Heterogeneous reservoir porosity and permeability relation construction method, device and equipment and storage medium

Abstract

The invention belongs to the technical field of oil and gas reservoir prediction, and discloses a heterogeneous reservoir porosity-permeability relation construction method, which comprises the following steps: respectively calculating the volume percentage of connected pores, the equivalent structure parameter of the connected pores and the permeability of the connected pores, and dividing the reservoir types through the equivalent structure parameter gamma of the connected pores to obtain the porosity-permeability relation of the connected pores. When the gamma of the reservoir sample is greater than 0.005, the reservoir sample is defined as a class I pore, and when the gamma of the reservoir sample is less than or equal to 0.005, the reservoir sample is defined as a class II pore; respectively establishing a pore-permeability relationship between the volume percentage alpha of the connected pores of the I-type pore sample and the II-type pore sample and the absolute permeability k of the connected pore space, so as to realize the pore-permeability relationship construction based on the connected pore equivalent structure; the invention further discloses a heterogeneous reservoir porosity and permeability relation construction device and equipment and a storage medium. The method is used for carrying out fine construction of the porosity and permeability relation for the heterogeneous reservoir, a more reasonable porosity and permeability relation is provided for fine development of different types of reservoirs, and therefore the permeability prediction precision of the heterogeneous reservoir is improved.

Description

Technical Field

[0001] The invention belongs to the technical field of oil and gas reservoir prediction, and relates to a method, a device, a equipment and a storage medium for constructing a porosity-permeability relationship of a heterogeneous reservoir. Background Art

[0002] The calculation of permeability plays a vital role in the development of oil and gas reservoirs. At present, the permeability is mainly calculated by using the porosity-permeability relationship based on the porosity inversion results. The accuracy of the porosity-permeability relationship affects the accuracy of the prediction of the permeability of oil and gas reservoirs and is a key indicator for predicting the sweet spots of high-quality reservoirs during oil and gas exploration and development. Therefore, the construction of a fine porosity-permeability relationship plays a decisive role in the calculation of the permeability of oil and gas reservoirs and becomes a core factor affecting the formulation of oil and gas development plans.

[0003] The internal space of rock pores, especially in heterogeneous reservoirs, is extremely complex. The internal space characteristics of pores in different types of reservoirs vary greatly. In particular, unconventional oil and gas reservoirs have strong heterogeneity, multi-scale pore space development, and large differences in pore structure characteristics. As a result, the porosity and permeability relationship inside the reservoir is very complex. Especially in the case of similar porosity, the difference in pore structure will lead to a difference of two orders of magnitude in the permeability of the reservoir. If the porosity and permeability relationship is established without considering the difference in pore structure, the accuracy of reservoir sweet spot prediction will be seriously restricted. At present, in practical applications, rock physics experiments or logging data are usually used to obtain porosity and permeability parameters and construct porosity and permeability relationships. However, the parameters obtained by these methods cannot be linked to their corresponding pore structure characteristics, and cannot distinguish the effects of different pore structures in heterogeneous reservoirs on permeability. The porosity and permeability relationship constructed on this basis is difficult to reasonably describe the porosity and permeability relationship of heterogeneous reservoirs, and cannot meet the permeability prediction needs of heterogeneous reservoirs with different pore structures.

[0004] Therefore, for complex oil and gas reservoirs with strong heterogeneity, it is urgent to develop a porosity-permeability relationship construction method that can fully consider the influence of differences in pore structure characteristics, accurately characterize the differential changes in porosity-permeability relationships within heterogeneous reservoirs, and provide a more reasonable and reliable model and basis for the calculation of oil and gas reservoir permeability, so as to more accurately calculate the permeability of heterogeneous reservoirs based on porosity data. Summary of the invention

[0005] The purpose of the present invention is to provide a method for constructing the porosity-permeability relationship of heterogeneous reservoirs. By introducing digital rock physics technology to carry out precise calculations on connected pores, the volume percentage of connected pores, the equivalent structural parameters of connected pores and the permeability of connected pores are obtained, and the classification construction of the porosity-permeability relationship is realized under the guidance of the equivalent structural parameters of connected pores, thereby obtaining a more precise porosity-permeability relationship for heterogeneous reservoirs.

[0006] Another object of the present invention is to provide a device, equipment and storage medium for constructing the porosity-permeability relationship of a heterogeneous reservoir, which can effectively improve the precision of the porosity-permeability relationship construction and provide a more reasonable basis for the calculation of the permeability of the heterogeneous reservoir.

[0007] In order to achieve the above object, the technical solution adopted by the present invention is as follows:

[0008] A method for constructing a porosity-permeability relationship of a heterogeneous reservoir comprises the following steps:

[0009] S1. Calculate the volume percentage of connected pores

[0010] Obtain a three-dimensional core image of the reservoir in the target area, determine connected pore clusters in the three-dimensional core image based on grid search, obtain connected pore space A according to the connected pore clusters, and calculate the connected pore volume percentage α of the connected pore space A;

[0011] S2. Calculate the equivalent structural parameters of connected pores

[0012] Use the structural element B to perform mathematical morphological expansion operation on the connected pore space A to obtain the pore space C; calculate the difference between the pore space C and the connected pore space A to obtain the surface pixel points of the connected pores, and traverse and count the number of surface pixel points of the connected pores N Surface , the equivalent structural parameter γ of the connected pores is obtained;

[0013] S3. Calculate the permeability of connected pores

[0014] According to the connected pore space A, the two opposite end faces in the coordinate axis direction of the core in the three-dimensional core image are set as the fluid injection end and the outflow end respectively, and the pressure difference between the fluid injection end and the outflow end is set to simulate the flow of single-phase fluid in the connected pore space A under the action of pressure gradient. When the flow velocity and flow rate reach stability, the absolute permeability k of the connected pore space is calculated;

[0015] S4. Construction of porosity-permeability relationship guided by equivalent structure of connected pores by type

[0016] The reservoir types are divided according to the equivalent structural parameter γ of the connected pores. When the reservoir sample γ>0.005, it is defined as Type I pores, and when the reservoir sample γ≤0.005, it is defined as Type II pores. The least squares fitting is used to establish the porosity-permeability relationship between the connected pore volume percentage α and the absolute permeability k of the connected pore space for Type I and Type II pore reservoir samples, respectively, to achieve the construction of the porosity-permeability relationship based on the equivalent structure of the connected pores.

[0017] As a limitation, in step S1, the connected pore clusters in the three-dimensional core image are determined based on the grid search, the connected pore space A is obtained according to the connected pore clusters, and the specific process of calculating the connected pore volume percentage α of the connected pore space A is:

[0018] Each pixel in the three-dimensional core image is set as a grid, the status of the pixels located in the pores is set to "occupied", and the status of the remaining pixels is set to "free";

[0019] If the edge of a pore pixel does not touch a pixel with the "occupied" state, the pore pixel is regarded as a new pore cluster and is assigned a new pore cluster label;

[0020] If the edge of a pore pixel contacts a pixel with the state "occupied", the pore pixel and the "occupied" pixel it contacts are regarded as a pore cluster, and the same pore cluster label as the pore pixel is used; where the number of pore cluster labels is i (i = 1, 2, ..., N), and N is the total number of pore clusters;

[0021] Determine whether there are pore clusters with the same pore cluster mark on two opposite end faces in the coordinate axis direction of the core in the three-dimensional core image. If so, the pore cluster forms a fluid migration channel running through the core, and all pixel points belonging to the pore cluster belong to the connected pore cluster; if there are multiple connected pore clusters, the pixels of all connected pore clusters belong to the connected pore space A;

[0022] Count the number of all pixels N in the three-dimensional core image Total , and count the number of all connected pore pixels N in the connected pore space A Percolated , calculate the connected pore volume percentage α of the connected pore space;

[0023]

[0024] As a further limitation, in step S2, the structural element B is set to a sphere with a radius of 1;

[0025] The calculation formula of pore space C is:

[0026]

[0027] in, is an empty set, and the pore space C is the result of the connected pore space A being expanded by the structural element B, denoted as is the dilation operator, x is the translation distance, is the space obtained by translating the structural element B by x;

[0028] The calculation formula of the equivalent structural parameter γ of the connected pores is:

[0029]

[0030] As a second limitation, in step S3, a lattice Boltzmann algorithm is used to simulate the flow of a single-phase fluid in a connected pore space A under the action of a pressure gradient;

[0031] The absolute permeability k of the connected pore space is calculated according to Darcy's law:

[0032]

[0033] Where, μ is the viscosity of the fluid, mPa·s; ΔP is the pressure difference between the fluid injection end and the outflow end, MPa; Q is the flow rate through the core, cm 3 / s; S is the cross-sectional area of ​​the core perpendicular to the coordinate axis of the core in the three-dimensional core image, cm 2 ; L is the length of the core in the three-dimensional core image in the direction of the coordinate axis where the core is located;

[0034]

[0035] The present invention also provides a device for constructing a porosity-permeability relationship of a heterogeneous reservoir, comprising:

[0036] A connected pore volume percentage calculation module is used to obtain a three-dimensional core image of a reservoir in a target area, determine connected pore clusters in the three-dimensional core image based on a grid search, obtain a connected pore space A based on the connected pore clusters, and calculate a connected pore volume percentage α of the connected pore space A;

[0037] The equivalent structural parameter calculation module of the connected pores is used to use the structural element B to perform mathematical morphological expansion operation on the connected pore space A to obtain the pore space C; calculate the difference between the pore space C and the connected pore space A to obtain the surface pixel points of the connected pores, and traverse and count the number of surface pixel points of the connected pores N Surface , the equivalent structural parameter γ of the connected pores is obtained;

[0038] The connected pore permeability calculation module is used to set the two opposite end faces of the core in the three-dimensional core image in the direction of the coordinate axis as the fluid injection end and the outflow end respectively according to the connected pore space A, set the pressure difference between the fluid injection end and the outflow end, simulate the flow of single-phase fluid in the connected pore space A under the action of pressure gradient, and calculate the absolute permeability k of the connected pore space when the flow velocity and flow rate reach stability;

[0039] The porosity-permeability relationship construction module is used to classify reservoir types according to the equivalent structural parameter γ of connected pores. When the reservoir sample γ>0.005, it is defined as Class I pores, and when the reservoir sample γ≤0.005, it is defined as Class II pores. The least squares fitting is used to establish the porosity-permeability relationship between the connected pore volume percentage α and the absolute permeability k of the connected pore space of Class I and Class II pore reservoir samples, respectively, to realize the construction of the porosity-permeability relationship based on the equivalent structure of connected pores.

[0040] The present invention also provides a computer device, which includes a processor and a memory, wherein the memory is used to store at least one computer program, and the at least one computer program is loaded by the processor and executes the method for constructing a porosity-permeability relationship of a heterogeneous reservoir.

[0041] The present invention also provides a storage medium, wherein the storage medium is used to store at least one section of a computer program, and the at least one section of the computer program is used to execute the method for constructing the porosity-permeability relationship of a heterogeneous reservoir.

[0042] Due to the adoption of the above technical solution, the present invention has the following technical advances compared with the prior art:

[0043] (1) The present invention introduces digital rock physics technology to carry out precise calculations on connected pores, obtain the volume percentage of connected pores, equivalent structural parameters of connected pores and permeability of connected pores, and realize the classification construction of porosity-permeability relationship under the guidance of equivalent structural parameters of connected pores, thereby obtaining a more precise porosity-permeability relationship of heterogeneous reservoirs;

[0044] (2) The fine porosity-permeability relationship correlation coefficients of type I pores and type II pores constructed based on the equivalent structure of connected pores in the present invention can reach 0.90 and 0.67, respectively. Compared with the porosity-permeability relationship correlation coefficient of 0.45 established with the same sample data without considering the pore structure, it not only effectively distinguishes the differences in heterogeneous reservoir characteristics, but also greatly improves the accuracy of the porosity-permeability relationship, providing a more reasonable basis for the calculation of the permeability of heterogeneous reservoirs.

[0045] In summary, the present invention is used to carry out fine construction of the porosity-permeability relationship for heterogeneous reservoirs, realize fine quantitative characterization of the complex porosity-permeability relationship of heterogeneous reservoirs, provide a more reasonable porosity-permeability relationship for the fine development of different types of reservoirs, and thus improve the permeability prediction accuracy of heterogeneous reservoirs. BRIEF DESCRIPTION OF THE DRAWINGS

[0046] Figure 1 Shown is a flow chart of the method of embodiment 1 of the present invention;

[0047] FIG2( a ) is a schematic diagram showing pixels of a three-dimensional core image in Example 1 of the present invention;

[0048] FIG2( b ) is a schematic diagram showing the pore cluster labeling in Example 1 of the present invention;

[0049] FIG3( a ) shows a three-dimensional grayscale image of a core in a connected pore space A in Example 1 of the present invention;

[0050] FIG3( b ) is a connectivity analysis diagram of the connected pore space A in Example 1 of the present invention;

[0051] FIG4( a ) is a schematic diagram showing the measurement of the surface area of ​​the interconnected pores in Example 1 of the present invention;

[0052] FIG4( b ) is a schematic diagram of surface pixels of connected pores in Example 1 of the present invention;

[0053] Figure 5 It is a schematic diagram of the simulation of the flow velocity distribution of the connected pore space A in Example 1 of the present invention;

[0054] Figure 6 Shown is a comparison diagram of the porosity-permeability relationship based on the connected pore equivalent structure of Example 1 of the present invention and the original result;

[0055] Figure 7 FIG. 2 is a block diagram of a device according to Embodiment 2 of the present invention;

[0056] Figure 8 FIG. 2 is a schematic diagram showing the structure of a computer device according to Embodiment 2 of the present invention;

[0057] Fig. 9 Shown is a schematic diagram of the structure of the computer storage medium of embodiment 2 of the present invention. DETAILED DESCRIPTION

[0058] In order to better explain the present invention and facilitate understanding, the present invention is described in detail below through specific implementation modes in conjunction with the accompanying drawings.

[0059] Example 1 A method for constructing a porosity-permeability relationship of a heterogeneous reservoir

[0060] like Figure 1 As shown, this embodiment provides a method for constructing a porosity-permeability relationship of a heterogeneous reservoir, comprising the following steps:

[0061] S1. Calculate the volume percentage of connected pores

[0062] Obtain a three-dimensional core image of the reservoir in the target area, determine connected pore clusters in the three-dimensional core image based on grid search, obtain connected pore space A according to the connected pore clusters, and calculate the connected pore volume percentage α of the connected pore space A;

[0063] In this step, the connected pore clusters in the three-dimensional core image are determined based on the grid search, and the connected pore space A is obtained according to the connected pore clusters. The specific process of calculating the connected pore volume percentage α of the connected pore space A is as follows:

[0064] As shown in Figure 2(a), each pixel in the 3D core image is set as a grid, the status of the pixels located in the pores is set to “occupied” and recorded as pore pixels, and the status of the remaining pixels is set to “idle”;

[0065] If the edge of a pore pixel does not touch a pixel with the "occupied" state, the pore pixel is regarded as a new pore cluster and is assigned a new pore cluster label;

[0066] If the edge of a pore pixel contacts a pixel with the state "occupied", the pore pixel and the "occupied" pixel it contacts are regarded as a pore cluster, and the same pore cluster label as the pore pixel is used; where the number of pore cluster labels is i (i = 1, 2, ..., N), and N is the total number of pore clusters;

[0067] As shown in FIG2(b), it is a schematic diagram of pore cluster marking. It can be seen from the figure that the number of pore cluster markings is 1 to 4, wherein pore cluster marking 1 is that there is a pixel in the "occupied" state at the edge of the pore pixel, so the pore pixel and the "occupied" pixel in contact are regarded as a pore cluster and represented by pore cluster marking 1; pore cluster marking 2 is that there is no pixel in the "occupied" state at the edge of the pore pixel, so the pore pixel is regarded as a new pore cluster and represented by pore cluster marking 2, and the same applies to pore cluster marking 3 and pore cluster marking 4;

[0068] Determine whether there is a pore cluster with the same pore cluster mark on the two opposite end faces in the X-axis direction in the coordinate axis where the core is located in the three-dimensional core image. If so, the pore cluster forms a fluid migration channel running through the core, and all pixel points belonging to the pore cluster belong to the connected pore cluster; if there are multiple connected pore clusters, the pixels of all connected pore clusters belong to the connected pore space A;

[0069] As shown in FIG3( a ), the obtained three-dimensional grayscale image of the core in the connected pore space A is shown. The three-dimensional grayscale image of the core in the figure is the original image of the core, and the connected pore space therein is the connected pore space A;

[0070] Figure 3(b) shows the connectivity analysis diagram of the connected pore space A. The green area in the figure is the connected pore space A, and the non-connected pores and rock skeleton are set to be transparent;

[0071] Count the number of all pixels N in the three-dimensional core image Total , and count the number of all connected pore pixels N in the connected pore space A Percolated, calculate the connected pore volume percentage α of the connected pore space;

[0072]

[0073] The core size of the 3D core image taken in this step is 300*300*300, and the number of all pixels in the 3D core image is M. Total = 27000000, the number of all connected pore pixels in the pore space A is N Percolated =2475630, so

[0074] S2. Calculate the equivalent structural parameters of connected pores

[0075] Use the structural element B to perform mathematical morphological expansion operation on the connected pore space A, and obtain the pore space C through the expansion operation;

[0076] In this step, the structural element B is set to a sphere with a radius of 1;

[0077] The calculation formula of pore space C is:

[0078]

[0079] in, is an empty set, and the pore space C is the result of the connected pore space A being expanded by the structural element B, denoted as is the dilation operator, x is the translation distance, is the space obtained by translating the structural element B by x; the expansion operation process described by this formula is that the structural element B first maps about its origin and then translates x; the expansion operation of the connected pore space A by the structural element B is After being translated by all x, there is at least one non-zero common element with the connected pore space A;

[0080] The difference between the pore space C and the connected pore space A is calculated to obtain the surface pixel points of the connected pores. FIG4(a) is a schematic diagram of the connected pore surface area measurement. The circle in the figure shows the pore space C obtained after the connected pore space A is expanded by the structural element B. The difference between the pore space C and the connected pore space A is calculated to obtain the surface pixel points of the connected pores. FIG4(b) is a schematic diagram of the surface pixel points of the connected pores. The number N of the surface pixel points of the connected pores is traversed and counted. Surface , the equivalent structural parameter γ of the connected pores is obtained;

[0081] The calculation formula of the equivalent structural parameter γ of the connected pores is:

[0082]

[0083] The number of surface pixels of connected pores taken in this step is N Surface =148537, then the equivalent structural parameters of the connected pores are obtained

[0084] S3. Calculate the permeability of connected pores

[0085] According to the connected pore space A, the coordinate axis of the core in the three-dimensional core image, that is, the two opposite end faces in the X-axis direction, are set as the fluid injection end and the outflow end respectively, and the pressure difference between the fluid injection end and the outflow end is set. The lattice Boltzmann algorithm is used to simulate the flow of single-phase fluid in the connected pore space A under the action of the pressure gradient, that is, the pressure difference between the fluid injection end and the outflow end, as shown in Figure 5 The figure shows a schematic diagram of the simulation of the flow velocity distribution of the connected pore space A. It can be seen from the figure that the fluid flows in from the left side along the X-axis direction and flows out from the right side. The curved streamlines in the figure represent the path of the fluid flow, and the color code of the streamlines represents the velocity of the fluid.

[0086] When the velocity and flow rate reach stability, the absolute permeability k of the connected pore space is calculated according to Darcy's law;

[0087]

[0088] Where, μ is the viscosity of the fluid, mPa·s; ΔP is the pressure difference between the fluid injection end and the outflow end, MPa; Q is the flow rate through the core, cm 3 / s; S is the cross-sectional area of ​​the core perpendicular to the X-axis in the three-dimensional core image, cm 2 ; L is the length of the core in the X-axis direction in the three-dimensional core image;

[0089] When selecting the ΔP value, since the equivalent structural parameter γ of the connected pores reflects the pore structure characteristics, the larger the γ value, the larger the pore surface area and the more irregular the shape. In order to improve the efficiency of the lattice Boltzmann simulation to calculate the absolute permeability k of the connected pore space, for different equivalent structural parameters γ of the connected pores, different pressure differences ΔP between the fluid injection end and the outflow end are selected to ensure that samples with different pore structures can obtain a reasonable absolute permeability k of the connected pore space:

[0090]

[0091] S4. Construction of porosity-permeability relationship guided by equivalent structure of connected pores by type

[0092] The reservoir types are divided according to the equivalent structural parameter γ of the connected pores. When the reservoir sample γ>0.005, it is defined as Type I pores, and when the reservoir sample γ≤0.005, it is defined as Type II pores. The least squares fitting is used to establish the porosity-permeability relationship between the connected pore volume percentage α and the absolute permeability k of the connected pore space for Type I and Type II pore reservoir samples, respectively, to achieve the construction of the porosity-permeability relationship based on the equivalent structure of the connected pores.

[0093] like Figure 6 The figure shows a comparison of the porosity-permeability relationship based on the connected pore equivalent structure of this embodiment and the porosity-permeability relationship established with the same sample data when the pore structure is not considered in the original result; the upper figure is the porosity-permeability relationship based on the connected pore equivalent structure of this embodiment, and the lower figure is the porosity-permeability relationship established with the same sample data without considering the pore structure; it can be seen from the figure that the correlation coefficient of the fine porosity-permeability relationship of Class I pores constructed based on the connected pore equivalent structure of the present invention is 0.44, and the correlation coefficient of the fine porosity-permeability relationship of Class II pores can reach 0.90, and the correlation of the porosity-permeability relationship established with the same sample data without considering the pore structure is 0.45, which shows that the present embodiment effectively distinguishes the differences in the characteristics of heterogeneous reservoirs, and greatly improves the accuracy of the porosity-permeability relationship, providing a more reasonable basis for the calculation of the permeability of heterogeneous reservoirs.

[0094] Therefore, this embodiment achieves a precise quantitative characterization of the complex porosity-permeability relationship of heterogeneous reservoirs, provides a more reasonable porosity-permeability relationship for the fine development of different types of reservoirs, and thus improves the accuracy of permeability prediction of heterogeneous reservoirs.

[0095] Example 2: A device, equipment and storage medium for constructing a porosity-permeability relationship of a heterogeneous reservoir

[0096] like Figure 7 As shown, this embodiment provides a device for constructing a porosity-permeability relationship of a heterogeneous reservoir, comprising:

[0097] A connected pore volume percentage calculation module is used to obtain a three-dimensional core image of a reservoir in a target area, determine connected pore clusters in the three-dimensional core image based on a grid search, obtain a connected pore space A based on the connected pore clusters, and calculate a connected pore volume percentage α of the connected pore space A;

[0098] The equivalent structural parameter calculation module of the connected pores is used to use the structural element B to perform mathematical morphological expansion operation on the connected pore space A to obtain the pore space C; calculate the difference between the pore space C and the connected pore space A to obtain the surface pixel points of the connected pores, and traverse and count the number of surface pixel points of the connected pores N Surface , the equivalent structural parameter γ of the connected pores is obtained;

[0099] The connected pore permeability calculation module is used to set the two opposite end faces of the core in the three-dimensional core image in the direction of the coordinate axis as the fluid injection end and the outflow end, respectively, according to the connected pore space A, set the pressure difference between the fluid injection end and the outflow end, simulate the flow of a single-phase fluid in the connected pore space A under the action of the pressure gradient, and calculate the absolute permeability k of the connected pore space when the flow velocity and flow rate reach stability;

[0100] The porosity-permeability relationship construction module is used to classify reservoir types according to the equivalent structural parameter γ of connected pores. When the reservoir sample γ>0.005, it is defined as Class I pores, and when the reservoir sample γ≤0.005, it is defined as Class II pores. The least squares fitting is used to establish the porosity-permeability relationship between the connected pore volume percentage α and the absolute permeability k of the connected pore space of Class I and Class II pore reservoir samples, respectively, to realize the construction of the porosity-permeability relationship based on the equivalent structure of connected pores.

[0101] Among them, when the heterogeneous reservoir porosity-permeability relationship construction device provided in this embodiment performs data processing, only the division of the above-mentioned functional modules is used as an example for explanation. In actual applications, the above-mentioned functions can be assigned to different functional modules as needed.

[0102] Based on the same inventive concept, Figure 8 As shown, this embodiment also provides a computer device, including: at least a processor and a memory, the memory is used to store at least one computer program, and the at least one computer program is loaded by the processor and executes the method for constructing the porosity-permeability relationship of a heterogeneous reservoir in Example 1.

[0103] Based on the same inventive concept, Fig. 9 As shown, this embodiment also provides a computer-readable storage medium, the storage medium is used to store at least one computer program, and the at least one computer program is used to execute the method for constructing the porosity-permeability relationship of the heterogeneous reservoir in Example 1.

[0104] It should be noted that a person skilled in the art can understand that all or part of the processes in the above-mentioned embodiment methods can be implemented by instructing related hardware through a computer program, and the program can be stored in a computer-readable storage medium. When the program is executed, it can include the processes of the embodiments of the above-mentioned methods.

[0105] Furthermore, it should be appreciated that the computer-readable storage medium (eg, memory) herein may be either a volatile memory or a nonvolatile memory, or may include both volatile and nonvolatile memory.

[0106] It will also be appreciated by those skilled in the art that various exemplary logic blocks, modules, circuits and algorithm steps described in conjunction with the disclosure herein can be implemented as electronic hardware, computer software or a combination of the two. In order to clearly illustrate this interchangeability of hardware and software, a general description has been given to the functions of various schematic components, blocks, modules, circuits and steps. Whether this function is implemented as software or hardware depends on specific applications and the design constraints imposed on the entire system. Those skilled in the art can implement the function in various ways for each specific application, but this implementation decision should not be interpreted as causing a departure from the disclosed scope of the embodiments of the present invention.

[0107] It should be noted that the above is only a preferred embodiment of the present invention and is not intended to limit the present invention. Although the present invention is described in detail with reference to the above embodiments, those skilled in the art can still modify the technical solutions described in the above embodiments or replace some of the technical features therein by equivalents. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A method for constructing a porosity-permeability relationship of a heterogeneous reservoir, characterized in that: The following steps are involved: S1. Calculate the volume percentage of connected pores Obtain a three-dimensional core image of the reservoir in the target area, determine connected pore clusters in the three-dimensional core image based on grid search, obtain connected pore space A according to the connected pore clusters, and calculate the connected pore volume percentage α of the connected pore space A; S2. Calculate the equivalent structural parameters of connected pores Use the structural element B to perform mathematical morphological expansion operations on the connected pore space A to obtain the pore space C; Calculate the difference between the pore space C and the connected pore space A, obtain the surface pixel points of the connected pores, and traverse and count the number of surface pixel points of the connected pores N Surface , the equivalent structural parameter γ of the connected pores is obtained; S3. Calculate the permeability of connected pores According to the connected pore space A, the two opposite end faces in the coordinate axis direction of the core in the three-dimensional core image are set as the fluid injection end and the outflow end respectively, and the pressure difference between the fluid injection end and the outflow end is set to simulate the flow of single-phase fluid in the connected pore space A under the action of pressure gradient. When the flow velocity and flow rate reach stability, the absolute permeability k of the connected pore space is calculated; S4. Construction of porosity-permeability relationship guided by equivalent structure of connected pores by type The reservoir types are divided according to the equivalent structural parameter γ of the connected pores. When the reservoir sample γ>0.005, it is defined as Type I pores, and when the reservoir sample γ≤0.005, it is defined as Type II pores. The least squares fitting is used to establish the porosity-permeability relationship between the connected pore volume percentage α and the absolute permeability k of the connected pore space for Type I and Type II pore reservoir samples, respectively, to achieve the construction of the porosity-permeability relationship based on the equivalent structure of the connected pores.

2. The method for constructing the porosity-permeability relationship of a heterogeneous reservoir according to claim 1, characterized in that: In step S1, the connected pore clusters in the three-dimensional core image are determined based on the grid search, the connected pore space A is obtained according to the connected pore clusters, and the specific process of calculating the connected pore volume percentage α of the connected pore space A is as follows: Set each pixel in the 3D core image as a grid, set the status of the pixels located in the pores to "occupied", and the status of the remaining pixels to "free"; If the edge of a pore pixel does not touch a pixel with the "occupied" state, the pore pixel is regarded as a new pore cluster and is assigned a new pore cluster label; If the edge of a pore pixel contacts a pixel with the state "occupied", the pore pixel and the "occupied" pixel it contacts are regarded as a pore cluster, and the same pore cluster label as the pore pixel is used; where the number of pore cluster labels is i (i = 1, 2, ..., N), and N is the total number of pore clusters; Determine whether there are pore clusters with the same pore cluster mark on two opposite end faces in the coordinate axis direction of the core in the three-dimensional core image. If so, the pore cluster forms a fluid migration channel running through the core, and all pixel points belonging to the pore cluster belong to the connected pore cluster; if there are multiple connected pore clusters, the pixels of all connected pore clusters belong to the connected pore space A; Count the number of all pixels N in the three-dimensional core image Total , and count the number of all connected pore pixels N in the connected pore space A Percolated , calculate the connected pore volume percentage α of the connected pore space; 3. The method for constructing the porosity-permeability relationship of a heterogeneous reservoir according to claim 2, characterized in that: In step S2, the structural element B is set to a sphere with a radius of 1; The calculation formula of pore space C is: in, is an empty set, and the pore space C is the result of the connected pore space A being expanded by the structural element B, denoted as is the dilation operator, x is the translation distance, is the space obtained by translating the structural element B by x; The calculation formula of the equivalent structural parameter γ of the connected pores is:

4. The method for constructing the porosity-permeability relationship of a heterogeneous reservoir according to claim 1, characterized in that: In step S2, in step S3, a lattice Boltzmann algorithm is used to simulate the flow of a single-phase fluid in a connected pore space A under the action of a pressure gradient; The absolute permeability k of the connected pore space is calculated according to Darcy's law: Where, μ is the viscosity of the fluid, mPa·s; ΔP is the pressure difference between the fluid injection end and the outflow end, MPa; Q is the flow rate through the core, cm 3 / s; S is the cross-sectional area of ​​the core perpendicular to the coordinate axis of the core in the three-dimensional core image, cm 2 ; L is the length of the core in the three-dimensional core image in the direction of the coordinate axis where the core is located; 5. A device for constructing porosity-permeability relationship of heterogeneous reservoirs, characterized in that: include: A connected pore volume percentage calculation module is used to obtain a three-dimensional core image of a reservoir in a target area, determine connected pore clusters in the three-dimensional core image based on a grid search, obtain a connected pore space A based on the connected pore clusters, and calculate a connected pore volume percentage α of the connected pore space A; The equivalent structural parameter calculation module of connected pores is used to perform mathematical morphological expansion operation on the connected pore space A using the structural element B to obtain the pore space C; Calculate the difference between the pore space C and the connected pore space A, obtain the surface pixel points of the connected pores, and traverse and count the number of surface pixel points of the connected pores N Surface , the equivalent structural parameter γ of the connected pores is obtained; The connected pore permeability calculation module is used to set the two opposite end faces of the core in the three-dimensional core image in the direction of the coordinate axis as the fluid injection end and the outflow end, respectively, according to the connected pore space A, set the pressure difference between the fluid injection end and the outflow end, simulate the flow of a single-phase fluid in the connected pore space A under the action of the pressure gradient, and calculate the absolute permeability k of the connected pore space when the flow velocity and flow rate reach stability; The porosity-permeability relationship construction module is used to classify reservoir types according to the equivalent structural parameter γ of connected pores. When the reservoir sample γ>0.005, it is defined as Class I pores, and when the reservoir sample γ≤0.005, it is defined as Class II pores. The least squares fitting is used to establish the porosity-permeability relationship between the connected pore volume percentage α and the absolute permeability k of the connected pore space of Class I and Class II pore reservoir samples, respectively, to realize the construction of the porosity-permeability relationship based on the equivalent structure of connected pores.

6. A computer device, characterized in that: The computer device comprises a processor and a memory, wherein the memory is used to store at least one computer program, and the at least one computer program is loaded by the processor and executed by the method for constructing the porosity-permeability relationship of a heterogeneous reservoir as claimed in any one of claims 1 to 4.

7. A storage medium, characterized in that: The storage medium is used to store at least one computer program, and the at least one computer program is used to execute the method for constructing the porosity-permeability relationship of a heterogeneous reservoir according to any one of claims 1 to 4.

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