Design method for large-scale fracturing construction plan of deep geothermal reservoir based on weak structure

Abstract

The invention discloses a design method for a large-scale fracturing construction plan of a deep geothermal reservoir based on a weak structure, which relates to the technical field of exploration and development of high-temperature geothermal resources. The steps include: characterizing and representing the weak structure of the deep geothermal reservoir large-scale fracturing formation to obtain a comprehensive representation large model; based on the comprehensive representation large model, delineating and evaluating the fracturability of the weak structure zone of the deep geothermal reservoir large-scale fracturing formation to obtain a delineated area; based on the delineated area, predicting the farthest disturbance range and distance of the weak structure fracturing transformation of the deep geothermal reservoir large-scale fracturing formation; based on the fracturability and the predicted farthest disturbance range and distance of the geothermal reservoir fracturing transformation, determining the well spacing, designing the well positions, deploying the well pattern and optimizing the fracturing intervals to complete the design of the large-scale fracturing construction plan of the deep geothermal reservoir. Through the construction and analysis of the comprehensive representation large model, the invention can accurately delineate the weak structure zone of the formation suitable for fracturing, predict the farthest disturbance range and distance of the fracturing transformation, and realize efficient exploitation.

Description

Technical Field

[0001] The present invention belongs to the technical field of exploration and development of high-temperature geothermal resources, and particularly relates to a design method for a large-scale fracturing construction plan for deep geothermal reservoirs based on weak structures. Background Art

[0002] As an important geothermal reservoir, a deep geothermal reservoir refers to high-temperature rock masses with a temperature greater than 150 °C and a burial depth greater than 3500 m. The exploration and development of deep geothermal resources in China and the research and development of related core technologies are still in the primary exploration stage. So far, no commercial exploitation has been successfully achieved, and no systematic exploration and development technical methods suitable for China's geothermal geological conditions have been formed. Although deep geothermal resources have advantages such as large reserves, renewable, green and environmental protection, compared with production, they are still low-value energy compared with traditional fossil fuels such as oil and natural gas. This means that to obtain the same value of thermal energy resources, a larger volume of high-temperature liquid needs to be extracted from the formation, with relatively high development costs and technical inputs. In other words, for the exploitation of deep geothermal reservoirs, under the existing conditions, the only way is to break through large-scale reservoir fracturing transformation to obtain an ideal larger volume of fracture network structure in order to successfully achieve commercial exploitation of enhanced geothermal systems (EGS). However, the relevant research has not yet made a breakthrough, which has always been the biggest technical problem restricting the large-scale development and utilization of deep geothermal resources in China. Summary of the Invention

[0003] The present invention proposes a design method for a large-scale fracturing construction plan for deep geothermal reservoirs based on weak structures, aiming to study the action mechanism of weak structures in large-scale fracturing of deep geothermal reservoirs, optimize the weak structure zones of the formation where large-scale fracturing can be implemented, and achieve good results through low-displacement and low-intensity fracturing.

[0004] To achieve the above object, the present invention provides the following solution:

[0005] A design method for a large-scale fracturing construction plan for deep geothermal reservoirs based on weak structures, characterized in that the steps include:

[0006] Characterize and represent the weak structures of the formation for large-scale fracturing of deep geothermal reservoirs to obtain a comprehensive characterization large model; the comprehensive characterization large model includes: a pore-permeability evolution model of deep geothermal reservoirs, a physical property characteristic model of deep geothermal reservoirs, an evolution model of the mechanical properties of deep geothermal reservoirs with temperature, a well storage geological model, a three-dimensional geological model of deep geothermal reservoirs at the site scale, a multi-scale embedded weak structure geological model, and a rock mechanics constitutive model;

[0007] Based on the comprehensive characterization large model, delineate and evaluate the fracturability of the weak structure zones of the formation for large-scale fracturing of deep geothermal reservoirs to obtain a delineated area;

[0008] Based on the delineated area, predict the farthest disturbance range and distance of the fracturing transformation of the weak structure in the deep geothermal reservoir formation with large-scale fracturing.

[0009] Based on the farthest disturbance range and distance of the fracturing transformation of the weak structure in the deep geothermal reservoir formation with large-scale fracturing, determine the well spacing, design the well positions, deploy the well pattern, and optimize the fracturing intervals to complete the design of the construction plan for large-scale fracturing in the deep geothermal reservoir.

[0010] Preferably, in the comprehensive characterization large model,

[0011] The pore-permeability evolution model of the deep geothermal reservoir is used to characterize the distribution of the physical properties of the geothermal reservoir at the laboratory scale.

[0012] The physical property model of the deep geothermal reservoir is used to characterize the distribution of the physical characteristics of the geothermal reservoir at the laboratory scale under high temperature.

[0013] The evolution model of the mechanical properties of the deep geothermal reservoir with temperature is used to characterize the distribution of the mechanical characteristics of the deep geothermal reservoir at the laboratory scale under high temperature.

[0014] The well-storage geological model is used to characterize the distribution characteristics of the geothermal reservoir at the well-storage scale.

[0015] The three-dimensional geological model of the deep geothermal reservoir at the site scale is used to analyze and interpret the accurate information of the deep geothermal reservoir formation with large-scale fracturing of different types and scales.

[0016] The multi-scale embedded weak structure geological model is used to locate and depict weak structures of different types and scales.

[0017] The rock mechanics constitutive model is used to characterize the complex weak structure characteristics of the deep geothermal reservoir.

[0018] Preferably, the method for delineation includes: using the comprehensive characterization large model to analyze the geothermal reservoir parameters, studying the non-linear evaluation method of the deep geothermal reservoir, evaluating the quality and weakness degree of the geothermal reservoir, and completing the delineation of the weak structure zone in the deep geothermal reservoir formation with large-scale fracturing.

[0019] Preferably, the method for evaluating the fracturability includes: establishing a mechanical brittleness index model that reflects the whole process characteristics of rock deformation and failure, analyzing the brittleness, activation conditions, and propagation modes of the weak structure in the geothermal reservoir, and obtaining the fracturability of the weak structure in the deep geothermal reservoir formation with large-scale fracturing based on the brittleness of the rock, the development characteristics of the weak structure, and the in-situ stress distribution.

[0020] Preferably, based on the comprehensive characterization large model, combined with the triaxial fracturing experiment, predict the farthest disturbance range and distance of the geothermal reservoir fracturing transformation.

[0021] The present invention also provides a deep geothermal reservoir large-scale fracturing construction plan design system based on weak structures, which is used to implement the above method and includes: a construction module, a delineation module, a prediction module, and a design module;

[0022] The construction module is used to characterize and represent the weak structures of the deep geothermal reservoir large-scale fracturing formation, and obtain a comprehensive characterization large model;

[0023] The delineation module is used to delineate and evaluate the fracturability of the weak structure zone of the deep geothermal reservoir large-scale fracturing formation based on the comprehensive characterization large model, and obtain a delineated area;

[0024] The prediction module is used to predict the farthest disturbance range and distance of the fracturing transformation of the weak structures of the deep geothermal reservoir large-scale fracturing formation based on the delineated area;

[0025] The design module is used to determine the well spacing, design the well positions, deploy the well pattern, and optimize the fracturing intervals based on the farthest disturbance range and distance of the fracturing transformation of the weak structures of the deep geothermal reservoir large-scale fracturing formation, and complete the design of the deep geothermal reservoir large-scale fracturing construction plan.

[0026] Preferably, the comprehensive characterization large model includes: a deep geothermal reservoir pore-permeability evolution model, a deep geothermal reservoir physical property characteristic model, a deep geothermal reservoir mechanical property evolution model with temperature, a well-storage geological model, a site-scale deep geothermal reservoir three-dimensional geological model, a multi-scale embedded weak structure geological model, and a rock mechanics constitutive model;

[0027] The deep geothermal reservoir pore-permeability evolution model is used to characterize the distribution of physical properties of the geothermal reservoir at the laboratory scale;

[0028] The deep geothermal reservoir physical property characteristic model is used to characterize the distribution of physical characteristics of the geothermal reservoir at the laboratory scale under high temperature;

[0029] The deep geothermal reservoir mechanical property evolution model with temperature is used to characterize the distribution of mechanical characteristics of the deep geothermal reservoir at the laboratory scale under high temperature;

[0030] The well-storage geological model is used to characterize the distribution characteristics of the geothermal reservoir at the well-storage scale;

[0031] The site-scale deep geothermal reservoir three-dimensional geological model is used to analyze and interpret the accurate information of the deep geothermal reservoir large-scale fracturing formation of different types and scales;

[0032] The multi-scale embedded weak structure geological model is used to locate and characterize weak structures of different types and scales;

[0033] The rock mechanics constitutive model is used to characterize the complex weak structure characteristics of the deep geothermal reservoir.

[0034] The beneficial effects of the present invention are:

[0035] Through the construction and analysis of the comprehensive characterization large model, the present invention can accurately delineate the formation weak structure zones suitable for fracturing, predict the farthest disturbance range and distance of fracturing transformation, thereby optimizing well location design, well pattern deployment, and the selection of fracturing intervals, achieving efficient exploitation under the conditions of low displacement and low intensity fracturing, and significantly improving the development efficiency and safety of deep geothermal reservoir resources. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] In order to more clearly illustrate the technical solutions of the present invention, the drawings required for use in the embodiments will be briefly introduced below. Obviously, the drawings in the following description are only some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can be obtained based on these drawings.

[0037] Figure 1 Schematic diagram of the multi-scale embedded weak structure geological model for the embodiments of the present invention;

[0038] Figure 2 Schematic diagram of the correlation model between the geophysical field and the mechanical characteristics of the geothermal reservoir for the embodiments of the present invention. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0039] The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention. Obviously, the described embodiments are only some, rather than all, of the embodiments of the present invention. All other embodiments obtained by those of ordinary skill in the art without creative efforts based on the embodiments of the present invention belong to the scope of protection of the present invention.

[0040] In order to make the above objects, features, and advantages of the present invention more obvious and understandable, the present invention will be further described in detail below with reference to the drawings and specific embodiments.

[0041] Embodiment 1

[0042] The design method of the deep geothermal reservoir large-scale fracturing construction plan based on the weak structure in this embodiment includes the following steps:

[0043] S1. Characterize and represent the weak structure of the deep geothermal reservoir large-scale fracturing formation to obtain a comprehensive characterization large model.

[0044] Specifically, in this embodiment, the weak structure of the deep geothermal reservoir large-scale fracturing formation (hereinafter referred to as the weak structure) is simulated in the laboratory, and then characterized and represented. Among them, the comprehensive characterization large model includes: the deep geothermal reservoir pore-permeability evolution model, the deep geothermal reservoir physical property model, the deep geothermal reservoir mechanical property evolution model with temperature, the well storage geological model, the multi-scale embedded weak structure geological model, and the rock mechanics constitutive model.

[0045] Specifically, through high-energy CT real-time scanning and triaxial experiments, a three-dimensional reconstruction technology is used to build a visualization numerical model of deep heat storage, combined with high-temperature and high-pressure servo permeability experiments, the visualization numerical model is optimized, and a deep heat storage porosity and permeability evolution model containing temperature and pressure parameters is constructed; and the deep heat storage porosity and permeability evolution model is used to characterize and characterize the distribution of laboratory-scale heat storage properties. Specifically, by testing the porosity and permeability parameters of deep heat storage under different temperature and pressure conditions, the porosity and permeability parameters under different conditions are fitted, and the evolution law of the porosity and permeability of deep heat storage with temperature and pressure parameters is obtained.

[0046] In this embodiment, the triaxial test steps include: placing the sample in a triaxial fracturing system and sealing it, heating it at a fixed rate, keeping it warm and pressurizing it according to preset conditions, and then injecting fracturing fluid for fracturing.

[0047] The steps of the high temperature and high pressure servo permeability test include: sealing the sample and placing it in the servo permeability test system, heating and keeping warm, applying axial load, confining pressure and pore pressure respectively, and forming an osmotic pressure difference at both ends of the sample by adjusting the pore pressure control system to complete the permeability test of the sample under high temperature and high pressure conditions.

[0048] Through cross-band rock physics experiments, the changes of thermal reservoir longitudinal and transverse wave velocity, resistivity, magnetism, polarizability, density and elastic parameters with temperature and pressure are studied, a deep thermal reservoir physical property characteristic model is established, and the distribution of laboratory-scale thermal reservoir physical characteristics at high temperature is described and characterized. Specifically, the steps of cross-band rock physics experiments include: using a cross-band rock parameter test system to measure the seismic wave velocity and ultrasonic wave velocity of the sample at different frequency bands, and calculating various rock parameters.

[0049] The deep thermal storage characteristics model is essentially obtained by conducting cross-band rock physics experiments at different temperatures to obtain various parameters under different temperature and pressure conditions, such as longitudinal and transverse wave velocities, resistivity, magnetism, polarizability, density and elastic parameters. The parameters are fitted with the changes in temperature and pressure conditions to obtain the corresponding formulas and then connected in parallel to obtain the deep thermal storage characteristics model.

[0050] Based on the analysis of indoor tests, the outcrop, drilling, logging and field test data are integrated to identify and interpret the structure of the well storage medium, establish a well storage geological model, and describe and characterize the distribution characteristics of the well storage scale heat storage. Specifically, based on the outcrop, drilling and logging, field test data, etc., a three-dimensional geological model can be initially constructed, the well location can be confirmed, and a well storage geological model can be established.

[0051] Based on rock physics experiments, logging data analysis, forward and inversion simulation, constrained inversion, geophysical structural interpretation, weak structural surface characterization and attribute analysis, the fine structural characteristics of deep heat reservoirs are obtained, and a three-dimensional geological model of deep heat reservoirs at the site scale is established. The specific steps include:

[0052] Through rock physics experiments, physical and mechanical parameters such as the tensile strength, compressive strength, porosity, and permeability of deep geothermal reservoirs can be obtained, providing mechanical parameter support for the model. Through logging data, not only thermal parameters such as the thermal conductivity of the geothermal reservoir can be obtained, but also the thermal structure of the geothermal reservoir can be deduced through comprehensive analysis of various logging parameters. Through forward and inverse simulation, constrained inversion, etc., quantitative analysis and calculation of the electrical characteristics, gravity and magnetic field characteristics, and geothermal field characteristics of the geothermal reservoir can be carried out, providing parameter support for interpreting the genetic mechanism of the geothermal reservoir and evaluating the resource volume. Through geophysical structure interpretation, weak structural plane characterization, etc., the weak structure of the geothermal reservoir can be accurately located, improving the accuracy of the three-dimensional geological model.

[0053] Using the established three-dimensional geological model of deep geothermal reservoirs at the site scale, analyze and interpret the accurate information of different types and scales of weak structures. The accurate information includes: spatial distribution, geometric shape, development density, scale, burial depth, superposition, and contact relationship, etc.

[0054] Using finite difference, finite element, finite volume method, etc., construct a multi-scale embedded weak structure geological model, as Figure 1 shown. Compared with the traditional model, the multi-scale embedded weak structure geological model uses an unstructured grid method to characterize fractures, avoiding the cumbersome problem of unstructured grid meshing in traditional modeling, and qualitatively analyzing the distribution of weak structures, with higher accuracy. In this embodiment, the finite element method is used to construct a multi-scale embedded weak structure geological model. The finite element method is a traditional numerical method that treats the weak structure as the boundary of the grid. The structural matrix displacement method is an early prototype of the finite element method, and subsequently, the weighted residual method finite element method and the variational principle finite element method have been developed. Among them, the Galerkin finite element method is a typical representative of the weighted residual method. Generally, based on the stress balance equation, the displacement field is first solved, then the strain and stress fields at the Gauss points are calculated, and finally the results at the Gauss points are extended to the grid nodes.

[0055] For complex weak structure characteristics (fracture type, fracture-porosity type, porosity type, cavity type, broken type, joint type, etc.), based on the effective medium (EMT) theory, a rock mechanics constitutive model of discontinuous geothermal reservoir media at high temperature is established using the parallel superposition calculation method of pore and matrix strain. Specifically, according to the theory of elasticity, the strain field conforms to the superposition principle. When constructing the rock constitutive model, the superposition principle of the strain field is also applied. The total strain is equal to the sum of the strains caused by each stress. By determining the boundary conditions of various weak structures, the distribution of stress and strain can be confirmed, and the strains of various weak structures can be calculated by parallel superposition to construct the mechanical constitutive model of discontinuous geothermal reservoir media.

[0056] S2. Based on the comprehensive characterization large model, delineate and evaluate the fracturability of the weak structural zones in the deep geothermal reservoir for large-scale fracturing, and obtain the delineated area.

[0057] Based on the comprehensive characterization model established in S1, analyze the obtained geothermal reservoir parameters, study the non-linear evaluation method of the deep geothermal reservoir, evaluate the quality and weakness degree of the geothermal reservoir, etc., delineate the weak structural zones that can be subjected to large-scale fracturing under the existing technical conditions, and obtain the delineated area. Among them, the geothermal reservoir parameters include all the mechanical parameters, thermal parameters, electrical parameters, etc. obtained through laboratory experiments, logging, drilling, field tests, forward and inverse modeling.

[0058] The steps of the non-linear evaluation method for the deep geothermal reservoir include: through the obtained parameters, confirm the area, thickness, temperature, porosity, rock density, etc. of the geothermal reservoir, calculate the geothermal reserves and recoverable amounts of different horizons of the model in segments, and calculate the production capacity according to the recoverable amount. In this embodiment, the criteria for evaluating the quality and weakness degree of the geothermal reservoir refer to "Geothermal Resource Evaluation Method" and "Geothermal Resource Geological Exploration Specification".

[0059] S3. Based on the delineated area, predict the farthest disturbance range and distance of the weak structural zone of the deep geothermal reservoir for large-scale fracturing.

[0060] Within the delineated area, combined with the triaxial fracturing experiment, predict the farthest possible disturbance range / distance of the geothermal reservoir fracturing transformation. The specific steps are as follows:

[0061] S301. Use a customized high-temperature and high-pressure multi-field coupling experimental system for geothermal reservoir rocks to carry out triaxial compression experiments under different temperature and pressure conditions, synchronously monitor acoustic emission, wave velocity and deformation (axial, circumferential), and clarify the triaxial compressive strength, deformation modulus, Poisson's ratio, plastic coefficient, elastic wave velocity and dynamic elastic modulus of geothermal reservoir rocks under high-temperature and high-pressure conditions and their evolution laws according to stress-strain, acoustic emission and wave velocity data;

[0062] S302. Based on the equivalent medium theory and different mechanical parameter data, establish an evolution model of the mechanical properties of geothermal reservoir rocks containing temperature parameters, and construct the correlation and constitutive relationship between the mechanical properties of geothermal reservoir rocks at high temperatures; the expression of the evolution model of the mechanical properties of geothermal reservoir rocks containing temperature parameters is as follows:

[0063] ,

[0064] Among them, T and T0 respectively represent temperature and initial temperature, represents the bulk modulus of the rock, represents the thermal expansion coefficient of the rock, represents the thermal conductivity, t represents time, and εT represents the volume strain; represents the specific heat capacity of water, represents the specific heat capacity of the rock skeleton, represents the specific heat capacity of the fluid-saturated porous medium, k represents the permeability of the continuous medium, and μ represents the dynamic viscosity of the fluid, represents the gradient operator, represents the pressure gradient.

[0065] S303. Based on the stress-strain relationship, calculate according to the results obtained from S301 - S302 or apply known elastic models to establish elastic mechanics equations, solve the stress distribution inside the geothermal reservoir rock under different temperature and pressure conditions, and determine the magnitude and direction of stress perturbations;

[0066] S304. Combining S301 - S303, study the correlation between the physical and mechanical properties of the geothermal reservoir rock, obtain empirical formulas for characterizing rock mechanical parameters using physical parameters, and calibrate and scale geophysical parameters for inverting the mechanical properties of the geothermal reservoir at the field scale;

[0067] S305. Through the correlation between the mechanical characteristics and geophysical property characteristics of the hot dry rock reservoir under high temperature and high pressure, analyze the response relationship between the mechanical characteristics of the geothermal reservoir and the multi - geophysical fields;

[0068] S306. Based on S301 - S305, establish a correlation model between the geophysical field and the mechanical characteristics of the geothermal reservoir (as shown in Figure 2 ), and combine the equivalent medium theory to clarify the variation law of the mechanical characteristics of the geothermal reservoir with temperature at the field scale, and estimate the possible farthest perturbation range / distance of reservoir fracturing transformation.

[0069] S4. Based on the farthest perturbation range and distance of the fracturing transformation of the weak structure in the deep geothermal reservoir, determine the well spacing, design well positions, deploy well patterns, and optimize the fracturing intervals to complete the design of the large - scale fracturing construction plan for the deep geothermal reservoir.

[0070] S401. According to the spatial distribution range and shape of the delineated weak structure zone in the formation, deploy well positions along the long - axis direction or the strike of the original weak structural plane;

[0071] S402. According to the predicted or estimated possible maximum perturbation range / distance L of reservoir fracturing transformation, considering the uncertainty of the estimation accuracy and the objective requirement of easy connectivity between wells, set a 20% overlapping section for the perturbation range between adjacent wells, then the well spacing R can be determined as approximately:

[0072] R = (L + L) × 80%,

[0073] and deploy well patterns within the entire weak structure zone;

[0074] S403. Optimize the fracturing intervals according to the burial depth of the weak structure zone at the designed well positions.

[0075] Example 2

[0076] This embodiment also provides a design system for large-scale fracturing construction plan of deep geothermal reservoir based on weak structures, including: a construction module, a delineation module, a prediction module and a design module; the construction module is used to characterize and represent the weak structures of the deep geothermal reservoir large-scale fracturing formation to obtain a comprehensive representation large model; the delineation module is used to delineate and evaluate the fracturability of the weak structure zones of the deep geothermal reservoir large-scale fracturing formation based on the comprehensive representation large model to obtain a delineated area; the prediction module is used to predict the farthest disturbance range and distance of the fracturing transformation of the weak structures of the deep geothermal reservoir large-scale fracturing formation based on the delineated area; the design module is used to determine the well spacing, design the well positions, deploy the well pattern and optimize the fracturing intervals based on the farthest disturbance range and distance of the fracturing transformation of the weak structures of the deep geothermal reservoir large-scale fracturing formation, and complete the design of the large-scale fracturing construction plan of the deep geothermal reservoir.

[0077] The above comprehensive representation large model includes: a deep geothermal reservoir porosity-permeability evolution model, a deep geothermal reservoir physical property characteristic model, a deep geothermal reservoir mechanical property evolution model with temperature, a well-reservoir geological model, a site-scale three-dimensional geological model of the deep geothermal reservoir, a multi-scale embedded weak structure geological model and a rock mechanics constitutive model; the deep geothermal reservoir porosity-permeability evolution model is used to characterize the distribution of physical properties of the geothermal reservoir at the laboratory scale; the deep geothermal reservoir physical property characteristic model is used to characterize the distribution of physical characteristics of the geothermal reservoir at the laboratory scale under high temperature; the deep geothermal reservoir mechanical property evolution model with temperature is used to characterize the distribution of mechanical characteristics of the deep geothermal reservoir at the laboratory scale under high temperature; the well-reservoir geological model is used to characterize the distribution characteristics of the well-reservoir scale geothermal reservoir; the site-scale three-dimensional geological model of the deep geothermal reservoir is used to analyze and interpret the accurate information of the deep geothermal reservoir large-scale fracturing formation of different types and scales; the multi-scale embedded weak structure geological model is used to locate and characterize weak structures of different types and scales; the rock mechanics constitutive model is used to characterize the complex weak structure characteristics of the deep geothermal reservoir.

[0078] The above-described embodiments are only descriptions of the preferred embodiments of the present invention, and do not limit the scope of the present invention. Without departing from the design spirit of the present invention, various deformations and improvements made by those of ordinary skill in the art to the technical solutions of the present invention shall fall within the protection scope determined by the claims of the present invention.

Claims

1. A method for designing a large-scale fracturing construction scheme for deep thermal reservoirs based on weak structures, characterized in that the steps include: Characterize and characterize the weak structure of deep thermal reservoir-scale fractured formations to obtain a comprehensive characterization large model; The comprehensive characterization large model includes: a deep heat reservoir porosity evolution model, a deep heat reservoir physical property characteristic model, a deep heat reservoir mechanical property evolution model with temperature, a well reservoir geological model, a site-scale deep heat reservoir three-dimensional geological model, a multi-scale embedded weak structure geological model and a rock mechanics constitutive model; Based on the comprehensive characterization large model, the weak structural zone of the deep thermal reservoir scale fracturing formation is delineated and the fracturing property is evaluated to obtain the delineated area; Based on the delineated area, combined with triaxial fracturing experiments, the disturbance range and distance of fracturing transformation of weak structures of deep thermal reservoir scale fracturing formations are predicted; the steps include: S301. Use a customized geothermal reservoir rock high temperature and high pressure multi-field coupling experimental system to carry out triaxial compression experiments under different temperature and pressure conditions; S302. Based on the equivalent medium theory and different mechanical parameter data, a geothermal reservoir rock mechanical property evolution model with temperature parameters is established: ， Where T and T0 represent temperature and initial temperature respectively. represents the bulk modulus of rock, represents the thermal expansion coefficient of rock, represents thermal conductivity, t represents time, and εT represents volume strain; is the specific heat capacity of water, represents the specific heat capacity of the rock skeleton, represents the specific heat capacity of the porous medium containing fluid, k represents the permeability of the continuous medium, μ represents the dynamic viscosity of the fluid, represents the gradient operator, represents the pressure gradient; S303. Based on the stress-strain relationship, the elastic mechanics equation is established according to the results obtained in S301-S302 or by applying a known elastic model for calculation; S304. Combined with S301-S303, study the correlation between the physical and mechanical properties of geothermal reservoir rocks, obtain empirical formulas that use physical parameters to characterize rock mechanical parameters, and calibrate and invert geophysical parameters of geothermal reservoir mechanical properties at the site scale; S305. Analyze the relationship between the mechanical characteristics of geothermal reservoirs and the response of multi-element geophysical fields by correlating the mechanical characteristics of hot dry rock reservoirs with geophysical properties under high temperature and high pressure; S306. On the basis of S301-S305, establish a correlation model between the geophysical field and the mechanical characteristics of the geothermal reservoir, and estimate the farthest possible disturbance range / distance of reservoir fracturing transformation; Based on the disturbance range and distance of fracturing transformation of weak structures of deep thermal reservoirs, determine the well spacing, design well locations, deploy well patterns and fracturing layers, and complete the design of deep thermal reservoir large-scale fracturing construction plan; the steps include: S401. Deploy wells along the long axis direction or the strike of the original weak structural surface according to the spatial distribution range and shape of the identified weak structural zone; S402. According to the predicted maximum disturbance range / distance L of reservoir fracturing transformation, the well spacing R is determined as: R = (L + L) × 80%, And deploy well patterns throughout the weak structural zone; S403. Optimize the fracturing layer section according to the buried depth of the weak structural zone at the well site.

2. The method for designing a large-scale fracturing construction scheme for deep thermal storage based on weak structure according to claim 1, characterized in that: In the comprehensive characterization model, The deep thermal reservoir porosity evolution model is used to characterize the distribution of thermal storage properties at laboratory scale; The deep heat storage physical property characteristic model is used to characterize the distribution of physical characteristics of heat storage at laboratory scale; The model of evolution of mechanical properties of deep heat reservoirs with temperature is used to characterize the distribution of mechanical characteristics of deep heat reservoirs at laboratory scale; The well reservoir geological model is used to characterize the distribution characteristics of well reservoir scale heat reservoir; The site-scale deep heat reservoir three-dimensional geological model is used to analyze and interpret accurate information on the scale of fractured formations of different types and scales of deep heat reservoirs; The multi-scale embedded weak structure geological model is used to locate and characterize weak structures of different types and scales; The rock mechanics constitutive model is used to characterize the complex weak structural characteristics of deep heat reservoirs.

3. The method for designing a large-scale fracturing construction scheme for deep thermal storage based on weak structure according to claim 1, characterized in that: The delineation method includes: using the comprehensive characterization large model to analyze heat reservoir parameters, studying the nonlinear evaluation method of deep heat reservoirs, evaluating the quality and weakness of heat reservoirs, and completing the delineation of weak structural zones of deep heat reservoir scale fracturing formations.

4. The method for designing a large-scale fracturing construction scheme for deep thermal storage based on weak structure according to claim 1, characterized in that: The methods for evaluating fracturing properties include: establishing a mechanical brittleness index model that reflects the characteristics of the entire process of rock deformation and destruction, analyzing the brittleness, activation conditions and expansion methods of the weak structure of the thermal reservoir, and obtaining the fracturing properties of the weak structure of the deep thermal reservoir formation based on the rock brittleness, development characteristics of the weak structure and the distribution of ground stress.

5. A system for designing large-scale fracturing construction schemes for deep thermal reservoirs based on weak structures, the system being used to implement the method according to any one of claims 1 to 4, characterized in that: include: Building module, delineating module, predicting module and designing module; The construction module is used to characterize and characterize the weak structure of the deep thermal reservoir scale fractured formation to obtain a comprehensive characterization large model; The delineation module is used to delineate and evaluate the fracturing properties of the weak structural zone of the deep thermal reservoir scale fracturing formation based on the comprehensive characterization large model to obtain the delineated area; The prediction module is used to predict the disturbance range and distance of the fracturing transformation of the weak structure of the deep thermal reservoir scale fracturing formation based on the delineated area; The design module is used to determine the well spacing, design the well location, deploy the well network and the fracturing layer section based on the disturbance range and distance of the fracturing transformation of the weak structure of the deep thermal reservoir large-scale fracturing formation, and complete the design of the deep thermal reservoir large-scale fracturing construction plan.

6. The deep thermal storage large-scale fracturing construction scheme design system based on weak structure according to claim 5 is characterized in that: The comprehensive characterization large model includes: a deep heat reservoir porosity evolution model, a deep heat reservoir physical property characteristic model, a deep heat reservoir mechanical property evolution model with temperature, a well reservoir geological model, a site-scale deep heat reservoir three-dimensional geological model, a multi-scale embedded weak structure geological model and a rock mechanics constitutive model; The deep thermal reservoir porosity evolution model is used to characterize the distribution of thermal storage properties at laboratory scale; The deep heat storage physical property characteristic model is used to characterize the distribution of physical characteristics of laboratory-scale heat storage at high temperatures; The model of evolution of deep heat storage mechanical properties with temperature is used to characterize the distribution of deep heat storage mechanical characteristics at laboratory scale under high temperature; The well reservoir geological model is used to characterize the distribution characteristics of well reservoir scale heat reservoir; The site-scale deep heat reservoir three-dimensional geological model is used to analyze and interpret accurate information on the scale of fractured formations of different types and scales of deep heat reservoirs; The multi-scale embedded weak structure geological model is used to locate and characterize weak structures of different types and scales; The rock mechanics constitutive model is used to characterize the complex weak structural characteristics of deep heat reservoirs.

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