Method, device and equipment for predicting mechanical properties of shale carbon sequestration in saline water layer

Abstract

The invention provides a salt water layer shale carbon sequestration mechanical property prediction method, device and equipment, and belongs to the field of shale reservoir oil and gas reservoir development.The method comprises the steps that a shale sample of a salt water layer is obtained, the corrosion reaction of the shale sample under the preset environment condition is simulated, and the porosity and the multi-scale mechanical property of the shale sample are obtained; fitting a first change rule of the porosity along with time; defining a corrosion damage variable, and determining a second change rule of the damage variable based on time; fitting a third change rule of the multi-scale mechanical property, the porosity and the damage variable; combining the second change rule and the third change rule to obtain a multi-scale mechanical property evolution prediction model of the shale; and obtaining target porosity data of the target shale, and obtaining mechanical property evolution prediction results of the salt water layer shale under different time scales according to the mechanical property evolution prediction model. Therefore, the mechanical properties of the shale under different time scales can be predicted, and the method has high accuracy and reliability.

Description

Technical Field

[0001] The present invention belongs to the field of shale reservoir oil and gas layer development, and particularly relates to a method, device and equipment for predicting the mechanical properties of carbon sequestration in saline shale formations. Background Art

[0002] With the increasingly serious problem of climate change, reducing carbon dioxide (CO2) emissions has become the core issue of global concern. To achieve this goal, carbon capture, utilization and storage (CCUS) technology is regarded as an important strategic means. Geological storage in deep saline aquifers is considered one of the most promising long-term storage methods due to its large storage capacity and wide distribution.

[0003] Among them, the shale caprock, as the natural barrier of the storage reservoir, the change of its long-term mechanical properties has a decisive impact on the safety of CO2 storage. However, the existing technology still lacks in-depth research on the quantitative characterization and cross-scale prediction of the performance evolution of shale under the multi-field coupling of chemistry-physics-mechanics.

[0004] Currently widely used simulation software such as TOUGH focuses more on the simulation of chemical reactions and fluid migration, lacks support for the degradation of the mechanical properties of the caprock, and the mechanical modeling mostly focuses on short time scales or single stress fields, failing to combine the influence of long-term chemical changes on the caprock performance, making it difficult to establish a complete cross-scale mechanical model, resulting in the inability to accurately predict the mechanical property changes of shale on long time scales. Summary of the Invention

[0005] In order to solve the problem in the existing technology that the mechanical property changes of shale on long time scales cannot be accurately predicted, the present invention provides a method, device and equipment for predicting the mechanical properties of carbon sequestration in saline shale formations.

[0006] To achieve the above object, the present invention provides the following technical solutions: Firstly, a method for predicting the mechanical properties of carbon sequestration in saline shale formations is provided, including the following steps: S1. Shale acquisition and dissolution simulation.

[0007] Obtain shale samples from the saline aquifer, simulate the dissolution reaction of the shale samples under preset environmental conditions, and provide basic data for obtaining the porosity and multi-scale mechanical property changes of the shale samples subsequently; S2. Modeling the evolution law of porosity.

[0008] Use the Boltzmann growth curve to fit the first change law of porosity with time; define the dissolution damage variable according to the change of porosity, and determine the second change law of the dissolution damage variable with time based on the first change law; S3. Modeling the relationship between shale mechanical properties and porosity.

[0009] Fitting the third variation law of multi-scale mechanical properties with porosity and dissolution damage variables using an exponential decay function; By combining the second and third variation laws, the evolution law of the multi-scale mechanical properties of shale is obtained, and the evolution law of the multi-scale mechanical properties is used as a prediction model; S4. Application of the prediction model.

[0010] Obtain the target porosity data of the target shale, input the target porosity data into the prediction model, and obtain the prediction results of the mechanical property evolution of shale in the saline aquifer at different time scales.

[0011] Optionally, the porosity includes pore volume and pore size distribution, and the multi-scale mechanical properties include microhardness and micro elastic modulus, as well as macro compressive strength and macro elastic modulus; Simulating the dissolution reaction of the shale sample under preset environmental conditions to obtain the porosity and multi-scale mechanical properties of the shale sample includes: Recording and analyzing the dissolution and precipitation process of mineral components in shale at preset time intervals using X-ray diffraction (XRD), measuring the pore volume and pore size distribution of shale at different dissolution times using nuclear magnetic resonance (NMR) technology, testing the microhardness and micro elastic modulus of shale using a nanoindentation instrument, and measuring the macro compressive strength and macro elastic modulus of shale using a triaxial compression system.

[0012] Optionally, the formula for the first variation law is: ; Where e is the natural constant, is the reaction rate constant; T and T0 are the observation time and the initial time respectively; The fitting constants A1 and A2 are related to the porosity in the initial state and the state where the minerals are completely dissolved after the dissolution reaction; Introduce the initial porosity and the final porosity for equivalent substitution to obtain an approximate expression of the first variation law: .

[0013] Optionally, the dissolution damage variable is defined according to the change in porosity as: ; Where is the porosity representation with respect to time T; is the initial porosity, is the theoretical maximum porosity when all soluble minerals are completely dissolved; The formula for the second variation law is: .

[0014] Optionally, the formula for the third variation law is: ; where P0 is the initial performance value, , , are material constants describing the degree of influence of dissolution damage on the mechanical properties of shale, where .

[0015] Optionally, the formula for the multi-scale mechanical property evolution law is: .

[0016] Secondly, a device for predicting the mechanical properties of saline aquifer shale carbon sequestration is provided, including: An acquisition module for acquiring shale samples of the saline aquifer, simulating the dissolution reaction of the shale samples under preset environmental conditions, and obtaining the porosity and multi-scale mechanical properties of the shale samples; A fitting module for fitting the first variation law of porosity with time using a Boltzmann growth curve; defining a dissolution damage variable according to the change of porosity, and determining the second variation law of the damage variable based on time based on the first variation law; fitting the third variation law of the multi-scale mechanical properties with porosity and the damage variable using an exponential decay function; obtaining the multi-scale mechanical property evolution law of shale by combining the second variation law and the third variation law, and using the multi-scale mechanical property evolution law as a prediction model; A determination module for acquiring target porosity data of the target shale, inputting the target porosity data into the prediction model, and obtaining the prediction results of the mechanical property evolution of the saline aquifer shale at different time scales.

[0017] In addition, a computer-readable storage medium is provided, and the storage medium stores a computer program, and when the computer program is executed by a processor, the above-mentioned method for predicting the mechanical properties of saline aquifer shale carbon sequestration is implemented.

[0018] Finally, a computer device is provided, including a memory, a processor, and a computer program stored on the memory and executable on the processor. When the processor executes the program, the above-mentioned method for predicting the mechanical properties of saline aquifer shale carbon sequestration is implemented.

[0019] The method for predicting the mechanical properties of saline aquifer shale carbon sequestration provided by the present invention has the following beneficial effects: By simulating the dissolution reaction of shale samples under preset environmental conditions, the state changes of shale samples at different time points can be accurately captured. By fitting the first variation law of porosity with time using the Boltzmann growth curve, how porosity increases or changes with time can be accurately described. By defining the dissolution damage variable and determining its second variation law based on the change of porosity, the damage degree caused by dissolution to shale samples can be quantified, and the process in which the mechanical properties of shale are affected by dissolution can be clarified. By fitting the third variation law of multi-scale mechanical properties with porosity and damage variable using the exponential decay function, the mathematical relationship between mechanical properties, porosity, and damage variable can be established, and then the variation law of the multi-scale mechanical properties of shale on the time scale can be constructed. This method determines the evolution process of the mechanical properties of shale with dissolution through comprehensive analysis of multi-scale mechanical properties, accurately simulates the deterioration process of shale on a long time scale, can predict the mechanical properties of shale on different time scales, has high accuracy and reliability, not only helps to design more efficient CO2 sequestration projects, but also reduces the potential leakage risk and provides a scientific basis for risk control and monitoring. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] To more clearly illustrate the embodiments of the present invention and their design schemes, the drawings required for this embodiment will be briefly introduced below. The drawings in the following description are only partial embodiments of the present invention. For those of ordinary skill in the art, other drawings can be obtained based on these drawings without creative efforts.

[0021] Figure 1 It is a schematic flow chart of a method for predicting the mechanical properties of saline aquifer shale carbon sequestration provided by the present invention according to an exemplary embodiment.

[0022] Figure 2 It is an XRD spectrum provided by the present invention according to an exemplary embodiment.

[0023] Figure 3 It is a diagram showing the change of the main mineral content in shale tested by XRD provided by the present invention according to an exemplary embodiment.

[0024] Figure 4 It is a schematic diagram of the change curve of the pore volume of shale and the transverse relaxation time T2 of NMR in the SC-CO2 + saline water environment at different times provided by the present invention according to an exemplary embodiment.

[0025] Figure 5 It is a schematic diagram of the porosity and pore size distribution law of shale at different dissolution times provided by the present invention according to an exemplary embodiment.

[0026] Figure 6Schematic diagram showing the variation trend of microhardness and microelastic modulus with reaction time according to an exemplary embodiment of the present invention.

[0027] Figure 7 Schematic diagram showing the variation law of macro compressive strength and macroelastic modulus with reaction time according to an exemplary embodiment of the present invention.

[0028] Figure 8 Schematic diagram showing the correlation between the porosity, microelastic modulus and macroelastic modulus of etched shale under different reaction time conditions according to an exemplary embodiment of the present invention; wherein, a is the schematic diagram showing the correlation between the porosity of etched shale and the microelastic modulus and macroelastic modulus, and b is the schematic diagram showing the correlation between the microelastic modulus and macroelastic modulus of etched shale.

[0029] Figure 9 Schematic diagram showing the correlation between the porosity, microhardness and macro compressive strength of etched shale under different reaction time conditions according to an exemplary embodiment of the present invention; wherein, a is the schematic diagram showing the correlation between the porosity of etched shale and the microhardness and macro compressive strength, and b is the schematic diagram showing the correlation between the microhardness and macro compressive strength of etched shale.

[0030] Figure 10 Block diagram of a mechanical property prediction device for shale carbon sequestration in saline aquifers according to an exemplary embodiment of the present invention. Detailed implementation manners

[0031] In order to enable those skilled in the art to better understand the technical solution of the present invention and be able to implement it, the present invention will be described in detail below with reference to the accompanying drawings and specific embodiments. The following embodiments are only used to more clearly illustrate the technical solution of the present invention, and cannot be used to limit the protection scope of the present invention.

[0032] The following will describe in detail the technical solutions provided by each embodiment of the present invention with reference to the accompanying drawings.

[0033] The object of the present invention is to propose a quantitative model and method capable of predicting the change of mechanical properties of shale caprock during the CO2 sequestration process in deep saline aquifers. This model quantifies the influence of mineral dissolution on porosity through experimental means, and establishes a bridge connection between this parameter of porosity and the physical and mechanical properties of rocks (such as hardness, compressive strength, elastic modulus), so as to realize the quantitative prediction of shale mechanical properties.

[0034] The present invention verifies through experiments and establishes a quantitative model for the evolution of dissolution with time, fully considering the dynamic changes in the dissolution process, and effectively describes the influence of mineral dissolution on porosity changes through a time-dependent damage variable (Ds(t)). Through this model, the evolution trend of the mechanical properties (such as hardness, compressive strength, elastic modulus, etc.) of shale during the CO2 sequestration process in deep saline aquifers over time can be predicted, thereby providing data support for the long-term sequestration safety assessment.

[0035] Through experimental research on the mineral dissolution process, the present invention establishes a quantitative influence relationship between mineral dissolution and porosity changes. This relationship can reflect the influence of different mineral dissolution rates on porosity evolution and provides a reliable basis for subsequent mechanical property prediction. This model can more accurately describe the influence of mineral dissolution on the pore structure of shale and further calculate the influence of porosity on mechanical properties.

[0036] Based on the traditional single-scale model, the present invention adopts a multi-scale coupling analysis method, considering the multi-dimensional interactions of mineral dissolution, porosity changes, mechanical properties, etc. Through this comprehensive model, the deterioration process of the shale caprock and its influence on mechanical properties during long-term sequestration can be predicted more comprehensively, thereby improving the accuracy and reliability of the prediction.

[0037] The model parameters of the present invention are obtained by fitting experimental data, avoiding the complex simulation calculation process in traditional methods, and the application of the model no longer depends on high-precision experimental conditions. By embedding this model into commercial software, the prediction and analysis of the CO2 sequestration environment can be carried out quickly and effectively, with high engineering application value.

[0038] First, the present invention provides a method for predicting the mechanical properties of carbon sequestration in saline aquifer shale, specifically as Figure 1 shown, including the following steps: S101. Obtain a shale sample from a saline aquifer, simulate the dissolution reaction of the shale sample under preset environmental conditions, and obtain the porosity and multi-scale mechanical properties of the shale sample.

[0039] Specifically, a long 8 shale sample can be collected from the actual reservoir environment, such as the deep 1610-meter saline aquifer in the Ordos Basin, and cut into cylindrical specimens with a diameter of 25 mm and a height of 50 mm. The sample is treated with vacuum-saturated salt solution to simulate the deep saline aquifer environment.

[0040] Simulate the dissolution reaction of supercritical carbon dioxide SC-CO2 and saline water on the shale sample under preset temperature and pressure, record and analyze the state of the shale sample at preset time intervals, and obtain the porosity and multi-scale mechanical properties of the shale sample. Among them, the preset temperature and pressure are the temperature and pressure conditions of the shale sample in the target formation.

[0041] In this step, it is necessary to simulate the long-term effects of the combined action of SC-CO2 and brine on shale under high temperature and high pressure conditions.

[0042] Exemplarily, a high temperature and high pressure reactor with a design pressure of 15.7 MPa and a temperature of 328.55 K is used, and a simulated brine solution containing Na + , Ca 2 + , Mg 2+ and other ions and SC-CO2 gas are injected. The ratio of SC-CO2 gas to the simulated brine solution in the reactor is set to 1:9. Multiple corrosion reaction time points (0, 7, 14, 21, 28, 35 days) are set, and chemical, physical, and mechanical experimental tests are carried out on the samples to observe the effects of different corrosion stages on shale.

[0043] Then, multi-dimensional performance tests are carried out on the shale samples. As shown in Figure 2 and Figure 3 , it includes the analysis of mineral composition: the dissolution and precipitation processes of various mineral components in shale are recorded and analyzed by X-ray diffraction (XRD). For example, the dissolution of carbonate minerals leads to the release of Ca 2+ , Mg 2+ .

[0044] S102. Fit the first variation law of porosity with time using the Boltzmann growth curve.

[0045] In this step, based on the above experimental data, fitting is carried out to explore the correlation between variables. Specifically, based on the experimental data and the fitting analysis results, a multi-scale coupling model of porosity-damage variable-mechanical properties is established. This model can uniformly describe the effects of SC-CO2 and brine corrosion on the properties of shale from micro to macro. Furthermore, through the time-dependence of the damage variable, the evolution trends of the pore structure and mechanical properties of shale at different time points are quantitatively predicted. Among them, nuclear magnetic resonance (NMR) technology can be used to measure the pore volume and pore size distribution of shale at different corrosion times, and quantitatively analyze the evolution trends of micropores, mesopores, and macropores, as shown in Figure 4 and Figure 5 .

[0046] First, explore the relationship between porosity (φ) and time (T): Through experimental data, use the Boltzmann growth curve for fitting to reveal the first variation law of porosity with time: ; where e is the natural constant, is the reaction rate constant; the fitting constants A1 and A2 are closely related to the porosity in the initial state and the completely dissolved state, respectively, and can be determined by experiments. To describe these two states, the initial porosity ([[]] ) and the final porosity ( ) are equivalently replaced to obtain an approximate expression of the first variation law: .

[0047] S103. Define the dissolution damage variable according to the change of porosity, and determine the second variation law of the dissolution damage variable with respect to time based on the first variation law.

[0048] In this step, first, define the dissolution damage variable according to the change of porosity : ; is the porosity representation with respect to time T; is the initial porosity, is the theoretical maximum porosity when all soluble minerals are completely dissolved. Then, combined with the first variation law, substitute the variation law of porosity with respect to time into the definition formula of the dissolution damage variable to determine the model of the damage variable with respect to time. That is, on the basis of the dissolution damage variable, further combine the porosity and time model to obtain the second variation law: .

[0049] S104. Use the exponential decay function to fit the third variation law of the multi-scale mechanical properties with respect to porosity and the dissolution damage variable.

[0050] In this step, it is necessary to explore the relationship between mechanical properties such as compressive strength and elastic modulus and porosity. First, conduct micro-mechanical property tests. Use a nano-indentation instrument to measure the micro-hardness and micro-elastic modulus of shale, and observe the decreasing trend of hardness at different dissolution time points, such as Figure 6 shown. Second, conduct macro-mechanical property tests. Use a triaxial compression system to measure the change of the macro-compressive strength and macro-elastic modulus of shale with dissolution time, such as Figure 7 shown.

[0051] Use the exponential decay function to fit and establish a quantitative relationship between porosity and its influence on micro-hardness, micro-elastic modulus and macro-properties, such as the correlation between porosity and micro- and macro-elastic modulus shown in Figure 8 and the correlation between porosity and micro-hardness, macro-compressive strength shown in Figure 9 .

[0052] For these multi-scale mechanical property parameters, such as micro-hardness, micro-elastic modulus, macro-elastic modulus and macro-compressive strength, they are all expressed by a unified exponential fitting function with respect to porosity. That is, the formula of the third variation law is: ; Wherein, P0 is the initial performance value, , , are material constants describing the influence degree of dissolution damage on the mechanical properties of shale, where .

[0053] S105. By combining the second variation law and the third variation law, the multi-scale mechanical property evolution law of shale is obtained, and this multi-scale mechanical property evolution law is used as a prediction model.

[0054] By combining the above second variation law and third variation law, the evolution model of the long-term mechanical properties of shale under the action of CO2 can be obtained, that is, the multi-scale mechanical property evolution law of shale. Taking this multi-scale mechanical property evolution law as a prediction model, the specific formula is: .

[0055] S106. Obtain the target porosity data of the target shale, input the target porosity data into the prediction model, and obtain the prediction results of the mechanical property evolution of shale in the saline aquifer at different time scales.

[0056] This model of the present invention can be directly applied to the design and risk assessment of CO2 storage sites, providing a scientific basis for ensuring the long-term stability of geological storage sites.

[0057] By adopting the above method, through simulating the dissolution reaction of SC-CO2 and brine under preset temperature and pressure, the state changes of shale samples at different time points can be accurately captured. Using the Boltzmann growth curve to fit the first variation law of porosity with time, the growth or change of porosity with time can be accurately described; by defining the dissolution damage variable and determining its second variation law based on the change of porosity, the damage degree caused by dissolution to shale samples can be quantified, and the process of the mechanical properties of shale being affected by dissolution can be clarified; using the exponential decay function to fit the third variation law of multi-scale mechanical properties with porosity and damage variables, this method can establish the mathematical relationship between mechanical properties, porosity, and damage variables, and then construct the change law of the multi-scale mechanical properties of shale on the time scale. By comprehensively analyzing the multi-scale mechanical properties, this method determines the evolution process of the mechanical properties of shale with dissolution, accurately simulates the deterioration process of shale on a long time scale, can predict the mechanical properties of shale at different time scales, has high accuracy and reliability, not only helps to design more efficient CO2 storage projects, but also can reduce the potential leakage risk, providing a scientific basis for risk control and monitoring.

[0058] Secondly, the present invention also provides a device for predicting the mechanical properties of carbon sequestration in saline aquifer shale, as Figure 10 shown, including: An acquisition module 1001 is configured to acquire shale samples from a saline aquifer, simulate the dissolution reaction of the shale samples under preset environmental conditions, and obtain the porosity and multi-scale mechanical properties of the shale samples.

[0059] A fitting module 1002 is configured to fit the first variation law of porosity with time using a Boltzmann growth curve; define a dissolution damage variable based on the change in porosity, and determine the second variation law of the damage variable with respect to time based on the first variation law; fit the third variation law of the multi-scale mechanical properties with porosity and the damage variable using an exponential decay function; and obtain the evolution law of the multi-scale mechanical properties of the shale by combining the second variation law and the third variation law, and use the evolution law of the multi-scale mechanical properties as a prediction model.

[0060] A determination module 1003 is configured to acquire target porosity data of a target shale, input the target porosity data into the prediction model, and obtain a prediction result of the mechanical property evolution of the saline aquifer shale at different time scales.

[0061] By using the above device, through simulating the dissolution reaction of SC-CO2 and saline water under preset temperature and pressure, the state changes of the shale samples at different time points can be accurately captured. Using the Boltzmann growth curve to fit the first variation law of porosity with time can accurately describe how the porosity increases or changes with time; by defining the dissolution damage variable and determining its second variation law based on the change in porosity, the degree of damage caused by dissolution to the shale samples can be quantified, and the process in which the mechanical properties of the shale are affected by dissolution can be clarified; using the exponential decay function to fit the third variation law of the multi-scale mechanical properties with porosity and the damage variable, this method can establish a mathematical relationship between the mechanical properties and porosity and the damage variable, and then construct the variation law of the multi-scale mechanical properties of the shale on the time scale. This method determines the evolution process of the mechanical properties of the shale with dissolution through comprehensive analysis of the multi-scale mechanical properties, accurately simulates the deterioration process of the shale on a long time scale, can predict the mechanical properties of the shale at different time scales, has high accuracy and reliability, not only helps to design more efficient CO2 sequestration projects, but also can reduce the potential leakage risk, and provides a scientific basis for risk control and monitoring.

[0062] The present invention also provides a computer-readable storage medium, which stores a computer program, and the computer program can be used to execute the steps of the above Figure 1 provided method for predicting the mechanical properties of carbon sequestration in saline aquifer shale.

[0063] The present invention also provides a computer device. At the hardware level, the computer device includes a processor, an internal bus, a network interface, a memory, and a non-volatile memory. Of course, it may also include other hardware required for other services. The processor reads the corresponding computer program from the non-volatile memory into the memory and then runs it to implement the above Figure 1 steps of the method for predicting the mechanical properties of saline shale carbon sequestration provided.

[0064] Those skilled in the art should understand that the embodiments of the present invention can be provided as a method, a system, or a computer program product. Therefore, the present invention can take the form of a complete hardware embodiment, a complete software embodiment, or an embodiment combining software and hardware aspects. Moreover, the present invention can take the form of a computer program product implemented 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.

[0065] The present invention is described with reference to the flowcharts and / or block diagrams of methods, apparatuses (systems), and computer program products according to embodiments of the present invention. It should be understood that each flow and / or block in the flowchart and / or block diagram can be implemented by computer program instructions, and the combination of the flows and / or blocks in the flowchart and / or block diagram can also be implemented. These computer program instructions can be provided to the processor of a general-purpose computer, a special-purpose computer, an embedded processor, or other programmable data processing devices to generate a machine, such that the instructions executed by the processor of the computer or other programmable data processing devices generate a device for implementing the specified functions in Figure 1 one or more flows and / or blocks Figure 1 one or more blocks.

[0066] These computer program instructions can also be stored in a computer-readable memory that can direct a computer or other programmable data processing device to work in a specific manner, such that the instructions stored in the computer-readable memory generate a manufactured article including an instruction device that implements the specified functions in Figure 1 one or more flows and / or blocks Figure 1 one or more blocks.

[0067] These computer program instructions can also be loaded onto a computer or other programmable data processing device, such that a series of operation steps are executed on the computer or other programmable device to generate a computer-implemented process, so that the instructions executed on the computer or other programmable device provide steps for implementing the specified functions in Figure 1 one or more flows and / or blocks Figure 1 one or more blocks.

[0068] It should be noted that the above specific implementation method can enable those skilled in the art to understand the invention more comprehensively, but does not limit the invention in any way. Therefore, although the present invention has been described in detail in this specification, those skilled in the art should understand that the invention can still be modified or replaced by equivalents; and all technical solutions and improvements that do not deviate from the spirit and scope of the invention are included in the protection scope of the patent for the invention. Any figure mark in the claims should not be regarded as limiting the claims involved.

Claims

1. A method for predicting the mechanical properties of shale carbon sequestration in saline aquifers, characterized in that, It includes the following steps: Obtain a shale sample from the saline aquifer, simulate the dissolution reaction of the shale sample under preset environmental conditions, and obtain the porosity and multi-scale mechanical properties of the shale sample; Use the Boltzmann growth curve to fit the first variation law of porosity with time; define the dissolution damage variable according to the change of porosity, and determine the second variation law of the dissolution damage variable based on time based on the first variation law; use the exponential decay function to fit the third variation law of the multi-scale mechanical properties with porosity and the dissolution damage variable; by combining the second variation law and the third variation law, obtain the evolution law of the multi-scale mechanical properties of the shale, and use the evolution law of the multi-scale mechanical properties as a prediction model; Obtain the target porosity data of the target shale, input the target porosity data into the prediction model, and obtain the prediction results of the mechanical property evolution of the saline aquifer shale at different time scales.

2. The mechanical property prediction method for saline aquifer shale carbon sequestration according to claim 1, wherein The porosity includes pore volume and pore size distribution, and the multi-scale mechanical properties include microhardness and microelastic modulus as well as macro compressive strength and macroelastic modulus; the simulation of the dissolution reaction of the shale sample under preset environmental conditions to obtain the porosity and multi-scale mechanical properties of the shale sample includes: Use X-ray diffraction (XRD) to record and analyze the dissolution and precipitation process of mineral components in the shale at preset time intervals, use nuclear magnetic resonance (NMR) technology to measure the pore volume and pore size distribution of the shale at different dissolution times, use a nanoindenter to test the microhardness and microelastic modulus of the shale, and use a triaxial compression system to measure the macro compressive strength and macroelastic modulus of the shale.

3. A method for predicting the mechanical properties of saline aquifer shale carbon sequestration according to claim 1, characterized in that, The formula for the first variation law is: ； Among them, e is the natural constant, is the reaction rate constant; T and T0 are the observation time and the initial time respectively; the fitting constants A1 and A2 are related to the porosity under the initial state and the state where the mineral is completely dissolved after the dissolution reaction respectively; the initial porosity and the final porosity are equivalently replaced to obtain an approximate expression of the first variation law: 。 4. A method for predicting the mechanical properties of saline aquifer shale carbon sequestration according to claim 3, characterized in that, Define the dissolution damage variable according to the change of porosity as: ； Among them, is the porosity representation with respect to time T; is the initial porosity, is the theoretical maximum porosity when all soluble minerals are completely dissolved; The formula for the second variation law is: 。 5. A method for predicting the mechanical properties of saline aquifer shale carbon sequestration according to claim 4, characterized in that, The formula for the third variation law is: ； Among them, P0 is the initial performance value, , , are material constants describing the influence degree of dissolution damage on the mechanical properties of shale, where .

6. A method for predicting the mechanical properties of saline aquifer shale carbon sequestration according to claim 5, characterized in that, The formula for the evolution law of the multi-scale mechanical properties is: 。 7. A mechanical property prediction device for shale carbon sequestration in saline aquifers, characterized in that, It includes: An acquisition module for obtaining a shale sample from the saline aquifer, simulating the dissolution reaction of the shale sample under preset environmental conditions, and obtaining the porosity and multi-scale mechanical properties of the shale sample; A fitting module for using the Boltzmann growth curve to fit the first variation law of porosity with time; defining the dissolution damage variable according to the change of porosity, and determining the second variation law of the damage variable based on time based on the first variation law; using the exponential decay function to fit the third variation law of the multi-scale mechanical properties with porosity and the damage variable; by combining the second variation law and the third variation law, obtaining the evolution law of the multi-scale mechanical properties of the shale, and using the evolution law of the multi-scale mechanical properties as a prediction model; A determination module for obtaining the target porosity data of the target shale, inputting the target porosity data into the prediction model, and obtaining the prediction results of the mechanical property evolution of the saline aquifer shale at different time scales.

8. A computer-readable storage medium, characterized in that, The storage medium stores a computer program, and when the computer program is executed by a processor, it implements the method described in any one of claims 1 to 6 above.

9. A computer device, characterized in that, It includes a memory, a processor, and a computer program stored on the memory and executable on the processor. When the processor executes the program, it implements the method described in any one of claims 1 to 6 above.

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