Multi-scale crack rock physical seismic wave velocity modeling method and device

Abstract

The embodiment of the invention provides a multi-scale fracture rock physical seismic wave velocity modeling method and device, a storage medium and a processor, and belongs to the technical field of geophysical survey. The method comprises the following steps: firstly, establishing a fractal distribution rule of multi-scale fractures of a target rock, and then gradually adding background pores, micro-fractures and medium and large-scale fractures to a rock physical model on the basis of the fractal distribution rule and based on an equivalent medium model and / or a linear slippage theory; and finally establishing an equivalent medium model which effectively combines microcosmic fractures and medium and large scale fractures into unification.

Description

Technical Field

[0001] The present invention relates to the technical field of geophysical exploration, and particularly relates to a multi-scale fracture rock physics seismic wave velocity modeling method, device, storage medium, and processor. Background Art

[0002] Measurements of heterogeneous rocks show that scale effects affect many rock properties; rocks with larger scales have lower velocities, mainly due to the presence of larger-scale inhomogeneities dominated by fractures. Therefore, it is difficult for core-scale samples to characterize the rock physical properties at the reservoir scale. Therefore, to interpret multi-scale fractures using cross-frequency geophysical measurement data, a multi-scale fracture rock physics model must be established.

[0003] Currently, various studies on fractured rocks regard fractures as inclusions at a single microscopic or single mesoscopic scale and assume that they are randomly oriented. However, a model that only focuses on the relationship between geophysical data at a single frequency band and fractures at the corresponding scale cannot describe the elastic properties and dispersion attenuation characteristics of rocks with coexisting multi-scale fractures that actually exist in nature. The coexistence of multi-scale fractures is the most significant feature of multi-scale heterogeneous reservoirs. Therefore, it is necessary to establish a new rock physics model to study the elastic and anisotropic responses of porous rocks containing multi-scale fractures. Summary of the Invention

[0004] The purpose of the embodiments of the present invention is to provide a method through which a multi-scale fracture rock physics model can be established, effectively combining the description of microscopic fractures and medium-large scale fractures into a unified equivalent medium model.

[0005] To achieve the above purpose, the embodiments of the present invention provide a multi-scale fracture rock physics seismic wave velocity modeling method, including:

[0006] According to the fractal distribution characteristics of multi-scale fractures of the target rock, determine the corresponding relationship between the number or density of fractures and different scales, and establish the fractal distribution law of multi-scale fractures of the target rock, where the multi-scale fractures include: background pores, micro-fractures, and medium-large scale fractures;

[0007] Based on the equivalent medium model and the fractal distribution law, add background pores and micro-fractures to the equivalent rock background of the target rock to obtain an equivalent elastic rock physics model including the influence of micro-scale fractures; and

[0008] Based on the linear slip theory and the fractal distribution law, add medium-large scale fractures to the equivalent elastic rock physics model including the influence of micro-scale fractures to obtain an equivalent elastic rock physics model including the influence of multi-scale fractures.

[0009] Optionally, the correspondence between the number of cracks and different scales is established through the following formula: N t (r) = C0·r -D , where N t (r) is the actual number of cracks with a scale greater than or equal to r, C0 is the proportionality coefficient, r is the crack radius, and D is the fractal dimension.

[0010] Preferably, the value of D is between 2 and 3.

[0011] Optionally, the equivalent rock background is a mineral matrix, and the bulk modulus and shear modulus of the equivalent elastic rock physics model including the influence of micro-scale cracks are calculated through the following formula:

[0012]

[0013]

[0014] where K2 and μ2 are the bulk modulus and shear modulus of the inclusions, y is the volume percentage of the inclusions, and P (*2) and Q (*2) represent the geometric factors of the inclusions in the equivalent rock.

[0015] Optionally, the medium and large-scale cracks with oriented arrangement and / or randomly oriented arrangement are added to the equivalent elastic rock physics model through the following formula:

[0016]

[0017] where i, j, k, l ∈ (1, 2, 3);

[0018] ΔS ijkl is the compliance tensor generated by the existence of medium and large-scale cracks in the target rock;

[0019] δ ik , δ il , δ jk , δ jl are the Kronecker delta functions;

[0020] α jl , α jk , α il , α ik is the second-order tensor of the total contribution of the tangential compliance per unit volume;

[0021] β ijkl is the fourth-order tensor of the total contribution of the difference between the normal compliance and the tangential compliance per unit volume.

[0022] Optionally, the calculation formula for the equivalent compliance tensor S of the target rock in the equivalent elastic rock physics model including multi-scale fracture effects is:

[0023] Where, is the compliance tensor generated by the existence of micro-scale fractures in the target rock.

[0024] Furthermore, when adding large-scale fractures with oriented arrangement and / or randomly oriented arrangement, the calculation formulas for the second-order tensor and the fourth-order tensor β ijkl are respectively:

[0025]

[0026]

[0027] Where, α ij is used to calculate the formulas for the second-order tensor α jl , α jk , α il , and α ik , B N and B T respectively represent the normal compliance and the tangential compliance of the corresponding fractures, S q represents the surface area of the q-th group of fractures, n i , n j , n k , n l are respectively the i-th, j-th, k-th, and 1-th components of the local normal vector of the fracture surface, and V represents the volume of the representative elementary volume REV of the target rock.

[0028] Furthermore, the following formula is used to perform spherical averaging on the large-scale fractures with oriented arrangement and / or randomly oriented arrangement, so that the large-scale fractures with oriented arrangement in the equivalent elastic rock physics model including multi-scale fracture effects are converted into fractures with randomly oriented directions:

[0029]

[0030]

[0031] Where, α ij is used to calculate the formulas for the second-order tensor α jl , α jk , α il , and α ik formulas, is the fracture azimuth angle; θ is the fracture polar angle, representing the angle between the fracture normal vector and the Z-axis; Z N and Z T are respectively the normal compliance and the tangential compliance of the overall oriented fracture group; n i , nj 、n k 、n l are the i-th, j-th, k-th, and l-th components of the local normal vector of the fracture surface, respectively.

[0032] Furthermore, the isotropic parameters of the randomly oriented fractures of the target rock in the equivalent elastic rock physics model considering multi-scale fracture effects are calculated according to the following formula:

[0033] I p = V p ·ρ,

[0034] where V p is the P-wave velocity of the target rock, V s is the S-wave velocity of the target rock, I p is the impedance of the target rock, ρ is the overall equivalent density of the target rock, C is the stiffness matrix of the target rock, and C 11 and C 44 are both elements of the stiffness matrix.

[0035] On the other hand, the present invention provides a multi-scale fracture rock physics seismic wave velocity modeling device, including: an analysis law determination module, a first modeling module, and a second modeling module, where

[0036] The analysis law determination module determines the corresponding relationship between the number of fractures or fracture density and different scales according to the fractal distribution characteristics of the multi-scale fractures of the target rock, and establishes the fractal distribution law of the multi-scale fractures of the target rock, where the multi-scale fractures include: background pores, micro-fractures, and medium and large-scale fractures;

[0037] The first modeling module adds background pores and micro-fractures to the equivalent rock background of the target rock based on the equivalent medium model and the fractal distribution law to obtain an equivalent elastic rock physics model considering micro-scale fracture effects; and

[0038] The second modeling module adds medium and large-sized fractures to the equivalent elastic rock physics model considering micro-scale fracture effects based on the linear slip theory and the fractal distribution law to obtain an equivalent elastic rock physics model considering multi-scale fracture effects.

[0039] The multi-scale fracture rock physics seismic wave velocity modeling device further includes a third modeling module, which calculates the isotropic parameters of the randomly oriented fractures of the target rock in the equivalent elastic rock physics model considering multi-scale fracture effects according to the following formula:

[0040] I p = V p ·ρ,

[0041] Among them, V p is the longitudinal wave velocity of the target rock, and V s is the shear wave velocity of the target rock. I p is the impedance of the target rock, ρ is the overall equivalent density of the target rock, C is the stiffness matrix of the target rock, and C 11 and C 44 are both elements of the stiffness matrix.

[0042] On the other hand, the present invention provides a machine-readable storage medium, on which instructions are stored, and the instructions are used to cause a machine to execute the multi-scale fracture rock physics seismic wave velocity modeling method of the present application.

[0043] On the other hand, the present invention provides a processor for running a program, wherein when the program is run, it is used to execute the multi-scale fracture rock physics seismic wave velocity modeling method of the present application.

[0044] Through the above technical solutions, first, the fractal distribution law of multi-scale fractures of the target rock is established, and then on the basis of the fractal distribution law, based on the equivalent medium model and / or the linear slip theory, background pores, micro-fractures, and medium and large-scale fractures are gradually added to the rock physics model, and finally an equivalent medium model that effectively combines the description of micro-fractures and medium and large-scale fractures is established.

[0045] Other features and advantages of the embodiments of the present invention will be described in detail in the subsequent specific implementation part. BRIEF DESCRIPTION OF THE DRAWINGS

[0046] The drawings are used to provide a further understanding of the embodiments of the present invention, and constitute a part of the specification. Together with the following specific implementation manners, they are used to explain the embodiments of the present invention, but do not constitute a limitation to the embodiments of the present invention. In the drawings:

[0047] Figure 1 is a flowchart of an embodiment of the multi-scale fracture rock physics seismic wave velocity modeling method of the present invention;

[0048] Figure 2 is Figure 1 a schematic diagram of gradually adding fractures of different scales to the rock physics model in the embodiment;

[0049] Figure 3 is Figure 1 the relationship between the velocity of the multi-scale fractured reservoir and the wavelength in the embodiment; and

[0050] Figure 4 is a composition structure diagram of an embodiment of the multi-scale fracture rock physics seismic wave velocity modeling method device of the present invention. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0051] The specific implementation manners of the embodiments of the present invention will be described in detail below with reference to the accompanying drawings. It should be understood that the specific implementation manners described herein are only for explaining and illustrating the embodiments of the present invention, and are not used to limit the embodiments of the present invention.

[0052] The embodiments of the present invention provide a multi-scale fracture rock physics seismic wave velocity modeling method for modeling the elastic properties and dispersion attenuation characteristics of rocks with multi-scale fractures coexisting. Through this method, a multi-scale fracture rock physics model can be established, effectively combining the description of micro-fractures and medium and large-scale fractures into a unified equivalent medium model. The following will be combined with Figures 1-3 to illustrate the specific implementation manners of this embodiment.

[0053] As Figure 1 shown, the embodiment includes the following main steps:

[0054] Step 1: According to the fractal distribution characteristics of the multi-scale fractures of the target rock, determine the corresponding relationship between the number or density of fractures and different scales, and establish the fractal distribution law of the multi-scale fractures of the target rock according to the corresponding relationship, where the multi-scale fractures include: background pores, micro-fractures, and medium and large-scale fractures;

[0055] Step 2: Based on the equivalent medium model and the fractal distribution law, add the background pores and micro-fractures to the equivalent rock background of the target rock to obtain an equivalent elastic rock physics model including the influence of micro-scale fractures;

[0056] Step 3: Based on the linear slip theory and the fractal distribution law, add the medium and large-scale fractures to the equivalent elastic rock physics model including the influence of micro-scale fractures to obtain an equivalent elastic rock physics model including the influence of multi-scale fractures.

[0057] It should be noted that rock is a natural porous medium with a very complex microporous structure. The structures of pores and skeletons are very complex and the scales span several orders of magnitude, randomly distributed in space to form a complex network. Therefore, in step 1 of this embodiment, the fractal geometry method is used to study the relationship between rock characteristics at different scales.

[0058] In this embodiment, the purpose of step 1 is to establish the fractal distribution law of multi-scale fractures, obtain the relationship between the number / density of fractures and the scale, and prepare for subsequent modeling. In steps 2 and 3, under the constraint of the fractal distribution law of fractures obtained in step 1, the background pores, micro-fractures, and medium and large-scale fractures are gradually added to the equivalent elastic rock physics model in the rock physics model. That is, as Figure 2As shown, the equivalent elastic rock physics model is gradually added to the equivalent rock background in the order from small scale to large scale. After all the fractures of different scales in the target rock are added, the obtained equivalent elastic rock physics model can reflect the characteristics under the combined influence of multi-scale fractures on the target rock, such as the elastic properties and dispersion attenuation characteristics of the target rock.

[0059] Even though both the background pores and micro-fractures are micro-scale fractures, they can still be further subdivided into multiple different scale ranges, and in the order from small to large, the background pores or micro-fractures in each scale range are added to the rock background one by one.

[0060] In the case of fractal distribution, the relationship between the seismic wave velocity and the wavelength is as Figure 3 shown. The rock physics parameters required for the multi-scale fracture rock modeling obtained according to the modeling process of this embodiment are shown in Table 1 below. From Figure 3 it can be seen that in the case of a short wavelength, the cracks that can be included in the REV are only randomly oriented and distributed micro-cracks. Although the number of micro-cracks is large, due to their too small scale, the crack density and crack porosity they occupy are both small, so they will not have an overly strong impact on the overall rock. As the wavelength increases, longer cracks can be seen within the REV, resulting in the rock gradually softening and the velocity decreasing.

[0061] Table 1

[0062] Mineral bulk modulus (GPa) 71 Total fracture density 0.1 Mineral shear modulus (GPa) 30 Fracture diameter (m) <![CDATA[1e -4 ~25 <!-- 4 -->]]> Mineral density (g / cc) 2.71 Fractal dimension 2.5 Porosity 0.1

[0063] In some embodiments, the correspondence between the number of fractures and different scales in step 1 is achieved through the following formula:

[0064] N t (r) = C0 · r -D , (1)

[0065] where, N t (r) is the actual number of fractures with a scale greater than or equal to r, C0 is the proportionality coefficient, r is the fracture radius, D is the fractal dimension, with a value between 2 and 3, which can be measured by methods such as the Divider method and the Box method, and represents the spatial distribution of the number of large-scale and small-scale fractures.

[0066] In some embodiments, the correspondence between the fracture density and different scales in step 1 is achieved through the following formula:

[0067]

[0068] Among them, N is the true number of cracks with a scale greater than or equal to r, V is the volume of the representative elementary volume (REV), and r is the radius of the crack. When the overall crack density remains unchanged, changing the fractal dimension of the rock actually changes the distribution of cracks with different lengths. The larger the fractal dimension, the larger the proportion of small cracks.

[0069] In step 2, using an equivalent medium model, such as the differential equivalent medium (DEM) model, randomly oriented background pores and microcracks are gradually added to the rock background from small to large. The small-scale modeling results will serve as the equivalent background for larger-scale crack modeling, and the dimension is gradually increased in this way.

[0070] In this embodiment, the equivalent rock background is the mineral matrix, and the bulk modulus of the equivalent elastic rock physics model including the influence of micro-scale cracks and the shear modulus are calculated by the following formula:

[0071]

[0072]

[0073] where K2 and μ2 are the bulk modulus and shear modulus of the inclusions, y is the volume percentage of the inclusions, and P (*2) and Q (*2) represent the geometric factors of the inclusions in the equivalent rock.

[0074] In summary, according to this embodiment, in step 2, the mineral matrix is used as the initial background, and isotropic background pores are added to it; subsequently, uniformly distributed randomly oriented microcracks are added to the equivalent rock background containing pores to obtain an equivalent rock including the influence of microcracks.

[0075] In step 3, randomly oriented medium and large-scale cracks are continuously added on the basis of the equivalent background containing multi-scale microcracks. Since larger-scale cracks can usually be regarded as weak planes in the rock, in this embodiment, the linear slip theory is used to construct medium and large-scale cracks.

[0076] In some embodiments, the linear slip theory is used to describe medium and large-scale cracks, which are arranged in an oriented and / or randomly oriented distribution, and are added to the equivalent elastic rock physics model containing the influence of micro-scale cracks obtained in step 2, so as to obtain an equivalent elastic rock physics model containing the influence of multi-scale cracks. Then, the medium and large-scale cracks arranged in an oriented and / or randomly oriented arrangement are spherically averaged to convert them into cracks arranged in a randomly oriented manner. Thus, an equivalent elastic rock physics model including background pores, microcracks, and randomly oriented medium and large-scale cracks is finally obtained.

[0077] Since the effective compliance tensor of the rock can be expressed as the average strain ε ij and the average stress σ kl over a certain volume V, for the fractured rock, the strain can be expressed as:

[0078]

[0079] where is the compliance tensor generated by the existence of microscale cracks in the target rock, that is, the compliance tensor of the target rock obtained from the equivalent elastic rock physics model including the influence of microscale cracks according to step 2; and ΔS ijkl represents the additional compliance tensor generated by the existence of medium and large-scale and oriented cracks, which depends on the influence of the geometry, position, size and direction of the cracks and can be expressed as:

[0080]

[0081] where i, j, k, l all ∈ (1, 2, 3);

[0082] δ ik 、δ il 、δ jk 、δ jl is the Kronecker delta function;

[0083] α jl 、α jk 、α il 、α ik is the second-order tensor of the total contribution of the tangential compliance per unit volume;

[0084] β ijkl is the fourth-order tensor of the total contribution of the difference between the normal compliance and the tangential compliance per unit volume.

[0085] Define the second-order tensor α ij and the fourth-order tensor β ijkl as:

[0086]

[0087]

[0088] where α ij is the formula for calculating the second-order tensor α jl 、α jk 、α il 、and α ik in equation (5), B N and B T represent the normal compliance and the tangential compliance of the corresponding cracks respectively, and S qDenote the surface area of the q-th group of fractures, n i , n j , n k , n l are the i-th, j-th, k-th, and l-th components of the local normal vector of the fracture surface respectively, and V represents the volume of the representative elementary volume (REV) of the target rock.

[0089] Generally speaking, the effects of multiple groups of fractures are not cumulative but interactive. However, for simplicity, a first-order approximation is usually adopted to ignore the interaction between fractures. For dry rocks with fractures, as long as the fracture volume is extremely small and the distribution is relatively sparse, ignoring the influence of pores in the background rock on fractures and ignoring the fluid effect, the interaction between fractures will not have a significant impact on the elastic properties of the rock.

[0090] In some embodiments, the following method is used to perform spherical averaging on medium and large-scale fractures with oriented arrangement and / or randomly oriented arrangement to convert them into fractures with randomly oriented arrangement.

[0091] When the fractures exhibit a randomly oriented distribution, the i-th component of the local normal vector of the fracture surface in three-dimensional space can be written as:

[0092]

[0093] where is the azimuth angle, representing the angle between the fracture normal vector and the X-axis; θ represents the polar angle, which is the angle between the fracture normal vector and the Z-axis.

[0094] The expression for the fracture compressibility in the case of a randomly oriented distribution is obtained by performing spherical averaging on the compressibility of the oriented fractures:

[0095]

[0096]

[0097] where, α ij is the second-order tensor α used in calculating Equation (5) jl , α jk , α il , and α ik formula, is the fracture azimuth angle, representing the angle between the fracture normal vector and the X-axis; θ is the fracture polar angle, representing the angle between the fracture normal vector and the Z-axis; Z N and Z T are the normal compliance and tangential compliance of the overall oriented fracture group respectively; n i , n j , n k , n lThey are the i-th, j-th, k-th, and l-th components of the local normal vector of the crack surface respectively. The integral and the coefficient 1 / 4π represent that the elastic influence of the oriented crack is averaged on the spherical surface, so as to obtain the isotropic result representing the cracks with random direction distributions. It should be noted that the above X-axis and Z-axis refer to the X-axis and Z-axis of the coordinate system where the established rock physics model is located.

[0098] Furthermore, formula (8) can be combined with formula (5) and substituted into formula (4), and then the equivalent compliance tensor of the target rock can be obtained.

[0099] Furthermore, the stiffness matrix tensor C of the target rock can also be calculated according to the following formula ijkl :

[0100]

[0101] In some embodiments, based on the equivalent compliance tensor and stiffness matrix tensor of the target rock obtained above, other equivalent elastic properties of the target rock are further calculated, such as: the longitudinal wave velocity V p , the shear wave velocity V s , the impedance I p , the ratio of longitudinal wave velocity to shear wave velocity V p / V s etc., so as to increase the elastic parameter information in the equivalent elastic rock physics model. The calculation formulas are as follows:

[0102]

[0103] Among them, V p is the longitudinal wave velocity of the target rock, V s is the shear wave velocity of the target rock, I p is the impedance of the target rock, ρ is the overall equivalent density of the target rock, C is the stiffness matrix of the target rock, and C 11 and C 44 are both stiffness matrix elements.

[0104] Furthermore, the elastic model of the rock containing multi-scale cracks can also be used for quantitative seismic interpretation of logging and seismic elastic data.

[0105] Compared with the prior art, the technical advantages of this embodiment are as follows:

[0106] (1) Under the law of fractal distribution, the equivalent medium models describing micro-cracks and medium and large-scale cracks are effectively combined, and a unified modeling framework for multi-scale cracks is established;

[0107] (2) A modeling method for the random distribution of medium and large-scale fractures was established by first adding medium and large-scale fractures with oriented and / or randomly oriented arrangements to the basic model, and then performing spherical averaging on the medium and large-scale fractures with oriented and / or randomly oriented arrangements to convert the medium and large-scale fractures with oriented arrangements into randomly oriented ones.

[0108] (3) Establishing a rock model containing multi-scale fractures can establish a connection between measurements at different scales such as seismic, logging, and laboratory, thus providing a new technical means for predicting oil and gas enrichment degree, characterizing and predicting reservoir physical property parameters based on logging and seismic data.

[0109] An embodiment of the present invention provides a multi-scale fracture rock physics seismic wave velocity modeling device, as Figure 4 shown, including: an analysis law determination module, a first modeling module, and a second modeling module. Among them, the analysis law determination module determines the corresponding relationship between the number of fractures or fracture density and different scales according to the fractal distribution characteristics of the multi-scale fractures of the target rock, and establishes the fractal distribution law of the multi-scale fractures of the target rock according to the corresponding relationship. The multi-scale fractures include: background pores, micro-fractures, and medium and large-scale fractures; the first modeling module adds background pores and micro-fractures to the equivalent rock background of the target rock based on the equivalent medium model and the fractal distribution law to obtain an equivalent elastic rock physics model including the influence of micro-scale fractures; the second modeling module adds medium and large-scale fractures to the equivalent elastic rock physics model including the influence of micro-scale fractures based on the linear slip theory and the fractal distribution law to obtain an equivalent elastic rock physics model including the influence of multi-scale fractures.

[0110] In some embodiments, the multi-scale fracture rock physics seismic wave velocity modeling device further includes a third modeling module, which calculates the isotropic parameters of the randomly distributed fractures of the target rock in the equivalent elastic rock physics model including the influence of multi-scale fractures according to the following formula:

[0111] I p =V p ·ρ,

[0112] where V p is the longitudinal wave velocity of the target rock, V s is the shear wave velocity of the target rock, I p is the impedance of the target rock, ρ is the overall equivalent density of the target rock, C is the stiffness matrix of the target rock, and C 11 and C 44 are both elements of the stiffness matrix.

[0113] For other preferred embodiments of the multi-scale fracture rock physics seismic wave velocity modeling device of the present invention, please refer to the embodiments of the above multi-scale fracture rock physics seismic wave velocity modeling method, which will not be elaborated here one by one.

[0114] An embodiment of the present invention provides a multi-scale fracture rock physics seismic wave velocity modeling device, including a processor and a memory. The above analysis rule determination module, first modeling module, second modeling module, third modeling module, etc. are all stored in the memory as program units, and the corresponding functions are realized by the processor executing the above program units stored in the memory.

[0115] The processor contains a kernel, and the kernel retrieves the corresponding program units from the memory. One or more kernels can be set, and by adjusting the kernel parameters, the description of micro-fractures and medium-large scale fractures can be effectively combined into a unified equivalent medium model.

[0116] The memory may include non-permanent memory in a computer-readable medium, forms such as random access memory (RAM) and / or non-volatile memory, such as read-only memory (ROM) or flash memory (flash RAM), and the memory includes at least one storage chip.

[0117] An embodiment of the present invention provides a storage medium, on which a program is stored, and when the program is executed by a processor, it realizes the multi-scale fracture rock physics seismic wave velocity modeling method of the present application.

[0118] An embodiment of the present invention provides a processor, and the processor is used to run a program. When the program runs, it executes the multi-scale fracture rock physics seismic wave velocity modeling method of the present application.

[0119] An embodiment of the present invention provides a device, which includes a processor, a memory, and a program stored on the memory and executable on the processor. When the processor executes the program, it realizes the steps of the multi-scale fracture rock physics seismic wave velocity modeling method of the present application. The device herein can be a server, PC, PAD, mobile phone, etc.

[0120] The present application also provides a computer program product, which is suitable for executing a program initialized with the steps of the multi-scale fracture rock physics seismic wave velocity modeling method of the present application when executed on a data processing device.

[0121] Those skilled in the art should understand that the embodiments of the present application can be provided as a method, a system, or a computer program product. Therefore, the present application can take the form of a complete hardware embodiment, a complete software embodiment, or an embodiment combining software and hardware aspects. Moreover, the present application can take the form of a computer program product implemented on one or more computer-usable storage media (including but not limited to disk storage, CD-ROM, optical storage, etc.) that contain computer-usable program code.

[0122] The present application is described with reference to the flowcharts and / or block diagrams of methods, apparatuses (systems), and computer program products according to the embodiments of the present application. It should be understood that each flow and / or block in the flowchart and / or block diagram, as well as the combination of flows and / or blocks in the flowchart and / or block diagram, can be implemented by computer program instructions. These computer program instructions can be provided to the processor of a general-purpose computer, a special-purpose computer, an embedded processor, or other programmable data processing devices to generate a machine, such that the instructions executed by the processor of the computer or other programmable data processing devices generate means for implementing the functions specified in Figure 1 one flow or multiple flows and / or blocks Figure 1 one block or multiple blocks.

[0123] These computer program instructions can also be stored in a computer-readable memory that can direct a computer or other programmable data processing device to work in a specific manner, such that the instructions stored in the computer-readable memory generate a manufactured article including instruction means that implement the functions specified in Figure 1 one flow or multiple flows and / or blocks Figure 1 one block or multiple blocks.

[0124] These computer program instructions can also be loaded onto a computer or other programmable data processing device, such that a series of operation steps are performed on the computer or other programmable device to generate a computer-implemented process, and thus the instructions executed on the computer or other programmable device provide steps for implementing the functions specified in Figure 1 one flow or multiple flows and / or blocks Figure 1 one block or multiple blocks.

[0125] In a typical configuration, a computing device includes one or more processors (CPUs), an input / output interface, a network interface, and memory.

[0126] The memory may include non-permanent memory in the computer-readable medium, in the form of random access memory (RAM) and / or non-volatile memory, such as read-only memory (ROM) or flash memory (flash RAM). The memory is an example of a computer-readable medium.

[0127] A computer-readable medium includes permanent and non-permanent, removable and non-removable media that can implement information storage by any method or technology. The information can be computer-readable instructions, data structures, program modules, or other data. Examples of computer storage media include, but are not limited to, phase change memory (PRAM), static random access memory (SRAM), dynamic random access memory (DRAM), other types of random access memory (RAM), read-only memory (ROM), electrically erasable programmable read-only memory (EEPROM), flash memory or other memory technologies, compact disc read-only memory (CD-ROM), digital versatile disc (DVD) or other optical storage, magnetic cassette tapes, magnetic tape magnetic disk storage or other magnetic storage devices, or any other non-transitory medium that can be used to store information that can be accessed by a computing device. As defined herein, a computer-readable medium does not include transitory computer-readable media such as modulated data signals and carrier waves.

[0128] It should also be noted that the term "comprising", "including" or any other variant thereof is intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a series of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such process, method, article, or apparatus. Without further limitation, an element defined by the phrase "comprising an..." does not exclude the presence of additional identical elements in the process, method, article, or apparatus that comprises the element.

[0129] The above are only embodiments of the present application and are not used to limit the present application. For those skilled in the art, various changes and modifications can be made to the present application. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application shall be included within the scope of the claims of the present application.

Claims

1. A multi-scale fracture rock physics seismic wave velocity modeling method, comprising: Determining the corresponding relationship between the number of fractures or fracture density and different scales according to the fractal distribution characteristics of multi-scale fractures of the target rock, and establishing the fractal distribution law of multi-scale fractures of the target rock according to the corresponding relationship, wherein the multi-scale fractures include: background pores, micro-fractures, and medium and large-scale fractures; Based on the equivalent medium model and the fractal distribution law, adding the background pores and the micro-fractures to the equivalent rock background of the target rock to obtain an equivalent elastic rock physics model including the influence of micro-scale fractures; and Based on the linear slip theory and the fractal distribution law, adding the medium and large-scale fractures to the equivalent elastic rock physics model including the influence of micro-scale fractures to obtain an equivalent elastic rock physics model including the influence of multi-scale fractures.

2. The method according to claim 1, characterized in that, The establishment of the corresponding relationship between the number of fractures and different scales is achieved through the following formula: N t (r) = C0·r -D , Among them, N t (r) is the true number of cracks with a scale greater than or equal to r, C0 is the proportionality coefficient, r is the crack radius, and D is the fractal dimension.

3. The method according to claim 2, wherein The value of D is between 2 and 3.

4. The method according to claim 1, wherein The equivalent rock background is the mineral matrix, and the bulk modulus and shear modulus of the equivalent elastic rock physics model incorporating the influence of microscale fractures are calculated by the following formulas: where K2 and μ2 are the bulk modulus and shear modulus of the inclusions, y is the volume percentage of the inclusions, and P (*2) and Q (*2) represent the geometric factors of the inclusions in the equivalent rock.

5. The method according to claim 1, characterized in that, Adding the medium and large-scale fractures with oriented arrangement and / or randomly oriented arrangement to the equivalent elastic rock physics model through the following formula: wherein, i, j, k, l all ∈ (1, 2, 3); ΔS ijkl is the compliance tensor generated by the presence of medium and large-scale fractures in the target rock; δ ik , δ il , δ jk , δ jl is the Kronecker delta function; α jl , α jk , α il , α ik is the second-order tensor of the total contribution of the tangential flexibility per unit volume; β ijkl is a fourth-order tensor of the total contribution of the difference between the normal compliance and the tangential compliance per unit volume.

6. The method according to claim 5, characterized in that The calculation formula of the equivalent compliance tensor S of the target rock in the equivalent elastic rock physics model including the influence of multi-scale fractures is: Among them, is the compliance tensor generated by the existence of microscale cracks in the target rock.

7. The method according to claim 5, wherein When adding the large-scale cracks with oriented arrangement and / or randomly oriented arrangement, the calculation formulas of the second-order tensor and the fourth-order tensor β ijkl are respectively as follows: Among them, α ij is the formula for calculating the second-order tensors α jl , α jk , α il , and α ik , B N and B T represent the normal compliance and the tangential compliance of the corresponding cracks respectively, S q represents the surface area of the q-th group of cracks, n i , n j , n k , n l are the i-th, j-th, k-th, and l-th components of the local normal vector of the crack surface respectively, and V represents the volume of the representative elementary volume REV of the target rock.

8. The method according to claim 7, wherein Spherically averaging the medium and large-scale fractures with oriented arrangement and / or randomly oriented arrangement through the following formula, so that the medium and large-scale fractures with oriented arrangement in the equivalent elastic rock physics model including the influence of multi-scale fractures are converted into fractures with randomly oriented arrangement: where α ij is a formula for calculating the second-order tensors α jl , α jk , α il , and α ik ; is the fracture azimuth; θ is the fracture polar angle; Z N and Z T are the normal compliance and the tangential compliance of the overall oriented fracture set, respectively; n i , n j , n k , n l are the i, j, k, and l components of the local normal vector of the fracture surface, respectively.

9. The method according to any one of claims 1-8, further comprising: Calculating the isotropic parameters of the randomly oriented distributed fractures of the target rock in the equivalent elastic rock physics model including the influence of multi-scale fractures according to the following formula: I p = V p · ρ, Among them, V p is the longitudinal wave velocity of the target rock, V s is the shear wave velocity of the target rock, I p is the impedance of the target rock, ρ is the overall equivalent density of the target rock, C is the stiffness matrix of the target rock, C 11 and C 44 are both elements of the stiffness matrix.

10. A multi-scale fracture rock physics seismic wave velocity modeling device, comprising: An analysis law determination module, determining the corresponding relationship between the number of fractures or fracture density and different scales according to the fractal distribution characteristics of multi-scale fractures of the target rock, and establishing the fractal distribution law of multi-scale fractures of the target rock according to the corresponding relationship, wherein the multi-scale fractures include: background pores, micro-fractures, and medium and large-scale fractures; A first modeling module, based on the equivalent medium model and the fractal distribution law, adding the background pores and the micro-fractures to the equivalent rock background of the target rock to obtain an equivalent elastic rock physics model including the influence of micro-scale fractures; and A second modeling module, based on the linear slip theory and the fractal distribution law, adding the medium and large-sized fractures to the equivalent elastic rock physics model including the influence of micro-scale fractures to obtain an equivalent elastic rock physics model including the influence of multi-scale fractures.

11. The device according to claim 10, further comprising: A third modeling module, calculating the isotropic parameters of the randomly oriented distributed fractures of the target rock in the equivalent elastic rock physics model including the influence of multi-scale fractures according to the following formula: I p = V p · ρ, Among them, V p is the longitudinal wave velocity of the target rock, V s is the shear wave velocity of the target rock, I p is the impedance of the target rock, ρ is the overall equivalent density of the target rock, C is the stiffness matrix of the target rock, C 11 and C 44 are both elements of the stiffness matrix.

12. A machine-readable storage medium having instructions stored thereon for causing a machine to execute: the multi-scale fracture rock physics seismic wave velocity modeling method according to any one of claims 1-10.

13. A processor, characterized in that, For running a program, wherein when the program is run, it is used to execute: the multi-scale fracture rock physics seismic wave velocity modeling method according to any one of claims 1-10.

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