and / or boxes Figure 1 The steps of the function specified in one or more boxes.

[0114] In a typical configuration, a computing device includes one or more processors (CPU), input / output interfaces, network interfaces, and memory.

[0115] Memory may include non-persistent storage in computer-readable media, such as random access memory (RAM) and / or non-volatile memory, such as read-only memory (ROM) or flash RAM. Memory is an example of computer-readable media.

[0116] Computer-readable media includes both permanent and non-permanent, removable and non-removable media that can store information using any method or technology. Information can be computer-readable instructions, data structures, modules of programs, or other data. Examples of computer storage media include, but are not limited to, phase-change memory (PRAM), static random access memory (SRAM), dynamic random access memory (DRAM), other types of random access memory (RAM), read-only memory (ROM), electrically erasable programmable read-only memory (EEPROM), flash memory or other memory technologies, CD-ROM, digital versatile optical disc (DVD) or other optical storage, magnetic tape, magnetic magnetic disk storage or other magnetic storage devices, or any other non-transferable medium that can be used to store information accessible by a computing device. As defined herein, computer-readable media does not include transient computer-readable media, such as modulated data signals and carrier waves.

[0117] It should also be noted that the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitation, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes said element.

[0118] Those skilled in the art will understand that embodiments of this application can be provided as methods, systems, or computer program products. Therefore, this application can take the form of a completely hardware embodiment, a completely software embodiment, or an embodiment combining software and hardware aspects. Furthermore, this application can take the form of a computer program product embodied on one or more computer-usable storage media (including, but not limited to, disk storage, CD-ROM, optical storage, etc.) containing computer-usable program code.

[0119] The above are merely embodiments of this application and are not intended to limit the scope of this application. Various modifications and variations can be made to this application by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this application should be included within the scope of the claims of this application.

Claims

1. A method for wellbore thermal coupling simulation based on fractional order model, characterized in that, The method comprises: assigning a geological geometry model of the thermal reservoir working area based on physical parameters of rocks and wellbores in the thermal reservoir working area, setting initial conditions of the geological geometry model of the thermal reservoir working area based on a temperature field and a stress field of the thermal reservoir working area, and setting boundary conditions for the geological geometry model of the thermal reservoir working area to construct a thermal force coupling model of the thermal reservoir working area; extracting a temperature field and a stress field around a target wellbore based on the thermal force coupling model of the thermal reservoir working area; setting outer boundary conditions for a geometry model of the target wellbore based on the temperature field and the stress field around the target wellbore, setting initial conditions and inner boundary conditions for the geometry model of the target wellbore, and constructing a wellbore thermal force coupling model; introducing a fractional order heat transfer model and a fractional order plasticity model into the wellbore thermal force coupling model to perform wellbore thermal force coupling simulation and obtain a temperature field and a stress field of the target wellbore evolving over time.

2. The method of claim 1, wherein, The geological geometry model of the thermal reservoir working area is established based on three-dimensional seismic survey results and wellbore structure data; The temperature field of the thermal reservoir working area is obtained by using a spatial interpolation method based on drilling temperature measurement data, geothermal exploration data, and well temperature monitoring data; The stress field of the thermal reservoir working area is obtained based on acoustic logging data, core mechanics experiment data, and seismic wave velocity inversion data.

3. The method of claim 1, wherein, The extraction of the temperature field and the stress field around the target wellbore based on the thermal force coupling model of the thermal reservoir working area comprises: modifying temperature and stress boundary conditions inside the wellbore, simulating thermal force responses of the thermal reservoir working area under injection-production conditions, and extracting a temperature field and a stress field of element nodes around the target wellbore.

4. The method of claim 1, wherein, The geometry model of the target wellbore is a geometry model of a casing-cement sheath-formation combination established based on the structure of the target wellbore, adopts a local encryption method in a radial cross-sectional area of the wellbore, and adopts a relatively sparse grid division method in a longitudinal direction of the wellbore; Initial temperature conditions of the geometry model of the target wellbore are set based on in-well monitoring data and the temperature field of the thermal reservoir working area, initial stress conditions of the geometry model are set based on in-well measured data and the stress field of the thermal reservoir working area, outer boundary conditions of the geometry model are set based on the temperature field and the stress field around the target wellbore, and inner boundary conditions of the geometry model are set based on injection-production modes.

5. The method of claim 1, wherein, The fractional order heat transfer model is realized by introducing a fractional order heat transfer constitutive model into a heat transfer equation in a thermal force coupling equation set: wherein, is the density, is the specific heat capacity, is the temperature, is the time; is the fractional heat conduction coefficient, is the fractional derivative operator, is the thermal expansion factor, is the reference temperature, is the volumetric strain.

6. The method of claim 1, wherein, The fractional order plasticity model is realized by introducing a fractional order plasticity constitutive model into a stress balance equation in the thermal force coupling equation set: wherein, is the stress, is the elastic matrix, is the strain, is the plastic strain, is the viscosity coefficient, is the fractional derivative operator, is the yield stress, is the yield function, is the equivalent stress, is the yield stress, is the thermal expansion coefficient, is the body force in each direction.

7. The method according to claim 5 or 6, characterized in that, The fractional order derivative is a GL fractional order derivative, and is approximately calculated by using a numerical method. wherein, is a fractional derivative operator, is a variable to be differentiated, is a weight function, is a fractional order, is an initial time is a time.

8. The method of claim 6, wherein, The method further comprises: When stress updating is performed, an elastic trial is performed; If the equivalent stress is less than the yield stress, the target wellbore is in an elastic range, and stress is updated based on a preset stress updating formula; If the equivalent stress is greater than or equal to the yield stress, the target wellbore is in a plastic range, and stress is updated based on a fractional order plasticity model.

9. An apparatus for wellbore thermal coupled simulation based on fractional order model, characterized in that, The device comprises: a construction module configured to assign a geological geometry model of a thermal reservoir working area based on physical parameters of rocks and wellbores in the thermal reservoir working area, set initial conditions of the geological geometry model of the thermal reservoir working area based on a temperature field and a stress field of the thermal reservoir working area, and set boundary conditions for the geological geometry model of the thermal reservoir working area to construct a thermal force coupling model of the thermal reservoir working area; The extraction module is configured to extract a temperature field and a stress field around a target wellbore based on the thermal-mechanical coupling model; The establishment module is further configured to set an outer boundary condition for a geometric model of the target wellbore based on the temperature field and the stress field around the target wellbore, set an initial condition and an inner boundary condition for the geometric model of the target wellbore, and construct the thermal-mechanical coupling model of the wellbore; The simulation module is configured to introduce a fractional heat transfer model and a fractional plasticity model into the thermal-mechanical coupling model of the wellbore, perform thermal-mechanical coupling simulation of the wellbore, and obtain a temperature field and a stress field of the target wellbore evolving over time.

10. An electronic device comprising: a processor; and a memory arranged to store computer executable instructions which, when executed, cause the processor to perform the steps of the method of thermal-mechanical coupling simulation of a wellbore based on a fractional model according to any one of claims 1-8.

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