A method, device and equipment for determining a mechanical model of rock

Abstract

The embodiment of the specification relates to the field of oil and gas resource development and shale reservoir mechanical property evaluation, in particular to a rock mechanical model determination method, device and equipment, comprising: constructing multiple pore supercell models according to geological data of a rock sample; one pore supercell model corresponds to one geometric structure of a rock sample pore; performing tensile simulation on the multiple pore supercell models to obtain corresponding tensile response data; calculating first mechanical property data of the rock sample according to the tensile response data; determining a mechanical model of the rock sample according to the first mechanical property data of the rock sample and first geometric structure data of the rock sample pore; the mechanical model represents the correlation between the rock sample pore geometric structure and the rock sample mechanical property. The embodiment of the specification can construct the correlation mechanical model between the rock sample pore geometric structure and the rock sample mechanical property according to the tensile response of the rock sample and the geometric structure characteristics of the multiple pores included in the rock sample.

Description

Technical Field

[0001] The embodiments in this specification relate to the technical field of oil and gas resource development and shale reservoir mechanical property assessment, specifically to a method, apparatus, and equipment for determining the mechanical model of rocks. Background Technology

[0002] As an important unconventional oil and gas reservoir, the tensile mechanical properties of shale are crucial to the propagation of hydraulic fracturing fractures, wellbore stability, and oil and gas recovery. Pore structure, as a core element of shale's microstructure, significantly affects key mechanical parameters such as tensile strength and Young's modulus.

[0003] However, existing technologies are insufficient for quantitatively assessing the impact of nanoscale pore structures on the mechanical properties of shale, necessitating targeted solutions. Currently, rock mechanical property testing primarily relies on traditional experimental methods such as the Brazilian splitting test and uniaxial compression. However, due to limitations in experimental conditions and samples, traditional methods struggle to accurately quantify the influence of nanoscale pores on mechanical parameters such as tensile strength and Young's modulus, and cannot reveal the microscopic failure mechanisms of different pore shapes. Furthermore, traditional experimental methods employ simplistic pore models, lacking quantitative analysis of the relationship between pore structure and mechanical properties.

[0004] Therefore, overcoming the problems of existing methods such as the simplistic pore model and the lack of quantitative analysis of the relationship between pore structure and mechanical properties under microscopic conditions, and proposing a comprehensive and accurate method for determining the mechanical model of rocks that can quantitatively quantify the relationship between pore structure and mechanical properties under microscopic conditions, is a key issue that urgently needs to be addressed. Summary of the Invention

[0005] The purpose of the embodiments in this specification is to provide a method, apparatus, and equipment for determining the mechanical model of rocks, so as to overcome the problems of existing methods for determining the mechanical model of rocks having a single pore model and lacking quantitative analysis of the relationship between pore structure and mechanical properties under microscopic conditions.

[0006] To solve the above-mentioned technical problems, the specific technical solutions of the embodiments in this specification are as follows:

[0007] On the one hand, embodiments of this specification provide a method for determining the mechanical model of a rock, the method comprising:

[0008] Based on the geological data of the rock samples, various pore supercell models are constructed; each pore supercell model corresponds to a rock sample pore with a specific geometric structure.

[0009] Tensile simulations were performed on the various porous supercell models to obtain the corresponding tensile response data;

[0010] Based on the tensile response data, calculate the first mechanical property data of the rock sample;

[0011] Based on the first mechanical property data and the first geometric structure data of the rock sample pores, a mechanical model of the rock sample is determined; the mechanical model represents the correlation between the geometric structure of the rock sample pores and the mechanical properties of the rock sample.

[0012] Furthermore, based on the geological data of the rock samples, various pore supercell models are constructed, including:

[0013] Based on the molecular structure data of the rock samples, multiple supercells were constructed;

[0014] Construct rock-like pores with various geometric structures within the multiple supercells;

[0015] Structural simulations were performed on the multiple supercells containing rock sample pores using geological data from the rock samples.

[0016] Molecular dynamics simulations were performed on multiple supercells containing rock sample pores after structural simulation to obtain various pore supercell models.

[0017] Furthermore, the structural simulation of the multiple supercells containing rock sample pores using geological data from the rock samples includes:

[0018] Based on the geological data of the rock sample, determine the force field corresponding to each mineral in the rock sample;

[0019] Based on preset periodic boundary conditions and the force fields corresponding to each mineral in the rock sample, the structure of the multiple supercells containing the pores of the rock sample is simulated.

[0020] Furthermore, the molecular dynamics simulation of multiple supercells containing rock-sample pores after structural simulation includes:

[0021] Based on the geological data of the rock sample, determine the corresponding temperature and pressure fields of the rock sample;

[0022] Based on the temperature and pressure fields corresponding to the rock samples, molecular dynamics simulations were performed on multiple supercells containing the pores of the rock samples after structural simulation.

[0023] Furthermore, the tensile simulation of the various porous supercell models to obtain the corresponding tensile response data includes:

[0024] Tensile stress is applied to the various porous supercell models along multiple preset crystal orientations to obtain the change data of tensile stress and tensile strain.

[0025] The calculation of the first mechanical property data of the rock sample based on the tensile response data includes:

[0026] By fitting the changes in tensile stress and tensile strain, the first mechanical property data of the rock sample are obtained.

[0027] Furthermore, the first geometric structure data includes second geometric structure data and third geometric structure data; the second geometric structure data includes at least pore diameter data; the third geometric structure data includes at least pore relative surface area data.

[0028] The process of determining the mechanical model of the rock sample based on its first mechanical property data and first geometric structure data of the pores includes:

[0029] Based on the second geometric structure data and the first mechanical property data, the first mechanical model of the rock sample is determined;

[0030] Based on the third geometric structure data and the first mechanical property data, a second mechanical model for the rock sample is determined.

[0031] Further, determining the first mechanical model of the rock sample based on the second geometric structure data and the first mechanical property data includes:

[0032] The second mechanical property data corresponding to the second geometric structure data is determined from the first mechanical property data; the second mechanical property data includes mechanical property data of various pore sizes;

[0033] Based on the second geometric structure data and the corresponding second mechanical property data, the first mechanical model of the rock sample is determined.

[0034] Further, determining the second mechanical model of the rock sample based on the third geometric structure data and the first mechanical property data includes:

[0035] The third mechanical property data corresponding to the third geometric structure data is determined from the first mechanical property data; the third mechanical property data includes mechanical property data of various pore relative surface areas;

[0036] Based on the aforementioned third geometric structure data and corresponding third mechanical property data, the second mechanical model of the rock sample is determined using the following formula:

[0037] X = β0 + β S S+β V lnV+β S×V S×lnV;

[0038] In the formula, β0, β S β V and β S×V Let S represent the constant coefficient of the mechanical property parameter, the influence coefficient of the relative surface area of ​​pores, the influence coefficient of pore volume, and the influence coefficient of pore volume on the relative surface area of ​​pores, respectively. Let S represent the relative surface area of ​​pores, V represent the pore volume, and X represent the mechanical property parameter of the rock sample.

[0039] On the other hand, embodiments of this specification also provide a device for determining the mechanical model of a rock, the device comprising:

[0040] A construction module is used to construct various pore supercell models based on the geological data of rock samples; each pore supercell model corresponds to a rock sample pore with a specific geometric structure.

[0041] The simulation module is used to perform tensile simulations on the various porous supercell models to obtain the corresponding tensile response data;

[0042] The calculation module is used to calculate the first mechanical property data of the rock sample based on the tensile response data;

[0043] The determination module is used to determine the mechanical model of the rock sample based on the first mechanical property data and the first geometric structure data of the rock sample pores; the mechanical model represents the correlation between the pore geometry and the mechanical properties of the rock sample.

[0044] Furthermore, embodiments of this specification also provide a computer device, including a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the processor performs the aforementioned method for determining the mechanical model of rocks.

[0045] Furthermore, embodiments of this specification also provide a computer program product, which, when run by the processor of a computer device, executes instructions for any of the methods described above.

[0046] As can be seen from the technical solutions provided in the embodiments of this specification above, the embodiments of this specification can construct multiple pore supercell models based on the geological data of rock samples; each pore supercell model corresponds to a rock sample pore with a specific geometric structure; tensile simulations are performed on the multiple pore supercell models to obtain corresponding tensile response data; based on the tensile response data, the first mechanical property data of the rock sample is calculated; based on the first mechanical property data of the rock sample and the first geometric structure data of the rock sample pores, the mechanical model of the rock sample is determined; the mechanical model represents the correlation between the geometric structure of the rock sample pores and the mechanical properties of the rock sample. Compared with existing methods, the embodiments of this specification can use the geological data of rock samples to construct pore supercell models under multiple geometric structures, and accurately determine the tensile response of the rock sample containing pores with multiple geometric structures under microscopic conditions through tensile simulations of multiple pore supercell models. Based on the tensile response of the rock sample and the geometric structural characteristics of the multiple pores it includes, a correlation mechanical model between the pore geometry and the mechanical properties of the rock sample can be constructed, and thus the quantitative relationship between pore structure and mechanical properties under microscopic conditions can be comprehensively and accurately quantified through the mechanical model. Attached Figure Description

[0047] To more clearly illustrate the technical solutions in the embodiments or prior art of this specification, the accompanying drawings used in the description of the embodiments or prior art will be briefly introduced below.

[0048] Figure 1 This is a flowchart of a method for determining the mechanical model of a rock, as provided in the embodiments of this specification.

[0049] Figure 2 This is an overall logic flowchart of a method for determining the mechanical model of a rock, as provided in the embodiments of this specification.

[0050] Figure 3 These are scanning electron microscope images of rock samples from area A provided in the embodiments of this specification;

[0051] Figure 4 These are slit-hole scanning electron microscope images of rock samples from area A provided in the embodiments of this specification;

[0052] Figure 5 These are cylindrical bore scanning electron microscope images of rock samples from area A provided in the embodiments of this specification;

[0053] Figure 6 These are scanning electron microscope images of triangular boreholes in rock samples from area A provided in the embodiments of this specification;

[0054] Figure 7 This is a square-hole scanning electron microscope image of a rock sample from area A provided in the embodiments of this specification;

[0055] Figure 8 This is a schematic diagram illustrating the process of establishing the kaolinite slot hole model in region A provided in the embodiments of this specification;

[0056] Figure 9 This is a schematic diagram of the cylindrical pore supercell model of region A provided in the embodiments of this specification;

[0057] Figure 10 This is a schematic diagram of the triangular pore supercell model of region A provided in the embodiments of this specification;

[0058] Figure 11 This is a schematic diagram of the square-pore supercell model of region A provided in the embodiments of this specification;

[0059] Figure 12 This is a schematic diagram of strain versus stress in quartz of region A with different aperture sizes in the

[010] crystal orientation, provided in the embodiments of this specification;

[0060] Figure 13 This is a schematic diagram of strain variation with stress for quartz in region A with different pore shapes in the

[010] crystal orientation, provided in the embodiments of this specification;

[0061] Figure 14This is a schematic diagram showing the variation of Young's modulus of quartz in region A in the

[010] crystal orientation with different pore shapes, provided in the embodiments of this specification.

[0062] Figure 15 This is a schematic diagram showing the degree of attenuation of the mechanical strength of kerogen in different crystal orientations in region A as the pore size increases (2nm-10nm), provided in the embodiments of this specification.

[0063] Figure 16 This is a schematic diagram of the structural composition of a rock mechanical model determination device provided in the embodiments of this specification;

[0064] Figure 17 This is a schematic diagram of the structural composition of the computer device provided in the embodiments of this specification. Detailed Implementation

[0065] The technical solutions in the embodiments of this specification will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this specification, and not all embodiments. Based on the embodiments in this specification, all other embodiments obtained by those skilled in the art without creative effort should fall within the scope of protection of this specification.

[0066] It should be noted that the terms "first," "second," etc., used in this specification, claims, and the foregoing drawings 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 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 a non-exclusive inclusion; for example, a process, method, apparatus, product, or device 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 devices.

[0067] In some embodiments, the mechanical properties of rocks may include tensile strength, Young's modulus, and ultimate strain. Tensile strength characterizes the ability of a rock to resist tensile stress failure; Young's modulus can be used as the stress-strain ratio during the elastic deformation stage, reflecting the stiffness characteristics of the rock; ultimate strain refers to the maximum strain that a rock can withstand before failure.

[0068] Figure 1 This is a flowchart illustrating a method for determining the mechanical model of a rock, as provided in the embodiments of this specification. Figure 2 This is an overall logic flowchart of a method for determining the mechanical model of a rock, provided in the embodiments of this specification. In specific implementation, it includes the following steps:

[0069] S101: Based on the geological data of the rock sample, construct multiple pore supercell models; each pore supercell model corresponds to a rock sample pore with a specific geometric structure.

[0070] In some embodiments, multiple supercells can be constructed based on the molecular structure data of the rock sample; rock sample pores with various geometric structures can be constructed in the multiple supercells; the geological data of the rock sample can be used to perform structural simulation on the multiple supercells containing rock sample pores; molecular dynamics simulation can be performed on the multiple supercells containing rock sample pores after structural simulation to obtain multiple pore supercell models.

[0071] The physical and chemical properties of rocks largely depend on their microscopic pore structure. At the atomic scale, the geometry, distribution, and surface properties of pores directly influence fluid storage and transport, as well as the mechanical behavior of rocks. Traditional experimental methods struggle to accurately characterize pore structures at the nanoscale. By constructing supercells based on molecular structure data as the basic unit of simulation, and designing various pore geometries within the supercells to cover pore morphologies under different geological conditions, the supercell structure can be optimized using geological data to conform to the mineral composition and physicochemical environment of real rocks. Furthermore, molecular dynamics simulations facilitate the study of pore evolution under dynamic conditions. Ultimately, multiple pore supercell models can be established, each corresponding to a specific pore geometry, providing a high-precision theoretical model for rock physics research.

[0072] Molecular structure data of rock samples can describe the atomic arrangement of the minerals that make up the rock, including: lattice parameters (cell size, angles); atomic coordinates (positions of elements within the cell); and bonding information (covalent bonds, ionic bonds, metallic bonds), etc. Molecular structure data of rock samples can be obtained from geological data derived through X-ray diffraction (XRD), neutron scattering, or first-principles calculations.

[0073] A supercell can be a periodic extension of the original unit cell, increasing the size of the simulation system and reducing size effects. Supercells allow for the introduction of more complex defect and pore structures, thus providing sufficient degrees of freedom to simulate the dynamic processes of pores in rock samples. Supercell construction typically employs matrix transformation methods, which will not be elaborated upon here. The size of the supercell requires a trade-off between computational cost and physical plausibility: for example, too small a size may fail to accommodate typical pores or lead to spurious periodic interactions, while too large a size will result in a dramatic increase in computational cost, potentially exceeding simulation resource limitations. Convergence tests can be used to determine the optimal supercell size, which will not be elaborated upon here.

[0074] The geometries of rock sample pores can be categorized into slit-like, triangular, cylindrical, square, and other regular / irregular geometric structures. Various rock sample pore structures with different geometries can be constructed within multiple supercells. Specifically, the geometric region containing the rock sample pores can be defined at the center of the supercell, and atoms within it can be removed. The presence of rock sample pores in the supercell alters the stress distribution of the surrounding lattice, necessitating structural simulation. Structural simulation can include local relaxation (optimizing the position of atoms on the pore surface) and global energy minimization (ensuring the system reaches a stable state). After structural simulation, molecular dynamics simulations can be performed on the supercell containing the rock sample pores to obtain a pore supercell model. Based on the geological data of the rock sample, an appropriate force field can be selected. For example, a ClayFF force field can be chosen for clay minerals. During molecular dynamics simulation, supercell energy can be minimized to avoid unreasonable high-energy states in the initial structure, and temperature / pressure can be controlled through NVT / NPT ensemble simulations. When energy, temperature, and pressure fluctuations stabilize, the molecular dynamics simulation is complete, yielding the pore supercell model. The pore supercell model of the pores of each type of rock sample can be considered as a tiny rock sample containing the pores of that geometric structure under microscopic conditions.

[0075] S102: Perform tensile simulation on the various pore supercell models to obtain the corresponding tensile response data.

[0076] In some embodiments, tensile stress can be applied to the various pore supercell models along multiple preset crystal orientations to obtain data on the changes in tensile stress and tensile strain.

[0077] The mechanical behavior of crystalline materials exhibits an inherent orientation dependence, a characteristic stemming from the anisotropy of atomic arrangement. In porous supercell models, this anisotropy is further complicated by the presence of pores, with significant differences in interplanar spacing, bonding density, and slip system activation thresholds across different crystal orientations. When external loads are applied, these microstructural features manifest macroscopically as orientation dependence of the mechanical response through mechanisms such as dislocation nucleation and motion, and lattice distortion. Therefore, by applying tensile stress to various porous supercell models along multiple predetermined crystal orientations and obtaining data on the changes in tensile stress and tensile strain, a precise data foundation can be laid for the quantitative analysis of the relationship between pore structure and mechanical properties.

[0078] The coupling effect between pore structure and crystal orientation can be manifested at three levels: at the geometric level, the orientation distribution of pores affects the local stress concentration factor; at the energy level, the pore surface changes the lattice vibration spectrum; and at the dynamic level, pores, as dislocation sources or traps, modulate the plastic deformation mechanism. This multi-physics coupling makes it difficult to accurately predict mechanical behavior using only continuum mechanics. Therefore, atomic-scale simulations can help reveal its mechanical response mechanism.

[0079] Applying tensile stress to the various porous supercell models along multiple preset crystal orientations ensures coverage of all possible mechanical response modes of the material, avoiding biases in conclusions due to specific orientation choices. Furthermore, it provides sufficient input data for establishing complete constitutive relations. In a cubic crystal system, at least one of the following can be selected: <100> , <110> and <111> There are three characteristic directions. For crystal systems with stronger anisotropy, the sampling density can be increased accordingly, which will not be elaborated here.

[0080] The displacement control method can be used to apply tensile stress to the various pore supercell models along multiple preset crystal orientations by fixing the strain rate. The displacement application direction is strictly along the target crystal orientation, and the stress state in non-tension directions is controlled to be zero, thereby obtaining the corresponding tensile strain. The continuous tensile stress data and continuous tensile strain data during the displacement application process are recorded, thereby obtaining the change data of tensile stress and tensile strain.

[0081] S103: Calculate the first mechanical property data of the rock sample based on the tensile response data.

[0082] In some embodiments, the variation data of tensile stress and tensile strain can be fitted to obtain the first mechanical property data of the rock sample.

[0083] Denoising and smoothing can be performed on tensile stress and strain variation data. Specifically, moving averages or Savitzky-Golay filtering can be used to eliminate thermal fluctuation noise in molecular dynamics simulations, which helps improve the accuracy of Young's modulus fitting (more accurate slope of the linear segment) and ensures that the determination of tensile strength and ultimate strain is not affected by noise (such as spurious peaks or fracture signals). It can also remove abrupt changes caused by numerical instability (such as singular values ​​before strain localization) and ensure that data from different geometries and crystal orientations have the same strain interval, facilitating direct comparison of the mechanical responses of different pore structures or crystal orientations.

[0084] The pore supercell model of a rock sample with each geometries can be considered as a microscopic rock sample containing pores of that geometries. Therefore, based on the tensile response data in the tensile simulation of the pore supercell model, the primary mechanical properties of the rock sample can be calculated. These primary mechanical properties can include tensile strength, Young's modulus, and ultimate strain of rock samples containing various geometries in different crystal orientations. For example, for the tensile strength of a rock sample with specific geometries in a specific crystal orientation, a stress-strain curve can be directly constructed using the changes in tensile stress and strain in that orientation. The stress value at the highest point of the stress-strain curve can be taken as the tensile strength. If the stress-strain curve has no significant peak (e.g., for tough materials), the stress value corresponding to a specific strain threshold (e.g., 2%) can be defined as the tensile strength. Similarly, for the Young's modulus of a rock sample with specific geometries in a specific crystal orientation, a stress-strain curve can be constructed, and the slope of the initial linear stage (usually strain <1%) of the stress-strain curve can be fitted using the least squares method. The fitted slope can then be taken as the Young's modulus. For rock samples containing pores with specific geometries, the ultimate strain in a specific crystal orientation can be recorded when the pore supercell model loses its load-bearing capacity (fracture) (stress drop or strain at simulation termination), and this strain can be used as the ultimate strain.

[0085] By applying the same criteria to all geometric structures and crystal orientations, it can be ensured that the differences between different parameter groups only reflect real physical effects (such as pore anisotropy), which helps to systematically analyze the influence of rock sample pore geometry on rock sample mechanical properties, or the influence of crystal orientation on rock sample mechanical properties.

[0086] S104: Based on the first mechanical property data and the first geometric structure data of the rock sample pores, determine the mechanical model of the rock sample; the mechanical model represents the correlation between the geometric structure of the rock sample pores and the mechanical properties of the rock sample.

[0087] In some embodiments, the first geometrical data may include second, third, and fourth geometrical data; the second geometrical data may include at least pore diameter data; the third geometrical data may include at least pore relative surface area data; the fourth geometrical data may include at least pore volume data; a first mechanical model of the rock sample can be determined based on the second geometrical data and the first mechanical property data; a second mechanical model of the rock sample can be determined based on the third geometrical data and the first mechanical property data; and a third mechanical model of the rock sample can be determined based on the third geometrical data and the first mechanical property data.

[0088] Pore ​​diameter can represent the circumcircle diameter of the pores in a pore supercell model. For a pore supercell model with arbitrary geometry, the pore volume can be kept constant while the pore diameter is changed, resulting in multiple pore supercell models with the same geometry but different pore diameters. Stress-strain curves for the same geometry under different crystal orientations and pore diameters can be obtained from the primary mechanical property data, thus determining the primary mechanical model of the rock sample under different crystal orientations and pore diameters. By combining the primary mechanical models of rock samples containing pores with different geometries, the influence of pore diameter on the mechanical properties of the rock sample can be accurately and quantitatively represented.

[0089] The relative surface area of ​​pores represents the ratio of the surface area to the volume of pores in a pore supercell model, reflecting the shape of the pores. For all pore supercell models with different geometries, stress-strain curves under different crystal orientations and relative surface areas of pores can be obtained from the first mechanical property data, thereby determining the second mechanical model of the rock sample under different crystal orientations and relative surface areas of pores. By combining the second mechanical model of the rock sample containing pores with different geometries, the influence of pore shape on the mechanical properties of the rock sample can be accurately and quantitatively represented.

[0090] For pore supercell models with arbitrary geometries, their relative surface area can be kept constant while the pore volume is changed, resulting in multiple pore supercell models with the same geometry but different pore volumes. Stress-strain curves for the same geometry under different crystal orientations and pore volumes can be obtained from the first mechanical property data, thus determining the third mechanical model of the rock sample under different crystal orientations and pore volumes. Combining the third mechanical models of rock samples containing pores with different geometries allows for a precise quantitative representation of the influence of pore volume on the mechanical properties of the rock sample.

[0091] In some embodiments, the force field corresponding to each mineral in the rock sample can be determined based on the geological data of the rock sample; based on the preset periodic boundary conditions and the force field corresponding to each mineral in the rock sample, the structure of the multiple supercells containing the pores of the rock sample can be simulated.

[0092] Precise matching of geological data and molecular force fields in rock samples is fundamental for conducting high-quality molecular simulations. X-ray diffraction analysis provides precise quantitative results of the mineral composition of the rock sample, including the specific proportions of major rock-forming minerals such as quartz, kaolinite, and kerogen. This mineral composition data directly determines the basic direction for subsequent force field selection. The force field of the supercell containing the pores of the rock sample is determined based on the mineral type; different force fields can be used for different minerals. For example, based on the geological data of the rock sample (such as mineral composition), the corresponding force field parameters for each mineral in the rock sample can be determined. For instance, the Universal force field can be used for quartz, the ClayFF force field for kaolinite, and the COMPASS II force field for kerogen.

[0093] After obtaining mineral composition data, the force field parameters can be further refined by combining the pore structure characteristics of the rock sample. Data such as porosity and pore size distribution obtained through micro-CT scanning or nitrogen adsorption experiments provide important basis for determining non-bonded interaction parameters in the force field. Especially for nanoscale pores, surface effects significantly influence intermolecular interactions; therefore, key parameters such as the van der Waals force cutoff radius can be adjusted according to the actual pore size. Simultaneously, surface analysis data such as X-ray photoelectron spectroscopy (XPS) can be used to describe potential surface hydroxylation, ion adsorption, and other chemical characteristics in the rock sample within the force field.

[0094] The setting of periodic boundary conditions can strictly correspond to the actual structural characteristics of the rock sample. For isotropic rock samples, a cubic simulation box combined with three-dimensional periodic boundary conditions can be used; while for sedimentary rocks with obvious bedding structures, the setting of boundary conditions needs to be adjusted according to their anisotropic characteristics. The size of the simulation box must meet two basic requirements: first, the box size must be more than three times the size of the studied feature (such as the maximum pore diameter) to avoid the spurious correlation effect caused by periodic mirroring; second, the repetition of the box in the three dimensions must not lead to the appearance of artificial periodicity.

[0095] Once the force field parameters and boundary conditions are determined, simulations of supercellular structures including pores can be conducted. For crystalline minerals, the unit cell structure can be accurately constructed based on their crystallographic data; for amorphous components, methods such as melt-quenching can be used to obtain a reasonable initial configuration. Parameter settings during the simulation must strictly adhere to the force field requirements. The selection of the integration step size needs to consider the fastest vibrational mode in the system; for hydrogen-containing systems, a time step of 0.5–1 fs can be used. Temperature control can utilize the Nosé-Hoover hot tub algorithm, while pressure control can employ the Parrinello-Rahman method; these algorithms better maintain the accuracy of the thermodynamic ensemble. During the simulation, the energy balance of the system needs to be closely monitored to ensure the stability and reliability of the simulation.

[0096] In some embodiments, the temperature and pressure fields corresponding to the rock sample can be determined based on the geological data of the rock sample; based on the temperature and pressure fields corresponding to the rock sample, molecular dynamics simulations can be performed on multiple supercells containing the pores of the rock sample after structural simulation.

[0097] The temperature and pressure information contained in rock sample geological data can be systematically transformed into physical fields suitable for molecular dynamics simulations. The temperature field can be determined by analyzing the thermal history data of the rock sample, which can include current geothermal measurements, vitrinite reflectance (Ro) indices, and fluid inclusion homogenization temperature test data. These data can be used to reconstruct the temperature evolution process experienced by the rock sample through thermodynamic inversion algorithms, ultimately determining the temperature gradient distribution required for the simulation. For heterogeneous rock samples, the differences in thermal conductivity among different mineral components lead to inhomogeneities in the temperature distribution at the microscale, which can be accurately characterized through multiphysics coupling calculations.

[0098] The construction of the pressure field can be achieved by integrating the analysis of the rock sample's burial history, acoustic emission Kessel effect test results, and differential stress marker observation data. A strain energy density inversion algorithm can be used to decompose the macroscopic geological data into two components: hydrostatic pressure and deviatoric stress tensor. For porous rock samples, the influence of pore fluid pressure can also be considered. Specifically, calculations can be performed by combining capillary pressure testing and the effective stress law. The final pressure field should include both hydrostatic pressure and deviatoric stress components and reflect the localized stress concentration phenomena within the rock sample caused by differences in mineral composition.

[0099] Transforming continuous temperature and pressure fields into discretized parameters suitable for molecular dynamics simulations requires specialized numerical processing methods. For the temperature field, the density of the spatial discrete grid can be determined based on the size of the simulation system, with the temperature gradient within each grid not exceeding 1 K / nm. Alternatively, cubic spline interpolation can be used to map the continuous temperature field onto discrete grid points, and adaptive grid refinement can be applied to regions with drastic temperature changes.

[0100] Discretization of the pressure field allows for separate handling of hydrostatic pressure and deviatoric stress components. The hydrostatic pressure components can be directly converted into isotropic pressure parameters for molecular dynamics simulations, while the deviatoric stress components require modification of the simulation box's shape matrix. The Parrinello-Rahman method can be used to implement periodic boundary conditions with variable shapes, enabling the precise application of stress tensors of arbitrary forms.

[0101] Once the temperature and pressure fields are determined, the parameters for the molecular dynamics simulation can be set. Temperature control can utilize the Nosé-Hoover chain bath algorithm, which produces accurate canonical distributions and maintains excellent numerical stability for systems with large temperature gradients. Pressure control can be achieved using different algorithms depending on the properties of the pressure field. For regions dominated by hydrostatic pressure, the Andersen-Hoover barometer can be used; while for regions with significant deviatoric stresses, the Parrinello-Rahman variable shape algorithm can be employed.

[0102] After applying temperature and pressure fields, the porous supercell model undergoes a sufficient equilibration process before formal data acquisition can begin. The equilibration process typically consists of three stages: first, a local energy minimization stage, using the conjugate gradient algorithm to eliminate excessive overlap between atoms; second, a short-term NVT ensemble equilibration to bring the system temperature to the set value; and finally, a long-term NPT ensemble equilibration to ensure that all components of the pressure tensor converge to the target value.

[0103] Furthermore, when there is strong coupling between the temperature and pressure fields, special simulation strategies can be employed. For example, in regions with significant thermo-pressure coupling, standard sequential coupling algorithms may lead to numerical instability; in such cases, fully coupled algorithms can be used. For instance, temperature-pressure joint control methods (such as the MTK algorithm) can better handle this situation. For systems involving chemical reactions, the gradients of the temperature and pressure fields may also affect the reaction rate; in these cases, transition state theory can be introduced for correction, which will not be elaborated upon here.

[0104] In some embodiments, second mechanical property data corresponding to the second geometric structure data can be determined from the first mechanical property data; the second mechanical property data may include mechanical property data of various pore sizes; based on the second geometric structure data and the corresponding second mechanical property data, a first mechanical model of the rock sample can be determined.

[0105] Pore ​​diameter is a key parameter characterizing pore size, and in a pore supercell model, it can be defined as the diameter of the circumcircle of the pore. To systematically study the influence of pore diameter on the mechanical properties of rock samples, a controlled variable method can be used: keeping the pore volume constant and only changing the pore diameter, a series of pore supercell models with the same geometry but different pore diameters can be generated. Through molecular dynamics (MD) or finite element method (FEM) simulations, stress-strain curves of these models under different crystal orientations (such as

[100] ,

[110] ,

[111] ) can be obtained, and secondary mechanical property data (such as Young's modulus, tensile strength, and ultimate strain) can be extracted from them.

[0106] For the second mechanical property data of each geometric structure, a quantitative relationship between pore size and mechanical properties can be established. For example, the first mechanical model can be obtained by fitting an empirical formula: E = E0·exp(-k·d); where E0 is the non-porous modulus, d is the pore size, and k is the fitting parameter. By comparing the mechanical response under the same geometric structure and different pore sizes through the first mechanical model, the effect of pore size increase on stress concentration of rock samples can be obtained. For example, pore size increase can lead to increased stress concentration in rock samples, reduce the tensile strength and fracture toughness of rock samples, and pore size increase can significantly affect the elastic modulus of rock samples, especially when pore connectivity is enhanced (such as when the pore size is close to the order of lattice constant). The dependence of rock sample mechanical properties on crystal orientation can be obtained. For example, in anisotropic materials, the effect of pore size on rock sample mechanical properties may vary with crystal orientation (such as the

[100] direction being more sensitive to pore size than the

[111] direction).

[0107] In some embodiments, the third mechanical property data corresponding to the third geometric structure data can be determined from the first mechanical property data; the third mechanical property data may include mechanical property data of various pore relative surface areas; based on the third geometric structure data and the corresponding third mechanical property data, the second mechanical model of the rock sample can be determined using the following formula: X = β0 + β S S+β V lnV+β S×V S×lnV; where β0 and β S β V and β S×V Let S represent the constant coefficient of the mechanical property parameter, the influence coefficient of the relative surface area of ​​pores, the influence coefficient of pore volume, and the influence coefficient of pore volume on the relative surface area of ​​pores, respectively. Let S represent the relative surface area of ​​pores, V represent the pore volume, and X represent the mechanical property parameter of the rock sample.

[0108] The relative surface area of ​​pores (the ratio of surface area to volume) is a core indicator for describing the complexity of pore shape. For example, spherical pores have the smallest relative surface area, while fissure-shaped or fractal pores have significantly higher surface areas. To quantify the shape effect, pore supercell models with different relative surface areas can be constructed and corresponding third mechanical property data can be obtained.

[0109] Based on the third geometric structure data and the corresponding third mechanical property data, the second mechanical model of the rock sample can be determined using the following formula: X = β0 + β S S+β V lnV+β S×V S×lnV; where β0 and β S β V and β S×VLet S represent the constant coefficients of the mechanical property parameters, the influence coefficients of the relative pore surface area, the influence coefficients of the pore volume, and the influence coefficients of the pore volume on the relative pore surface area, respectively. Let S represent the relative pore surface area, V represent the pore volume, and X represent the mechanical property parameters of the rock sample. Specifically, a regression model can be used to fit the third geometric structure data and the corresponding third mechanical property data to obtain β0 and β1 in the second mechanical model. S β V and β S×V Equal coefficients were used. By comparing the mechanical responses under different geometries and different relative surface areas of pores using the constructed second mechanical model of the rock samples, the influence of increased relative surface area on the mechanical response can be obtained. For example, pores with a high relative surface area can lead to greater local stress concentration, accelerate microcrack initiation, thereby reducing strength and ductility, and potentially significantly affecting the failure mode (such as the shift from uniform plastic deformation to local brittle fracture). Furthermore, based on the second mechanical model, it can be found that in non-equiaxed pores, the mechanical response strongly depends on the angle between the tensile direction and the long axis of the pore.

[0110] In some embodiments, the third mechanical property data corresponding to the third geometric structure data can be determined from the first mechanical property data; the third mechanical property data may include mechanical property data of various pore volumes; based on the third geometric structure data and the corresponding third mechanical property data, the third mechanical model of the rock sample can be determined.

[0111] For the fourth mechanical property data for each volume, a quantitative relationship between volume and mechanical properties can be established, for example, by fitting an empirical formula to obtain a third mechanical model. By comparing the mechanical responses under the same geometry and different volumes using the third mechanical model, the impact of volume increase on stress concentration can be obtained. For example, volume increase can lead to high porosity, and the failure mechanism of rock samples is mainly pore coalescence; conversely, volume decrease can lead to low porosity, and the failure mechanism of rock samples is mainly matrix failure. Furthermore, in highly anisotropic materials (such as layered shale), the influence of volume-related porosity on certain crystal orientations (such as those perpendicular to bedding planes) may be amplified. By integrating data from different geometries, a volume-mechanical property phase diagram can be constructed to clarify critical porosity (such as the threshold for a sharp drop in strength), providing quantitative guidance for engineering applications (such as oil and gas reservoir fracturing assessment).

[0112] The following is a specific embodiment of this specification:

[0113] 1. Based on the composition of shale in region A, organic kerogen, brittle mineral quartz, and clay mineral kaolinite were selected as research objects.

[0114] 2. Please refer to Figure 2 , Figure 3 , Figure 4 , Figure 5 , Figure 6 and Figure 7 The scanning electron microscope (SEM) experiment was conducted on a shale sample from region A, and the actual geometry of the pores was obtained.

[0115] 3. Based on the actual geological data of region A, construct a basic molecular model for the tensile mechanical properties of shale using Materials Studio software. Import quartz (SiO2) and kaolinite (Al4[Si4O2]) from the Materials Studio structure library. 10 [(OH)8), expands into a supercell. The supercell parameters of the Shi Yingchao are... α = 90.00°, β = 90.00°, γ = 120.00°. The supercell parameters of kaolinite are... α = 91.47°, β = 104.52°, γ = 90.49°. Kerogen (C 200 H 228 N6O 14 The S4 model is a geological model of region A established based on experimental data from actual samples collected in region A. The specific parameters of the kerogen model are as follows: α=90.00°. β=90.00°, γ=90.00°.

[0116] 4. Please refer to Figure 8 The model shown is built using a molecular model with different pore sizes, set to 2nm, 6nm, and 10nm. The pore size and volume are consistent by using the "Build Layers" tool.

[0117] 5. Please refer to Figure 9 , Figure 10 and Figure 11 Based on the pore morphology observed by scanning electron microscopy, four geometric shapes (slit-like, triangular, cylindrical, and square) of pores were constructed. Slit-like pores: The supercell was cut along the crystal orientation

[001] , and then the slit-like pores were created using the "Build Layers" tool. Triangular pores: A triangular prism pore with an equilateral triangle base was constructed, with the height consistent with the supercell. Cylindrical pores: A central cylindrical region was defined, and atoms within the cylinder were removed to form a cylindrical pore. Square pores: A cubic pore was constructed at the center of the supercell. All pores have the same geometric shape and pore volume.

[0118] 6. The established model is first subjected to structural optimization and relaxation. During the simulation, the convergence accuracy is set to Fine level. The Ewald summation method is used to calculate the Coulomb electrostatic force, with a cutoff radius of 0.6 nm and a buffer width of 0.05 nm. The Atom-based method is selected to calculate the long-range van der Waals force. This ensures that the model reaches the lowest energy state. During the simulation, a Universal force field is used for quartz, a ClayFF force field for kaolinite, and a COMPASS II force field for kerogen to ensure accurate simulation of the intermolecular interactions of different minerals. Periodic boundary conditions are applied throughout the simulation.

[0119] 7. The optimized model was used for MD simulation through the Forcite module. The simulation was based on actual formation conditions, with a temperature of 360K and a pressure of 35MPa. The NPT ensemble was used with a step size of 0.5fs. The system was subjected to a kinetic simulation of 2000ps under the NPT ensemble to ensure the accuracy of the simulation results.

[0120] 8. Apply tensile stress to the model completed by MD simulation using the Perl language stress-strain calculation script, in the crystal orientations of

[100] (OA),

[010] (OB), and

[001] (OC), balancing 1000ps per step.

[0121] 9. Please refer to Figure 12 and Figure 13 The simulation, which uses Perl language to apply stress and calculate strain, shows the strain variation with stress under different pore sizes and shapes.

[0122] 10. Please refer to Figure 14 As shown, the least squares method is used to fit the stress-strain data during the elastic deformation stage, and the slope is calculated to obtain the Young's modulus of each crystal direction under different pore shapes.

[0123] 11. Please refer to Figure 15 The influence of pore geometry on mechanical properties was quantitatively analyzed.

[0124] 12: Parameterize the pore structure, shape parameter (S): Introduce the shape factor S = surface area / volume to quantify the pore geometry.

[0125] Slit: S = 2(LH + WH + WL) / LWH (L is the length, W is the width, and H is the height);

[0126] Triangular hole: (a is the side length of the triangle, and H is the height);

[0127] Cylindrical hole: S = (2πR) 2 +2πRH) / πR2 H (R is the radius, H is the height);

[0128] Square hole: S = 6L 2 / L 3 =6 / L (L is the side length).

[0129] 11. Using Python, construct a three-dimensional multiple linear regression model combining mineral type, crystal orientation, geometric factor S, and pore volume V to calculate mechanical parameters (e.g., Young's modulus). The established model is as follows:

[0130] X = β0 + β S S+β V lnV+β S×V S×lnV;

[0131] The specific values ​​of the parameters corresponding to different organic matter and minerals in different crystal directions are obtained by fitting, as shown in Table 1. When calculating the Young's modulus of organic matter or minerals, the parameters of different crystal directions can be substituted in.

[0132] Table 1

[0133]

[0134] The method for determining the mechanical model of rocks provided in this specification can construct multiple pore supercell models based on the geological data of rock samples. Each pore supercell model corresponds to a specific geometric structure of the rock sample pores. Tensile simulations are performed on the multiple pore supercell models to obtain corresponding tensile response data. Based on the tensile response data, the first mechanical property data of the rock sample is calculated. Based on the first mechanical property data and the first geometric structure data of the rock sample pores, the mechanical model of the rock sample is determined. The mechanical model represents the correlation between the pore geometry and the mechanical properties of the rock sample. Compared with existing methods, this specification can use the geological data of rock samples to construct pore supercell models with multiple geometric structures, and accurately determine the tensile response of the rock sample under microscopic conditions when it contains pores with multiple geometric structures through tensile simulations of the multiple pore supercell models. Based on the tensile response of the rock sample and the geometric characteristics of the multiple pores it contains, a correlation mechanical model between the pore geometry and the mechanical properties of the rock sample can be constructed. Furthermore, the mechanical model can comprehensively and accurately quantify the quantitative relationship between pore structure and mechanical properties under microscopic conditions.

[0135] Based on the above-described method for determining the mechanical model of rocks, this specification also provides embodiments of a device for determining the mechanical model of rocks. For example... Figure 16 As shown, the rock mechanical model determination device 1600 may specifically include the following modules:

[0136] The construction module 1601 can be used to construct various pore supercell models based on the geological data of rock samples; one of the pore supercell models corresponds to a rock sample pore with a certain geometric structure.

[0137] The simulation module 1602 can be used to perform tensile simulations on the various pore supercell models to obtain the corresponding tensile response data.

[0138] The calculation module 1603 can be used to calculate the first mechanical property data of the rock sample based on the tensile response data.

[0139] The determination module 1604 can be used to determine the mechanical model of the rock sample based on the first mechanical property data and the first geometric structure data of the rock sample pores; the mechanical model represents the correlation between the geometric structure of the rock sample pores and the mechanical properties of the rock sample.

[0140] In some embodiments, the above-mentioned construction module 1601 can be specifically used to construct multiple supercells based on the molecular structure data of the rock sample; construct rock sample pores with various geometric structures in the multiple supercells; perform structural simulation on the multiple supercells containing rock sample pores using the geological data of the rock sample; and perform molecular dynamics simulation on the multiple supercells containing rock sample pores after structural simulation to obtain multiple pore supercell models.

[0141] In some embodiments, the above-mentioned construction module 1601 can also be used to determine the force field corresponding to the rock sample based on the geological data of the rock sample; and to perform structural simulation on the plurality of supercells containing rock sample pores based on preset periodic boundary conditions and the force field corresponding to the rock sample.

[0142] In some embodiments, the above-mentioned construction module 1601 can also be used to determine the temperature field and pressure field corresponding to the rock sample based on the geological data of the rock sample; and to perform molecular dynamics simulation on multiple supercells containing rock sample pores after structural simulation based on the temperature field and pressure field corresponding to the rock sample.

[0143] In some embodiments, the simulation module 1602 described above can be used to apply tensile stress to the various pore supercell models along multiple preset crystal orientations to obtain data on the changes in tensile stress and tensile strain.

[0144] In some embodiments, the calculation module 1603 described above can be used to fit the changes in tensile stress and tensile strain to obtain the first mechanical property data of the rock sample.

[0145] In some embodiments, the determining module 1604 may be specifically used to determine a first mechanical model of the rock sample based on the second geometric structure data and the first mechanical property data; and to determine a second mechanical model of the rock sample based on the third geometric structure data and the first mechanical property data.

[0146] In some embodiments, the determining module 1604 may further be used to determine the second mechanical property data corresponding to the second geometric structure data in the first mechanical property data; the second mechanical property data includes mechanical property data of various pore sizes; and to determine the first mechanical model of the rock sample based on the second geometric structure data and the corresponding second mechanical property data.

[0147] In some embodiments, the determining module 1604 may further be used to determine the third mechanical property data corresponding to the third geometric structure data in the first mechanical property data; the third mechanical property data includes mechanical property data of various pore relative surface areas; based on the third geometric structure data and the corresponding third mechanical property data, the second mechanical model of the rock sample is determined using the following formula:

[0148] X = β0 + β S S+β V lnV+β S×V S×lnV;

[0149] In the formula, β0, β S β V and β S×V Let S represent the constant coefficient of the mechanical property parameter, the influence coefficient of the relative surface area of ​​pores, the influence coefficient of pore volume, and the influence coefficient of pore volume on the relative surface area of ​​pores, respectively. Let S represent the relative surface area of ​​pores, V represent the pore volume, and X represent the mechanical property parameter of the rock sample.

[0150] The rock mechanical model determination device provided in the embodiments of this specification can construct multiple pore supercell models based on the geological data of the rock sample; each pore supercell model corresponds to a rock sample pore with a specific geometric structure; tensile simulations are performed on the multiple pore supercell models to obtain corresponding tensile response data; based on the tensile response data, the first mechanical property data of the rock sample is calculated; based on the first mechanical property data of the rock sample and the first geometric structure data of the rock sample pores, the mechanical model of the rock sample is determined; the mechanical model represents the correlation between the pore geometry and the mechanical properties of the rock sample. Compared with existing methods, the embodiments of this specification can use the geological data of the rock sample to construct pore supercell models with multiple geometric structures, and accurately determine the tensile response of the rock sample containing pores with multiple geometric structures under microscopic conditions through tensile simulations of multiple pore supercell models. Based on the tensile response of the rock sample and the geometric structural characteristics of the multiple pores it includes, a correlation mechanical model between the pore geometry and the mechanical properties of the rock sample can be constructed, and thus the quantitative relationship between pore structure and mechanical properties under microscopic conditions can be comprehensively and accurately quantified through the mechanical model.

[0151] It should be noted that the units, devices, or modules described in the above embodiments can be implemented by computer chips or physical entities, or by products with certain functions. For ease of description, the above devices are described by dividing them into various modules according to their functions. Of course, in implementing this specification, the functions of each module can be implemented in one or more software and / or hardware, or the module that implements the same function can be implemented by a combination of multiple sub-modules or sub-units, etc. The device embodiments described above are merely illustrative. For example, the division of units is only a logical functional division, and there may be other division methods in actual implementation. For example, multiple units or components can be combined or integrated into another system, or some features can be ignored or not executed. Furthermore, the coupling or direct coupling or communication connection between the devices or units shown or discussed can be through some interfaces, and the indirect coupling or communication connection between devices or units can be electrical, mechanical, or other forms.

[0152] This specification also provides a computer device for determining a mechanical model of a rock, including a processor and a memory for storing processor-executable instructions. Specifically, the processor can perform the following tasks according to the instructions: constructing multiple pore supercell models based on geological data of the rock sample; each pore supercell model corresponds to a specific geometric structure of the rock sample pores; performing tensile simulations on the multiple pore supercell models to obtain corresponding tensile response data; calculating first mechanical property data of the rock sample based on the tensile response data; and determining a mechanical model of the rock sample based on the first mechanical property data and the first geometric structure data of the rock sample pores; the mechanical model represents the correlation between the pore geometry and the mechanical properties of the rock sample.

[0153] To execute the above instructions more accurately, please refer to... Figure 17 As shown in the embodiments of this specification, another specific computer device 1700 is also provided, wherein the computer device 1700 includes a network communication port 1701, a processor 1702 and a memory 1703, and the above structures are connected by internal cables so that the various structures can perform specific data interaction.

[0154] The processor 1702 can be specifically used to construct multiple pore supercell models based on the geological data of the rock sample; each pore supercell model corresponds to a rock sample pore with a specific geometric structure; perform tensile simulations on the multiple pore supercell models to obtain corresponding tensile response data; calculate the first mechanical property data of the rock sample based on the tensile response data; and determine the mechanical model of the rock sample based on the first mechanical property data and the first geometric structure data of the rock sample pores; the mechanical model represents the correlation between the pore geometry of the rock sample and the mechanical properties of the rock sample.

[0155] The memory 1703 can be used to store the corresponding instruction program.

[0156] In this embodiment, the network communication port 1701 can be a virtual port bound to different communication protocols, thereby enabling the sending or receiving of different data. For example, the network communication port can be a port responsible for web data communication, a port responsible for FTP data communication, or a port responsible for email data communication. Furthermore, the network communication port can also be a physical communication interface or communication chip. For example, it can be a wireless mobile network communication chip, such as GSM or CDMA; it can also be a Wi-Fi chip; or it can be a Bluetooth chip.

[0157] In this embodiment, the processor 1702 can be implemented in any suitable manner. For example, the processor can take the form of a microprocessor or processor and a computer-readable medium storing computer-readable program code (e.g., software or firmware) executable by the (micro)processor, logic gates, switches, application-specific integrated circuits (ASICs), programmable logic controllers, and embedded microcontrollers, etc. This specification is not limiting.

[0158] In this embodiment, the memory 1703 includes volatile memory and non-volatile memory. The memory 1703 can include multiple layers. In digital systems, anything that can store binary data can be a memory; in integrated circuits, a circuit with storage function but no physical form is also called a memory, such as RAM, FIFO, etc.; in a system, a storage device with a physical form is also called a memory, such as a memory stick, TF card, etc.

[0159] This specification also provides a computer program product, including at least one instruction or at least one program segment, wherein the at least one instruction or the at least one program segment is loaded and executed by a processor to achieve the following: Figure 1 The method is illustrated. It should be understood that in the various embodiments of this specification, the sequence number of each process does not imply the order of execution. The execution order of each process should be determined by its function and internal logic, and should not constitute any limitation on the implementation process of the embodiments of this specification.

[0160] It should also be understood that, in the embodiments of this specification, the term "and / or" is merely a description of the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent: A existing alone, A and B existing simultaneously, and B existing alone. Additionally, the character " / " in this specification generally indicates that the preceding and following related objects have an "or" relationship.

[0161] Those skilled in the art will understand that embodiments of the present invention can be provided as methods, systems, or computer program products. Therefore, the present invention can take the form of a completely hardware embodiment, a completely software embodiment, or an embodiment combining software and hardware aspects. Furthermore, the present invention can take the form of a computer program product embodied on one or more computer-usable storage media (including, but not limited to, disk storage, CD-ROM, optical storage, etc.) containing computer-usable program code.

[0162] This invention is described with reference to flowchart illustrations and / or block diagrams of methods, apparatus (systems), and computer program products according to embodiments of the invention. It will be understood that each block of the flowchart illustrations and / or block diagrams, and combinations of blocks in the flowchart illustrations and / or block diagrams, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, special-purpose computer, embedded processor, or other programmable data processing apparatus to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing apparatus, generate instructions for implementing the flowchart illustrations and / or block diagrams. Figure 1 One or more processes and / or boxes Figure 1 A device that provides the functions specified in one or more boxes.

[0163] These computer program instructions may also be stored in a computer-readable storage medium that can direct a computer or other programmable data processing device to function in a particular manner, such that the instructions stored in the computer-readable storage medium produce an article of manufacture including instruction means, which are implemented in a process Figure 1 One or more processes and / or boxes Figure 1 The function specified in one or more boxes.

[0164] These computer program instructions may also be loaded onto a computer or other programmable data processing equipment to cause a series of operational tasks to be performed on the computer or other programmable equipment to produce a computer-implemented process, thereby providing instructions that execute on the computer or other programmable equipment for implementing the process. Figure 1 One or more processes and / or boxes Figure 1 The task is a function specified in one or more boxes.

[0165] The specific embodiments described above further illustrate the purpose, technical solution, and beneficial effects of the present invention. It should be understood that the above descriptions are merely specific embodiments of the present invention and are not intended to limit the scope of protection of the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A method of determining a mechanical model of a rock, characterized in that, The method includes: Based on the geological data of the rock samples, various pore supercell models are constructed, including: constructing multiple supercells based on the molecular structure data of the rock samples; constructing rock sample pores with various geometric structures within the multiple supercells; performing structural simulations on multiple supercells containing rock sample pores using the geological data of the rock samples; reconstructing the temperature evolution process experienced by the rock samples based on the thermal history data of the rock samples using a thermodynamic inversion algorithm to determine the simulated temperature gradient distribution and obtain the temperature field; calculating a pressure field containing hydrostatic pressure tensor and deviatoric stress tensor by combining capillary pressure testing and the effective stress law to reflect the local stress concentration phenomenon caused by differences in mineral composition within the rock samples; and performing molecular dynamics simulations on multiple supercells containing rock sample pores after structural simulation based on the temperature field and pressure field to obtain various pore supercell models; each pore supercell model corresponds to a rock sample pore with a specific geometric structure. Tensile simulations were performed on the various porous supercell models to obtain the corresponding tensile response data; Based on the tensile response data, calculate the first mechanical property data of the rock sample; Based on the first mechanical property data and the first geometric structure data of the rock sample's pores, a mechanical model of the rock sample is determined, including: determining the third mechanical property data corresponding to the third geometric structure data from the first mechanical property data; the third mechanical property data includes mechanical property data of various pore relative surface areas; based on the third geometric structure data and the corresponding third mechanical property data, a second mechanical model of the rock sample is determined using the following formula: X = β 0 + β S S + β V lnV + β S×V S×lnV; where, β 0 , β S , β V and β S×V The constant coefficients of the mechanical property parameters, the influence coefficients of the relative surface area of ​​pores, the influence coefficients of pore volume, and the influence coefficients of pore volume on the relative surface area of ​​pores are respectively represented. S represents the relative surface area of ​​pores, V represents the pore volume, and X represents the mechanical property parameters of the rock sample. The mechanical model represents the correlation between the pore geometry of the rock sample and the mechanical properties of the rock sample.

2. The method according to claim 1, characterized in that, The tensile simulation of the various porous supercell models yields corresponding tensile response data, including: Tensile stress is applied to the various porous supercell models along multiple preset crystal orientations to obtain the change data of tensile stress and tensile strain. The calculation of the first mechanical property data of the rock sample based on the tensile response data includes: By fitting the changes in tensile stress and tensile strain, the first mechanical property data of the rock sample are obtained.

3. The method according to claim 1, characterized in that, The first geometric structure data includes second geometric structure data and third geometric structure data; the second geometric structure data includes at least pore size data; The process of determining the mechanical model of the rock sample based on its first mechanical property data and first geometric structure data of the pores includes: Based on the second geometric structure data and the first mechanical property data, the first mechanical model of the rock sample is determined.

4. The method according to claim 3, characterized in that, The step of determining the first mechanical model of the rock sample based on the second geometric structure data and the first mechanical property data includes: The second mechanical property data corresponding to the second geometric structure data is determined from the first mechanical property data; the second mechanical property data includes mechanical property data of various pore sizes; Based on the second geometric structure data and the corresponding second mechanical property data, the first mechanical model of the rock sample is determined.

5. A device for determining the mechanical model of a rock, characterized in that, The device includes: A construction module is used to construct various pore supercell models based on the geological data of rock samples. This includes: constructing multiple supercells based on the molecular structure data of the rock samples; constructing rock sample pores with various geometric structures within the multiple supercells; performing structural simulations on multiple supercells containing rock sample pores using the geological data of the rock samples; reconstructing the temperature evolution process experienced by the rock samples based on the thermal history data of the rock samples using a thermodynamic inversion algorithm to determine the simulated temperature gradient distribution and obtain a temperature field; calculating a pressure field including hydrostatic pressure tensor and deviatoric stress tensor by combining capillary pressure testing and the effective stress law to reflect the local stress concentration phenomenon inside the rock samples caused by differences in mineral composition; and performing molecular dynamics simulations on multiple supercells containing rock sample pores after structural simulation based on the temperature field and pressure field to obtain various pore supercell models; each pore supercell model corresponds to a rock sample pore with a specific geometric structure. The simulation module is used to perform tensile simulations on the various porous supercell models to obtain the corresponding tensile response data; The calculation module is used to calculate the first mechanical property data of the rock sample based on the tensile response data; The determination module is used to determine the mechanical model of the rock sample based on the first mechanical property data and the first geometric structure data of the rock sample pores. This includes: determining the third mechanical property data corresponding to the third geometric structure data from the first mechanical property data; the third mechanical property data includes mechanical property data of various pore relative surface areas; and determining the second mechanical model of the rock sample using the following formula based on the third geometric structure data and the corresponding third mechanical property data: X = β 0 + β S S + β V lnV + β S×V S×lnV; where, β 0 , β S , β V and β S×V The constant coefficients of the mechanical property parameters, the influence coefficients of the relative surface area of ​​pores, the influence coefficients of pore volume, and the influence coefficients of pore volume on the relative surface area of ​​pores are respectively represented. S represents the relative surface area of ​​pores, V represents the pore volume, and X represents the mechanical property parameters of the rock sample. The mechanical model represents the correlation between the pore geometry of the rock sample and the mechanical properties of the rock sample.

6. A computer device, characterized in that, include: Memory, used to store computer programs; A processor for executing the computer program to implement the method of any one of claims 1-4.

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