Rock physical equivalent elastic parameter modeling method, system and equipment and storage medium

Abstract

The embodiment of the invention relates to the field of oil and gas geophysical exploration, and discloses a rock physics equivalent elastic parameter modeling method, system and device and a storage medium, and the method comprises the steps: obtaining the parameters of a discrete large-scale crack; establishing a discrete grid, wherein the discrete grid comprises a plurality of local grids; inputting a background medium stiffness tensor model; performing discrete sampling on the background medium stiffness tensor model through the discrete grid to obtain a stiffness tensor of the background medium; and calculating an equivalent stiffness tensor in each local grid one by one based on the stiffness tensor of the background medium and the parameters of the cracks to form a macroscopic non-uniform stiffness tensor model. According to the embodiment of the invention, the grid is used as a unit, so that an area without crack distribution maintains the characteristics of a background medium, the grid with cracks shows anisotropy induced by the cracks, and the anisotropy characteristics are subjected to space-variant along with the grid under the common influence of the length, the direction, the local flexibility and the number of the cracks in the grid.

Description

Technical Field

[0001] The embodiments of the present disclosure relate to the technical field of oil and gas geophysical exploration, and in particular to a rock physics equivalent elastic parameter modeling method, system, device and storage medium. Background Art

[0002] The forward and inversion techniques have established a bridge between macro elastic parameters and seismic response, and rock physics equivalent research is a key means to communicate the micro physical parameters of the reservoir with the macro elastic parameters. The main rock physics equivalent medium theories, such as the Hudson theory and the Schoenberg linear sliding theory, are based on the long wavelength assumption, that is, the scale of the fracture is much smaller than the wavelength of the seismic wavelet. Under the long wavelength condition, the influence of fractures on elastic parameters is reflected in the anisotropic characteristics, and the influence on the macro heterogeneity of elastic parameters can be ignored. Therefore, this type of equivalent medium theory coarsens the scale of micro heterogeneous fracture media and obtains the uniform and anisotropic elastic parameters of the entire medium at a macro level. However, when large-scale fractures are developed or small-scale fractures constitute large-scale fracture belts, the long wavelength condition does not hold, and the fractures have a significant impact on the macro heterogeneity of elastic parameters, and the further impact on seismic response is manifested as wave reflection.

[0003] For media containing large-scale fractures, Coates and Schoenberg proposed a local equivalent medium method to achieve macroscopic inhomogeneous elastic parameter rock physics modeling. The local equivalent medium method uses linear sliding theory to calculate the equivalent elastic parameters of the background medium and fractures in the local area, so as to construct a macroscopic inhomogeneous elastic model. However, existing work only focuses on the simple cases of single large-scale fractures and directional large-scale fractures. In actual formation media, the distribution of fractures is relatively complex, and the existing technology lacks a corresponding macroscopic inhomogeneous elastic parameter modeling method. Summary of the invention

[0004] The embodiments of the present disclosure provide a rock physics equivalent elastic parameter modeling method, system, device and storage medium to solve or alleviate one or more of the above technical problems in the prior art.

[0005] According to one aspect of the present disclosure, a rock physics equivalent elastic parameter modeling method is provided, comprising:

[0006] Obtain parameters of discrete large-scale fractures;

[0007] Establishing a discrete grid, wherein the discrete grid includes a plurality of local grids;

[0008] Input background medium stiffness tensor model;

[0009] Discretely sampling the background medium stiffness tensor model through the discrete grid to obtain the stiffness tensor of the background medium;

[0010] Based on the stiffness tensor of the background medium and the parameters of the crack, the equivalent stiffness tensor in each local grid is calculated one by one to form a macroscopic non-uniform stiffness tensor model.

[0011] In a possible implementation, the parameters of the crack include the endpoint coordinates and flexibility parameters of the crack, and the flexibility parameters include normal flexibility and tangential flexibility.

[0012] In a possible implementation, the size of the discrete grid is set according to the sampling interval magnitude of the elastic parameter model in seismic forward and inversion processing.

[0013] In a possible implementation, the step of calculating the equivalent stiffness tensor in each local grid one by one based on the stiffness tensor of the background medium and the parameters of the crack includes:

[0014] According to the coordinates of the two end points of the crack and the coordinate area of ​​the discrete grid, the calculation of the crack passing through the local grid (x i ,z j The length of each crack in the local grid and the coordinates of the two endpoints of the crack segment and Where i = 1, 2, ..., N x ,j=1,2,…,N z , i and j represent the grid numbers in the x and z directions in the coordinate area of ​​the discrete grid, respectively. x and N z They represent the number of grids in the x and z directions, k represents the number of cracks, and f represents the cracks. Represents passing through the local grid (x i ,z j ) number of cracks;

[0015] The flexibility of each point in the crack is described as gradually decaying from the center point of the crack to the two end points. The flexibility calculation formula of the large-scale crack grid point is:

[0016]

[0017] In the formula, Z max represents the normal or tangential flexibility of the crack center, d represents the distance from the point on the crack to the crack center, and l represents the half length of the crack;

[0018] According to the flexibility calculation formula of the crack grid, the local grid (x i ,z j ) Crack flexibility at both ends of the inner crack segment and Approximate flexibility of the crack segment That is:

[0019]

[0020] Local grid (x i ,z j )The flexibility matrix of each crack segment in the intrinsic coordinate system is for:

[0021]

[0022] Where ΔA represents the local grid (x i ,z j ), Represents the local grid (x i ,z j ) is the normal flexibility of the kth crack segment, Represents the local grid (x i ,z j ) the tangential flexibility of the kth crack segment in;

[0023] The flexibility matrix Transform from intrinsic coordinates to mesh coordinates:

[0024]

[0025] In the formula, represents the flexibility matrix in the grid coordinate system; Represents the Bond transformation matrix:

[0026]

[0027] The coefficient α in the Bond transformation matrix pq (p,q=x,y,z) is the direction cosine of the p-axis of the grid coordinate system and the q-axis of the intrinsic coordinate system corresponding to the crack segment. The Bond transformation matrix of crack segments with different normal directions is different;

[0028] Local grid (x i ,z j The total flexibility of all crack segments in the grid coordinate system for:

[0029]

[0030] The linear sliding theory is used to calculate each local grid (x i ,z j )'s equivalent stiffness tensor c i,j :

[0031]

[0032] In the formula, Represents the local grid (x i ,z j ) is the stiffness tensor matrix of the background medium, and I represents the unit matrix.

[0033] In a possible implementation, the intrinsic coordinate system is a coordinate system in which the x-axis is perpendicular to the crack normal and the z-axis is parallel to the crack normal, and the grid coordinate system is a coordinate system in which the x-axis is in the horizontal direction and the z-axis is in the vertical direction.

[0034] According to one aspect of the present disclosure, a rock physics equivalent elastic parameter modeling system is provided, comprising:

[0035] An acquisition unit, used to acquire parameters of discrete large-scale fractures;

[0036] An establishing unit, used for establishing a discrete grid, wherein the discrete grid includes a plurality of local grids;

[0037] An input unit, used for inputting a background medium stiffness tensor model;

[0038] A sampling unit, used for discretely sampling the background medium stiffness tensor model through the discrete grid to obtain the stiffness tensor of the background medium;

[0039] The calculation unit is used to calculate the equivalent stiffness tensor in each local grid one by one based on the stiffness tensor of the background medium and the parameters of the crack to form a macroscopic non-uniform stiffness tensor model.

[0040] In a possible implementation, the parameters of the crack include the endpoint coordinates and flexibility parameters of the crack, and the flexibility parameters include normal flexibility and tangential flexibility.

[0041] In a possible implementation, the size of the discrete grid is set according to the sampling interval magnitude of the elastic parameter model in seismic forward and inversion processing.

[0042] In a possible implementation, the computing unit includes:

[0043] The first calculation module is used to calculate the coordinates of the two end points of the crack and the coordinate area of ​​the discrete grid. i ,z j The length of each crack in the local grid and the coordinates of the two endpoints of the crack segment and Where i = 1, 2, ..., N x ,j=1,2,…,N z , i and j represent the grid numbers in the x and z directions in the coordinate area of ​​the discrete grid, respectively. x and N z They represent the number of grids in the x and z directions, k represents the number of cracks, and f represents the cracks. Represents passing through the local grid (x i ,z j ) number of cracks;

[0044] The flexibility of each point in the crack is described as gradually decaying from the center point of the crack to the two end points. The flexibility calculation formula of the large-scale crack grid point is:

[0045]

[0046] In the formula, Z max represents the normal or tangential flexibility of the crack center, d represents the distance from the point on the crack to the crack center, and l represents the half length of the crack;

[0047] The second calculation module is used to calculate the local grid (x i ,z j ) Crack flexibility at both ends of the inner crack segment and Approximate flexibility of the crack segment That is:

[0048]

[0049] Local grid (x i ,z j )The flexibility matrix of each crack segment in the intrinsic coordinate system is for:

[0050]

[0051] Where ΔA represents the local grid (x i ,z j ), Represents the local grid (x i ,z j ) is the normal flexibility of the kth crack segment, Represents the local grid (x i ,z j ) the tangential flexibility of the kth crack segment in;

[0052] Transformation module, used to transform the flexibility matrix Transform from intrinsic coordinates to mesh coordinates:

[0053]

[0054] In the formula, represents the flexibility matrix in the grid coordinate system; Represents the Bond transformation matrix:

[0055]

[0056] The coefficient α in the Bond transformation matrix pq (p,q=x,y,z) is the direction cosine of the p-axis of the grid coordinate system and the q-axis of the intrinsic coordinate system corresponding to the crack segment. The Bond transformation matrix of crack segments with different normal directions is different;

[0057] Local grid (x i ,z j The total flexibility of all crack segments in the grid coordinate system for:

[0058]

[0059] The third calculation module is used to calculate each local grid (x i ,z j )'s equivalent stiffness tensor c i,j :

[0060]

[0061] In the formula, Represents the local grid (x i ,z j ) is the stiffness tensor matrix of the background medium, and I represents the unit matrix.

[0062] In a possible implementation, the intrinsic coordinate system is a coordinate system in which the x-axis is perpendicular to the crack normal and the z-axis is parallel to the crack normal, and the grid coordinate system is a coordinate system in which the x-axis is in the horizontal direction and the z-axis is in the vertical direction.

[0063] According to one aspect of the present disclosure, a rock physics equivalent elastic parameter modeling device is provided, comprising:

[0064] Processor and memory;

[0065] The memory is used to store computer programs, and the processor calls the computer programs stored in the memory to execute any of the rock physics equivalent elastic parameter modeling methods described above.

[0066] According to one aspect of the present disclosure, a computer-readable storage medium is provided, in which a computer program is stored. When the computer program is executed by a processor, the processor is enabled to execute any of the rock physics equivalent elastic parameter modeling methods described above.

[0067] The exemplary embodiments of the present disclosure have the following beneficial effects: by using the exemplary embodiments of the present disclosure, on the one hand, the inhomogeneity of equivalent elastic parameters on the macro scale caused by the inhomogeneous distribution of large-scale cracks can be reflected, and on the other hand, the local anisotropic characteristics of the model space can be reflected. The exemplary embodiments of the present disclosure use grids as units, so that areas without crack distribution maintain the characteristics of the background medium, while the grids with distributed cracks show crack-induced anisotropy, and are jointly affected by the length, direction, local flexibility and number of cracks in the grid, and the anisotropic characteristics vary spatially with the grid.

[0068] The details of one or more embodiments of the present application are presented in the following drawings and descriptions. Other features and advantages of the present application will become apparent from the accompanying drawings. It should be understood that the above general description and the detailed descriptions below are only exemplary and explanatory and cannot limit the present disclosure. BRIEF DESCRIPTION OF THE DRAWINGS

[0069] The accompanying drawings herein are incorporated into the specification and constitute a part of the specification, illustrate embodiments consistent with the present disclosure, and together with the specification are used to explain the principles of the present disclosure. Obviously, the accompanying drawings described below are only some embodiments of the present disclosure, and for ordinary technicians in this field, other accompanying drawings can be obtained based on these accompanying drawings without creative work.

[0070] Figure 1 is a flow chart of a rock physics equivalent elastic parameter modeling method of the exemplary embodiment;

[0071] Figure 2 is a schematic diagram of a model of an isotropic layered medium containing large-scale fractures in this exemplary embodiment;

[0072] Figure 3 This exemplary embodiment Figure 2 Schematic diagram of the equivalent stiffness tensor model of the medium crack model;

[0073] Figure 4 is a schematic diagram of a model of isotropic and anisotropic double-layer media containing large-scale cracks in this exemplary embodiment;

[0074] Figure 5 This exemplary embodiment Figure 4 Schematic diagram of the equivalent stiffness tensor model of the medium crack model;

[0075] Figure 6 is a block diagram of a rock physics equivalent elastic parameter modeling system of the exemplary embodiment;

[0076] Figure 7 It is a structural schematic diagram of a rock physics equivalent elastic parameter modeling device of this exemplary embodiment. DETAILED DESCRIPTION

[0077] Example embodiments will now be described more fully with reference to the accompanying drawings. However, example embodiments can be implemented in a variety of forms and should not be construed as being limited to the examples set forth herein; on the contrary, these embodiments are provided so that the present disclosure will be more comprehensive and complete, and the concepts of the example embodiments are fully conveyed to those skilled in the art. The described features, structures, or characteristics may be combined in one or more embodiments in any suitable manner. In the following description, many specific details are provided to provide a full understanding of the embodiments of the present disclosure. However, those skilled in the art will appreciate that the technical solutions of the present disclosure may be practiced while omitting one or more of the specific details, or other methods, components, devices, steps, etc. may be adopted. In other cases, known technical solutions are not shown or described in detail to avoid obscuring various aspects of the present disclosure.

[0078] In addition, the accompanying drawings are only schematic illustrations of the present disclosure and are not necessarily drawn to scale. The same reference numerals in the figures represent the same or similar parts, and thus their repeated description will be omitted. Some of the block diagrams shown in the accompanying drawings are functional entities and do not necessarily correspond to physically or logically independent entities. These functional entities can be implemented in software form, or implemented in one or more hardware units or integrated circuits, or implemented in different networks and / or processor devices and / or microcontroller devices.

[0079] The flowcharts shown in the accompanying drawings are only exemplary and do not necessarily include all the steps. For example, some steps may be decomposed, while some steps may be combined or partially combined, so the actual execution order may change according to the actual situation.

[0080] The terms "first", "second", etc. in the specification and claims of the present application and the above-mentioned drawings are used to distinguish similar objects, and are not necessarily used to describe a specific order or sequence. It should be understood that the terms used in this way can be interchanged where appropriate, so that the embodiments of the present application described herein can be implemented in an order other than those illustrated or described herein, for example.

[0081] In addition, the terms "include" and "have" and any variations thereof are intended to cover non-exclusive inclusions. For example, a process, method, system, product, or apparatus comprising a series of steps or sub-modules is not necessarily limited to those steps or sub-modules explicitly listed, but may include other steps or sub-modules not explicitly listed or inherent to these processes, methods, products, or apparatuses.

[0082] Figure 1 is a flow chart of a rock physics equivalent elastic parameter modeling method of this exemplary embodiment. Figure 1As shown, an exemplary embodiment of the present disclosure provides a rock physics equivalent elastic parameter modeling method, comprising:

[0083] S1 obtains the parameters of discrete large-scale fractures;

[0084] S2 establishes a discrete grid, wherein the discrete grid includes a plurality of local grids;

[0085] S3 inputs the background medium stiffness tensor model;

[0086] S4 discretely samples the background medium stiffness tensor model through the discrete grid to obtain the stiffness tensor of the background medium;

[0087] S5 calculates the equivalent stiffness tensor in each local grid one by one based on the stiffness tensor of the background medium and the parameters of the crack to form a macroscopic non-uniform stiffness tensor model.

[0088] Exemplarily, the large-scale cracks in this embodiment are cracks with a size greater than 10 of the seismic wavelength.

[0089] This exemplary embodiment provides a modeling method for macroscopically inhomogeneous rock physical equivalent elastic parameters of a medium containing large-scale fractures. This exemplary embodiment is applicable to fracture media with fracture scales close to or larger than the wavelength of seismic wavelets, and can be used in situations where fracture distribution characteristics are complex. Figure 2 is a schematic diagram of a model of an isotropic layered medium containing large-scale fractures in this exemplary embodiment, Figure 2 (a) is an isotropic three-layer background medium model. The horizontal coordinate (Distance) and the vertical coordinate (Depth) are the horizontal and vertical spatial positions, respectively, in meters (m). V P represents the P-wave velocity, V S represents the S-wave velocity, and ρ represents the density; Figure 2 (b) is the spatial distribution diagram of large-scale cracks. The black lines represent cracks with two scales of 50 m and 100 m. The normal and tangential flexibility of the 50 m scale cracks are 10 -5 Meter / Pa (m / Pa) and 3×10 -5 m / Pa, the normal and tangential compliances of a 100-m-scale crack are 3×10 -5 Meter / Pa (m / Pa) and 8×10 -5 Meter / Pa (m / Pa), the horizontal coordinate (Distance) and the vertical coordinate (Depth) are the horizontal and vertical spatial positions respectively, and the unit is meter (m); Figure 3 This exemplary embodiment Figure 2 Schematic diagram of the equivalent stiffness tensor model of the medium crack model. Figure 3In the figure, C11-C66 represent the stiffness tensor, and the color scale values, such as 1.0e+8 to 4.0e+10, represent the range of the stiffness tensor model, and its unit is "Pa". No model (white blank space) means that the tensor is 0 in the entire model space. Figure 3 In the paper, the rock physics equivalent stiffness tensor model is constructed on a grid scale of 10 × 10 m, and the stiffness tensor without the model means that the tensor is equal to zero in the whole model space. Figure 4 is a schematic diagram of a model of isotropic and anisotropic double-layer media containing large-scale cracks in this exemplary embodiment; Figure 4 (a) is a two-layer background medium model, the upper layer is an isotropic medium, and the lower layer is a TTI medium (transverse isotropy with a tilted axis of symmetry). The horizontal coordinate (Distance) and the vertical coordinate (Depth) are the horizontal and vertical spatial positions, respectively, and the unit is meter (m); V P represents the P-wave velocity, V S represents the S-wave velocity, and ρ represents the density; Figure 4 (b) is the spatial distribution diagram of large-scale cracks. The black lines represent cracks. The normal and tangential flexibility of all cracks are 2×10 -5 Meter / Pa (m / Pa) and 5×10 -5 Meter / Pa (m / Pa), the horizontal coordinate (Distance) and the vertical coordinate (Depth) are the horizontal and vertical spatial positions respectively, and the unit is meter (m). Figure 5 This exemplary embodiment Figure 4 Schematic diagram of the equivalent stiffness tensor model of the medium crack model; Figure 5 In the figure, C11-C66 represent the stiffness tensor, and the color scale values, such as 2.0e+8 to 4.8e+10, represent the range of the stiffness tensor model, and its unit is "Pa". No model (white blank space) means that the tensor is 0 in the entire model space. Figure 5 In the paper, the rock physics equivalent stiffness tensor model is constructed on a grid scale of 10 × 10 m, and the stiffness tensor without the model means that the tensor is equal to zero in the whole model space.

[0090] like Figure 2-5 As shown, the method includes the following main steps:

[0091] Input the endpoint coordinates and flexibility parameters of the discrete large-scale fracture;

[0092] Establish a discrete grid, the grid size of which is equivalent to the sampling interval of the elastic parameter model in the seismic forward and inversion processing, input the stiffness tensor model of the background medium, and perform discrete sampling on the stiffness tensor model based on the discrete grid;

[0093] According to the stiffness tensor of the background medium and the coordinate and flexibility data of the crack, the equivalent stiffness tensor in each discrete grid is calculated one by one based on the local equivalent medium method, and finally a macroscopic inhomogeneous stiffness tensor model of the grid scale is obtained.

[0094] Exemplarily, calculating the equivalent stiffness tensor within a single discrete grid includes the following steps:

[0095] According to the coordinates of the crack endpoints and the coordinate area of ​​the discrete grid, the length of the crack segment Δl of each crack passing through the grid is picked up. k and the coordinates of the two endpoints of the crack segment (x 1,k ,z 1,k ) and (x 2,k ,z 2,k ), where k = 1, 2, ..., n f , n f represents the number of cracks that pass through the grid;

[0096] Determine the approximate normal flexibility Z of the crack segment in the grid N,k and tangential flexibility Z T,k ;

[0097] The flexibility matrix of each crack segment in the grid in its intrinsic coordinate system is:

[0098]

[0099] Where ΔA is the mesh area, and the flexibility matrix is ​​transformed from the intrinsic coordinate system to the mesh coordinate system:

[0100]

[0101] Where N k is the Bond transformation matrix of the kth crack segment in the grid, which is constructed by the direction cosines of the grid coordinate system and the intrinsic coordinate system corresponding to the crack segment. The total flexibility of all crack segments in the grid in the grid coordinate system is:

[0102]

[0103] The intrinsic coordinate system in this step is a coordinate system in which the x-axis is perpendicular to the crack normal and the z-axis is parallel to the crack normal, and the grid coordinate system is a coordinate system in which the x-axis is in the horizontal direction and the z-axis is in the vertical direction;

[0104] The equivalent stiffness tensor of this mesh is calculated using linear sliding theory:

[0105] c=c b (I+s f c b ) -1 ;

[0106] In the formula, c b is the stiffness tensor matrix of the background medium, and I is the unit matrix.

[0107] Specifically, the parameters of the crack include the endpoint coordinates and flexibility parameters of the crack, and the flexibility parameters include normal flexibility and tangential flexibility.

[0108] Specifically, the size of the discrete grid is set according to the sampling interval magnitude of the elastic parameter model in seismic forward and inversion processing.

[0109] Specifically, the step of calculating the equivalent stiffness tensor in each local grid one by one based on the stiffness tensor of the background medium and the parameters of the crack includes:

[0110] According to the coordinates of the two end points of the crack and the coordinate area of ​​the discrete grid, the calculation of the crack passing through the local grid (x i ,z j The length of each crack in the local grid and the coordinates of the two endpoints of the crack segment and Where i = 1, 2, ..., N x ,j=1,2,…,N z , i and j represent the grid numbers in the x and z directions in the coordinate area of ​​the discrete grid, respectively. x and N z They represent the number of grids in the x and z directions, k represents the number of cracks, and f represents the cracks. Represents passing through the local grid (x i ,z j ) number of cracks;

[0111] The flexibility of each point in the crack is described as gradually decaying from the center point of the crack to the two end points. The flexibility calculation formula of the large-scale crack grid point is:

[0112]

[0113] In the formula, Z max represents the normal or tangential flexibility of the crack center, d represents the distance from the point on the crack to the crack center, and l represents the half length of the crack;

[0114] According to the flexibility calculation formula of the crack grid, the local grid (x i ,z j ) Crack flexibility at both ends of the inner crack segment and Approximate flexibility of the crack segment That is:

[0115]

[0116] Local grid (x i ,z j )The flexibility matrix of each crack segment in the intrinsic coordinate system is for:

[0117]

[0118] Where ΔA represents the local grid (x i ,z j ), Represents the local grid (x i ,z j ) is the normal flexibility of the kth crack segment, Represents the local grid (x i ,z j ) the tangential flexibility of the kth crack segment in;

[0119] The flexibility matrix Transform from intrinsic coordinates to mesh coordinates:

[0120]

[0121] In the formula, represents the flexibility matrix in the grid coordinate system; Represents the Bond transformation matrix:

[0122]

[0123] The coefficient α in the Bond transformation matrix pq (p,q=x,y,z) is the direction cosine of the p-axis of the grid coordinate system and the q-axis of the intrinsic coordinate system corresponding to the crack segment. The Bond transformation matrix of crack segments with different normal directions is different;

[0124] Local grid (x i ,z j The total flexibility of all crack segments in the grid coordinate system for:

[0125]

[0126] The linear sliding theory is used to calculate each local grid (x i ,z j )'s equivalent stiffness tensor c i,j :

[0127]

[0128] In the formula, Represents the local grid (x i ,zj ) is the stiffness tensor matrix of the background medium, and I represents the unit matrix.

[0129] Specifically, the intrinsic coordinate system is a coordinate system in which the x-axis is perpendicular to the crack normal and the z-axis is parallel to the crack normal, and the grid coordinate system is a coordinate system in which the x-axis is in the horizontal direction and the z-axis is in the vertical direction.

[0130] In this exemplary embodiment, the specific implementation scheme includes the following steps:

[0131] S10 Input the coordinates of the two endpoints of the discrete large-scale fracture {(x beg ,z beg ),(x end ,z end )} m and normal and tangential flexibility {Z N ,Z T} m ,m=1,2,…,N f , N f is the number of cracks in the model space;

[0132] S20 establishes a discrete grid whose size is equivalent to the sampling interval of the elastic parameter model in seismic forward and inversion processing (meter or ten-meter level). The discrete grid is used to perform discrete sampling on the input background medium stiffness tensor model. The grid (x i ,z j ) corresponds to the coordinate area [x i-1 / 2 ,x i+1 / 2 ]×[z j-1 / 2 ,z j+1 / 2 ];

[0133] S30 uses the equation of a line through two points to mathematically describe the discrete large-scale fracture. Based on the coordinates of the two end points of the large-scale fracture and the coordinate area of ​​the discrete grid, the line passing through the grid (x i ,z j ) is the length of each crack in the grid. and the coordinates of the two endpoints of the crack segment and Where i = 1, 2, ..., N x ,j=1,2,…,N z , N x and N z Represents the number of grids in the x and z directions, Represents passing through the grid (x i ,z j ) number of cracks;

[0134] In order to match the actual situation, the flexibility of each point of the large-scale crack is described as gradually decaying from the center point of the crack to the two end points:

[0135]

[0136] In the formula, Z max is the normal or tangential flexibility of the crack center, d is the distance from the crack point to the crack center, l is the half length of the crack, and the grid (x i ,z j ) Crack flexibility at the end point of the inner crack segment and The approximate flexibility of the crack segment is:

[0137]

[0138] S50 Grid (x i ,z j ) The flexibility matrix of each crack segment in its eigencoordinate system is:

[0139]

[0140] Where ΔA is the mesh area, and the flexibility matrix is ​​transformed from the intrinsic coordinate system to the mesh coordinate system:

[0141]

[0142] In the formula, is the Bond transformation matrix:

[0143]

[0144] The coefficient α in the Bond transformation matrix pq (p,q=x,y,z) is the direction cosine of the p-axis of the grid coordinate system and the q-axis of the intrinsic coordinate system corresponding to the crack segment. The Bond transformation matrix of the crack segments with different normal directions is different. i ,z j The total flexibility of all crack segments in the grid coordinate system is:

[0145]

[0146] The intrinsic coordinate system described in this step is a coordinate system in which the x-axis is perpendicular to the crack normal and the z-axis is parallel to the crack normal, and the grid coordinate system is a coordinate system in which the x-axis is in the horizontal direction and the z-axis is in the vertical direction;

[0147] S60 uses linear sliding theory to calculate the grid (x i ,z j ) is the equivalent stiffness tensor:

[0148]

[0149] In the formula, is the grid (x i ,z j ) is the stiffness tensor matrix of the background medium, and I is the unit matrix.

[0150] S70 repeats steps S30 - S70 to complete the calculation of equivalent stiffness tensors of all grids.

[0151] This exemplary embodiment provides a method for modeling equivalent elastic parameters of macroscopic inhomogeneous rock physics under conditions of complex distribution characteristics of large-scale fractures. On the one hand, it can reflect the inhomogeneity of equivalent elastic parameters on the macroscopic scale caused by the inhomogeneous distribution of large-scale fractures, and on the other hand, it can reflect the local anisotropy characteristics of the model space. Different from the equivalent medium theory under the long wavelength assumption, the present invention uses the grid as a unit, so that the area without crack distribution maintains the characteristics of the background medium, while the grid with distributed cracks shows the anisotropy induced by the cracks, and is jointly affected by the length, direction, local flexibility and number of cracks in the grid, and the anisotropic characteristics vary with the grid.

[0152] Figure 6 is a block diagram of a rock physics equivalent elastic parameter modeling system of the exemplary embodiment, such as Figure 6 As shown, an exemplary embodiment of the present disclosure provides a rock physics equivalent elastic parameter modeling system, comprising:

[0153] An acquisition unit 10, used to acquire parameters of discrete large-scale fractures;

[0154] An establishing unit 20, used for establishing a discrete grid, wherein the discrete grid includes a plurality of local grids;

[0155] An input unit 30, used for inputting a background medium stiffness tensor model;

[0156] A sampling unit 40, configured to perform discrete sampling on the background medium stiffness tensor model through the discrete grid to obtain the stiffness tensor of the background medium;

[0157] The calculation unit 50 is used to calculate the equivalent stiffness tensor in each local grid one by one based on the stiffness tensor of the background medium and the parameters of the crack to form a macroscopic non-uniform stiffness tensor model.

[0158] Specifically, the parameters of the crack include the endpoint coordinates and flexibility parameters of the crack, and the flexibility parameters include normal flexibility and tangential flexibility.

[0159] Specifically, the size of the discrete grid is set according to the sampling interval magnitude of the elastic parameter model in seismic forward and inversion processing.

[0160] Specifically, the calculation unit 50 includes:

[0161] The first calculation module is used to calculate the coordinates of the two end points of the crack and the coordinate area of ​​the discrete grid. i ,z j The length of each crack in the local grid and the coordinates of the two endpoints of the crack segment and Where i = 1, 2, ..., N x ,j=1,2,…,N z , i and j represent the grid numbers in the x and z directions in the coordinate area of ​​the discrete grid, respectively. x and N z They represent the number of grids in the x and z directions, k represents the number of cracks, and f represents the cracks. Represents passing through the local grid (x i ,z j ) number of cracks;

[0162] The flexibility of each point in the crack is described as gradually decaying from the center point of the crack to the two end points. The flexibility calculation formula of the large-scale crack grid point is:

[0163]

[0164] In the formula, Z max represents the normal or tangential flexibility of the crack center, d represents the distance from the point on the crack to the crack center, and l represents the half length of the crack;

[0165] The second calculation module is used to calculate the local grid (x i ,z j ) Crack flexibility at both ends of the inner crack segment and Approximate flexibility of the crack segment That is:

[0166]

[0167] Local grid (x i ,z j )The flexibility matrix of each crack segment in the intrinsic coordinate system is for:

[0168]

[0169] Where ΔA represents the local grid (x i ,z j ), Represents the local grid (xi ,z j ) is the normal flexibility of the kth crack segment, Represents the local grid (x i ,z j ) the tangential flexibility of the kth crack segment in;

[0170] Transformation module, used to transform the flexibility matrix Transform from intrinsic coordinates to mesh coordinates:

[0171]

[0172] In the formula, represents the flexibility matrix in the grid coordinate system; Represents the Bond transformation matrix:

[0173]

[0174] The coefficient α in the Bond transformation matrix pq (p,q=x,y,z) is the direction cosine of the p-axis of the grid coordinate system and the q-axis of the intrinsic coordinate system corresponding to the crack segment. The Bond transformation matrix of crack segments with different normal directions is different;

[0175] Local grid (x i ,z j The total flexibility of all crack segments in the grid coordinate system for:

[0176]

[0177] The third calculation module is used to calculate each local grid (x i ,z j )'s equivalent stiffness tensor c i,j :

[0178]

[0179] In the formula, Represents the local grid (x i ,z j ) is the stiffness tensor matrix of the background medium, and I represents the unit matrix.

[0180] Specifically, the intrinsic coordinate system is a coordinate system in which the x-axis is perpendicular to the crack normal and the z-axis is parallel to the crack normal, and the grid coordinate system is a coordinate system in which the x-axis is in the horizontal direction and the z-axis is in the vertical direction.

[0181] Figure 7 FIG. 1 is a schematic diagram of the structure of a rock physics equivalent elastic parameter modeling device of the exemplary embodiment. Figure 7As shown, corresponding to the rock physics equivalent elastic parameter modeling method provided above, the present invention also provides a rock physics equivalent elastic parameter modeling device. Since the embodiment of the device is similar to the above method embodiment, the description is relatively simple. For relevant parts, please refer to the description of the above method embodiment part. The device described below is only schematic. The device may include: a processor (processor) 1, a memory (memory) 2 and a communication bus (i.e., the above device bus) and a search engine, wherein the processor 1 and the memory 2 communicate with each other through the communication bus and communicate with the outside through the communication interface. The processor 1 can call the logic instructions in the memory 2 to execute the rock physics equivalent elastic parameter modeling method.

[0182] In addition, the logic instructions in the above-mentioned memory 2 can be implemented in the form of a software functional unit and can be stored in a computer-readable storage medium when it is sold or used as an independent product. Based on such an understanding, the technical solution of the present invention, in essence, or the part that contributes to the prior art or the part of the technical solution, can be embodied in the form of a software product, and the computer software product is stored in a storage medium, including a number of instructions for a computer device (which can be a personal computer, a server, or a network device, etc.) to perform all or part of the steps of the methods of each embodiment of the present invention. The aforementioned storage medium includes: a storage chip, a U disk, a mobile hard disk, a read-only memory (ROM, Read-Only Memory), a random access memory (RAM, Random Access Memory), a disk or an optical disk, and other media that can store program codes.

[0183] On the other hand, an embodiment of the present invention further provides a processor-readable storage medium, on which a computer program 3 is stored. When the computer program 3 is executed by the processor 1, the rock physics equivalent elastic parameter modeling method provided in the above embodiments is implemented.

[0184] The processor-readable storage medium can be any available medium or data storage device that can be accessed by the processor 1, including but not limited to magnetic storage (such as floppy disks, hard disks, magnetic tapes, magneto-optical disks (MO), etc.), optical storage (such as CD, DVD, BD, HVD, etc.), and semiconductor storage (such as ROM, EPROM, EEPROM, non-volatile memory (NANDFLASH), solid-state drive (SSD)), etc.

[0185] The above are only preferred implementations of the present disclosure, and the protection scope of the present disclosure is not limited to the above embodiments. All technical solutions under the concept of the present disclosure belong to the protection scope of the present disclosure. It should be pointed out that for ordinary technicians in this technical field, some improvements and modifications without departing from the principle of the present disclosure should be regarded as the protection scope of the present disclosure.

Claims

1. A rock physics equivalent elastic parameter modeling method, characterized in that: include: Obtain parameters of discrete large-scale fractures; Establishing a discrete grid, wherein the discrete grid includes a plurality of local grids; Input background medium stiffness tensor model; Discretely sampling the background medium stiffness tensor model through the discrete grid to obtain the stiffness tensor of the background medium; Based on the stiffness tensor of the background medium and the parameters of the crack, the equivalent stiffness tensor in each local grid is calculated one by one to form a macroscopic non-uniform stiffness tensor model.

2. The rock physics equivalent elastic parameter modeling method according to claim 1, characterized in that: The parameters of the crack include the endpoint coordinates and flexibility parameters of the crack, and the flexibility parameters include normal flexibility and tangential flexibility.

3. The rock physics equivalent elastic parameter modeling method according to claim 1 or 2, characterized in that: The size of the discrete grid is set according to the sampling interval magnitude of the elastic parameter model in seismic forward and inversion processing.

4. The rock physics equivalent elastic parameter modeling method according to claim 2, characterized in that: The step of calculating the equivalent stiffness tensor in each local grid one by one based on the stiffness tensor of the background medium and the parameters of the crack includes: According to the coordinates of the two end points of the crack and the coordinate area of ​​the discrete grid, the calculation of the crack passing through the local grid (x i ,z j The length of each crack in the local grid and the coordinates of the two endpoints of the crack segment and Where i = 1, 2, ..., N x ,j=1,2,…,N z , i and j represent the grid numbers in the x and z directions in the coordinate area of ​​the discrete grid, respectively. x and N z They represent the number of grids in the x and z directions, k represents the number of cracks, and f represents the cracks. Represents passing through the local grid (x i ,z j ) number of cracks; The flexibility of each point in the crack is described as gradually decaying from the center point of the crack to the two end points. The flexibility calculation formula of the large-scale crack grid point is: In the formula, Z max represents the normal or tangential flexibility of the crack center, d represents the distance from the point on the crack to the crack center, and l represents the half length of the crack; According to the flexibility calculation formula of the crack grid, the local grid (x i ,z j ) Crack flexibility at both ends of the inner crack segment and Approximate flexibility of the crack segment That is: Local grid (x i ,z j )The flexibility matrix of each crack segment in the intrinsic coordinate system is for: Where ΔA represents the local grid (x i ,z j ), Represents the local grid (x i ,z j ) is the normal flexibility of the kth crack segment, Represents the local grid (x i ,z j ) the tangential flexibility of the kth crack segment in; The flexibility matrix Transform from intrinsic coordinates to mesh coordinates: In the formula, represents the flexibility matrix in the grid coordinate system; Represents the Bond transformation matrix: The coefficient α in the Bond transformation matrix pq (p,q=x,y,z) is the direction cosine of the p-axis of the grid coordinate system and the q-axis of the intrinsic coordinate system corresponding to the crack segment. The Bond transformation matrix of crack segments with different normal directions is different; Local grid (x i ,z j The total flexibility of all crack segments in the grid coordinate system for: The linear sliding theory is used to calculate each local grid (x i ,z j )'s equivalent stiffness tensor c i,j : In the formula, Represents the local grid (x i ,z j ) is the stiffness tensor matrix of the background medium, and I represents the unit matrix.

5. The rock physics equivalent elastic parameter modeling method according to claim 4, characterized in that: The intrinsic coordinate system is a coordinate system in which the x-axis is perpendicular to the crack normal and the z-axis is parallel to the crack normal, and the grid coordinate system is a coordinate system in which the x-axis is in the horizontal direction and the z-axis is in the vertical direction.

6. A rock physics equivalent elastic parameter modeling system, characterized in that: include: An acquisition unit, used to acquire parameters of discrete large-scale fractures; An establishing unit, used for establishing a discrete grid, wherein the discrete grid includes a plurality of local grids; An input unit, used for inputting a background medium stiffness tensor model; A sampling unit, used for discretely sampling the background medium stiffness tensor model through the discrete grid to obtain the stiffness tensor of the background medium; The calculation unit is used to calculate the equivalent stiffness tensor in each local grid one by one based on the stiffness tensor of the background medium and the parameters of the crack to form a macroscopic non-uniform stiffness tensor model.

7. The rock physics equivalent elastic parameter modeling system according to claim 6, characterized in that: The parameters of the crack include the endpoint coordinates and flexibility parameters of the crack, and the flexibility parameters include normal flexibility and tangential flexibility.

8. The rock physics equivalent elastic parameter modeling system according to claim 6 or 7, characterized in that: The size of the discrete grid is set according to the sampling interval magnitude of the elastic parameter model in seismic forward and inversion processing.

9. The rock physics equivalent elastic parameter modeling system according to claim 7, characterized in that: The computing unit comprises: The first calculation module is used to calculate the coordinates of the two end points of the crack and the coordinate area of ​​the discrete grid. i ,z j The length of each crack in the local grid and the coordinates of the two endpoints of the crack segment and Where i = 1, 2, ..., N x ,j=1,2,…,N z , i and j represent the grid numbers in the x and z directions in the coordinate area of ​​the discrete grid, respectively. x and N z They represent the number of grids in the x and z directions, k represents the number of cracks, and f represents the cracks. Represents passing through the local grid (x i ,z j ) number of cracks; The flexibility of each point in the crack is described as gradually decaying from the center point of the crack to the two end points. The flexibility calculation formula of the large-scale crack grid point is: In the formula, Z max represents the normal or tangential flexibility of the crack center, d represents the distance from the point on the crack to the crack center, and l represents the half length of the crack; The second calculation module is used to calculate the local grid (x i ,z j ) Crack flexibility at both ends of the inner crack segment and Approximate flexibility of the crack segment That is: Local grid (x i ,z j )The flexibility matrix of each crack segment in the intrinsic coordinate system is for: Where ΔA represents the local grid (x i ,z j ), Represents the local grid (x i ,z j ) is the normal flexibility of the kth crack segment, Represents the local grid (x i ,z j ) the tangential flexibility of the kth crack segment in; Transformation module, used to transform the flexibility matrix Transform from intrinsic coordinates to mesh coordinates: In the formula, represents the flexibility matrix in the grid coordinate system; Represents the Bond transformation matrix: The coefficient α in the Bond transformation matrix pq (p,q=x,y,z) is the direction cosine of the p-axis of the grid coordinate system and the q-axis of the intrinsic coordinate system corresponding to the crack segment. The Bond transformation matrix of crack segments with different normal directions is different; Local grid (x i ,z j The total flexibility of all crack segments in the grid coordinate system for: The third calculation module is used to calculate each local grid (x i ,z j )'s equivalent stiffness tensor c i,j : In the formula, Represents the local grid (x i ,z j ) is the stiffness tensor matrix of the background medium, and I represents the unit matrix.

10. The rock physics equivalent elastic parameter modeling system according to claim 9, characterized in that: The intrinsic coordinate system is a coordinate system in which the x-axis is perpendicular to the crack normal and the z-axis is parallel to the crack normal, and the grid coordinate system is a coordinate system in which the x-axis is in the horizontal direction and the z-axis is in the vertical direction.

11. A rock physics equivalent elastic parameter modeling device, characterized in that: include: Processor and memory; The memory is used to store a computer program, and the processor calls the computer program stored in the memory to execute the rock physics equivalent elastic parameter modeling method described in any one of claims 1 to 5.

12. A computer-readable storage medium, characterized in that: The computer-readable storage medium stores a computer program, and when the computer program is executed by a processor, the processor is enabled to execute the rock physics equivalent elastic parameter modeling method described in any one of claims 1 to 5.

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