A method, device and equipment for physical modeling of multi-scale fractured tight sandstone

Abstract

The present specification relates to the technical field of exploration and development, and particularly relates to a physical modeling method, device and equipment for multi-scale fractured tight sandstone. The method comprises the following steps: through scale-based rock physical modeling, firstly, internal characteristic structures of rocks at three scales of micro, meso and macro are extracted, then, the three scales of micro, meso and macro are modeled step by step, equivalent elastic modulus obtained at a previous step is taken as a background, and equivalent elastic parameters at each scale are obtained by following the principle of "adding heterogeneous bodies step by step from small to large", the rock physical model reflects the role of internal characteristic structure parameters of rocks at each scale, rock physical modulus of fluid-saturated tight sandstone containing multi-scale fractures is obtained, and a tight sandstone model containing multi-scale fractured tight sandstone is generated. Thus, the response characteristics and change rules can be used to guide geophysical exploration and development of complex oil and gas reservoirs such as fractured tight sandstone.

Description

Technical Field

[0001] This specification relates to the field of exploration and development technology, and in particular to a physical modeling method, apparatus and equipment for multi-scale fractured dense sandstone. Background Technology

[0002] In seismic exploration of oil and gas, rock physics serves as a bridge between reservoir physical parameters and rock seismic elastic parameters, and is fundamental to understanding the propagation characteristics of seismic waves in rocks. Modeling fluid-bearing fractured reservoirs, calculating their elastic parameters, and analyzing their response characteristics and variation patterns are of great theoretical and practical significance for the geophysical exploration and development of complex oil and gas reservoirs such as fractured tight sandstone.

[0003] Complex oil and gas reservoirs can be broadly categorized as fluid-bearing fractured-pore reservoirs, composed of solid rock, a pore system, and contained fluids. Most physical modeling methods for fractured tight sandstone focus on calculating the elastic modulus of sandstone containing single-scale fractures. However, in actual sandstone formations, due to geological processes occurring at different times, the rocks possess highly complex internal structures, including intricate pore systems often composed of pores of various morphologies and multi-scale fractures. Reservoir rocks exhibit different elastic and permeability characteristics at the micro, meso, and macro scales. Therefore, rock physical modeling requires consideration of multi-scale internal structural features. However, each current rock physical theory has its specific applicability; no single theory can adequately represent the multi-scale internal structural features and systems present within rocks, thus limiting its application in the exploration of complex oil and gas reservoirs.

[0004] Therefore, a multi-scale rock physical modeling method for fractured tight sandstone is established to realize a new method for rock physical analysis of complex oil and gas reservoirs. Summary of the Invention

[0005] To address the problem that no single rock physics theory in existing technologies can adequately and quantitatively characterize the multi-scale internal structural features and systems within rocks, thus limiting its application in the exploration of complex oil and gas reservoirs, this specification provides a physical modeling method, apparatus, and equipment for multi-scale fractured tight sandstone. This method obtains the rock physical response and its variation patterns within multi-scale fractured tight sandstone reservoirs, allowing the use of these response characteristics and variation patterns to guide the geophysical exploration and development of complex oil and gas reservoirs, such as those containing fractured tight sandstone. The specific technical solutions of this specification's embodiments are as follows:

[0006] On the one hand, the embodiments of this specification provide a physical modeling method for multi-scale fractured tight sandstone, the method comprising:

[0007] Select minerals suitable for constructing sandstone models based on actual core and logging data, and record the basic values ​​corresponding to the selected minerals;

[0008] The microscale mineral matrix is ​​obtained by calculating based on the basic values ​​of the selected minerals.

[0009] By adding bound water modulus, dry fracture modulus, and dry pore modulus to the mineral matrix, the background elastic modulus of mesoscale fractures is obtained.

[0010] The elastic modulus of fractured saturated tight sandstone at the low-frequency limit and high-frequency limit is calculated based on the background elastic modulus of the mesoscale fractures. The elastic stiffness matrix of the mesoscale fractured sandstone is obtained based on the elastic modulus at different frequencies.

[0011] Substitute the elastic stiffness matrix containing the mesoscopic crack into a discrete mesh-partitioned crack model that meets the accuracy of wave field forward modeling, and calculate the equivalent stiffness tensor of the discrete mesh-partitioned crack model according to the linear sliding theory.

[0012] Based on the equivalent stiffness tensor, the rock physical modulus of fluid-saturated tight sandstone with multi-scale fractures is obtained, and a tight sandstone model with multi-scale fractures is generated.

[0013] Furthermore, the recording of the basic values ​​corresponding to the selected minerals further includes,

[0014] Given N mineral components, record the bulk modulus K of each mineral. m and shear modulus μ m Density ρ i Component volume fraction f i , i represents the sequence number of the mineral component, i∈[1,N].

[0015] Furthermore, calculations based on the fundamental values ​​of the selected minerals yield a microscale mineral matrix that further includes,

[0016]

[0017] Among them, K m and μ m These are the bulk modulus and shear modulus of the mineral matrix, respectively; ρ m This represents the density value of the mineral matrix at the microscopic scale.

[0018] Furthermore, adding bound water modulus, dry fracture modulus, and dry pore modulus to the mineral matrix to obtain the background elastic modulus of mesoscale fractures further includes,

[0019] The bound water modulus, dry fracture modulus, and dry pore modulus are added to the mineral matrix to obtain the corrected bulk modulus and shear modulus K of the matrix. cand μ c And the bulk modulus and shear modulus K of the dry rock skeleton. dry and μ dry The formula is,

[0020]

[0021] K2 and μ2 represent the bulk modulus and shear modulus of the added bound water, respectively; y is the proportion of the second component; d and dy are differential operators used to calculate the corrected matrix modulus K. c μ c At that time, the initial conditions were The equivalent shear modulus, initially valued at μm, needs to be calculated iteratively. The skeleton modulus K is then calculated. dry μ dry At that time, the initial conditions were Both K2 and μ2 are zero;

[0022] By adding fluid to the dry pore modulus and the dry fracture modulus, the elastic modulus value K of the fluid-uniformly saturated rock is obtained. sat and μ sat The formula is,

[0023]

[0024] Among them, K dry K0 and K fl These are the bulk moduli of the rock skeleton, matrix, and fluid, respectively; φ is the rock porosity; K sat It is and μ sat The elastic modulus of a fluid-uniformly saturated rock;

[0025] Based on the elastic modulus value of homogeneous saturated rock, the elastic modulus of isotropic saturated rock is obtained. And the elastic modulus of isotropic dry rocks and The background elastic modulus of the mesoscopic-scale crack.

[0026] Furthermore, the calculation of the elastic modulus of fracture-saturated tight sandstone at the low-frequency limit and high-frequency limit based on the background elastic modulus of the mesoscale fractures further includes,

[0027] Calculate the elastic modulus C of a fractured dry sandstone skeleton. 0 :

[0028]

[0029] in, It is the flexibility of the dry rock skeleton. It is the additional flexibility of dry cracks;

[0030] Calculate the elastic modulus of the fractured saturated tight sandstone at the low-frequency limit. The formula is:

[0031]

[0032] in,

[0033]

[0034] Among them, K g K f These are the bulk modulus of the background rock mineral particles and the fluid, respectively, α. m It can be αi or αj;

[0035] Calculate the elastic modulus of the fractured saturated tight sandstone at the high-frequency limit. The formula is:

[0036]

[0037] in, It is the softness of saturated rock. It is an additional compliance feature for fluid-containing cracks;

[0038] Based on the elastic modulus at different frequencies, the elastic stiffness matrix containing mesoscopic cracks is obtained, and the frequency-dependent longitudinal wave modulus is obtained:

[0039]

[0040] In the above formula, α and M are Biot parameters of the background rock, i and j are different components; κ and η represent the permeability and fluid viscosity of the background rock, respectively, and a is the fracture radius. This refers to crack density; other equivalent elastic parameters are as follows:

[0041]

[0042] Finally, the elastic stiffness matrix C containing mesoscopic cracks is obtained. medium And it serves as the large-scale background medium stiffness tensor matrix.

[0043] Furthermore, substituting the elastic stiffness matrix containing the mesoscopic crack into a discrete mesh-partitioned crack model that satisfies the accuracy of wave field forward modeling, the equivalent stiffness tensor of the discrete mesh-partitioned crack model is calculated based on linear sliding theory, and further includes...

[0044] A discrete grid-based crack model that meets the accuracy requirements of wavefield forward modeling is adopted, and the number of cracks passing through the grid and the length of each crack segment are picked in each grid.

[0045] Given the crack compliance condition, the compliance matrix of the intrinsic coordinate system within the mesh is:

[0046]

[0047] Where ΔA is the grid area, Δl k Z is the length of the k-th crack segment within the grid. N,k Z T,k These represent the normal and tangential compliance of the k-th crack segment, respectively.

[0048] Transform the crack compliance matrix from the crack intrinsic coordinate system to the mesh coordinate system:

[0049]

[0050] Where, N k This represents the transformation matrix for the k-th crack segment;

[0051] The total compliance of all crack segments within the grid is:

[0052]

[0053] Where, n f This indicates the number of crack segments within the grid.

[0054] The equivalent stiffness tensor of the mesh is calculated based on linear sliding theory:

[0055] C = C medium (I+S f C medium ) -1

[0056] Among them, C medium Let I represent the stiffness tensor matrix of the background medium, and let I represent the identity matrix.

[0057] On the other hand, embodiments of this specification also provide a physical modeling device for multi-scale fractured tight sandstone, the device comprising:

[0058] The basic data acquisition module is used to select minerals suitable for constructing sandstone models based on actual core and logging data, and to record the basic values ​​corresponding to the selected minerals.

[0059] The microscale acquisition module is used to calculate based on the basic values ​​of the selected mineral to obtain the mineral matrix at the microscale.

[0060] The mesoscale acquisition module is used to add bound water modulus, dry fracture modulus and dry pore modulus to the mineral matrix to obtain the background elastic modulus of mesoscale fractures.

[0061] The mesoscopic matrix acquisition module is used to calculate the elastic modulus of fractured saturated tight sandstone at the low-frequency limit and high-frequency limit based on the background elastic modulus of the mesoscopic-scale fractures, and to obtain the elastic stiffness matrix containing mesoscopic fractures based on the elastic modulus at different frequencies.

[0062] The equivalent stiffness tensor acquisition module is used to substitute the elastic stiffness matrix containing mesoscopic cracks into a discrete mesh-partitioned crack model that meets the accuracy of wave field forward modeling, and calculate the equivalent stiffness tensor of the discrete mesh-partitioned crack model according to the linear sliding theory.

[0063] The tight sandstone model construction module is used to obtain the rock physical modulus of fluid-saturated tight sandstone with multi-scale fractures based on the equivalent stiffness tensor, and generate a tight sandstone model of tight sandstone with multi-scale fractures.

[0064] On the other hand, embodiments of this specification also provide a computer device, including a memory, a processor, and a computer program stored in the memory, wherein the processor executes the computer program to implement the above-described method.

[0065] On the other hand, embodiments of this specification also provide a computer-readable storage medium storing a computer program that, when executed by a processor, implements the above-described method.

[0066] Finally, this specification also provides a computer program product, which includes a computer program that, when executed by a processor, implements the above-described method.

[0067] This specification provides a detailed method for rock physics modeling of tight sandstone containing multi-scale fractures, using examples from its embodiments. Appropriate minerals are selected for constructing the sandstone model based on actual core and logging data, and their corresponding baseline values ​​are recorded. Then, calculations are performed based on these baseline values ​​to obtain the microscale mineral matrix. This allows for the extraction of microscale internal rock features. Binding water modulus, dry fracture modulus, and dry pore modulus are added to the microscale mineral matrix to obtain the background elastic modulus of mesoscale fractures. This yields the mesoscale internal rock features, and the low-frequency limit is calculated based on the background elastic modulus of the mesoscale fractures. The elastic modulus of fractured saturated tight sandstone at high frequency limits is used to obtain the elastic stiffness matrix of mesoscopic fractures. This matrix is ​​then substituted into a discrete grid fracture model that meets the accuracy requirements of wavefield forward modeling. The equivalent stiffness tensor model of the discrete grid fracture model is calculated using linear sliding theory, thereby extracting the internal structural features of the rock at the macroscopic scale. Equivalent elastic parameters at each scale are obtained, and the rock physics model reflects the role of the internal structural parameters at each scale. The rock physics modulus of fluid-saturated tight sandstone with multi-scale fractures is obtained based on the equivalent stiffness tensor model. These response characteristics and variation patterns can then guide the geophysical exploration and development of complex oil and gas reservoirs such as fractured tight sandstone. Furthermore, this method can perform rock physics modeling of fluid-saturated tight rocks with multi-scale fractures to analyze the influence of different physical properties on the elastic parameters, anisotropy, velocity dispersion, and attenuation of the sandstone. Attached Figure Description

[0068] To more clearly illustrate the technical solutions in the embodiments of this specification or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the embodiments of this specification. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0069] Figure 1 The figure shown is a schematic diagram of the implementation system of a physical modeling method for multi-scale fractured dense sandstone in an embodiment of this specification.

[0070] Figure 2 The diagram shown is a flowchart illustrating a physical modeling method for multi-scale fractured dense sandstone according to an embodiment of this specification.

[0071] Figure 3 The diagram shown is a flowchart illustrating the implementation of a numerical simulation method for the rock physical response of dense sandstone with multi-scale fractures in an embodiment of this specification.

[0072] Figure 4aThe figure shows the longitudinal wave velocity calculated under different porosity and connectivity conditions by modeling rocks at the microscale in the embodiments of this specification.

[0073] Figure 4b The figure shows the transverse wave velocity calculated under different porosity and connectivity conditions by modeling rocks at the microscale in the embodiments of this specification.

[0074] Figures 5a-5b The figure shown is a schematic diagram of the rock physical modulus of dense sandstone with multi-scale fractures established in the embodiments of this specification.

[0075] Figures 6a-6d The diagram shown is a schematic representation of a dense sandstone model containing large-scale cracks in different directions, as described in the embodiments of this specification.

[0076] Figures 7a-7d The diagram shown is a schematic representation of the rock physical modulus of dense sandstone containing large-scale cracks in different directions in the embodiments of this specification.

[0077] Figure 8 The diagram shown is a schematic diagram of a physical modeling device for multi-scale fractured dense sandstone according to an embodiment of this specification.

[0078] Figure 9 The diagram shown is a structural schematic of the computer device in an embodiment of this specification.

[0079] [Explanation of Figure Markers]:

[0080] 101. Terminal;

[0081] 102. Server;

[0082] 801. Basic Data Acquisition Module;

[0083] 802. Microscale acquisition module;

[0084] 803. Mesoscale Acquisition Module;

[0085] 804. Mesoscopic Matrix Acquisition Module;

[0086] 805. Equivalent Stiffness Tensor Acquisition Module;

[0087] 806. Dense Sandstone Model Construction Module;

[0088] 902. Computer equipment;

[0089] 904. Processing equipment;

[0090] 906. Storage resources;

[0091] 908. Drive system;

[0092] 910. Input / Output Module;

[0093] 912. Input devices;

[0094] 914. Output devices;

[0095] 916. Presentation equipment;

[0096] 918. Graphical User Interface;

[0097] 920. Network interface;

[0098] 922. Communication link;

[0099] 924. Communication bus. Detailed Implementation

[0100] The technical solutions in the embodiments of this specification will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the embodiments of this specification, and not all embodiments. Based on the embodiments of this specification, all other embodiments obtained by those skilled in the art without creative effort are within the protection scope of the embodiments of this specification.

[0101] It should be noted that the terms "first," "second," etc., in the description, claims, and accompanying drawings of the embodiments herein are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that such data can be interchanged where appropriate so that embodiments of the embodiments described herein can be implemented in orders other than those illustrated or described herein. Furthermore, the terms "comprising" and "having," and any variations thereof, are intended to cover non-exclusive inclusion; for example, a process, method, apparatus, product, or device that includes a series of steps or units is not necessarily limited to those steps or units explicitly listed, but may include other steps or units not explicitly listed or inherent to such processes, methods, products, or devices.

[0102] It should be noted that the acquisition, storage, use, and processing of data in the technical solutions of the embodiments of this specification all comply with the relevant provisions of national laws and regulations.

[0103] It should be noted that in the embodiments of this specification, certain software, components, models and other existing solutions in the industry may be mentioned. These should be regarded as exemplary and are only intended to illustrate the feasibility of implementing the technical solution of this application. However, they do not mean that the applicant has used or necessarily used the solution.

[0104] like Figure 1The diagram illustrates a system implementation of a physical modeling method for multi-scale fractured tight sandstone according to an embodiment of this specification, including a terminal 101 and a server 102. The terminal 101 and server 102 can communicate via a network, which may include a local area network (LAN), a wide area network (WAN), the Internet, or a combination thereof, and be connected to a website, user equipment (e.g., computing devices), and a backend system.

[0105] Data collectors can input actual core and logging data into server 102 via terminal 101. Server 102 selects suitable minerals from multiple sources to construct a sandstone model. Then, through multi-scale rock physical modeling, it obtains equivalent elastic parameters at each scale and displays the results via terminal 101. Optionally, server 102 can be a node in a cloud computing system (not shown in the figure), or each server can be a separate cloud computing system, comprising multiple computers interconnected by a network and operating as a distributed processing system.

[0106] In addition, it should be noted that, Figure 1 The examples shown are merely one application environment provided by the embodiments in this specification. In practical applications, other application environments may also be included, and this specification does not impose any limitations.

[0107] To address the problems existing in the prior art, this specification provides a physical modeling method for multi-scale fractured tight sandstone, which obtains the rock physical response and variation law of reservoirs containing multi-scale fractured tight sandstone. These response characteristics and variation laws can be used to guide the geophysical exploration and development of complex oil and gas reservoirs such as those containing fractured tight sandstone. Figure 2 The diagram illustrates a flowchart of the physical modeling method for multi-scale fractured tight sandstone in an embodiment of this specification. The process of physical modeling multi-scale fractured tight sandstone is described in this diagram. The order of steps listed in the embodiment is merely one possible execution order among many steps and does not represent the only possible execution order. In actual system or device products, the methods shown in the embodiments or accompanying drawings can be executed sequentially or in parallel.

[0108] Specific examples Figure 2 As shown, the method may include:

[0109] Step 201: Select minerals suitable for constructing sandstone models based on actual core and logging data, and record the basic values ​​corresponding to the selected minerals;

[0110] Step 202: Calculate based on the basic values ​​of the selected mineral to obtain the mineral matrix at the microscale;

[0111] Step 203: Add bound water modulus, dry fracture modulus and dry pore modulus to the mineral matrix to obtain the background elastic modulus of mesoscale fractures;

[0112] Step 204: Calculate the elastic modulus of fractured saturated tight sandstone at the low-frequency limit and high-frequency limit based on the background elastic modulus of the mesoscale fractures, and obtain the elastic stiffness matrix of the mesoscale fractured sandstone based on the elastic modulus at different frequencies.

[0113] Step 205: Substitute the elastic stiffness matrix containing the mesoscopic crack into the discrete mesh partitioned crack model that meets the accuracy of wave field forward modeling, and calculate the equivalent stiffness tensor of the discrete mesh partitioned crack model according to the linear sliding theory.

[0114] Step 206: Obtain the rock physical modulus of fluid-saturated tight sandstone with multi-scale fractures based on the equivalent stiffness tensor, and generate a tight sandstone model of tight sandstone with multi-scale fractures.

[0115] This specification provides a detailed method for rock physics modeling of tight sandstone containing multi-scale fractures, using examples from its embodiments. Appropriate minerals are selected for constructing the sandstone model based on actual core and logging data, and their corresponding baseline values ​​are recorded. Then, calculations are performed based on these baseline values ​​to obtain the microscale mineral matrix. This allows for the extraction of microscale internal rock features. Binding water modulus, dry fracture modulus, and dry pore modulus are added to the microscale mineral matrix to obtain the background elastic modulus of mesoscale fractures. This yields the mesoscale internal rock features, and the low-frequency limit is calculated based on the background elastic modulus of the mesoscale fractures. The elastic modulus of fractured saturated tight sandstone at high frequency limits is used to obtain the elastic stiffness matrix of mesoscopic fractures. This matrix is ​​then substituted into a discrete grid fracture model that meets the accuracy requirements of wavefield forward modeling. The equivalent stiffness tensor model of the discrete grid fracture model is calculated using linear sliding theory, thereby extracting the internal structural features of the rock at the macroscopic scale. Equivalent elastic parameters at each scale are obtained, and the rock physics model reflects the role of the internal structural parameters at each scale. The rock physics modulus of fluid-saturated tight sandstone with multi-scale fractures is obtained based on the equivalent stiffness tensor model. These response characteristics and variation patterns can then guide the geophysical exploration and development of complex oil and gas reservoirs such as fractured tight sandstone. Furthermore, this method can perform rock physics modeling of fluid-saturated tight rocks with multi-scale fractures to analyze the influence of different physical properties on the elastic parameters, anisotropy, velocity dispersion, and attenuation of the sandstone.

[0116] In the embodiments of this specification, it is first necessary to extract the internal structural features of rocks at three scales—microscopic, mesoscopic, and macroscopic—through multi-scale rock physical modeling, and record the basic values ​​corresponding to the selected minerals. Further, this includes...

[0117] Given N mineral components, record the bulk modulus K of each mineral. m and shear modulus μ m Density ρ i Component volume fraction f i , i represents the sequence number of the mineral component, i∈[1,N].

[0118] Specifically, based on actual core and logging data, suitable mineral components are selected for constructing a fractured tight sandstone model. N mineral components are used, and the elastic modulus (K) of each mineral is recorded. i ,μ i ), density ρ i Component volume fraction f i , i represents the index of the mineral component, i∈[1,N];

[0119] In the embodiments of this specification, after obtaining the basic values ​​corresponding to the minerals, it is necessary to model the microscopic, mesoscopic, and macroscopic scales step by step. First, a mineral matrix at the microscopic scale is constructed. Based on the basic values ​​of the selected minerals, calculations are performed to obtain the mineral matrix at the microscopic scale, which further includes...

[0120] The formula for calculating the microscale mineral matrix is ​​as follows:

[0121]

[0122] Among them, K m and μ m These are the bulk modulus and shear modulus of the mineral matrix, respectively; ρ m This represents the density value of the mineral matrix at the microscopic scale.

[0123] In the embodiments of this specification, after obtaining the microscale mineral matrix, microscale modeling can be performed. Next, mesoscale modeling is required. This involves adding bound water modulus, dry fracture modulus, and dry pore modulus to the mineral matrix to obtain the background elastic modulus of the mesoscale fractures. Further, this includes...

[0124] The bound water modulus, dry fracture modulus, and dry pore modulus are added to the mineral matrix to obtain the corrected bulk modulus and shear modulus K of the matrix. c and μ c And the bulk modulus and shear modulus K of the dry rock skeleton. dry and μ dry The formula is,

[0125]

[0126] K2 and μ2 represent the bulk modulus and shear modulus of the added bound water, respectively; y is the proportion of the second component; d and dy are differential operators used to calculate the corrected matrix modulus K. c μ c At that time, the initial conditions were The initial value is μ, representing the equivalent shear modulus that needs to be calculated iteratively. m Calculate the skeleton modulus K dry μ dry At that time, the initial conditions were Both K2 and μ2 are zero;

[0127] By adding fluid to the dry pore modulus and the dry fracture modulus, the elastic modulus value K of the fluid-uniformly saturated rock is obtained. sat and μ sat The formula is,

[0128]

[0129] Among them, K dry K0 and K fl These are the bulk moduli of the rock skeleton, matrix, and fluid, respectively; φ is the rock porosity; K sat It is and μ sat The elastic modulus of a fluid-uniformly saturated rock;

[0130] Based on the elastic modulus value of homogeneous saturated rock, the elastic modulus of isotropic saturated rock is obtained. And the elastic modulus of isotropic dry rocks and The background elastic modulus of the mesoscopic-scale crack.

[0131] Specifically, the elastic modulus and bulk modulus K of the selected mineral are used. m and shear modulus μ m Density ρ, volume fraction f i The elastic modulus and density K of the sandstone model background matrix at the microscale were calculated. m μ m ρ m By adding bound water, dry cracks, and dry pores to the background matrix, the corrected matrix elastic modulus (K) is obtained. c μ c ) and skeleton modulus (K dry μ dry ); By adding fluid to dry pores and cracks, the elastic modulus (K) of fluid-uniformly saturated rock can be obtained. sat μ satThe distribution of P-wave and S-wave velocities in fluid-saturated tight sandstone with variations in porosity and pore connectivity is shown in the figure below. Figure 2 As shown; the isotropic elastic moduli of saturated sandstone and dry sandstone were finally obtained. and The background elastic modulus of mesoscale fractures. (Based on the flexibility of dry sandstone) and dry crack flexibility Calculate the elastic modulus C of a fractured dry sandstone skeleton. 0 Then according to C 0 Calculate the elastic modulus of fractured saturated tight sandstone at the low-frequency limit. Utilizing saturated rock flexibility and fluid-containing crack compliance Calculate the elastic modulus of fractured saturated tight sandstone at the high-frequency limit. Finally, the frequency-dependent anisotropic elastic modulus C of the fractured saturated tight sandstone was calculated. sat (ω), the velocity dispersion attenuation of the dense sandstone containing mesoscopic fractures is as follows: Figures 5a-5b As shown.

[0132] In the embodiments of this specification, in order to obtain macroscopic-scale modeling, it is also necessary to calculate the elastic modulus of fracture-saturated tight sandstone at the low-frequency limit and high-frequency limit based on the background elastic modulus of the mesoscopic-scale fractures. This further includes...

[0133] Calculate the elastic modulus C of a fractured dry sandstone skeleton. 0 :

[0134]

[0135] in, It is the flexibility of the dry rock skeleton. It is the additional flexibility of dry cracks;

[0136] Calculate the elastic modulus of the fractured saturated tight sandstone at the low-frequency limit. The formula is:

[0137]

[0138] in,

[0139]

[0140] Among them, K g K f These are the bulk modulus of the background rock mineral particles and the fluid, respectively, α. m For α i or α j ;

[0141] Calculate the elastic modulus of the fractured saturated tight sandstone at the high-frequency limit. The formula is:

[0142]

[0143] in, It is the softness of saturated rock. It is an additional compliance feature for fluid-containing cracks;

[0144] Based on the elastic modulus at different frequencies, the elastic stiffness matrix containing mesoscopic cracks is obtained, and the frequency-dependent longitudinal wave modulus is obtained:

[0145]

[0146] In the above formula, α and M are Biot parameters of the background rock, i and j are different components; κ and η represent the permeability and fluid viscosity of the background rock, respectively, and a is the fracture radius. This refers to crack density; other equivalent elastic parameters are as follows:

[0147]

[0148] Finally, the elastic stiffness matrix C containing mesoscopic cracks is obtained. medium And it serves as the large-scale background medium stiffness tensor matrix.

[0149] Specifically, within each grid cell, the number of cracks passing through that grid cell and the length of each crack segment are collected, and the compliance matrix of the intrinsic coordinate system within the grid cell is calculated. Transform the crack compliance matrix from the crack intrinsic coordinate system to the mesh coordinate system S f,k ; Calculate the total compliance S of all crack segments within the mesh using background compliance. f The equivalent stiffness tensor C of the mesh is calculated based on linear slip theory. This is then applied to a large-scale crack model with different directions, such as... Figures 6a-6d As shown, the velocity equivalent model of this crack model can then be obtained, such as... Figures 7a-7d As shown.

[0150] In another embodiment of this specification, the elastic stiffness matrix containing mesoscopic cracks is substituted into a discrete mesh-partitioned crack model that meets the accuracy requirements of wave field forward modeling. The calculation of the equivalent stiffness tensor of the discrete mesh-partitioned crack model based on linear sliding theory further includes...

[0151] A discrete grid-based crack model that meets the accuracy requirements of wavefield forward modeling is adopted, and the number of cracks passing through the grid and the length of each crack segment are picked in each grid.

[0152] Given the crack compliance condition, the compliance matrix of the intrinsic coordinate system within the mesh is:

[0153]

[0154] Where ΔA is the grid area, Δl k Z is the length of the k-th crack segment within the grid. N,k Z T,k These represent the normal and tangential compliance of the k-th crack segment, respectively.

[0155] Transform the crack compliance matrix from the crack intrinsic coordinate system to the mesh coordinate system:

[0156]

[0157] Where, N k This represents the transformation matrix for the k-th crack segment;

[0158] The total compliance of all crack segments within the grid is:

[0159]

[0160] Where, n f This indicates the number of crack segments within the grid.

[0161] The equivalent stiffness tensor of the mesh is calculated based on linear sliding theory:

[0162] C = C medium (I+S f C medium ) -1

[0163] Among them, C medium Let I represent the stiffness tensor matrix of the background medium, and let I represent the identity matrix.

[0164] For example, the specific implementation process of this specification is as follows: Figure 3 The flowchart of the numerical simulation method for the rock physical response of dense sandstone with multi-scale fractures in this specification shows the process of establishing fluid-saturated dense sandstone with multi-scale fractures at the micro, meso, and large scales. Figures 4a-4b This manual describes the calculation of longitudinal wave velocities under different porosity and connectivity conditions using microscale rock modeling. Figure 4a ), transverse wave velocity ( Figure 4b The dark areas represent dense sandstone. As porosity and connectivity increase, the lithology changes to general sandstone and high-quality sandstone. Figures 5a-5b This specification establishes the petrophysical modulus of dense sandstone containing multi-scale fractures, and calculates the frequency-dependent quasi-longitudinal wave phase velocities for different fracture directions. Figure 5a ) and reverse quality factor ( Figure 5bIt can be observed that changes in the crack direction have a significant impact on the P-wave velocity and attenuation. The quasi-P-wave velocity is the lowest and the attenuation is the highest when the crack direction is parallel to the crack direction; the quasi-P-wave velocity is the highest and the attenuation is the lowest when the crack direction is perpendicular to the crack direction. Figures 6a-6d It is a dense sandstone model containing large-scale fractures in different directions. Its P-wave velocity is 4000 m / s, S-wave velocity is 2600 m / s, density is 2.65 g / cm³, and porosity is 0.05. The fracture filling has a P-wave velocity of 2000 m / s and a density of 1.2 g / cm³. 3 The main length of the crack is 40m, the crack density is 8%, and the angles of the large-scale cracks are selected at 0° in four directions. Figure 6a ), 50° Figure 6b ), 90° Figure 6c ), 120° Figure 6d ). Figures 7a-7d Is with Figures 6a-6d Correspondingly, the calculated rock physical modulus—longitudinal wave velocity—of dense sandstone containing large-scale fractures in different directions, where: 0° ( Figure 7a ), 50° Figure 7b ), 90° Figure 7c ), 120° Figure 7d As can be seen from the figure, the directionality of the cracks in the rock leads to a clear directionality in the sandstone velocity.

[0165] Based on the same inventive concept, embodiments of this specification also provide a physical modeling device for multi-scale fractured dense sandstone, such as... Figure 8 As shown, the device includes:

[0166] The basic data acquisition module 801 is used to select minerals suitable for constructing sandstone models based on actual core and logging data, and record the basic values ​​corresponding to the selected minerals.

[0167] The microscale acquisition module 802 is used to calculate based on the basic values ​​of the selected mineral to obtain the mineral matrix at the microscale.

[0168] The mesoscale acquisition module 803 is used to add bound water modulus, dry fracture modulus and dry pore modulus to the mineral matrix to obtain the background elastic modulus of mesoscale fractures.

[0169] The mesoscopic matrix acquisition module 804 is used to calculate the elastic modulus of fractured saturated tight sandstone at the low-frequency limit and high-frequency limit based on the background elastic modulus of the mesoscopic scale fractures, and to obtain the elastic stiffness matrix containing mesoscopic fractures based on the elastic modulus at different frequencies.

[0170] The equivalent stiffness tensor acquisition module 805 is used to substitute the elastic stiffness matrix containing mesoscopic cracks into a discrete mesh-partitioned crack model that meets the accuracy of wave field forward modeling, and calculate the equivalent stiffness tensor of the discrete mesh-partitioned crack model according to the linear sliding theory.

[0171] The tight sandstone model construction module 806 is used to obtain the rock physical modulus of fluid-saturated tight sandstone with multi-scale fractures based on the equivalent stiffness tensor, and generate a tight sandstone model of tight sandstone with multi-scale fractures.

[0172] like Figure 9 The diagram shown is a structural schematic of a computer device according to an embodiment of this specification. The methods described in this specification can be applied to the computer device of this embodiment.

[0173] Specifically, such as Figure 9 As shown, computer device 902 may include one or more processing devices 904, such as one or more central processing units (CPUs), each of which may implement one or more hardware threads. Computer device 902 may also include any storage resource 906 for storing information of any kind, such as code, settings, data, etc. Non-limitingly, for example, storage resource 906 may include any combination of one or more of the following: any type of RAM, any type of ROM, flash memory devices, hard disks, optical disks, etc. More generally, any storage resource can use any technology to store information.

[0174] Furthermore, any storage resource can provide volatile or non-volatile retention of information.

[0175] Furthermore, any storage resource can represent a fixed or removable component of the computer device 902. In one case, when the processing device 904 executes associated instructions stored in any storage resource or combination of storage resources, the computer device 902 can perform any operation of the associated instructions. The computer device 902 also includes one or more drive systems 908 for interacting with any storage resource, such as a hard disk drive system, an optical disk drive system, etc.

[0176] Computer device 902 may also include an input / output module 910 (I / O) for receiving various inputs (via input device 912) and providing various outputs (via output device 914). A specific output mechanism may include a presentation device 916 and an associated graphical user interface (GUI) 918. In other embodiments, the input / output module 910 (I / O), input device 912, and output device 914 may be omitted, and the device may function solely as a computer device within a network. Computer device 902 may also include one or more network interfaces 920 for exchanging data with other devices via one or more communication links 922. One or more communication buses 924 couple the components described above together.

[0177] Communication link 922 can be implemented in any way, such as via a local area network (LAN), a wide area network (WAN) (e.g., the Internet), a point-to-point connection, or any combination thereof. Communication link 922 may include any combination of hardwired links, wireless links, routers, gateway functions, name servers, etc., governed by any protocol or combination of protocols.

[0178] This specification also provides a computer-readable storage medium storing a computer program that, when executed by a processor, implements the above-described method.

[0179] This specification also provides computer-readable instructions, wherein when a processor executes the instructions, the program therein causes the processor to perform the above-described method.

[0180] It should be understood that in the various embodiments of this specification, the sequence number of each process does not imply the order of execution. The execution order of each process should be determined by its function and internal logic, and should not constitute any limitation on the implementation process of the embodiments of this specification.

[0181] It should also be understood that, in the embodiments of this specification, the term "and / or" is merely a description of the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent: A existing alone, A and B existing simultaneously, and B existing alone. Furthermore, in the embodiments of this specification, the character " / " generally indicates that the preceding and following related objects have an "or" relationship.

[0182] Those skilled in the art will recognize that the units and algorithm steps of the various examples described in conjunction with the embodiments disclosed in this specification can be implemented in electronic hardware, computer software, or a combination of both. To clearly illustrate the interchangeability of hardware and software, the components and steps of each example have been generally described in terms of functionality in the foregoing description. Whether these functions are implemented in hardware or software depends on the specific application and design constraints of the technical solution. Those skilled in the art can use different methods to implement the described functions for each specific application, but such implementations should not be considered beyond the scope of the embodiments in this specification.

[0183] Those skilled in the art will clearly understand that, for the sake of convenience and brevity, the specific working processes of the systems, devices, and units described above can be referred to the corresponding processes in the foregoing method embodiments, and will not be repeated here.

[0184] In the embodiments provided in this specification, it should be understood that the disclosed systems, apparatuses, and methods can be implemented in other ways. For example, the apparatus embodiments described above are merely illustrative; for instance, the division of units is only a logical functional division, and in actual implementation, there may be other division methods. For example, multiple units or components may be combined or integrated into another system, or some features may be ignored or not executed. Furthermore, the couplings or direct couplings or communication connections shown or discussed may be indirect couplings or communication connections through some interfaces, devices, or units, or they may be electrical, mechanical, or other forms of connection.

[0185] The units described as separate components may or may not be physically separate. The components shown as units may or may not be physical units; that is, they may be located in one place or distributed across multiple network units. Some or all of the units can be selected to achieve the purpose of the embodiments described in this specification, depending on actual needs.

[0186] Furthermore, the functional units in the various embodiments of this specification can be integrated into one processing unit, or each unit can exist physically separately, or two or more units can be integrated into one unit. The integrated unit can be implemented in hardware or as a software functional unit.

[0187] If the integrated unit is implemented as a software functional unit and sold or used as an independent product, it can be stored in a computer-readable storage medium. Based on this understanding, the technical solutions of the embodiments of this specification, in essence, or the parts that contribute to the prior art, or all or part of the technical solutions, can be embodied in the form of a software product. This computer software product is stored in a storage medium and includes several instructions to cause a computer device (which may be a personal computer, server, or network device, etc.) to execute all or part of the steps of the methods described in the various embodiments of this specification. The aforementioned storage medium includes various media capable of storing program code, such as USB flash drives, portable hard drives, read-only memory (ROM), random access memory (RAM), magnetic disks, or optical disks.

[0188] This specification describes the principles and implementation methods of the embodiments using specific examples. The above descriptions of the embodiments are only for the purpose of helping to understand the methods and core ideas of the embodiments in this specification. At the same time, for those skilled in the art, there will be changes in the specific implementation methods and application scope based on the ideas of the embodiments in this specification. Therefore, the content of this specification should not be construed as a limitation on the embodiments in this specification.

Claims

1. A physical modeling method for multi-scale fractured tight sandstone, characterized in that, The method includes: Select minerals suitable for constructing sandstone models based on actual core and logging data, and record the basic values ​​corresponding to the selected minerals; The microscale mineral matrix is ​​obtained by calculating based on the basic values ​​of the selected minerals. By adding bound water modulus, dry fracture modulus, and dry pore modulus to the mineral matrix, the background elastic modulus of mesoscale fractures is obtained. The elastic modulus of fractured saturated tight sandstone at the low-frequency limit and high-frequency limit is calculated based on the background elastic modulus of the mesoscale fractures. The elastic stiffness matrix of the mesoscale fractured sandstone is obtained based on the elastic modulus at different frequencies. Substitute the elastic stiffness matrix containing the mesoscopic crack into a discrete mesh-partitioned crack model that meets the accuracy of wave field forward modeling, and calculate the equivalent stiffness tensor of the discrete mesh-partitioned crack model according to the linear sliding theory. Based on the equivalent stiffness tensor, the rock physical modulus of fluid-saturated tight sandstone with multi-scale fractures is obtained, and a tight sandstone model with multi-scale fractures is generated.

2. The physical modeling method for multi-scale fractured tight sandstone according to claim 1, characterized in that, The basic values ​​corresponding to the selected minerals are further recorded, including: Given N mineral components, record the bulk modulus K of each mineral. m and shear modulus μ m Density r i Component volume fraction f i , i represents the sequence number of the mineral component, i∈[1,N].

3. The physical modeling method for multi-scale fractured tight sandstone according to claim 2, characterized in that, Based on the basic values ​​of the selected minerals, calculations are performed to obtain the microscopic mineral matrix, which further includes: Among them, K m and μ m These are the bulk modulus and shear modulus of the mineral matrix, respectively; r m This represents the density value of the mineral matrix at the microscopic scale.

4. The physical modeling method for multi-scale fractured tight sandstone according to claim 3, characterized in that, Adding bound water modulus, dry fracture modulus, and dry pore modulus to the mineral matrix to obtain the background elastic modulus of mesoscale fractures further includes... The bound water modulus, dry fracture modulus, and dry pore modulus are added to the mineral matrix to obtain the corrected bulk modulus and shear modulus K of the matrix. c and μ c And the bulk modulus and shear modulus K of the dry rock skeleton. dry and μ dry The formula is, K2 and m2 represent the bulk modulus and shear modulus of the added bound water, respectively; y is the proportion of the second component; d and dy are differential operators used to calculate the corrected matrix modulus K. c m c At that time, the initial conditions were The initial value is μ, representing the equivalent shear modulus that needs to be calculated iteratively. m Calculate the skeleton modulus K dry m dry At that time, the initial conditions were Both K2 and m2 are zero; By adding fluid to the dry pore modulus and the dry fracture modulus, the elastic modulus value K of the fluid-uniformly saturated rock is obtained. sat and μ sat The formula is, Among them, K dry K0 and K fl These are the bulk moduli of the rock skeleton, matrix, and fluid, respectively; f is the rock porosity; K sat It is and μ sat The elastic modulus of a fluid-uniformly saturated rock; Based on the elastic modulus value of homogeneous saturated rock, the elastic modulus of isotropic saturated rock is obtained. And the elastic modulus of isotropic dry rocks and The background elastic modulus of the mesoscopic-scale crack.

5. The physical modeling method for multi-scale fractured tight sandstone according to claim 4, characterized in that, The calculation of the elastic modulus of fracture-saturated tight sandstone at the low-frequency and high-frequency limits based on the background elastic modulus of the mesoscale fractures further includes, Calculate the elastic modulus C of a fractured dry sandstone skeleton. 0 : in, It is the flexibility of the dry rock skeleton. It is the additional flexibility of dry cracks; Calculate the elastic modulus of the fractured saturated tight sandstone at the low-frequency limit. The formula is: in, Among them, K g K f These are the bulk modulus of the background rock mineral particles and the fluid, respectively, α. m For α i or α j ; Calculate the elastic modulus of the fractured saturated tight sandstone at the high-frequency limit. The formula is: in, It is the softness of saturated rock. It is an additional compliance feature for fluid-containing cracks; Based on the elastic modulus at different frequencies, the elastic stiffness matrix containing mesoscopic cracks is obtained, and the frequency-dependent longitudinal wave modulus is obtained: In the above formula, a and M are Biot parameters of the background rock, i and j are different components; k and h represent the permeability and fluid viscosity of the background rock, respectively, and a is the fracture radius. This refers to crack density; other equivalent elastic parameters are as follows: Finally, the elastic stiffness matrix C containing mesoscopic cracks is obtained. medium And it serves as the large-scale background medium stiffness tensor matrix.

6. The physical modeling method for multi-scale fractured tight sandstone according to claim 5, characterized in that, Substituting the elastic stiffness matrix containing the mesoscopic cracks into a discrete mesh-partitioned crack model that satisfies the accuracy of wavefield forward modeling, the equivalent stiffness tensor of the discrete mesh-partitioned crack model is further calculated based on linear slip theory. A discrete grid-based crack model that meets the accuracy requirements of wavefield forward modeling is adopted, and the number of cracks passing through the grid and the length of each crack segment are picked in each grid. Given the crack compliance condition, the compliance matrix of the intrinsic coordinate system within the mesh is: Where DA is the grid area, Dl k Z is the length of the k-th crack segment within the grid. N,k Z T,k These represent the normal and tangential compliance of the k-th crack segment, respectively. Transform the crack compliance matrix from the crack intrinsic coordinate system to the mesh coordinate system: Where, N k This represents the transformation matrix for the k-th crack segment; The total compliance of all crack segments within the grid is: Where, n f This indicates the number of crack segments within the grid. The equivalent stiffness tensor of the mesh is calculated based on linear sliding theory: C=C medium (I+S f C medium ) -1 Among them, C medium Let I represent the stiffness tensor matrix of the background medium, and let I represent the identity matrix.

7. A physical modeling device for multi-scale fractured tight sandstone, characterized in that, The device includes: The basic data acquisition module is used to select minerals suitable for constructing sandstone models based on actual core and logging data, and to record the basic values ​​corresponding to the selected minerals. The microscale acquisition module is used to calculate based on the basic values ​​of the selected mineral to obtain the mineral matrix at the microscale. The mesoscale acquisition module is used to add bound water modulus, dry fracture modulus and dry pore modulus to the mineral matrix to obtain the background elastic modulus of mesoscale fractures. The mesoscopic matrix acquisition module is used to calculate the elastic modulus of fractured saturated tight sandstone at the low-frequency limit and high-frequency limit based on the background elastic modulus of the mesoscopic-scale fractures, and to obtain the elastic stiffness matrix containing mesoscopic fractures based on the elastic modulus at different frequencies. The equivalent stiffness tensor acquisition module is used to substitute the elastic stiffness matrix containing mesoscopic cracks into a discrete mesh-partitioned crack model that meets the accuracy of wave field forward modeling, and calculate the equivalent stiffness tensor of the discrete mesh-partitioned crack model according to the linear sliding theory. The tight sandstone model construction module is used to obtain the rock physical modulus of fluid-saturated tight sandstone with multi-scale fractures based on the equivalent stiffness tensor, and generate a tight sandstone model of tight sandstone with multi-scale fractures.

8. A computer device comprising a memory, a processor, and a computer program stored in the memory, characterized in that, When the processor executes the computer program, it implements the method according to any one of claims 1 to 6.

9. A computer-readable storage medium, characterized in that, The computer-readable storage medium stores a computer program that, when executed by a processor, implements the method of any one of claims 1 to 6.

10. A computer program product, characterized in that, The computer program product includes a computer program that, when executed by a processor, implements the method of any one of claims 1 to 6.

Images