A method, device and storage medium for local grid encryption in a shale oil reservoir

Abstract

The present application discloses a method, device and storage medium for local grid encryption in a shale oil reservoir, which relates to the technical field of oil extraction and solves the problem in the prior art that local grids cannot be encrypted. The method includes embedding fractures into the original background grid and calculating the fracture conductivity; dividing the fracture control area according to the fracture conductivity, calculating the conductivity between the grids and the fractures in the fracture control area, further calculating the equivalent distance between the grids and the fractures in the fracture control area, setting a threshold value, and judging the size relationship between the equivalent distance and the threshold value; for the grids with conductivity greater than or equal to the threshold value, performing double-grid encryption multiple times until the conductivity of all grids is less than the threshold value; and recalculating the conductivity of the grids. This method realizes the encryption of local grids, reduces the influence of unsteady seepage on the accuracy of flow calculation, and improves the numerical simulation accuracy of the discrete fracture model embedded in the shale oil reservoir.

Description

Technical Field

[0001] The present application relates to the technical field of oil extraction, and particularly relates to a method, device and storage medium for local grid encryption in a shale oil reservoir. Background Art

[0002] The shale matrix permeability is extremely low, only a few hundred nanodarcies to microdarcies, which is one millionth of that of a conventional oil reservoir. Microfractures, horizontal bedding fractures, and secondary pores formed by constructive diagenesis are the main spaces for the occurrence of free liquid hydrocarbons, and it is difficult to effectively exploit them by conventional development methods.

[0003] Currently, for the volume fracturing reform area of the embedded discrete fracture model, a higher-precision grid is required to reduce the influence of matrix-fracture unsteady seepage flow on the flow calculation accuracy. However, if a high-precision grid system is adopted for the whole area, the number of model calculation nodes will be greatly increased, and the calculation efficiency will be significantly reduced. How to encrypt the local grid is an urgent problem to be solved currently. Summary of the Invention

[0004] By providing a method, device and storage medium for local grid encryption in an oil reservoir, the embodiments of the present application solve the problem in the prior art that the local grid cannot be encrypted, realize the encryption of the local grid, reduce the influence of unsteady seepage on the flow calculation accuracy, and improve the numerical simulation accuracy of the embedded discrete fracture model in the shale oil reservoir.

[0005] In the first aspect, an embodiment of the present invention provides a method for local grid encryption in a shale oil reservoir, and the method includes:

[0006] Embed the fracture into the original background grid and calculate the fracture conductivity;

[0007] [[ID=२५]]Divide the fracture control area according to the fracture conductivity, calculate the conductivity between the grid in the fracture control area and the fracture, and further calculate the equivalent distance between the grid in the fracture control area and the fracture according to the conductivity;

[0008] Set a threshold value and judge the size relationship between the equivalent distance and the threshold value;

[0009] For the grid with the conductivity greater than or equal to the threshold value, perform double grid encryption multiple times until the conductivity of all grids is less than the threshold value;

[0010] And recalculate the conductivity of the grid.

[0011] In combination with the first aspect, in a possible implementation, embedding the crack into the original background grid includes: selecting different embedding methods to embed the crack into the original background grid according to the relative position between the crack and the grid.

[0012] In combination with the first aspect, in a possible implementation, dividing the crack control area according to the crack diversion ability includes: calculating and demarcating the crack control area according to the following formula:

[0013] R D = {P|D(f, P) < c · t f},

[0014] where c represents the relaxation coefficient; D(f, P) represents the distance from point P to the crack, and its calculation formula is: t f represents the crack diversion ability, and its calculation formula is: t f = k f d f , where k f represents the permeability of the embedded unit crack; d f represents the crack width.

[0015] In combination with the first aspect, in a possible implementation, calculating the conductivity between the grid in the crack control area and the crack includes: calculating by using the grid equivalent distance method, and the calculation formula is:

[0016]

[0017] where A fm represents the area of the embedded crack; k f represents the permeability of the embedded unit crack; k m represents the permeability of the background unit; <d> represents the equivalent distance between the background grid and the embedded discrete crack; n represents the normal vector of the embedded crack; x represents the distance vector from a point in the background grid to the crack; S represents the volume of the background grid.

[0018] In combination with the first aspect, in a possible implementation, performing double grid encryption includes: dividing the grid into two grids along the XYZ direction and encrypting the two grids into 8 grids, or dividing the grid into two grids along the XY direction and encrypting the two grids into 4 grids.

[0019] In combination with the first aspect, in a possible implementation, recalculating the conductivity of the grid includes: calculating the conductivity between any two adjacent grids, and its calculation formula is:

[0020]

[0021] Among them, A l represents the area of the contact part of any two adjacent grids; k represents the grid permeability; D1 and D2 respectively represent the distances from the center points of any two adjacent grids to the common plane; c coor represents the local grid conductivity correction coefficient.

[0022] In a second aspect, an embodiment of the present invention provides a local grid encryption device for a shale oil reservoir, and the device includes:

[0023] A diversion calculation module, configured to embed a fracture into an original background grid and calculate the fracture conductivity;

[0024] An equivalent distance calculation module, configured to divide a fracture control area according to the fracture conductivity, calculate the conductivity between the grid in the fracture control area and the fracture, and further calculate the equivalent distance between the grid in the fracture control area and the fracture according to the conductivity;

[0025] A judgment module, configured to set a threshold value and judge the magnitude relationship between the equivalent distance and the threshold value;

[0026] A grid encryption module, configured to perform multiple double-grid encryptions on the grids whose conductivity is greater than or equal to the threshold value until the conductivity of all the grids is less than the threshold value;

[0027] A secondary conductivity calculation module, configured to recalculate the conductivity of the grids.

[0028] In combination with the second aspect, in a possible implementation manner, the diversion calculation module is configured to select different embedding methods to embed the fracture into the original background grid according to the relative positions of the fracture and the grid.

[0029] In combination with the second aspect, in a possible implementation manner, the equivalent distance calculation module is configured to calculate and delimit the fracture control area according to the following formula:

[0030] R D ={P|D(f,P)<c·t f},

[0031] where c represents a relaxation coefficient; D(f,P) represents the distance from point P to the fracture, and its calculation formula is: t f represents the fracture conductivity, and its calculation formula is: t f =k f d f where k frepresents the permeability of the embedded unit fracture; d f represents the fracture width.

[0032] Combined with the second aspect, in a possible implementation, the equivalent distance calculation module is used to calculate by using the grid equivalent distance method, and the calculation formula is:

[0033]

[0034] where A fm represents the area of the embedded fracture; k f represents the permeability of the embedded unit fracture; k m represents the permeability of the background unit; <d> represents the equivalent distance between the background grid and the embedded discrete fracture; n represents the normal vector of the embedded fracture; x represents the distance vector from a point in the background grid to the fracture; S represents the volume of the background grid.

[0035] Combined with the second aspect, in a possible implementation, the grid encryption module is used to divide the grid into two grids along the XYZ direction and encrypt the two grids into 8 grids, or divide the grid into two grids along the XY direction and encrypt the two grids into 4 grids.

[0036] Combined with the second aspect, in a possible implementation, the secondary conduction calculation module is used to calculate the conductivity between any two adjacent grids, and its calculation formula is:

[0037]

[0038] where A l represents the area of the contact part of the two adjacent grids; k represents the grid permeability; D1 and D2 respectively represent the distances from the center points of the two adjacent grids to the common plane; c coor represents the local grid conductivity correction coefficient.

[0039] In a third aspect, an embodiment of the present invention provides a local grid encryption server for a shale oil reservoir, including a memory and a processor;

[0040] The memory is used to store computer-executable instructions;

[0041] The processor is used to execute the computer-executable instructions to implement the method according to the first aspect and any one of the first aspect.

[0042] In a fourth aspect, an embodiment of the present invention provides a computer-readable storage medium, and the computer-readable storage medium stores executable instructions, and when the computer executes the executable instructions, it can implement the method according to the first aspect and any one of the first aspect.

[0043] One or more technical solutions provided in the embodiments of the present invention have at least the following technical effects or advantages:

[0044] In the embodiments of the present invention, a method, device and storage medium for locally encrypting grids in a shale reservoir are adopted. The method includes embedding fractures into the original background grid and calculating the fracture conductivity; dividing the fracture control area according to the fracture conductivity, calculating the conductivity between the grids and the fractures in the fracture control area, further calculating the equivalent distance between the grids and the fractures in the fracture control area according to the conductivity, setting a threshold value, and judging the size relationship between the equivalent distance and the threshold value; for the grids with conductivity greater than or equal to the threshold value, performing double-grid encryption multiple times until the conductivity of all grids is less than the threshold value; and recalculating the conductivity of the grids; embedding fractures into the original background grid, using the model to estimate the actual situation, and the size of the threshold value can be freely set, and the corresponding threshold value can be set according to the requirements of the calculation results, screening out the grids that need to be encrypted and performing encryption, effectively solving the problem in the prior art that local grids cannot be encrypted, realizing the encryption of local grids, reducing the influence of unsteady-state seepage on the accuracy of flow calculation, and improving the numerical simulation accuracy of the discrete fracture model embedded in the shale reservoir. Description of the Drawings

[0045] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required for the description of the embodiments of the present invention or the prior art. Obviously, the following drawings are some embodiments of the present invention. For those of ordinary skill in the art, other drawings can be obtained based on these drawings without creative efforts.

[0046] Figure 1 It is a flowchart of the grid encryption method provided in the embodiments of the present application;

[0047] Figure 2 It is a schematic diagram of different fractures embedded in the original background grid provided in the embodiments of the present application;

[0048] Figure 3 It is a schematic diagram of the fracturing horizontal model of the shale reservoir provided in the embodiments of the present application;

[0049] Figure 4 It is a schematic diagram of fractures embedded in the original background grid provided in the embodiments of the present application;

[0050] Figure 5 It is a schematic diagram of dividing the fracture control area provided in the embodiments of the present application;

[0051] Figure 6 It is a schematic diagram of the local grid encryption area provided in the embodiments of the present application;

[0052] Figure 7 Schematic diagram of the first encryption result of the local grid provided by the embodiment of the present application;

[0053] Figure 8 Schematic diagram of the second encryption result of the local grid provided by the embodiment of the present application;

[0054] Figure 9 Schematic diagram of the local grid encryption device for shale oil reservoirs provided by the embodiment of the present application;

[0055] Figure 10 Schematic diagram of the local grid encryption server for shale oil reservoirs provided by the embodiment of the present application. Detailed implementation manners

[0056] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, rather than all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

[0057] At present, shale oil in China has the following characteristics: (1) The permeability of the shale matrix is extremely low, only a few hundred nanodarcies to microdarcies, which is one millionth of that of conventional oil reservoir reservoirs. Microfractures, horizontal bedding fractures, and secondary pores formed by constructive diagenesis are the main spaces for the occurrence of free liquid hydrocarbons, and it is difficult to effectively exploit them by conventional development methods; (2) Due to the relatively high degree of thermal evolution, it is in the window where liquid hydrocarbons and gaseous hydrocarbons coexist. It is mainly composed of crude oil with a relatively small density, light oil quality, high gas-oil ratio, and good fluidity. Economic development can be achieved by relying on horizontal well volume fracturing technology; (3) The content of brittle minerals in continental mixed sedimentary rocks and carbonate-bearing shale formations is high. By using artificial fracturing and transformation technology to form an effective artificial fracture network system, a relatively high single-well production and cumulative EUR (cumulative production of a single well) can be achieved.

[0058] Research and practice have shown that horizontal well + volume fracturing is an effective way to achieve large-scale development of continental shale oil reservoirs: The fracture network formed by hydraulic fracturing provides a high-permeability channel for fluid flow, increasing the formation permeability while expanding the contact area between the reservoir and the wellbore, thereby achieving the effect of increasing production.

[0059] To further achieve refined and economical development, an efficient and equivalent productivity prediction method for fractured horizontal wells is required. In order to accurately characterize the influence of the fracture network on fluid flow, people have begun to represent fractures based on the discrete fracture model. The discrete fracture model (full name: Discrete_Fracture_Network, abbreviated: DFM) is a model that describes fractures completely and explicitly according to their actual distribution and morphology. Its development stems from the proposal of the discrete fracture modeling (full name: Discrete Fracture Network Model, abbreviated: DFN) method in the 1970s and has evolved with the widespread use of artificial fracturing technology in unconventional oil and gas reservoirs. Early discrete fracture models were all based on conforming grids, that is, fractures were regarded as internal boundaries and used as constraint surfaces for grid meshing.

[0060] Due to the complexity of fracture geometry, unstructured grid technology needs to be adopted, and its meshing process is very complex and cumbersome. Especially when the distance or angle between fractures is very small, it often leads to calculation difficulties due to poor grid quality. In response, Lee et al. and Moinfar et al. proposed the embedded discrete fracture model (full name: Embedded Discrete FractureModel, abbreviated: EDFM). This model directly embeds the fracture network into the bedrock structured grid system, avoiding the above complex unstructured grid meshing process. Although the geometric information between fractures and grids still needs to be calculated, compared with the complex unstructured grid meshing process, its computational complexity is greatly reduced, thus improving the computational efficiency. For the volume fracturing reform area of the embedded discrete fracture model, a higher-precision (higher-resolution) grid is required to reduce the influence of matrix-fracture unsteady seepage on the flow calculation accuracy. However, if a high-precision grid system is adopted throughout the area, it will greatly increase the number of model calculation nodes and significantly reduce the computational efficiency. Therefore, the optimal method is to adopt the local grid refinement method and only refine the grid in the volume fracturing reform area. However, there is currently a lack of targeted local grid refinement technology, resulting in the still use of a uniform grid model for numerical simulation calculations.

[0061] The embodiment of the present invention provides a local grid refinement method for shale oil reservoirs, as Figure 1 shown. This method includes the following steps S101 to S105.

[0062] S101, embed the fractures into the original background grid and calculate the fracture conductivity.

[0063] S102, divide the fracture control area according to the fracture conductivity, calculate the conductivity between the grids and fractures in the fracture control area, and further calculate the equivalent distance between the grids and fractures in the fracture control area according to the conductivity.

[0064] S103. Set the threshold value and determine the magnitude relationship between the equivalent distance and the threshold value.

[0065] S104. For the grids with conductivity greater than or equal to the threshold value, perform double-grid encryption multiple times until the conductivity of all grids is less than the threshold value.

[0066] S105. Recalculate the conductivity of the grids.

[0067] The method provided by this application can perform local encryption on the grids that need to be encrypted, thereby reducing the computational pressure and improving the computational efficiency. The method provided by this application can perform grid encryption only within the volume fracturing transformation area, which can reduce the impact of matrix-fracture unsteady seepage on the accuracy of flow calculation and improve the data simulation calculation accuracy of the shale reservoir embedded fracture model.

[0068] In step S101, embedding the fractures into the original background grid includes: according to the relative positions of the fractures and the grids, selecting different embedding methods to embed the fractures into the original background grid. Embedding the volume fracturing sealing network for discrete fracture modeling, that is: calculating the geometric intersection relationship between the fractures and the deformation and the background grid, intercepting the polygon parts falling within the target background grid, and cutting the fracture polygons into many small polygons. According to the relative positions of the fractures and the grids, there are different embedding situations, such as Figure 2 The figures show different situations of embedding the fractures into the original background grid.

[0069] In step S102, dividing the fracture control area according to the fracture conductivity includes: calculating and demarcating the fracture control area according to the following formula:

[0070] R D ={P|D(f,P)<c·t f},

[0071] where c represents the relaxation coefficient; D(f,P) represents the distance from point P to the fracture, and its calculation formula is: t f represents the fracture conductivity, and its calculation formula is: t f [[ID=�4]]=k f d f , where k f represents the permeability of the embedded unit fracture; d f represents the fracture width.

[0072] In step S102, calculating the conductivity between the grids within the fracture control area and the fractures includes: calculating using the grid equivalent distance method, and the calculation formula is:

[0073]

[0074] Among them, A fm represents the area of the embedded fracture; k f represents the permeability of the unit embedded fracture; k m represents the permeability of the background unit; <d> represents the equivalent distance between the background grid and the embedded discrete fracture; n represents the normal vector of the embedded fracture; x represents the distance vector from a point in the background grid to the fracture; S represents the volume of the background grid.

[0075] In steps S102 and S103, the fracture control area is divided according to the fracture conductivity. For the divided area, the fracture conductivity is calculated and compared with the set threshold value. In this process, since the threshold value is set, that is, the threshold value can be set according to one's own requirements for the result. If more accurate calculation results are needed, the threshold value is set smaller. If faster calculation speed is needed, the threshold value is set larger. For accuracy and calculation speed, a trade-off is made according to the actual situation during use.

[0076] In step S104, double-grid encryption is performed, including: dividing the grid into two grids along the XYZ directions and encrypting the two grids into 8 grids, or dividing the grid into two grids along the XY directions and encrypting the two grids into 4 grids. It should be noted in step S104 that in order to improve the calculation accuracy of the model, the grid is not necessarily the grid where the fracture actually intersects, that is, all grids within the fracture control area need to be judged.

[0077] The grid that has been encrypted once is judged again. The judgment condition is the condition in step S103. If it does not meet the condition, double-grid encryption is performed here again. Of course, the double-grid mentioned here is just a kind of encrypted grid, and it can also be multi-grid encryption.

[0078] Since the model adopts multi-grid local encryption, conventional reservoir numerical simulation suddenly cannot be directly analyzed, and the conductivity between adjacent grids needs to be recalculated as the reservoir numerical value. In step S105, the conductivity of the grid is recalculated again, including: calculating the conductivity between any two adjacent grids, and its calculation formula is:

[0079]

[0080] Among them, A l represents the area of the contact part between any two adjacent grids; k represents the grid permeability; D1 and D2 respectively represent the distances from the center points of any two adjacent grids to the common plane; c coor represents the local grid conductivity correction coefficient. The calculation formula of c coor is: Among them, DH12 Denotes the square of the horizontal component of the connecting line between the centers of any two adjacent grids, DV 12 Denotes the square of the vertical component of the connecting line between the centers of any two adjacent grids. Wherein, P1 and P2 are the coordinates of the centers of any two adjacent grids respectively, and are the unit vectors in the x, y, and z directions respectively.

[0081] The present application provides a specific embodiment to illustrate this method. As Figure 3 shown is a schematic diagram of a fractured horizontal well model in a shale reservoir. The detailed parameters are shown in Table 1.

[0082] Table 1 Mechanism model parameters

[0083]

[0084] Combining steps S101 and S102 to embed the fracture into the original background grid and divide the fracture control area, such as Figure 4 the irregular grid area in. Combining step S103 to calculate the equivalent distance and divide the local grid encryption area, such as Figure 5 shown. According to S104, grid encryption is performed on the local grid encryption area, such as Figure 6 shown, which is a schematic diagram of the local grid encryption area, Figure 7 and Figure 8 are the diagrams of the first encryption and second encryption results respectively. According to step S105, the conductivity is calculated, and the calculation results are compared with the original model and compared with the reference model with a 5m grid size, as shown in Table 2.

[0085] Table 2 Comparison model parameters

[0086]

[0087] The embodiment of the present invention provides a local grid encryption device for a shale reservoir, such as Figure 9 shown. The device includes: a diversion calculation module 901, an equivalent distance calculation module 902, a judgment module 903, a grid encryption module 904, and a secondary conduction calculation module 905.

[0088] The diversion calculation module 901 is used to embed the fracture into the original background grid and calculate the fracture conductivity; the diversion calculation module 901 is used to select different embedding methods to embed the fracture into the original background grid according to the relative position of the fracture and the grid.

[0089] The equivalent distance calculation module 902 is used to divide the fracture control area according to the fracture conductivity, calculate the conductivity between the grid in the fracture control area and the fracture, and further calculate the equivalent distance between the grid in the fracture control area and the fracture according to the conductivity. The equivalent distance calculation module 902 is used to calculate and delimit the fracture control area according to the following formula: R D ={P|D(f,P) < c·t f}, where c represents the relaxation coefficient; D(f,P) represents the distance from point P to the fracture, and its calculation formula is:

[0090] t f represents the fracture conductivity, and its calculation formula is: t f = k f d f , where k f represents the permeability of the unit fracture; d f represents the fracture width. The equivalent distance calculation module 902 is used to calculate by the grid equivalent distance method, and the calculation formula is: where A fm represents the area of the embedded fracture; k f represents the permeability of the unit fracture; k m represents the permeability of the background unit; <d> represents the equivalent distance between the background grid and the embedded discrete fracture; n represents the normal vector of the embedded fracture; x represents the distance vector from a point in the background grid to the fracture; S represents the volume of the background grid.

[0091] The judgment module 903 is used to set a threshold value and judge the size relationship between the equivalent distance and the threshold value.

[0092] The grid encryption module 904 is used to perform multiple two-fold grid encryptions on the grids with conductivity greater than or equal to the threshold value until the conductivity of all grids is less than the threshold value; the grid encryption module 904 is used to divide the grid into two grids along the XYZ direction and encrypt the two grids into 8 grids, or divide the grid into two grids along the XY direction and encrypt the two grids into 4 grids.

[0093] The secondary conductivity calculation module 905 is used to recalculate the conductivity of the grids. The secondary conductivity calculation module 905 is used to calculate the conductivity between any two adjacent grids, and its calculation formula is: where A l represents the area of the contact part between any two adjacent grids; k represents the grid permeability; D1 and D2 respectively represent the distances from the center points of any two adjacent grids to the common plane; c coor represents the local grid conductivity correction coefficient.

[0094] The devices or modules illustrated in the above embodiments can be specifically implemented by computer chips or entities, or by products with certain functions. For the convenience of description, when describing the above devices, they are divided into various modules according to functions and described separately. When implementing the present application, the functions of each module can be implemented in the same or multiple software and / or hardware. Of course, the module that implements a certain function can also be implemented by combining multiple sub-modules or sub-units.

[0095] An embodiment of the present invention provides a local grid encryption server for shale reservoirs, as Figure 10 shown, including a memory 1001 and a processor 1002; the memory 1001 is used to store computer-executable instructions; the processor 1002 is used to execute the computer-executable instructions to implement the method provided by the present application.

[0096] An embodiment of the present invention provides a computer-readable storage medium, and the computer-readable storage medium stores executable instructions, and when the computer executes the executable instructions, it can implement the method provided by the present application.

[0097] The above storage medium includes, but is not limited to, random access memory (English: Random Access Memory; abbreviation: RAM), read-only memory (English: Read-Only Memory; abbreviation: ROM), cache (English: Cache), hard disk (English: Hard Disk Drive; abbreviation: HDD) or memory card (English: Memory Card). The memory can be used to store computer program instructions.

[0098] The methods, devices or modules described in this application can be implemented in the form of computer-readable program code. The controller can be implemented in any appropriate manner. For example, the controller can take the form of, for example, a microprocessor or a processor, and a computer-readable medium that stores computer-readable program code (such as software or firmware) executable by the (micro)processor, logic gates, switches, application specific integrated circuits (ASICs), programmable logic controllers, and embedded microcontrollers. Examples of controllers include, but are not limited to, the following microcontrollers: ARC 625D, Atmel AT91SAM, Microchip PIC18F26K20, and Silicone Labs C9051F320. The memory controller can also be implemented as part of the control logic of the memory. Those skilled in the art also know that in addition to implementing the controller in the form of pure computer-readable program code, the method steps can be logically programmed to enable the controller to be implemented in the form of logic gates, switches, application specific integrated circuits, programmable logic controllers, and embedded microcontrollers to achieve the same function. Therefore, such a controller can be considered a hardware component, and the devices included therein for implementing various functions can also be regarded as the structures within the hardware component. Or even, the devices for implementing various functions can be regarded as either software modules for implementing the method or the structures within the hardware component.

[0099] From the description of the above embodiments, those skilled in the art can clearly understand that this application can be implemented by means of software plus necessary hardware. Based on this understanding, the technical solution of this application, in essence or the part that contributes to the prior art, can be embodied in the form of a software product, or can also be reflected in the implementation process of data migration. This computer software product can be stored in a storage medium, such as ROM / RAM, magnetic disk, optical disk, etc., and includes several instructions to enable a computer device (which can be a personal computer, a mobile terminal, a server, or a network device, etc.) to execute the methods described in various embodiments or some parts of the embodiments of this application.

[0100] The above embodiments are only used to illustrate the technical solution of this application, rather than to limit this application. Although this application has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that they can still modify the technical solution described in the foregoing embodiments, or perform equivalent replacements on some or all of the technical features therein; and these modifications or replacements do not cause the essence of the corresponding technical solution to deviate from the scope of the technical solution of this application.

Claims

1. A method for locally encrypting a shale reservoir grid, characterized in that Including: Embedding the fracture into the original background grid and calculating the fracture conductivity; Dividing the fracture control area according to the fracture conductivity, calculating the conductivity between the grid in the fracture control area and the fracture, and further calculating the equivalent distance between the grid in the fracture control area and the fracture according to the conductivity; Setting a threshold value and judging the magnitude relationship between the equivalent distance and the threshold value; For the grids with conductivity greater than or equal to the threshold value, performing double-grid encryption multiple times until the conductivity of all grids is less than the threshold value; And recalculating the conductivity of the local grid encryption model.

2. The method according to claim 1, wherein The embedding of the fracture into the original background grid includes: selecting different embedding methods to embed the fracture into the original background grid according to the relative position between the fracture and the grid.

3. The method according to claim 1, wherein The dividing of the fracture control area according to the fracture conductivity includes: calculating and demarcating the fracture control area according to the following formula: R D = {P | D(f, P) < c · t f}, where c represents the relaxation coefficient; D(f, P) represents the distance from point P to the fracture, and its calculation formula is: t f represents the fracture conductivity, and its calculation formula is: t f = k f d f , where k f represents the permeability of the unit fracture; d f represents the fracture width.

4. The method according to claim 1, wherein The calculating of the conductivity between the grid in the fracture control area and the fracture includes: calculating by using the grid equivalent distance method, and the calculation formula is: Among them, A fm represents the area of the embedded crack; k f represents the permeability of the unit embedded crack; k m represents the permeability of the background unit; D * represents the equivalent distance between the background grid and the embedded discrete crack; n represents the normal vector of the embedded crack; x represents the distance vector from a point in the background grid to the crack, and S represents the volume of the background grid.

5. The method according to claim 1, characterized in that, The performing of double-grid encryption includes: dividing the grid into two grids along the XYZ direction and encrypting the two grids into 8 grids, or dividing the grid into two grids along the XY direction and encrypting the two grids into 4 grids.

6. The method according to claim 1, characterized in that, The recalculating of the conductivity of the grid includes: calculating the conductivity between any two adjacent grids, and the calculation formula is: Among them, A l represents the area of the contact part of any two adjacent grids; k represents the grid permeability; D1 and D2 respectively represent the distances from the center points of any two adjacent grids to the common surface; c coor represents the local grid conductivity correction coefficient.

7. A local grid encryption device for a shale oil reservoir, characterized in that Including: A flow calculation module for embedding the fracture into the original background grid and calculating the fracture conductivity; An equivalent distance calculation module for dividing the fracture control area according to the fracture conductivity, calculating the conductivity between the grid in the fracture control area and the fracture, and further calculating the equivalent distance between the grid in the fracture control area and the fracture according to the conductivity; A judgment module for setting a threshold value and judging the magnitude relationship between the equivalent distance and the threshold value; A grid encryption module for performing double-grid encryption multiple times on the grids with conductivity greater than or equal to the threshold value until the conductivity of all grids is less than the threshold value; A secondary conductivity calculation module for recalculating the conductivity of the local grid encryption model.

8. A local grid encryption server for a shale reservoir, characterized in that Including a memory and a processor; The memory is used to store computer-executable instructions; The processor is used to execute the computer-executable instructions to implement the method according to any one of claims ① - ⑥.

9. A computer-readable storage medium, characterized in that, The computer-readable storage medium stores executable instructions, and when the computer executes the executable instructions, it can implement the method according to any one of claims ① - ⑥. Note: In the above translation, "① - ⑥" in claim 20 and 21 should be replaced with the actual claim numbers in the original text. Since the original claim numbers are not provided in the question, this is a placeholder for now.

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