Method, device and equipment for determining mechanical model of rock

Abstract

The embodiment of the invention 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, and the method comprises the following steps: constructing a plurality of pore supercell models according to geological data of a rock sample; one pore supercell model corresponds to a rock sample pore of one geometric structure; 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 the first geometric structure data of the pores of the rock sample; the mechanical model represents the incidence relation between the rock sample pore geometric structure and the rock sample mechanical property. According to the embodiment of the invention, the associated mechanical model of the rock sample pore geometric structure and the rock sample mechanical property can be constructed according to the tensile response of the rock sample and the geometric structure characteristics of various pores included in the rock sample.

Description

TECHNICAL FIELD

[0001] Embodiments of the present specification relate to the technical field of oil and gas resource development and shale reservoir mechanical property evaluation, and in particular to a rock mechanical model determination method, device and equipment. BACKGROUND

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

[0003] However, the prior art has deficiencies in quantitatively evaluating the mechanical properties of shale with respect to nanoscale pore structure, and targeted solutions are urgently needed. Currently, rock mechanical property testing mainly relies on traditional experimental methods such as Brazilian splitting test and uniaxial compression. However, due to the limitations of experimental conditions and samples, it is difficult for traditional experimental methods to accurately quantify the influence of nanoscale pores on mechanical parameters such as tensile strength and Young's modulus, and to reveal the micro failure mechanism of different pore shapes. In addition, the pore model of traditional experimental methods is single, and lacks quantitative relationship analysis of the influence of pore structure on mechanical properties.

[0004] Therefore, how to overcome the problems of single pore model and lack of quantitative relationship analysis of pore structure and mechanical properties under micro conditions in the existing method, and propose a rock mechanical model determination method that can accurately quantify the quantitative relationship between pore structure and mechanical properties under micro conditions is a key problem to be solved. SUMMARY

[0005] The purpose of the embodiments of the present specification is to provide a rock mechanical model determination method, device and equipment to overcome the problems of single pore model and lack of quantitative relationship analysis of pore structure and mechanical properties under micro conditions in the existing rock mechanical model determination method.

[0006] To solve the above technical problems, the specific technical solutions of the embodiments of the present specification are as follows:

[0007] On the one hand, the embodiments of the present specification provide a rock mechanical model determination method, which comprises:

[0008] According to the geological data of the rock sample, a plurality of pore supercell models are constructed; one of the pore supercell models corresponds to a pore of a rock sample with a geometric structure;

[0009] Performing tensile simulation on the plurality of pore supercell models to obtain corresponding tensile response data;

[0010] According to the tensile response data, calculating first mechanical property data of the rock sample;

[0011] determine a mechanical model of the rock sample according to the first mechanical property data of the rock sample and the first geometric structure data of the rock sample pores; the mechanical model represents a correlation between the rock sample pore geometry and the rock sample mechanical property.

[0012] Further, the constructing a plurality of pore supercell models according to the geological data of the rock sample comprises:

[0013] constructing a plurality of supercells according to the molecular structure data of the rock sample;

[0014] constructing a plurality of geometric structure rock sample pores in the plurality of supercells;

[0015] performing structure simulation on the plurality of supercells containing rock sample pores using the geological data of the rock sample;

[0016] performing molecular dynamics simulation on the plurality of supercells containing rock sample pores after structure simulation to obtain a plurality of pore supercell models.

[0017] Further, the performing structure simulation on the plurality of supercells containing rock sample pores using the geological data of the rock sample comprises:

[0018] determining a force field corresponding to each mineral in the rock sample according to the geological data of the rock sample;

[0019] performing structure simulation on the plurality of supercells containing rock sample pores based on a preset periodic boundary condition and the force field corresponding to each mineral in the rock sample.

[0020] Further, the performing molecular dynamics simulation on the plurality of supercells containing rock sample pores after structure simulation comprises:

[0021] determining a temperature field and a pressure field corresponding to the rock sample according to the geological data of the rock sample;

[0022] performing molecular dynamics simulation on the plurality of supercells containing rock sample pores after structure simulation based on the temperature field and the pressure field corresponding to the rock sample.

[0023] Further, the performing tensile simulation on the plurality of pore supercell models to obtain corresponding tensile response data comprises:

[0024] applying tensile stress to the plurality of pore supercell models along a plurality of preset crystal directions to obtain variation data of the tensile stress and the tensile strain;

[0025] The calculating the first mechanical property data of the rock sample according to the tensile response data comprises:

[0026] fitting the variation data of the tensile stress and the tensile strain to obtain the first mechanical property data of the rock sample.

[0027] Further, the first geometric structure data comprises second geometric structure data and third geometric structure data; the second geometric structure data comprises at least pore size data; and the third geometric structure data comprises at least pore relative surface area data.

[0028] The first mechanical model of the rock sample is determined according to the first mechanical property data of the rock sample and the first geometric structure data of the pore of the rock sample.

[0029] The first mechanical model of the rock sample is determined according to the second geometric structure data and the first mechanical property data.

[0030] The second mechanical model of the rock sample is determined according to the third geometric structure data and the first mechanical property data.

[0031] Further, the first mechanical model of the rock sample is determined according to the second geometric structure data and the first mechanical property data, comprising:

[0032] The second mechanical property data corresponding to the second geometric structure data is determined in the first mechanical property data; the second mechanical property data comprises mechanical property data of multiple pore sizes;

[0033] The first mechanical model of the rock sample is determined according to the second geometric structure data and the corresponding second mechanical property data.

[0034] Further, the second mechanical model of the rock sample is determined according to the third geometric structure data and the first mechanical property data, comprising:

[0035] The third mechanical property data corresponding to the third geometric structure data is determined in the first mechanical property data; the third mechanical property data comprises mechanical property data of multiple pore relative surface areas;

[0036] The second mechanical model of the rock sample is determined according to the third geometric structure data and the corresponding third mechanical property data by 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 respectively represent a constant coefficient of a mechanical property parameter, an influence coefficient of a pore relative surface area, an influence coefficient of a pore volume, and an influence coefficient of a pore volume on a pore relative surface area, S represents a pore relative surface area, V represents a pore volume, and X represents a mechanical property parameter of the rock sample.

[0039] In another aspect, the present specification also provides a rock mechanical model determination device, comprising:

[0040] a construction module configured to construct a plurality of pore supercell models according to geological data of the rock sample, wherein one of the pore supercell models corresponds to a pore of the rock sample with a geometric structure;

[0041] a simulation module configured to perform tensile simulation on the plurality of pore supercell models to obtain corresponding tensile response data;

[0042] a calculation module configured to calculate first mechanical property data of the rock sample according to the tensile response data;

[0043] a determination module configured to determine 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 pore of the rock sample, wherein the mechanical model represents a correlation between the geometric structure of the pore of the rock sample and the mechanical property of the rock sample.

[0044] In yet another aspect, the present specification also provides a computer device, comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the processor executes the rock mechanical model determination method described above.

[0045] In yet another aspect, the present specification also provides a computer program product, which, when executed by a processor of a computer device, executes the instructions of any one of the methods described above.

[0046] As can be seen from the technical solutions provided by the present specification, the present specification can construct a plurality of pore supercell models according to geological data of a rock sample, wherein one of the pore supercell models corresponds to a pore of the rock sample with a geometric structure; perform tensile simulation on the plurality of pore supercell models to obtain corresponding tensile response data; calculate first mechanical property data of the rock sample according to the tensile response data; and determine 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 pore of the rock sample, wherein the mechanical model represents a correlation between the geometric structure of the pore of the rock sample and the mechanical property of the rock sample. Compared with existing methods, the present specification can construct pore supercell models under a plurality of geometric structures using geological data of a rock sample, and accurately determine tensile response of the rock sample under microscopic conditions when the rock sample contains pores with a plurality of geometric structures through tensile simulation on the plurality of pore supercell models. According to the tensile response of the rock sample and the geometric structure characteristics of the plurality of pores included in the rock sample, a correlation mechanical model between the geometric structure of the pore of the rock sample and the mechanical property of the rock sample can be constructed, and then the microscopic quantitative relationship between the pore structure and the mechanical property can be comprehensively and accurately quantified through the mechanical model. BRIEF DESCRIPTION OF DRAWINGS

[0047] In order to more clearly illustrate the technical solutions in the embodiments of the present specification or the prior art, the drawings required to be used in the embodiments or prior art description will be briefly introduced as follows.

[0048] Figure 1 is a flowchart of a rock mechanical model determination method provided by an embodiment of the present specification;

[0049] Figure 2 is a whole logical flowchart of a rock mechanical model determination method provided by an embodiment of the present specification;

[0050] Figure 3 is a scanning electron microscope image of a rock sample in region A provided by an embodiment of the present specification;

[0051] Figure 4 is a slit hole scanning electron microscope image of a rock sample in region A provided by an embodiment of the present specification;

[0052] Figure 5 is a cylindrical hole scanning electron microscope image of a rock sample in region A provided by an embodiment of the present specification;

[0053] Figure 6 is a triangular hole scanning electron microscope image of a rock sample in region A provided by an embodiment of the present specification;

[0054] Figure 7 is a square hole scanning electron microscope image of a rock sample in region A provided by an embodiment of the present specification;

[0055] Figure 8 is a schematic diagram of a kaolinite slit hole model establishment process in region A provided by an embodiment of the present specification;

[0056] Figure 9 is a schematic diagram of a cylindrical hole supercell model in region A provided by an embodiment of the present specification;

[0057] Figure 10 is a schematic diagram of a triangular hole supercell model in region A provided by an embodiment of the present specification;

[0058] Figure 11 is a schematic diagram of a square hole supercell model in region A provided by an embodiment of the present specification;

[0059] Figure 12 is a schematic diagram of strain change with stress of quartz in

[010] crystal direction with different pore sizes in region A provided by an embodiment of the present specification;

[0060] Figure 13 is a schematic diagram of strain change with stress of quartz in

[010] crystal direction with different pore shapes in region A provided by an embodiment of the present specification;

[0061] Figure 14is a schematic view of variation of Young's modulus of quartz in A region in

[010] direction with different pore shapes provided by the embodiment of the present specification;

[0062] Figure 15 is a schematic view of variation of mechanical strength of cheese in different crystal directions with pore size increase (2nm-10nm) provided by the embodiment of the present specification;

[0063] Figure 16 is a schematic view of structural composition of a rock mechanical model determination device provided by the embodiment of the present specification;

[0064] Figure 17 is a schematic view of structural composition of a computer device provided by the embodiment of the present specification. DETAILED DESCRIPTION

[0065] The technical solutions in the embodiments of the present specification will be described clearly and completely below with reference to the drawings in the embodiments of the present specification. Obviously, the described embodiments are only part of the embodiments of the present specification, rather than all the embodiments. Based on the embodiments in the present specification, all other embodiments obtained by those skilled in the art without creative labor should belong to the scope of protection of the present specification.

[0066] It should be noted that the terms "first", "second", and the like in the present specification and claims and the above-described drawings are used to distinguish similar objects, and do not necessarily indicate a specific order or sequence. It should be understood that the data thus used can be interchanged under appropriate circumstances, so that the embodiments of the present specification described herein can be implemented in an order other than those illustrated or described herein. In addition, the terms "include" and "have" and any variations thereof are intended to cover non-exclusive inclusion, for example, a process, method, device, product or equipment including a series of steps or units does not necessarily have to be limited to those steps or units clearly listed, but can include other steps or units not clearly listed or inherent to these processes, methods, products or equipment.

[0067] In some embodiments, the mechanical property parameters of the rock can include tensile strength, Young's modulus, and ultimate strain, etc. The tensile strength can represent the ability of the rock to resist tensile stress failure; the Young's modulus can be used as the stress-strain ratio in the elastic deformation stage, reflecting the stiffness characteristics of the rock; and the ultimate strain can refer to the maximum strain that the rock can withstand before failure.

[0068] Figure 1 is a flowchart of a rock mechanical model determination method provided by the embodiment of the present specification, Figure 2 is a whole logical flowchart of a rock mechanical model determination method provided by the embodiment of the present specification, and in specific implementation, includes the following steps:

[0069] S101: constructing a plurality of pore supercell models according to geological data of the rock sample; one of the pore supercell models corresponds to a rock sample pore of a certain geometric structure.

[0070] In some embodiments, multiple supercells can be constructed based on the molecular structure data of the rock sample; rock sample pores of 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 are largely determined by their microscopic pore structure. At the atomic scale, the geometry, distribution, and surface characteristics of pores directly affect the storage and migration of fluids and the mechanical behavior of rocks. Traditional experimental methods make it difficult to accurately characterize pore structures at the nanoscale. By constructing supercells based on molecular structure data as the basic unit of simulation, and designing a variety of pore geometries within the supercell to cover pore morphologies under different geological conditions, geological data can be used to optimize the supercell structure to make it consistent with the mineral composition and physical and chemical environment of real rocks. In addition, molecular dynamics simulations can help study the evolution of pores 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] The molecular structure data of a rock sample describes the atomic arrangement of the rock's constituent minerals, including lattice parameters (unit cell dimensions and angles); atomic coordinates (the positions of each element in the unit cell); and bonding information (covalent, ionic, metallic). Molecular structure data of a rock sample can be derived from geological data obtained through X-ray diffraction (XRD), neutron scattering, or first-principles calculations.

[0073] Supercells can be periodic extensions of the original unit cell, which can increase the size of the simulation system and reduce size effects. Supercells allow the introduction of more complex defects and pore structures, thereby providing sufficient degrees of freedom to simulate the dynamic processes of rock sample pores. Supercell construction is generally achieved using matrix transformation methods, which will not be described in detail here. The size of the supercell requires a trade-off between computational cost and physical rationality: for example, too small a size may result in an inability to accommodate typical pores or lead to spurious periodic interactions, while too large a size will lead to a dramatic increase in computational complexity, potentially exceeding simulation resource constraints. Convergence tests can be used to determine the optimal supercell size, which will not be described in detail here.

[0074] The geometry of the rock sample pores can be divided into slit, triangle, cylinder, square, and other regular / irregular geometric structures. A variety of different geometric structures of rock sample pores can be constructed in multiple supercells, specifically, the geometric region to which the rock sample pore belongs can be demarcated in the center of the supercell and the atoms therein can be removed. The presence of the rock sample pore in the supercell changes the stress distribution of the surrounding lattice, and structural simulation is required. The structural simulation can include local relaxation (optimizing the positions of the atoms on the pore surface) and global energy minimization (ensuring that the system reaches a stable state). After the structural simulation, molecular dynamics simulation can also be performed on the supercell containing the rock sample pore to obtain a pore supercell model. According to the geological data of the rock sample, a suitable force field can be selected. For example, the ClayFF force field can be selected for clay minerals. During the molecular dynamics simulation, the supercell energy can be minimized to avoid an unreasonably high energy state of the initial structure, and the temperature / pressure can be controlled through NVT / NPT ensemble simulation. When the energy, temperature, and pressure fluctuations are stable, the molecular dynamics simulation is complete, i.e., the pore supercell model is obtained. The pore supercell model of each geometric structure of the rock sample pore can be considered as a microcosm containing a geometric structure of the rock sample.

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

[0076] In some embodiments, a tensile stress can be applied to the plurality of pore supercell models along a plurality of preset crystal directions to obtain tensile stress and tensile strain change data.

[0077] The mechanical behavior of a crystal material has inherent orientation dependence, which is due to the anisotropy of atomic arrangement. In the pore supercell model, this anisotropy is further complicated by the presence of pores, with significant differences in atomic plane spacing, bonding density, and slip system activation threshold in different crystal directions. When an external load is applied, these microstructure characteristics manifest macroscopically as direction-dependent mechanical response through mechanisms such as dislocation nucleation and motion, lattice distortion, etc. Therefore, by applying a tensile stress to the plurality of pore supercell models along a plurality of preset crystal directions, tensile stress and tensile strain change data can be obtained, which can lay a precise data foundation for quantitative analysis of the relationship between pore structure and mechanical properties.

[0078] The coupling between pore structure and crystal orientation can be reflected in three aspects: geometric aspect, the orientation distribution of pores affects the local stress concentration factor; energy aspect, the pore surface changes the lattice vibration spectrum; dynamic aspect, the pore acts as a dislocation source or trap and modulates the plastic deformation mechanism. This multi-physical coupling makes it difficult to accurately predict the mechanical behavior relying solely on continuum mechanics, so atomic-scale simulation is helpful to reveal the mechanical response mechanism.

[0079] Applying tensile stress to the plurality of porous supercell models along a plurality of preset crystal orientations can ensure all possible mechanical response modes of the covering material and avoid biased conclusions due to the selection of a specific orientation. In the cubic system, at least three characteristic directions, <100>, <110>, and <111>, can be selected, and for more anisotropic crystal systems, the sampling density can be increased accordingly, which will not be described here.

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

[0081] S103: According to the tensile response data, the first mechanical property data of the rock sample is calculated.

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

[0083] The change data of the tensile stress and the tensile strain can be denoised and smoothed. Specifically, moving average or Savitzky-Golay filtering can be used to eliminate thermal fluctuation noise in molecular dynamics simulation, which helps to improve the fitting accuracy of Young's modulus (more accurate linear segment slope) and ensures that the determination of tensile strength and ultimate strain is not disturbed by noise (such as false peak or fracture signal). It can also delete sudden points caused by unstable values (such as singular values before strain localization), and ensure that data of different geometrical structures and different crystal orientations have the same strain interval, which is convenient for directly comparing the mechanical response of different porous structures or crystal orientations.

[0084] The pore supercell model of the rock sample pore of each geometry can be considered as a microcosmic condition containing the micro rock sample of the pore of the geometry, and thus, according to the tensile response data in the tensile simulation of the pore supercell model, the first mechanical property data of the rock sample can be calculated. The first mechanical property data can include the tensile strength, Young's modulus, and ultimate strain of the rock sample containing the pores of multiple geometries in different crystal directions. For example, for the tensile strength of the rock sample containing a specific geometric pore in a specific crystal direction, the stress-strain curve can be directly constructed using the change data of the tensile stress and tensile strain of the rock sample in the specific crystal direction. 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 value (such as ductile material), the stress value corresponding to a specific strain threshold (such as 2%) can be defined as the tensile strength. For the Young's modulus of the rock sample containing a specific geometric pore in a specific crystal direction, the stress-strain curve can also 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 slope obtained by fitting can be taken as the Young's modulus. For the ultimate strain of the rock sample containing a specific geometric pore in a specific crystal direction, the strain when the pore supercell model loses bearing capacity (fracture) (the strain when the stress drops suddenly or the simulation is terminated) can be recorded, and this strain can be taken as the ultimate strain.

[0085] By using the same determination criteria for all geometries and crystal directions, it can be ensured that the differences between different parameter groups only reflect the true physical effects (such as pore anisotropy), which is helpful for systematically analyzing the influence of the pore geometry of the rock sample on the mechanical properties of the rock sample or the influence of the crystal direction on the mechanical properties of the rock sample.

[0086] S104: determining a mechanical model of the rock sample according to the first mechanical property data of the rock sample and the first geometry data of the rock sample pore; the mechanical model represents the correlation between the geometry of the rock sample pore and the mechanical properties of the rock sample.

[0087] In some embodiments, the first geometry data can include second geometry data, third geometry data, and fourth geometry data; the second geometry data can at least include pore size data; the third geometry data can at least include pore relative surface area data; the fourth geometry data can at least include pore volume data; according to the second geometry data and the first mechanical property data, a first mechanical model of the rock sample can be determined; according to the third geometry data and the first mechanical property data, a second mechanical model of the rock sample can be determined; and according to the third geometry data and the first mechanical property data, a third mechanical model of the rock sample can be determined.

[0088] The pore diameter can represent the diameter of the circumscribed circle of the pore in the pore unit cell model. For a pore unit cell model of any geometric structure, the pore volume can be kept constant, and the pore diameter can be changed to obtain multiple pore unit cell models of the same geometric structure with different pore diameters. The stress-strain curves of the same geometric structure under different crystal orientations and different pore diameters can be obtained in the first mechanical property data, and then the first mechanical model of the rock sample under different crystal orientations and different pore diameters can be determined. Combined with the first mechanical model of the rock sample containing pores of different geometric structures, the influence of the pore diameter size on the mechanical properties of the rock sample can be accurately quantified.

[0089] The pore relative surface area can represent the ratio of the surface area to the volume of the pore in the pore unit cell model, which can reflect the shape of the pore. For all pore unit cell models with different geometric structures, the stress-strain curves under different crystal orientations and different pore relative surface areas can be obtained in the first mechanical property data, and then the second mechanical model of the rock sample under different crystal orientations and different pore relative surface areas can be determined. Combined with the second mechanical model of the rock sample containing pores of different geometric structures, the influence of the pore shape on the mechanical properties of the rock sample can be accurately quantified.

[0090] For a pore unit cell model of any geometric structure, the relative surface area can be kept constant, and the volume of the pore can be changed to obtain multiple pore unit cell models of the same geometric structure with different pore volumes. The stress-strain curves of the same geometric structure under different crystal orientations and different pore volumes can be obtained in the first mechanical property data, and then the third mechanical model of the rock sample under different crystal orientations and different pore volumes can be determined. Combined with the third mechanical model of the rock sample containing pores of different geometric structures, the influence of the pore volume size on the mechanical properties of the rock sample can be accurately quantified.

[0091] In some embodiments, according to the geological data of the rock sample, a force field corresponding to each mineral in the rock sample can be determined; based on a preset periodic boundary condition and the force field corresponding to each mineral in the rock sample, a structure simulation can be performed on the plurality of unit cells containing pores of the rock sample.

[0092] The accurate matching of the geological data of the rock sample and the molecular force field is a basic work for carrying out high-quality molecular simulation. Through X-ray diffraction analysis, accurate quantitative results of the mineral composition data of the rock sample can be obtained, including the specific content proportion of the main rock-forming minerals such as quartz, kaolinite, and kerogen. These mineral composition data directly determine the basic direction of subsequent force field selection. The force field of the unit cell containing the pores of the rock sample is determined according to the type of the mineral. Different force fields can be used for different minerals. For example, according to the geological data (such as mineral composition) of the rock sample, the force field parameters corresponding to each mineral in the rock sample can be determined. For example: quartz can adopt the Universal force field, kaolinite can adopt the ClayFF force field, and kerogen can adopt the COMPASS II force field.

[0093] After obtaining the mineral composition data, the force field parameters can be further improved in combination with the pore structure characteristics of the rock sample. The porosity, pore size distribution, and other data obtained through micro-CT scanning or nitrogen adsorption experiments provide important basis for determining the non-bonding interaction parameters in the force field. In particular, for nanoscale pores, the surface effect can significantly affect intermolecular interactions, so the key parameters such as van der Waals force interaction cutoff radius can be adjusted according to the actual pore size. At the same time, based on surface analysis data such as X-ray photoelectron spectroscopy (XPS), the possible surface hydroxylation, ion adsorption, and other chemical characteristics in the rock sample can be described in the force field.

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

[0095] After the force field parameters and boundary conditions are determined, the simulation of the supercell structure containing pores can be carried out. For crystalline minerals, the unit cell structure can be accurately constructed based on their crystallographic data; for non-crystalline components, reasonable initial configurations can be obtained by methods such as melting-quenching. The parameter settings during simulation need to strictly follow the requirements of the force field. The selection of integration step needs to consider the fastest vibration mode in the system, and for hydrogen-containing systems, a time step of 0.5-1 fs can be used. Temperature control can use the Nosé-Hoover heat bath algorithm, and pressure control can use the Parrinello-Rahman method, which can better maintain the correctness of the thermodynamic ensemble. During the simulation process, the energy balance state of the system needs to be closely monitored to ensure the stability and reliability of the simulation.

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

[0097] The temperature and pressure information contained in the geological data of rock samples can be converted into physical fields suitable for molecular dynamics simulation by a systematic method. The temperature field can be determined by analyzing the thermal history data of the rock sample, which can include present-day geothermal measurements, vitrinite reflectance (Ro) indicators, and fluid inclusion homogenization temperature test data. These data can be reconstructed by a thermokinetic inversion algorithm to determine the temperature gradient distribution required for simulation. For heterogeneous rock samples, the difference in thermal conductivity of different mineral components will cause the inhomogeneity of the microscale temperature distribution, which can be accurately characterized by multi-physics coupling calculation.

[0098] The construction of the pressure field can integrate the burial history analysis of the rock sample, the acoustic emission Kaiser effect test results, and the differential stress marker observation data. The 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 effect of pore fluid pressure can also be considered. Specifically, capillary pressure testing and effective stress law can be combined for calculation. The final pressure field should include hydrostatic pressure and deviatoric stress components and can reflect the local stress concentration phenomenon inside the rock sample due to the difference in mineral components.

[0099] Continuous temperature and pressure fields need special numerical processing methods to be converted into discrete parameters suitable for molecular dynamics simulation. For the temperature field, the density of the spatial discrete grid can be determined according to the size of the simulation system, and the temperature gradient in each grid should not exceed 1 K / nm. The cubic spline interpolation algorithm can also be used to map the continuous temperature field to discrete grid points, and adaptive grid refinement processing can also be performed for areas with severe temperature changes.

[0100] The discretization of the pressure field can handle the hydrostatic pressure and deviatoric stress components separately. The hydrostatic pressure component can be directly converted into the isotropic pressure parameter in molecular dynamics simulation, while the deviatoric stress component needs to be modified by the shape matrix of the simulation box. The Parrinello-Rahman method can be used to implement the deformable periodic boundary condition, which can accurately apply any form of stress tensor.

[0101] After the temperature field and pressure field are determined, parameters of the molecular dynamics simulation can be set. Temperature control can use the Nosé-Hoover chain thermostat algorithm, which can produce the correct canonical distribution and maintain good numerical stability for systems with large temperature gradients. Pressure control can select different algorithms according to the nature of the pressure field. For regions dominated by hydrostatic pressure, the Andersen-Hoover constant pressure device can be used; for regions with significant deviatoric stress, the Parrinello-Rahman variable shape algorithm can be used.

[0102] After the temperature field and pressure field are applied, the porous supercell model undergoes a sufficient equilibration process before formal data collection begins. The equilibration process usually consists of three stages: first, a local energy minimization stage, using the conjugate gradient algorithm to eliminate excessive overlap between atoms; second, a short time NVT ensemble equilibration to make the system temperature reach the set value; and finally, a long time NPT ensemble equilibration to ensure that all components of the pressure tensor converge to the target value.

[0103] In addition, when there is a strong coupling between the temperature field and the pressure field, special simulation strategies can be used. For example, in regions where thermal pressure coupling is significant, standard sequential coupling algorithms can lead to numerical instability, and full coupling algorithms can be used. For example, the temperature-pressure joint control method (such as the MTK algorithm) can better handle such cases. For systems with chemical reactions, the gradients of the temperature field and the pressure field can also affect the reaction rate, and the transition state theory can be introduced for correction, which will not be described here.

[0104] In some embodiments, the second geometric structure data can be determined in the first mechanical property data; the second mechanical property data can include mechanical property data of multiple pore diameters; and a first mechanical model of the rock sample can be determined according to the second geometric structure data and the corresponding second mechanical property data.

[0105] Pore diameter is a key parameter for characterizing pore size, which can be defined as the diameter of the circumscribed circle of the pore in the porous supercell model. To systematically study the effect of pore diameter on the mechanical properties of the rock sample, the control variable method can be used: keeping the pore volume constant and only changing the pore diameter, a series of porous supercell models with the same geometric structure but different pore diameters are generated. Through molecular dynamics (MD) or finite element (FEM) simulation, stress-strain curves of these models in different crystal directions (such as

[100] ,

[110] ,

[111] ) can be obtained, and second 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 geometry, a quantitative relationship between pore size and mechanical property can be established, for example, by fitting an empirical formula to obtain a first mechanical model: E = E0·exp(-k·d); where E0 is the pore-free modulus, d is the pore size, and k is a fitting parameter. By comparing the mechanical responses of the same geometry with different pore sizes using the first mechanical model, the effect of increasing pore size on stress concentration in the rock sample can be obtained. For example, increasing pore size can lead to increased stress concentration in the rock sample, reducing the tensile strength and fracture toughness of the rock sample, and increasing pore size can significantly affect the elastic modulus of the rock sample, especially when the pore connectivity is enhanced (e.g., when the pore size is close to the order of magnitude of the lattice constant). The dependence of the mechanical properties of the rock sample on the crystal orientation can be obtained. For example, in anisotropic materials, the effect of pore size on the mechanical properties of the rock sample may vary with the crystal orientation (e.g., the

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

[111] direction).

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

[0108] The pore relative surface area (surface area to volume ratio) is a key indicator for describing the complexity of pore shape. For example, the relative surface area of spherical pores is the smallest, while the surface area of fissure-like or fractal pores is significantly higher. 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] A second mechanical model of the rock sample can be determined using the following formula based on the third geometry data and the corresponding third mechanical property data: X = β0+ β S S+β V lnV+β S×V S×lnV; where β0, β S , β V and β S×V, respectively, are the constant coefficients representing 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, S represents the relative pore surface area, V represents the pore volume, and X represents the mechanical property parameters of the rock sample. Specifically, the regression model can be used to fit the third geometric structure data and the corresponding third mechanical property data to obtain the coefficients β S , β V , and β S×V in the second mechanical model. According to the second mechanical model of the constructed rock sample, the mechanical response under different geometric structures and different relative pore surface areas can be obtained. For example, high relative surface area pores can cause greater local stress concentration, accelerate micro-crack initiation, and thus reduce strength and ductility, and can significantly affect the failure mode (such as from uniform plastic deformation to local brittle fracture). In addition, based on the second mechanical model, it can be found that in non-equiaxed pores, the mechanical response is strongly dependent 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 in the first mechanical property data; the third mechanical property data can include mechanical property data of multiple pore volumes; and a third mechanical model of the rock sample can be determined according to the third geometric structure data and the corresponding third mechanical property data.

[0111] For each volume of fourth mechanical property data, a volume-mechanical property quantitative relationship can be established, such as a third mechanical model obtained by fitting an empirical formula. By comparing the mechanical response under the same geometric structure and different volumes through the third mechanical model, the influence of volume increase on stress concentration can be obtained. For example, volume increase can lead to high porosity, and the failure mechanism of the rock sample is mainly pore coalescence, and volume reduction can lead to low porosity, and the failure mechanism of the rock sample is mainly matrix damage. In addition, in high anisotropic materials (such as layered shale), the influence of volume-related porosity on certain crystal directions (such as perpendicular to the bedding direction) can be amplified. By integrating data of different geometric structures, a volume-mechanical property phase diagram can be constructed to clearly define the critical porosity (such as the threshold of strength drop) and provide quantitative guidance for engineering applications (such as oil and gas reservoir fracturing evaluation).

[0112] One specific embodiment of the present specification is provided below:

[0113] 1. According to the shale components in A area, organic matter cheddar cheese, brittle mineral quartz, clay mineral kaolinite are selected as research objects.

[0114] 2. Please refer to Figure 2 , Figure 3 , Figure 4 ,Figure 5 、 Figure 6 and Figure 7 As shown in the figure, a scanning electron microscope experiment was conducted on the shale sample in area A to obtain the actual pore geometry.

[0115] 3. Based on the actual geological data of area A, the basic molecular model for the tensile mechanical properties of shale was constructed using Materials Studio software. Quartz (SiO2), kaolinite (Al4[Si4O 10 ](OH)8) is expanded into a supercell. The supercell parameters of the quartz crystal 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°。 200 H 228 N6O 14 The S4) model is an actual geological model of area A established through experimental analysis based on actual samples from area A. The specific parameters of the kerogen model are α=90.00°. β=90.00°, γ=90.00°.

[0116] 4. Please refer to Figure 8 The figure shows how to build models with different pore sizes using the molecular foundation model, with the pore sizes set to 2nm, 6nm, and 10nm. The "Build Layers" tool was used to create and adjust the pore sizes and volumes to be consistent.

[0117] 5. Please refer to Figure 9 、 Figure 10 and Figure 11 The figure shows pore models with four geometric shapes (slit, triangle, cylindrical, and square) based on shale pore morphology observed experimentally using scanning electron microscopy. Slit pores: Supercells are cut along the crystal direction

[001] and then slit pores are created using the "Build Layers" tool. Triangular pores: Triangular prisms with equilateral triangle bases are constructed, with the same height as the supercell. Cylindrical pores: A central cylindrical region is defined and atoms within the cylinder are removed to form a cylindrical pore. Square pores: A cubic pore is constructed at the center of the supercell. The pore volumes of each pore geometry are consistent.

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

[0119] 7、The optimized model is simulated by Forcite module. The simulation is based on actual formation conditions, with temperature set to 360 K and pressure set to 35 MPa, using NPT ensemble, step size of 0.5 fs, and 2000 ps of dynamics simulation under NPT ensemble to ensure the accuracy of the simulation results.

[0120] 8、The model completed by MD simulation is subjected to stress-strain calculation script using Perl language, and tensile stress is applied in the

[100] (OA),

[010] (OB), and

[001] (OC) crystal directions, with 1000 ps of equilibrium at each step.

[0121] 9、Please refer to Figure 12 and Figure 13 for the stress-strain calculation script using Perl language after simulation, the strain variation with stress under different pore size and pore shape is obtained.

[0122] 10、Please refer to Figure 14 for the least squares fitting of stress-strain data during the elastic deformation stage, the slope is calculated, and the Young's modulus of each crystal direction under different pore shapes is obtained.

[0123] 11、Please refer to Figure 15 for quantitative analysis of the influence of pore geometry on mechanical properties.

[0124] 12: Parameterization of pore structure, shape parameter (S): introduce shape factor S = surface area / volume, quantify pore geometric characteristics:

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

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

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

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

[0129] 11. A three-dimensional multiple linear regression model is constructed using Python combined with mineral type, crystal direction, geometric factor S, and pore volume V to calculate mechanical parameters (such as Young's modulus), and the model is:

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

[0131] The specific values of each parameter corresponding to different organic matters and minerals in different crystal directions are shown in Table 1. When calculating the Young's modulus of organic matter or mineral, the parameters of different crystal directions can be brought in.

[0132] Table 1

[0133]

[0134] The rock mechanical model determination method provided by the embodiments of the present specification can construct a plurality of pore supercell models according to the geological data of the rock sample; one of the pore supercell models corresponds to a rock sample pore of one geometric structure; the plurality of pore supercell models are subjected to tensile simulation to obtain corresponding tensile response data; the first mechanical property data of the rock sample is calculated according to the tensile response data; the mechanical model of the rock sample is determined according to the first mechanical property data of the rock sample and the first geometric structure data of the rock sample pore; and the mechanical model represents the correlation between the rock sample pore geometric structure and the rock sample mechanical property. Compared with the prior art, the embodiments of the present specification can construct pore supercell models under a plurality of geometric structures using the geological data of the rock sample, and accurately determine the tensile response of the rock sample under microscopic conditions when containing a plurality of geometric structure pores through tensile simulation of a plurality of pore supercell models. According to the tensile response of the rock sample and the geometric structure characteristics of the plurality of pores included therein, a correlation mechanical model of the rock sample pore geometric structure and the rock sample mechanical property can be constructed, and then the quantitative relationship between the pore structure and the mechanical property under microscopic conditions can be comprehensively and accurately quantified through the mechanical model.

[0135] Based on the above rock mechanical model determination method, the present specification further proposes an embodiment of a rock mechanical model determination device. As shown in Figure 16 the rock mechanical model determination device 1600 can specifically include the following modules:

[0136] The constructing module 1601 can be configured to construct a plurality of pore supercell models according to geological data of the rock sample, and one of the pore supercell models corresponds to a pore of the rock sample with one geometric structure.

[0137] The simulating module 1602 can be configured to perform tensile simulation on the plurality of pore supercell models to obtain corresponding tensile response data.

[0138] The calculating module 1603 can be configured to calculate first mechanical property data of the rock sample according to the tensile response data.

[0139] The determining module 1604 can be configured to determine 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 pore of the rock sample, and the mechanical model represents a correlation between the geometric structure of the pore of the rock sample and the mechanical property of the rock sample.

[0140] In some embodiments, the constructing module 1601 can be specifically configured to construct a plurality of supercells according to molecular structure data of the rock sample, construct a plurality of pores of the rock sample with different geometric structures in the plurality of supercells, perform structure simulation on the plurality of supercells containing the pores of the rock sample by using the geological data of the rock sample, and perform molecular dynamics simulation on the plurality of supercells containing the pores of the rock sample after the structure simulation to obtain a plurality of pore supercell models.

[0141] In some embodiments, the constructing module 1601 can be specifically configured to determine a force field corresponding to the rock sample according to the geological data of the rock sample, and perform structure simulation on the plurality of supercells containing the pores of the rock sample based on a preset periodic boundary condition and the force field corresponding to the rock sample.

[0142] In some embodiments, the constructing module 1601 can be specifically configured to determine a temperature field and a pressure field corresponding to the rock sample according to the geological data of the rock sample, and perform molecular dynamics simulation on the plurality of supercells containing the pores of the rock sample after the structure simulation based on the temperature field and the pressure field corresponding to the rock sample.

[0143] In some embodiments, the simulating module 1602 can be specifically configured to apply tensile stress to the plurality of pore supercell models along a plurality of preset crystal directions to obtain variation data of tensile stress and tensile strain.

[0144] In some embodiments, the calculating module 1603 can be specifically configured to fit the variation data of the tensile stress and the tensile strain to obtain the first mechanical property data of the rock sample.

[0145] In some embodiments, the determining module 1604 can be specifically configured to determine a first mechanical model of the rock sample according to second geometric structure data and the first mechanical property data, and determine a second mechanical model of the rock sample according to third geometric structure data and the first mechanical property data.

[0146] In some embodiments, the determination module 1604 can be further configured to determine, from the first mechanical property data, second mechanical property data corresponding to the second geometric structure data; the second mechanical property data comprises mechanical property data of multiple pore sizes; and determine the first mechanical model of the rock sample according to the second geometric structure data and the corresponding second mechanical property data.

[0147] In some embodiments, the determination module 1604 can be further configured to determine, from the first mechanical property data, third mechanical property data corresponding to the third geometric structure data; the third mechanical property data comprises mechanical property data of multiple pore relative surface areas; and determine the second mechanical model of the rock sample according to the third geometric structure data and the corresponding third mechanical property data using the following formula:

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

[0149] wherein β0, β S , β V and β S×V respectively represent a constant coefficient of a mechanical property parameter, an influence coefficient of a pore relative surface area, an influence coefficient of a pore volume, and an influence coefficient of a pore volume on a pore relative surface area, S represents a pore relative surface area, V represents a pore volume, and X represents a mechanical property parameter of the rock sample.

[0150] The rock mechanical model determination apparatus provided by the embodiments of the present specification can construct multiple pore supercell models according to the geological data of the rock sample; one of the pore supercell models corresponds to a geometric structure of a rock sample pore; perform tensile simulation on the multiple pore supercell models to obtain corresponding tensile response data; calculate first mechanical property data of the rock sample according to the tensile response data; determine 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; and the mechanical model represents the correlation between the geometric structure of the rock sample pore and the mechanical property of the rock sample. Compared with the prior art, the embodiments of the present specification can construct pore supercell models under multiple geometric structures using the geological data of the rock sample, and accurately determine the tensile response of the rock sample under microscopic conditions when containing multiple geometric structure pores through tensile simulation on the multiple pore supercell models. According to the tensile response of the rock sample and the geometric structure characteristics of the multiple pores included therein, a correlation mechanical model of the geometric structure of the rock sample pore and the mechanical property of the rock sample can be constructed, and then the quantitative relationship between the pore structure and the mechanical property under microscopic conditions can be comprehensively and accurately quantified through the mechanical model.

[0151] It should be noted that the units, devices or modules and the like illustrated in the above embodiments can be specifically implemented by computer chips or entities, or by products with certain functions. For the convenience of description, the above device is described as various modules with functions. Of course, in the implementation of the present specification, the functions of each module can be implemented in the same or more software and / or hardware, or the modules implementing the same function can be implemented by a combination of multiple sub-modules or sub-units. The above-described device embodiments are only illustrative, for example, the division of the units is only a logical function division, and actual implementation can have another division manner, for example, multiple units or components can be combined or integrated into another system, or some features can be ignored or not executed. Another point, the coupling or direct coupling or communication connection between the displayed or discussed each other can be through some interface, indirect coupling or communication connection between devices or units, which can be electrical, mechanical or other forms.

[0152] The embodiment of the present specification also provides a computer device for determining a mechanical model of rock. The computer device comprises a processor and a memory for storing executable instructions of the processor. When the processor is implemented, the following tasks can be performed according to the instructions: constructing a plurality of pore supercell models according to geological data of a rock sample; one of the pore supercell models corresponds to a pore of the rock sample with a geometric structure; performing tensile simulation on the plurality of 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 pore of the rock sample; and the mechanical model represents a correlation between the geometric structure of the pore of the rock sample and the mechanical property of the rock sample.

[0153] In order to be able to more accurately complete the above instructions, referring to Figure 17 The embodiment of the present specification also provides another specific computer device 1700. The computer device 1700 comprises a network communication port 1701, a processor 1702 and a memory 1703. The above structures are connected by internal cables so that each structure can specifically interact with data.

[0154] The processor 1702 can be specifically used to construct a plurality of pore supercell models according to geological data of a rock sample; one of the pore supercell models corresponds to a pore of the rock sample with a geometric structure; perform tensile simulation on the plurality of pore supercell models to obtain corresponding tensile response data; calculate first mechanical property data of the rock sample according to the tensile response data; determine 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 pore of the rock sample; and the mechanical model represents a correlation between the geometric structure of the pore of the rock sample and the mechanical property of the rock sample.

[0155] The memory 1703 can be specifically configured to store corresponding instruction programs.

[0156] In the embodiment, the network communication port 1701 can be a virtual port bound with different communication protocols, so as to send or receive 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 mail data communication. In addition, the network communication port can also be an entity communication interface or a communication chip. For example, it can be a wireless mobile network communication chip such as GSM, CDMA, etc.; it can also be a Wifi chip; it can also be a Bluetooth chip.

[0157] In the embodiment, the processor 1702 can be implemented in any appropriate manner. For example, the processor can take the form of, for example, 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, an Application Specific Integrated Circuit (ASIC), a programmable logic controller, and an embedded microcontroller, etc. The present specification does not make any limitation.

[0158] In the embodiment, the memory 1703 includes a volatile memory and a non-volatile memory. The memory 1703 can include multiple levels, and in a digital system, as long as it can save binary data, it can be a memory; in an integrated circuit, a circuit without a physical form and with a storage function 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, a TF card, etc.

[0159] The embodiments of the present specification also provide a computer program product, including at least one instruction or at least one program, which is loaded and executed by a processor to implement the method as shown in Figure 1 It should be understood that in various embodiments of the present specification, the size of the serial number of each process described above does not mean the order of execution, and the execution order of each process should be determined according to its function and inherent logic, and should not constitute any limitation on the implementation process of the embodiments of the present specification.

[0160] It should also be understood that in the embodiments of the present specification, the term "and / or" only describes the association relationship of the associated objects, and means that there can be three relationships. For example, A and / or B can mean that A exists alone, A and B exist together, and B exists alone. In addition, the character " / " in the present specification generally means that the front and rear associated objects are in an "or" relationship.

[0161] Those skilled in the art will appreciate that embodiments of the present application can be readily used as software, hardware, or a combination of software and hardware. In a software embodiment, the methods can be tangibly embodied in a machine-readable storage medium having stored thereon instructions that can be used to program a computing device to perform the methods. The program instructions can be software supplied in a computer program product, such as a diskette, CD-ROM, or

[0162] The present application is described in reference to the drawings using a flowchart and / or a block diagram of methods, apparatus (systems) and computer program products according to embodiments of the application. It will be understood that each block of the flowchart and / or block diagram, and combinations of blocks in the flowchart and / or block diagram, 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 processing system 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, create means for implementing the functions specified in the flowchart and / or block diagram block or blocks. Figure 1 one or more functions specified by one or more blocks Figure 1 one or more functions specified by one or more blocks

[0163] These computer program instructions can also be stored in a computer- readable memory that can direct a computer or other programmable data processing apparatus to function in a particular manner, such that the instructions stored in the computer-readable memory produce an article of manufacture including instructions which implement the function specified in the flowchart and / or block diagram block or blocks. Figure 1 one or more functions specified by one or more blocks Figure 1 one or more functions specified by one or more blocks

[0164] The computer program instructions can also be loaded onto a computer or other programmable data processing apparatus to cause a series of operational tasks to be performed on the computer or other programmable apparatus to produce a computer implemented process such that the instructions that are executed on the computer or other programmable apparatus provide tasks that implement the functions specified in the flowchart and / or block diagram block or blocks. Figure 1 one or more functions specified by one or more blocks Figure 1 one or more functions specified by one or more blocks

[0165] The specific embodiments described above have been disclosed by way of example and that, obviously, any modifications and / or alterations to the disclosed embodiment are conceivable to the skilled in the art falls within the scope of the present application. Although the present application has been described in detail with reference to particular embodiments, it should be understood that various other adaptations and / or modifications are possible.

Claims

1. A method for determining a rock mechanical model, characterized in that: The method comprises: Based on the geological data of the rock sample, multiple pore supercell models are constructed; one pore supercell model corresponds to a rock sample pore with a geometric structure; Performing stretching simulation on the multiple pore supercell models to obtain corresponding stretching response data; Calculating first mechanical property data of the rock sample according to the tensile response data; A mechanical model of the rock sample is determined 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 represents the correlation between the geometric structure of the rock sample pores and the mechanical properties of the rock sample.

2. The method according to claim 1, characterized in that According to the geological data of the rock sample, a variety of pore supercell models are constructed, including: Construct multiple supercells based on the molecular structure data of the rock sample; constructing rock sample pores of various geometric structures in the plurality of supercells; Performing structural simulation on the plurality of supercells containing pores of the rock sample using geological data of the rock sample; Molecular dynamics simulations were performed on multiple supercells containing rock sample pores after structural simulation to obtain various pore supercell models.

3. The method according to claim 2, characterized in that The method of using geological data of the rock sample to perform structural simulation on the plurality of supercells containing the rock sample pores includes: Determine the force field corresponding to each mineral in the rock sample based on the geological data of the rock sample; Based on preset periodic boundary conditions and the force fields corresponding to the minerals in the rock sample, structural simulation is performed on the multiple supercells containing the rock sample pores.

4. The method according to claim 2, characterized in that The molecular dynamics simulation of the multiple supercells containing rock sample pores after structural simulation includes: Determine the temperature field and pressure field corresponding to the rock sample based on its geological data; Based on the temperature field and pressure field corresponding to the rock sample, molecular dynamics simulation is performed on multiple supercells containing rock sample pores after structural simulation.

5. The method according to claim 1, characterized in that: The stretching simulation of the multiple pore supercell models to obtain corresponding stretching response data includes: Applying tensile stress to the plurality of pore supercell models along a plurality of preset crystal directions to obtain variation data of tensile stress and tensile strain; Calculating first mechanical property data of the rock sample according to the tensile response data includes: The variation data of the tensile stress and the tensile strain are fitted to obtain the first mechanical property data of the rock sample.

6. 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 diameter data; The third geometric structure data at least includes pore relative surface area data; Determining the mechanical model of the rock sample based on the first mechanical property data of the rock sample and the first geometric structure data of the pores of the rock sample includes: determining a first mechanical model of the rock sample based on the second geometric structure data and the first mechanical property data; A second mechanical model of the rock sample is determined based on the third geometric structure data and the first mechanical property data.

7. The method according to claim 6, characterized in that Determining a first mechanical model of the rock sample based on the second geometric structure data and the first mechanical property data includes: Determining second mechanical property data corresponding to the second geometric structure data from the first mechanical property data; the second mechanical property data includes mechanical property data of multiple pore diameters; A first mechanical model of the rock sample is determined based on the second geometric structure data and the corresponding second mechanical property data.

8. The method according to claim 6, characterized in that Determining a second mechanical model of the rock sample based on the third geometric structure data and the first mechanical property data includes: Determining 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 relative surface areas of a plurality of pores; According to 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: X=β0+β S S+β V lnV+β S×V S×lnV; Where, β0, β S , β V and β S×V They respectively represent the constant coefficient of the mechanical property parameters, the influence coefficient of the relative pore surface area, the influence coefficient of the pore volume, and the influence coefficient of the pore volume on the relative pore surface area. S represents the relative pore surface area, V represents the pore volume, and X represents the mechanical property parameters of the rock sample.

9. A device for determining a rock mechanical model, characterized in that: The device comprises: A construction module is used to construct multiple pore supercell models based on geological data of the rock sample; one of the pore supercell models corresponds to a rock sample pore of a certain geometric structure; A simulation module, configured to perform stretching simulation on the plurality of pore supercell models to obtain corresponding stretching response data; a calculation module, configured to calculate 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 of the rock sample 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.

10. A computer device, characterized in that: include: memory for storing computer programs; A processor, configured to execute the computer program to implement the method according to any one of claims 1 to 8.

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