Method and equipment for simulating mechanical degradation of hydrate-containing sediment induced by hydrate decomposition based on discrete element and medium
By simulating the volume reduction and cementation damage during the decomposition process of hydrates using the discrete element method, a mechanical degradation model is constructed, which solves the problem of insufficient simulation accuracy in existing technologies and achieves a more efficient risk assessment for natural gas hydrate extraction.
Patent Information
- Application Number
- CN202511603897.1
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-11-04
- Publication Date
- 2026-02-06
AI Technical Summary
Existing discrete element methods cannot simultaneously account for hydrate phase volume reduction and cementation damage during the simulation of natural gas hydrate decomposition, resulting in insufficient simulation accuracy and an inability to effectively assess geological hazards and engineering risks during natural gas hydrate extraction.
A discrete element method-based simulation was adopted. By randomly removing some hydrate particles during hydrate decomposition to simulate volume reduction, and by reducing the parallel cohesion radius multiplier to simulate cementation damage, a mechanical degradation model was constructed. Combined with the trial-and-error method to calibrate the microscopic parameters, the mechanical properties of sediments with multiple coexisting morphologies were analyzed.
It improves the accuracy and computational efficiency of mechanical degradation models, significantly reduces relative errors, and can accurately characterize the mechanical degradation behavior of hydrate-bearing sediments. It is suitable for the analysis of mechanical properties of sediments with multiple occurrence forms and supports geological and engineering risk assessment in the process of hydrate mining.
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Abstract
Description
Technical Field
[0001] This invention belongs to the field of geomechanical analysis and risk assessment technology, and relates to a simulation method, equipment and medium for hydride-bearing sediment mechanical degradation induced by hydrate decomposition based on discrete element method. Background Technology
[0002] Natural gas hydrates are ice-like crystals formed from natural gas and water under high pressure and low temperature conditions. Their gas storage capacity per unit volume is approximately 160-180 times that of conventional natural gas, and their global resources are about twice the total proven reserves of fossil fuels. They are widely recognized as one of the most promising alternative energy sources of the 21st century. Large-scale development of natural gas hydrates is of irreplaceable significance for alleviating dependence on imported oil and gas, ensuring national energy security, and supporting the country's energy strategic transformation.
[0003] However, natural gas hydrates exist in reservoirs in various forms, including cementation, skeletal support, pore filling, and particle encapsulation. They are both part of the solid framework and act as the cementing medium between particles. Any extraction activity (such as decompression, thermal shock, or chemical injection) disrupts the original thermo-fluid-mechanical balance, leading to hydrate decomposition and the release of methane and water, accompanied by a rapid contraction of both phases. During this process, the cementation strength between reservoir particles is lost, effective stress changes abruptly, and pore pressure surges, macroscopically manifesting as softening of strength, reduction of modulus, shear dilatation-contraction transformation, and non-uniform deformation. When the deformation accumulates to a certain extent, it can induce a chain of geological and engineering disasters such as wellbore collapse, sand production, formation subsidence, and even submarine landslides. Therefore, understanding the dynamic changes and intrinsic mechanisms of the mechanical properties of hydrate-bearing sediments during hydrate decomposition is crucial for the long-term, safe, and efficient extraction of natural gas hydrates.
[0004] The Discrete Element Method (DEM), using particles as units and contacts as constitutive models, is naturally adept at describing the microscopic mechanical behavior and macroscopic response of granular systems, and has become an important numerical tool for studying the mechanical degradation mechanisms of hydrate-bearing sediments. Regarding DEM simulations of hydrate decomposition, scholars both domestically and internationally have proposed three equivalent methods:
[0005] (1) Random particle removal method: The hydrate is regarded as an independent spherical particle, and decomposition is achieved by randomly removing some hydrate particles. This method only reflects the volume disappearance of the hydrate phase, completely ignoring the cementing effect of hydrate on sand particles and its strength deterioration, resulting in a significant underestimation of the decline in macroscopic strength and cohesion.
[0006] (2) Particle volume reduction method: Similarly, hydrates are treated as independent particles, and decomposition simulation is achieved by reducing the size of each hydrate particle. Although it can reflect volume changes, the unit mass and moment of inertia decrease synchronously after particle size reduction. The critical time step decreases with the square of the particle size, and the computational load increases exponentially, resulting in reduced computational efficiency. In addition, this method still cannot describe cementation damage, and the macroscopic mechanical response deviates significantly from the experimental results.
[0007] (3) Hydrate cementation damage method: Hydrates are abstracted as virtual cementation between sand particles, and decomposition is simulated by reducing the cementation radius or strength parameters. This approach can reflect the strength degradation caused by cementation degradation, but it assumes that hydrates only exist in the form of "cementation" and cannot describe other forms such as pore filling and skeleton support; at the same time, it cannot characterize the effect of hydrate volume reduction and shear fragmentation on volumetric strain.
[0008] In summary, the aforementioned methods all suffer from limited applicability and insufficient simulation accuracy, severely restricting the quantitative evaluation and risk prediction of long-term safe exploitation of natural gas hydrates. Therefore, there is an urgent need to construct a unified discrete element decomposition simulation method that can simultaneously consider hydrate phase volume reduction and cementation damage, and is applicable to various occurrence forms such as cementation, framework support, pore filling, and particle encapsulation, providing reliable theoretical tools and technical support for the commercial development of natural gas hydrates. Summary of the Invention
[0009] The purpose of this invention is to provide a simulation method, equipment, and medium for hydride decomposition-induced mechanical degradation of hydrate-bearing sediments based on discrete element method. By comprehensively considering the volume reduction and cementation damage effects of hydrate phases during hydrate decomposition, the mechanical degradation behavior of hydrate-bearing sediments can be accurately characterized. This method is applicable to the analysis of mechanical properties of hydrate-bearing sediments with multiple coexisting forms and can be used to assess geological hazards and engineering risks during hydrate extraction.
[0010] To achieve this objective, the present invention adopts the following technical solution:
[0011] In a first aspect, the present invention provides a simulation method for the mechanical degradation of hydrate-bearing sediments induced by hydrate decomposition based on discrete element method, the simulation method comprising:
[0012] S1. Prepare hydrate-containing sediment samples;
[0013] S2. Numerical triaxial or biaxial compression tests were conducted on hydrate-bearing sediment samples. The microscopic parameters associated with the relevant contact model were calibrated using a trial-and-error method. A mechanical degradation model of hydrate-bearing sediments during hydrate decomposition based on discrete element method was constructed.
[0014] In the mechanical degradation model, some hydrate particles are randomly removed according to the set hydrate decomposition rate to simulate the reduction of hydrate phase volume, and the hydrate cementation damage caused by decomposition is simulated by reducing the parallel bonding radius multiplier.
[0015] S3. Output of mechanical degradation model results.
[0016] This invention comprehensively considers the volume reduction of hydrate phases and cementation damage effects caused by hydrate decomposition, and proposes a simulation method based on discrete element method (DEM) for hydrate decomposition-induced mechanical degradation of hydrate-bearing sediments. This method is applicable to the mechanical property analysis of hydrate-bearing sediments with multiple coexisting morphologies. The simulation method first prepares hydrate-bearing sediment samples, then performs numerical triaxial or biaxial compression tests on the samples, and calibrates the microscopic parameters associated with relevant contact models using a trial-and-error method. This constructs a mechanical degradation model of hydrate-bearing sediments during hydrate decomposition based on the DEM, and finally outputs the mechanical degradation model results. This simulation method has a more standardized process, considers more comprehensive factors, and significantly reduces the relative error in predicting the mechanical degradation behavior of hydrate-bearing sediment decomposition compared to traditional methods. It also boasts high computational efficiency and strong applicability, and can be used for geological and engineering risk assessment during hydrate extraction.
[0017] It should be noted that, in constructing the mechanical degradation model, the reduction in hydrate phase volume and hydrate cementation damage caused by hydrate decomposition are considered simultaneously, which improves the accuracy of the mechanical degradation model and enables precise characterization of the mechanical degradation behavior of hydrate-bearing sediments. Using the simulation method provided by this invention, not only can the deformation and damage of hydrate-bearing sediments during decomposition be presented intuitively at a macroscopic level, but their underlying mechanisms can also be revealed in depth.
[0018] Preferably, in step S1, the method for preparing hydrate-containing sediment samples specifically includes:
[0019] S11. First sediment sample;
[0020] S12. Second hydrate-containing sediment sample;
[0021] S13. Set the boundary conditions for hydrate-containing sediment samples;
[0022] S14. Determine the contact model for each component in the hydrate-bearing sediment sample.
[0023] Preferably, in step S11, the method for generating the first sediment sample specifically includes:
[0024] S111. Adjust the size of the sediment sample;
[0025] S112. Based on the grain size distribution of the sediments in the experiment, determine the grain size distribution of the framework sand particles in the hydrate-bearing sediment sample;
[0026] S113. Randomly fill the target size area of the sediment sample with framework sand particles according to the predetermined porosity and the determined grain size distribution to generate the first sediment sample;
[0027] Preferably, in step S12, the method for generating the second hydrate-containing sediment sample specifically includes:
[0028] In the pore space of the sediment sample, relatively small and uniform hydrate particles are randomly generated one by one until the number of hydrate particles is consistent with the target initial hydrate saturation. Then, a second hydrate-containing sediment sample is generated.
[0029] Preferably, the relationship between the number of hydrate particles and the target initial hydrate saturation is shown in the following formula (I):
[0030]
[0031] In formula (I), The number of hydrate particles, The volume of a single hydrate particle. This represents the total volume of hydrates in the sediment sample. The target initial hydrate saturation, This represents the total pore volume of the sediment sample.
[0032] Preferably, in step S13, setting the boundary conditions for the hydrate-containing sediment sample specifically includes:
[0033] S131. Coating the surface of hydrate-containing sediment samples with a particulate film serves as a flexible boundary, providing effective lateral confining pressure;
[0034] S132. Construct two loading walls, including an upper loading wall and a lower loading wall, both of which are flat plates used to apply axial loads.
[0035] Preferably, in step S14, determining the contact model for each component specifically includes:
[0036] S141. An anti-rolling linear contact model is adopted between sand particles;
[0037] S142. Parallel bonding model is used between hydrate particles and between sand and hydrate particles;
[0038] S143. A linear contact bonding model with strong adhesion is adopted between flexible membrane particles.
[0039] Preferably, in step S2, the construction method specifically includes:
[0040] S21. The mechanical behavior of hydrate-bearing sediment samples with a hydrate decomposition rate of 100% is first calibrated to determine the values of the microscopic contact parameters associated with the anti-rolling linear contact model.
[0041] S22. The mechanical behavior of hydrate-bearing sediment samples with a hydrate decomposition rate of 0% is calibrated a second time to determine the values of the microscopic contact parameters associated with the linear parallel bond contact model.
[0042] S23. During the hydrate decomposition process of hydrate-containing sediment samples, the values of the parallel bonding radius multipliers in the parallel bonding models with different hydrate decomposition rates are calibrated in the third way to simulate the cementation damage effect caused by hydrate decomposition.
[0043] S24. Based on the definition of the microscopic damage factor and the calibration results of the parallel bonding radius multiplier, the empirical relationship between the microscopic damage factor and the hydrate decomposition rate is derived.
[0044] Preferably, in step S21, after the first calibration, the following is also included:
[0045] If the test simulation results of mechanical behavior are consistent with the corresponding indoor experimental results, the microscopic contact parameters of the anti-rolling linear contact model will be used as the basic contact parameters between sand particles in hydrate-bearing sediment samples corresponding to hydrate decomposition rates of 0%, 20%, 40%, 60%, and 80%. If the test simulation results of mechanical behavior are inconsistent with the corresponding indoor experimental results, the values of the microscopic contact parameters associated with the anti-rolling linear contact model will be updated until the test simulation results of mechanical behavior are consistent with the corresponding indoor experimental results.
[0046] Preferably, in step S23, the third calibration method specifically includes:
[0047] S231. In the process of simulating hydrate decomposition, the volume of hydrate to be decomposed and the corresponding number of hydrate particles are calculated based on the hydrate decomposition rate and in combination with the following formulas (II) and (III).
[0048]
[0049] In formula (II), The volume of the hydrate to be decomposed. This represents the total volume of hydrates in the sediment sample. The hydrate decomposition rate;
[0050]
[0051] In formula (III), The number of hydrate particles to be decomposed. The volume of the hydrate to be decomposed. The volume of a single hydrate particle;
[0052] S232. Randomly remove the number of hydrate particles to be decomposed to simulate a reduction in the volume of the hydrate phase;
[0053] S233. Reduce the value of the parallel bond radius multiplier to simulate hydrate cementation damage caused by decomposition;
[0054] S234. If the test simulation result of the parallel bonding radius multiplier under the target hydrate decomposition rate is consistent with the corresponding indoor experimental result, output the result; if the test simulation result of the parallel bonding radius multiplier under the target hydrate decomposition rate is inconsistent with the corresponding indoor experimental result, update the value of the parallel bonding radius multiplier in the parallel bonding model under the target hydrate decomposition rate, and repeat step S233 until the test simulation result of the parallel bonding radius multiplier under the target hydrate decomposition rate is consistent with the corresponding indoor experimental result.
[0055] Preferably, in step S24, the definition of the mesoscopic damage factor is as shown in equation (IV):
[0056]
[0057] In equation (IV), To examine the damage factors in detail, This is the parallel bond radius multiplier after the third calibration. The initial parallel bond radius multiplier before decomposition.
[0058] Preferably, in step S24, the empirical relationship between the microscopic damage factor and the hydrate decomposition rate is shown in the following equation (V):
[0059]
[0060] In equation (V), To examine the damage factors in detail, The decomposition rate of hydrates.
[0061] Preferably, in step S3, the output of the mechanical degradation model results specifically includes:
[0062] Based on steps S1-S2 and formula (V), discrete element simulation of the progressive mechanical degradation of hydrate-containing sediments during hydrate decomposition can be realized, and then the discrete element simulation results can be output.
[0063] The discrete element simulation results include macroscopic mechanical data such as stress-strain curves, volumetric strain-strain, cementation fracture quantity-strain curves, solid phase component stress contribution rate diagrams, particle rotation diagrams, particle displacement diagrams, and contact force chain network diagrams.
[0064] In a second aspect, the present invention provides an electronic device, the electronic device comprising:
[0065] At least one processor; and
[0066] A memory communicatively connected to the at least one processor; wherein,
[0067] The memory stores a computer program that can be executed by the at least one processor, the computer program being executed by the at least one processor to enable the at least one processor to perform the simulation method for hydrate decomposition-induced mechanical degradation of hydrate-bearing sediments based on discrete element method as described in the first aspect.
[0068] Thirdly, the present invention provides a computer-readable storage medium storing computer instructions, the computer instructions being used to cause a processor to execute and implement the simulation method for mechanical degradation of hydrate-containing sediments induced by hydrate decomposition based on discrete element method described in the first aspect.
[0069] Compared with the prior art, the present invention has the following beneficial effects:
[0070] (1) The simulation method provided by the present invention considers the reduction in hydrate phase volume and hydrate cementation damage caused by hydrate decomposition during the construction of the mechanical degradation model, thereby improving the accuracy of the mechanical degradation model and accurately characterizing the mechanical degradation behavior of hydrate-bearing sediments. Moreover, the simulation method is applicable to the mechanical property analysis of hydrate-bearing sediments with multiple coexisting forms, and is closer to the actual presence and distribution of hydrates in hydrate-bearing sediments, with a wider range of applications.
[0071] (2) The simulation method provided by this invention significantly improves the prediction accuracy of the mechanical degradation behavior of hydrate-bearing sediments compared with the traditional random particle removal method. Specifically, in terms of the peak intensity of hydrate decomposition rate, the average relative error between this simulation method and the indoor experimental results is 2.7%, while the average relative error of the traditional random particle removal method is 15.2%, which is 6 times that of the simulation method of this invention. In addition, compared with the traditional particle volume reduction method, it does not cause a reduction in particle size, thus significantly improving computational efficiency. Attached Figure Description
[0072] To more clearly illustrate the technical solutions in the embodiments of this application, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.
[0073] Figure 1A simplified flowchart of the simulation method for mechanical degradation of hydrate-bearing sediments induced by hydrate decomposition based on discrete element method provided in Example 1;
[0074] Figure 2 A schematic diagram of hydrate decomposition considering both hydrate phase volume reduction and hydrate cementation damage, provided for Example 1;
[0075] Figure 3 An empirical relationship diagram between the discrete element method-based microstructure damage factor and the hydrate decomposition rate provided in Example 1;
[0076] Figure 4 A comparison chart of the simulation method provided in Example 2, the traditional random particle deletion method, and the results of indoor experiments characterizing the mechanical degradation of hydrate-containing sediments during hydrate decomposition.
[0077] Figure 5 A comparison chart of the peak intensity results of the simulation method provided in Example 2, the traditional random particle deletion method, and the indoor experiment of hydrate-containing sediments during hydrate decomposition.
[0078] Figure 6 This is a schematic diagram of the electronic device structure provided in Example 3 for implementing a simulation method of mechanical degradation of hydrate-containing sediments induced by hydrate decomposition. Detailed Implementation
[0079] To enable those skilled in the art to better understand the present application, the technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present application, and not all embodiments. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative effort should fall within the scope of protection of the present application.
[0080] It should be noted that the terms "first," "second," "candidate," "target," etc., used in the specification, claims, and accompanying drawings of this application are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that such data can be interchanged where appropriate so that the embodiments of this application described herein can be implemented in orders other than those illustrated or described herein. Furthermore, the terms "comprising" and "having," and any variations thereof, are intended to cover non-exclusive inclusion; for example, a process, method, system, product, or apparatus that comprises a series of steps or units is not necessarily limited to those steps or units explicitly listed, but may include other steps or units not explicitly listed or inherent to such processes, methods, products, or apparatus.
[0081] Example 1
[0082] This embodiment provides a simulation method for the mechanical degradation of hydrate-bearing sediments induced by hydrate decomposition based on discrete element method (DEM). This method is applicable to the analysis of the mechanical properties of hydrate-bearing sediments with multiple coexisting hydrate forms, and accurately characterizes the mechanical degradation behavior of hydrate-bearing sediments. This simulation method for the mechanical degradation of hydrate-bearing sediments induced by hydrate decomposition based on DEM can be implemented in hardware and / or software.
[0083] like Figure 1 As shown, the simulation method provided in this embodiment includes:
[0084] S1. Preparation of hydrate-containing sediment samples, specifically including the following steps:
[0085] S11. First sediment sample;
[0086] Further, in step S11, the method for generating the first sediment sample specifically includes:
[0087] S111. Considering computational efficiency, the sediment sample size is reasonably reduced;
[0088] S112. Based on the grain size distribution of the sediments in the experiment, determine the grain size distribution of the framework sand particles in the hydrate-bearing sediment sample;
[0089] S113. Randomly fill the target size area of the sediment sample with framework sand particles according to the predetermined porosity and the determined grain size distribution to generate the first sediment sample.
[0090] S12. Second hydrate-containing sediment sample;
[0091] Further, in step S12, the method for generating the second hydrate-containing sediment sample specifically includes:
[0092] In the pore space of the sediment sample, relatively small and uniform hydrate particles are randomly generated one by one until the number of hydrate particles matches the target initial hydrate saturation, and then a second hydrate-containing sediment sample is generated.
[0093] Specifically, the relationship between the number of hydrate particles and the target initial hydrate saturation is shown in the following equation (I):
[0094]
[0095] In formula (I), The number of hydrate particles, The volume of a single hydrate particle (m³) 3 ), The total hydrate volume in the sediment sample (m³) 3 ), The target initial hydrate saturation, The total pore volume of the sediment sample (m³) 3 ).
[0096] It should be noted that the hydrate occurrence morphology obtained through the above-mentioned random generation method will naturally exhibit a multi-morphological coexistence, that is, simultaneously including pore-filling, bearing, cementing, and particle-encapsulated types. This multi-morphological coexistence characteristic is consistent with the occurrence morphologies observed in natural or artificially synthesized hydrate-bearing sediments in laboratory experiments.
[0097] S13. Set the boundary conditions for hydrate-containing sediment samples;
[0098] Furthermore, in step S13, setting the boundary conditions for the hydrate-containing sediment sample specifically includes:
[0099] S131. Coating the surface of hydrate-containing sediment samples with a particulate film serves as a flexible boundary, providing effective lateral confining pressure;
[0100] S132. Construct two loading walls, including an upper loading wall and a lower loading wall, both of which are flat plates used to apply axial loads.
[0101] In step S131, the material and thickness of the particulate membrane are not specifically limited; for example, a thickness of 4.5 × 10⁻⁶ can be used. -5 A latex film with a density of m corresponds to a density of 1800 kg / m³. 3 .
[0102] S14. Determine the contact model for each component in the hydrate-bearing sediment sample;
[0103] Further, in step S14, determining the contact model for each component specifically includes:
[0104] S141. An anti-rolling linear contact model is adopted between sand particles;
[0105] S142. Parallel bonding model is used between hydrate particles and between sand and hydrate particles;
[0106] S143. A linear contact bonding model with strong adhesion is adopted between flexible membrane particles.
[0107] It should be noted that an anti-rolling linear contact model is used between sand particles to capture the self-locking effect and rolling resistance between irregularly shaped skeleton sand particles; a parallel bonding model is used between hydrate particles and between sand and hydrate particles to simulate the cementing effect of hydrates, and this model can transmit both force and torque simultaneously; and a linear contact bonding model with strong bonding force is used between flexible membrane particles to transmit only force and not torque.
[0108] It should also be noted that the values of the microscopic contact parameters in the linear contact bonding model of strong bonding force can be determined according to the methods provided by existing technology, and no specific limitations are made here.
[0109] S2. Numerical triaxial or biaxial compression tests are performed on hydrate-containing sediment samples. The mesoscopic parameters associated with relevant contact models are calibrated using a trial-and-error method. A discrete element method-based hydrate decomposition process (e.g., ...) is then constructed. Figure 2 The mechanical degradation model of hydrate-bearing sediments (shown) specifically includes the following steps:
[0110] S21. The mechanical behavior of hydrate-bearing sediment samples with a hydrate decomposition rate of 100% is first calibrated to determine the values of the microscopic contact parameters associated with the anti-rolling linear contact model.
[0111] Furthermore, in step S21, after the first calibration, the following is also included:
[0112] If the test simulation results of mechanical behavior are consistent with the corresponding indoor experimental results, the microscopic contact parameters of the anti-rolling linear contact model will be used as the basic contact parameters between sand particles in hydrate-bearing sediment samples corresponding to hydrate decomposition rates of 0%, 20%, 40%, 60%, and 80%. If the test simulation results of mechanical behavior are inconsistent with the corresponding indoor experimental results, the values of the microscopic contact parameters associated with the anti-rolling linear contact model will be updated until the test simulation results of mechanical behavior are consistent with the corresponding indoor experimental results.
[0113] It should be noted that the indoor experiments were conducted in accordance with the methods provided in the literature, Lee, Y., Deusner, C., Kossel, E., Choi, W., Seo, Y., Haeckel, M., 2020. Influence of CH4 hydrate exploitation using depressurization and replacement methods on mechanical strength of hydrate-bearing sediment. Appl. Energy, 277, 115569.
[0114] S22. A second calibration is performed on the mechanical behavior of hydrate-bearing sediment samples with a hydrate decomposition rate of 0% to determine the values of the microscopic contact parameters associated with the linear parallel bond contact model.
[0115] S23. During the hydrate decomposition process of hydrate-containing sediment samples, the values of the parallel bonding radius multipliers in the parallel bonding models with different hydrate decomposition rates are calibrated in the third way to simulate the cementation damage effect caused by hydrate decomposition.
[0116] Furthermore, in step S23, the third calibration method specifically includes:
[0117] S231. In the process of simulating hydrate decomposition, the volume of hydrate to be decomposed and the corresponding number of hydrate particles are calculated based on the hydrate decomposition rate and in combination with the following formulas (II) and (III).
[0118]
[0119] In formula (II), The volume of the hydrate to be decomposed (m) 3 ), The total hydrate volume in the sediment sample (m³) 3 ), The hydrate decomposition rate;
[0120]
[0121] In formula (III), The number of hydrate particles to be decomposed. The volume of the hydrate to be decomposed (m) 3 ), The volume of a single hydrate particle (m³) 3 );
[0122] S232. Randomly remove the number of hydrate particles to be decomposed to simulate a reduction in the volume of the hydrate phase;
[0123] S233. Reduce the value of the parallel bond radius multiplier to simulate hydrate cementation damage caused by decomposition;
[0124] S234. If the test simulation result of the parallel bonding radius multiplier under the target hydrate decomposition rate is consistent with the corresponding indoor experimental result, then output the result; if the test simulation result of the parallel bonding radius multiplier under the target hydrate decomposition rate is inconsistent with the corresponding indoor experimental result, then update the value of the parallel bonding radius multiplier in the parallel bonding model under the target hydrate decomposition rate, and repeat step S233 until the test simulation result of the parallel bonding radius multiplier under the target hydrate decomposition rate is consistent with the corresponding indoor experimental result. Specifically, in step S234, the third calibration is first performed for a hydrate decomposition rate of 20%. After the parallel bonding radius multiplier under a 20% hydrate decomposition rate is calibrated, the third calibration is then performed for parallel bonding radius multipliers at 40%, 60%, and 80% hydrate decomposition rates, respectively.
[0125] It should be noted that since the number of particles to be removed can be determined according to formula (III), no calibration is required. Therefore, only the value of the parallel bonding radius multiplier needs to be calibrated.
[0126] It should also be noted that the parallel bond radius multiplier in the parallel bond model is positively correlated with the hydrate cementing force. Therefore, the cementing damage effect caused by hydrate decomposition can be equivalently simulated by reducing the parallel bond radius multiplier.
[0127] S24. Based on the definition of the microscopic damage factor and the calibration results of the parallel bonding radius multiplier, the empirical relationship between the microscopic damage factor and the hydrate decomposition rate is derived.
[0128] Furthermore, in step S24, the mesoscopic damage factor is defined as shown in equation (IV):
[0129]
[0130] In equation (IV), To examine the damage factors in detail, This is the parallel bond radius multiplier after the third calibration. The initial parallel bond radius multiplier before decomposition;
[0131] Further, in step S24, the empirical relationship between the microscopic damage factor and the hydrate decomposition rate (e.g., Figure 3 As shown in the following formula (V):
[0132]
[0133] In equation (V), To examine the damage factors in detail, The decomposition rate of hydrates.
[0134] It should be noted that by introducing a microscopic damage factor, the degree of hydrate cementation damage can be quantitatively characterized. Furthermore, by fitting a small number of hydrate decomposition rate points (e.g., 0%, 20%, 40%, 60%, 80%, 100%), a curve showing the relationship between the microscopic damage factor and the hydrate decomposition rate can be obtained. This curve can comprehensively cover all data points from 0% to 100% of the hydrate decomposition rate (e.g., 10%, 15%, 25%), enabling accurate prediction of the microscopic damage factor.
[0135] S3. Output of mechanical degradation model results, specifically including:
[0136] Based on steps S1-S2 and formula (V), discrete element simulation of the progressive mechanical degradation of hydrate-containing sediments during hydrate decomposition can be realized, and then the discrete element simulation results can be output.
[0137] The discrete element simulation results include macroscopic mechanical data such as stress-strain curves, volumetric strain-strain, cementation fracture quantity-strain curves, solid phase component stress contribution rate diagrams, particle rotation diagrams, particle displacement diagrams, and contact force chain network diagrams.
[0138] It should be noted that the discrete element simulation results can comprehensively reflect the mechanical degradation response characteristics of hydrate-containing sediment samples during the hydrate decomposition process.
[0139] This embodiment comprehensively considers the volume reduction of hydrate phases and cementation damage effects caused by hydrate decomposition, and proposes a simulation method based on discrete element method (DEM) for hydrate decomposition-induced mechanical degradation of hydrate-bearing sediments. This method is applicable to the mechanical property analysis of hydrate-bearing sediments with multiple coexisting morphologies. The simulation method first prepares hydrate-bearing sediment samples, then performs numerical triaxial or biaxial compression tests on the samples, and calibrates the microscopic parameters associated with relevant contact models using a trial-and-error method. A mechanical degradation model of hydrate-bearing sediments during hydrate decomposition is constructed based on the DEM. In constructing the mechanical degradation model, both the volume reduction of hydrate phases and cementation damage caused by hydrate decomposition are considered. Finally, the mechanical degradation model results are output. This simulation method has a more standardized process, considers more comprehensive factors, and significantly reduces the relative error in predicting the mechanical degradation behavior of hydrate-bearing sediments compared to traditional methods. It also boasts high computational efficiency and strong applicability, and can be used for geological and engineering risk assessment during hydrate extraction.
[0140] Example 2
[0141] This embodiment provides a simulation method for mechanical degradation of hydrate-bearing sediments induced by hydrate decomposition based on discrete element method, and further explains the composition of the specific technical solution.
[0142] First, based on step S1, the required hydrate-containing sediment samples are prepared.
[0143] Then, based on step S2, numerical triaxial compression tests were conducted on hydrate-containing sediment samples, and the microscopic parameters associated with the relevant contact model were calibrated using a trial-and-error method, thereby constructing a mechanical degradation model of hydrate-containing sediments during the hydrate decomposition process based on discrete elements.
[0144] In the process of constructing the mechanical degradation model, the combination of experiments and simulation tests not only enables the accurate calibration of the values of microscopic parameters in the relevant contact model (as shown in Table 1), but also allows the derivation of the empirical relationship between the microscopic damage factor and the hydrate decomposition rate, thus quantitatively describing the degree of hydrate cementation damage.
[0145] Table 1
[0146]
[0147] Finally, based on step S3, the simulation results of hydrate decomposition-induced mechanical degradation of hydrate-bearing sediments based on discrete element method are output (e.g., Figure 4-5 As shown), and compared with the simulation results and indoor experimental results of the traditional particle random deletion method (e.g.) Figure 4-5 (as shown)
[0148] Depend on Figure 4-5 It can be seen that, in terms of deviatoric stress, the simulation method provided by this invention is basically consistent with the indoor experimental results, exhibiting consistent strain softening behavior. Although the traditional random particle deletion method also shows strain softening behavior, the average relative error between the simulation method provided by this invention and the indoor experimental results is only 2.7% in terms of the peak intensity of hydrate decomposition rate. In contrast, the average relative error of the traditional random particle deletion method is 15.2%, which is 6 times that of the simulation method of this invention. This indicates that there are certain differences between the secant modulus and peak intensity presented by the traditional random particle deletion method and the indoor experimental results, especially the peak intensity.
[0149] In summary, the simulation method provided in this embodiment accurately characterizes the mechanical degradation behavior of hydrate-bearing sediments by simultaneously considering the reduction in hydrate phase volume and hydrate cementation damage caused by hydrate decomposition. As a result, the relative error in predicting the mechanical degradation behavior of hydrate-bearing sediment decomposition is significantly reduced compared with traditional methods. Furthermore, it has high computational efficiency and strong applicability, and can be used for geological and engineering risk assessment in the hydrate mining process.
[0150] Example 3
[0151] This embodiment provides an electronic device for implementing a simulation method for the mechanical degradation of hydrate-bearing sediments induced by hydrate decomposition based on discrete element method, such as... Figure 6 As shown, this electronic device is intended to represent various forms of digital computers, such as laptop computers, desktop computers, workstations, personal digital assistants, servers, blade servers, mainframe computers, and other suitable computers. This electronic device can also represent various forms of mobile devices, such as personal digital processors, cellular phones, smartphones, wearable devices (such as helmets, glasses, watches, etc.), and other similar computing devices. The components shown herein, their connections and relationships, and their functions are merely illustrative and are not intended to limit the implementation of the present application described and / or claimed herein.
[0152] like Figure 6As shown, the electronic device 10 includes at least one processor 11 and a memory, such as a read-only memory (ROM) 12 or a random access memory (RAM) 13, communicatively connected to the at least one processor 11. The memory stores computer programs executable by the at least one processor. The processor 11 can perform various appropriate actions and processes based on the computer program stored in the ROM 12 or loaded from storage unit 18 into the RAM 13. The RAM 13 can also store various programs and data required for the operation of the electronic device 10. The processor 11, ROM 12, and RAM 13 are interconnected via a bus 14. An input / output (I / O) interface 15 is also connected to the bus 14.
[0153] Multiple components in electronic device 10 are connected to I / O interface 15, including: input unit 16, such as keyboard, mouse, etc.; output unit 17, such as various types of displays, speakers, etc.; storage unit 18, such as secondary storage area, optical disc, etc.; and communication unit 19, such as network card, modem, wireless transceiver, etc. Communication unit 19 allows electronic device 10 to exchange information / data with other devices through computer networks such as the Internet and / or various telecommunications networks.
[0154] Processor 11 can be a variety of general-purpose and / or special-purpose processing components with processing and computing capabilities. Some examples of processor 11 include, but are not limited to, central processing unit (CPU), graphics processing unit (GPU), various special-purpose artificial intelligence (AI) computing chips, various processors running machine learning model algorithms, digital signal processors (DSPs), and any suitable processor, controller, microcontroller, etc. Processor 11 performs the various methods and processes described above, such as the discrete element method-based simulation method for hydrate decomposition-induced mechanical degradation of hydrate-bearing sediments.
[0155] In some embodiments, the discrete element method-based simulation method for hydrate decomposition-induced mechanical degradation of hydrate-bearing sediments can be implemented as a computer program tangibly contained in a computer-readable storage medium, such as storage unit 18. In some embodiments, part or all of the computer program can be loaded and / or installed on electronic device 10 via ROM 12 and / or communication unit 19. When the computer program is loaded into RAM 13 and executed by processor 11, one or more steps of the discrete element method-based simulation method for hydrate decomposition-induced mechanical degradation of hydrate-bearing sediments described above can be performed. Alternatively, in other embodiments, processor 11 can be configured by any other suitable means (e.g., by means of firmware) to perform the discrete element method-based simulation method for hydrate decomposition-induced mechanical degradation of hydrate-bearing sediments.
[0156] Various embodiments of the systems and techniques described above herein can be implemented in digital electronic circuit systems, integrated circuit systems, field-programmable gate arrays (FPGAs), application-specific integrated circuits (ASICs), application-specific standard products (ASSPs), systems-on-a-chip (SoCs), payload-programmable logic devices (CPLDs), computer hardware, firmware, software, and / or combinations thereof. These various embodiments may include implementations in one or more computer programs that can be executed and / or interpreted on a programmable system including at least one programmable processor, which may be a dedicated or general-purpose programmable processor, capable of receiving data and instructions from a storage system, at least one input device, and at least one output device, and transmitting data and instructions to the storage system, the at least one input device, and the at least one output device.
[0157] Computer programs used to implement the methods of this application may be written in any combination of one or more programming languages. These computer programs may be provided to the processor of a general-purpose computer, a special-purpose computer, or other programmable target-determining device, such that when executed by the processor, the computer programs cause the functions / operations specified in the flowcharts and / or block diagrams to be implemented. The computer programs may be executed entirely on a machine, partially on a machine, or as a standalone software package, partially on a machine and partially on a remote machine, or entirely on a remote machine or server.
[0158] In the context of this application, a computer-readable storage medium can be a tangible medium that may contain or store a computer program for use by or in conjunction with an instruction execution system, apparatus, or device. A computer-readable storage medium can be, but is not limited to, electronic, magnetic, optical, electromagnetic, infrared, or semiconductor systems, apparatus, or devices, or any suitable combination of the foregoing. Alternatively, a computer-readable storage medium can be a machine-readable signal medium. More specific examples of machine-readable storage media include electrical connections based on one or more wires, portable computer disks, hard disks, random access memory (RAM), read-only memory (ROM), erasable programmable read-only memory (EPROM or flash memory), optical fiber, portable compact disk read-only memory (CD-ROM), optical storage devices, magnetic storage devices, or any suitable combination of the foregoing.
[0159] To provide interaction with a user, the systems and techniques described herein can be implemented on an electronic device having: a display device (e.g., a CRT (cathode ray tube) or LCD (liquid crystal display) monitor) for displaying information to the user; and a keyboard and pointing device (e.g., a mouse or trackball) through which the user provides input to the electronic device. Other types of devices can also be used to provide interaction with the user; for example, feedback provided to the user can be any form of sensory feedback (e.g., visual feedback, auditory feedback, or tactile feedback); and input from the user can be received in any form (including sound input, voice input, or tactile input).
[0160] The systems and technologies described herein can be implemented in computing systems that include backend components (e.g., as data servers), or middleware components (e.g., application servers), or frontend components (e.g., user computers with graphical user interfaces or web browsers through which users can interact with implementations of the systems and technologies described herein), or any combination of such backend, middleware, or frontend components. The components of the system can be interconnected via digital data communication of any form or medium (e.g., communication networks). Examples of communication networks include local area networks (LANs), wide area networks (WANs), blockchain networks, and the Internet.
[0161] A computing system can include clients and servers. Clients and servers are generally located far apart and typically interact through communication networks. The client-server relationship is created by computer programs running on the respective computers and having a client-server relationship with each other. The server can be a cloud server, also known as a cloud computing server or cloud host, which is a hosting product within the cloud computing service system to address the shortcomings of traditional physical hosts and VPS services, such as high management difficulty and weak business scalability.
[0162] It should be understood that the various forms of processes shown above can be used to rearrange, add, or delete steps. For example, the steps described in this application can be executed in parallel, sequentially, or in different orders, as long as the desired information of the technical solution of this application can be achieved, and this is not limited herein.
[0163] The present invention has been illustrated with the above embodiments to illustrate its detailed structural features. However, the present invention is not limited to the above detailed structural features, that is, it does not mean that the present invention must rely on the above detailed structural features to be implemented. Those skilled in the art should understand that any improvements to the present invention, equivalent substitutions for the components used in the present invention, additions of auxiliary components, and selection of specific methods, etc., all fall within the protection scope and disclosure scope of the present invention.
Claims
1. A simulation method for mechanical degradation of hydrate-bearing sediments induced by hydrate decomposition based on discrete element method, characterized in that, The simulation method includes: S1. Prepare hydrate-containing sediment samples; S2. Numerical triaxial or biaxial compression tests were conducted on hydrate-bearing sediment samples. The microscopic parameters associated with the relevant contact model were calibrated using a trial-and-error method. A mechanical degradation model of hydrate-bearing sediments during hydrate decomposition based on discrete element method was constructed. In the mechanical degradation model, some hydrate particles are randomly removed according to the set hydrate decomposition rate to simulate the reduction of hydrate phase volume, and the hydrate cementation damage caused by decomposition is simulated by reducing the parallel bonding radius multiplier. S3. Output of mechanical degradation model results.
2. The simulation method according to claim 1, characterized in that, In step S1, the method for preparing hydrate-containing sediment samples specifically includes: S11. First sediment sample; S12. Second hydrate-containing sediment sample; S13. Set the boundary conditions for hydrate-containing sediment samples; S14. Determine the contact model for each component in the hydrate-bearing sediment sample.
3. The simulation method according to claim 2, characterized in that, In step S11, the method for generating the first sediment sample specifically includes: S111. Adjust the size of the sediment sample; S112. Based on the grain size distribution of the sediments in the experiment, determine the grain size distribution of the framework sand particles in the hydrate-bearing sediment sample; S113. Randomly fill the target size area of the sediment sample with framework sand particles according to the predetermined porosity and the determined grain size distribution to generate the first sediment sample; Preferably, in step S12, the method for generating the second hydrate-containing sediment sample specifically includes: In the pore space of the sediment sample, relatively small and uniform hydrate particles are randomly generated one by one until the number of hydrate particles is consistent with the target initial hydrate saturation. Then, a second hydrate-containing sediment sample is generated. Preferably, the relationship between the number of hydrate particles and the target initial hydrate saturation is shown in the following formula (I): In formula (I), The number of hydrate particles, The volume of a single hydrate particle. This represents the total volume of hydrates in the sediment sample. The target initial hydrate saturation, This represents the total pore volume of the sediment sample.
4. The simulation method according to claim 2, characterized in that, In step S13, setting the boundary conditions for the hydrate-bearing sediment sample specifically includes: S131. Coating the surface of hydrate-containing sediment samples with a particulate film serves as a flexible boundary, providing effective lateral confining pressure; S132. Construct two loading walls, including an upper loading wall and a lower loading wall. Both the upper and lower loading walls are flat plates used to apply axial loads. Preferably, in step S14, determining the contact model for each component specifically includes: S141. An anti-rolling linear contact model is adopted between sand particles; S142. Parallel bonding model is used between hydrate particles and between sand and hydrate particles; S143. A linear contact bonding model with strong adhesion is adopted between flexible membrane particles.
5. The simulation method according to claim 1, characterized in that, In step S2, the construction method specifically includes: S21. The mechanical behavior of hydrate-bearing sediment samples with a hydrate decomposition rate of 100% is first calibrated to determine the values of the microscopic contact parameters associated with the anti-rolling linear contact model. S22. The mechanical behavior of hydrate-bearing sediment samples with a hydrate decomposition rate of 0% is calibrated a second time to determine the values of the microscopic contact parameters associated with the linear parallel bond contact model. S23. During the hydrate decomposition process of hydrate-containing sediment samples, the values of the parallel bonding radius multipliers in the parallel bonding models with different hydrate decomposition rates are calibrated in the third way to simulate the cementation damage effect caused by hydrate decomposition. S24. Based on the definition of the microscopic damage factor and the calibration results of the parallel bonding radius multiplier, the empirical relationship between the microscopic damage factor and the hydrate decomposition rate is derived.
6. The simulation method according to claim 5, characterized in that, In step S21, after the first calibration, the following is also included: If the test simulation results of mechanical behavior are consistent with the corresponding indoor experimental results, the microscopic contact parameters of the anti-rolling linear contact model will be used as the basic contact parameters between sand particles in hydrate-bearing sediment samples corresponding to hydrate decomposition rates of 0%, 20%, 40%, 60%, and 80%. If the test simulation results of mechanical behavior are inconsistent with the corresponding indoor experimental results, the values of the microscopic contact parameters associated with the anti-rolling linear contact model will be updated until the test simulation results of mechanical behavior are consistent with the corresponding indoor experimental results.
7. The simulation method according to claim 5, characterized in that, In step S23, the third calibration method specifically includes: S231. In the process of simulating hydrate decomposition, the volume of hydrate to be decomposed and the corresponding number of hydrate particles are calculated based on the hydrate decomposition rate and in combination with the following formulas (II) and (III). In formula (II), The volume of the hydrate to be decomposed. This represents the total volume of hydrates in the sediment sample. The decomposition rate of hydrates; In formula (III), The number of hydrate particles to be decomposed. The volume of the hydrate to be decomposed. The volume of a single hydrate particle; S232. Randomly remove the number of hydrate particles to be decomposed to simulate a reduction in the volume of the hydrate phase; S233. Reduce the value of the parallel bond radius multiplier to simulate hydrate cementation damage caused by decomposition; S234. If the test simulation result of the parallel bonding radius multiplier under the target hydrate decomposition rate is consistent with the corresponding indoor experimental result, output the result; if the test simulation result of the parallel bonding radius multiplier under the target hydrate decomposition rate is inconsistent with the corresponding indoor experimental result, update the value of the parallel bonding radius multiplier in the parallel bonding model under the target hydrate decomposition rate, and repeat step S233 until the test simulation result of the parallel bonding radius multiplier under the target hydrate decomposition rate is consistent with the corresponding indoor experimental result. Preferably, in step S24, the definition of the mesoscopic damage factor is as shown in equation (IV): In equation (IV), To examine the damage factors in detail, This is the parallel bond radius multiplier after the third calibration. The initial parallel bond radius multiplier before decomposition; Preferably, in step S24, the empirical relationship between the microscopic damage factor and the hydrate decomposition rate is shown in the following equation (V): In equation (V), To examine the damage factors in detail, The decomposition rate of hydrates.
8. The simulation method according to claim 1, characterized in that, In step S3, the output of the mechanical degradation model specifically includes: Based on steps S1-S2 and formula (V), discrete element simulation of the progressive mechanical degradation of hydrate-containing sediments during hydrate decomposition can be realized, and then the discrete element simulation results can be output. The discrete element simulation results include macroscopic mechanical data such as stress-strain curves, volumetric strain-strain, cementation fracture quantity-strain curves, solid phase component stress contribution rate diagrams, particle rotation diagrams, particle displacement diagrams, and contact force chain network diagrams.
9. An electronic device, characterized in that, The electronic device includes: At least one processor; and A memory communicatively connected to the at least one processor; wherein, The memory stores a computer program that can be executed by the at least one processor, the computer program being executed by the at least one processor to enable the at least one processor to perform the simulation method for mechanical degradation of hydrate-bearing sediments induced by hydrate decomposition based on any one of claims 1-8.
10. A computer-readable storage medium, characterized in that, The computer-readable storage medium stores computer instructions that cause a processor to execute the simulation method for mechanical degradation of hydrate-bearing sediments induced by hydrate decomposition based on discrete element method as described in any one of claims 1-8.