CN107655908B - Method and device for constructing digital core - Google Patents
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- CN107655908B CN107655908B CN201711084891.3A CN201711084891A CN107655908B CN 107655908 B CN107655908 B CN 107655908B CN 201711084891 A CN201711084891 A CN 201711084891A CN 107655908 B CN107655908 B CN 107655908B
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Abstract
The embodiment of the application discloses a method and a device for constructing a digital core. The method comprises the following steps: carrying out CT scanning on the core sample to obtain a three-dimensional CT gray image of the core sample; wherein, three-dimensional CT grayscale image includes: a two-dimensional CT gray image corresponding to a designated area on the surface of the core sample; scanning the designated area by using a scanning electron microscope to obtain a two-dimensional scanning electron microscope picture; determining the porosity corresponding to the designated pixel point in the two-dimensional CT gray image according to the two-dimensional scanning electron microscope image; testing the designated area by using an electronic probe to obtain a mineral type corresponding to a designated pixel point in the two-dimensional CT gray image; determining a corresponding relation between the porosity and the gray scale distribution range; and determining the porosity of the pixel points in the three-dimensional CT gray image, and establishing the four-dimensional digital core of the target area based on the porosity of the pixel points in the three-dimensional CT gray image. According to the technical scheme provided by the embodiment of the application, the accuracy of the determined digital core can be improved.
Description
Technical Field
The application relates to the technical field of logging rock physical analysis in petroleum exploration, in particular to a method and a device for constructing a digital core.
Background
In the process of oil exploration, one of the key tasks of well logging interpretation is to accurately calculate the saturation of the oil-gas-bearing stratum, and when calculating the saturation of the oil-gas-bearing stratum, a saturation index corresponding to the saturation of the oil-gas-bearing stratum needs to be determined. At present, a displacement experiment is usually required to be carried out in a laboratory to determine the saturation index, wherein the displacement experiment is a process for simulating oil gas displacement water in the early stage of rock reservoir formation so as to observe the size of resistivity at different oil saturation degrees to analyze and determine the saturation index.
However, for an extra-low pore permeability sandstone or a compact sandstone reservoir, a displacement experiment in a laboratory is difficult to perform, and the main reason is that the permeability of a core sample is extremely low, a pressure difference as high as 20 MPa or even higher is required for completing the displacement process of oil displacement and water displacement, and the pressure difference is difficult to achieve by the conventional displacement rock electrical measurement equipment. Meanwhile, the porosity of the compact sandstone reservoir is low, the total pore volume is small, the amount of brine which can be expelled in the oil-water displacement process is extremely small, accurate measurement is difficult, and the precision of a displacement experiment result can be influenced.
Aiming at the problems, at present, a pore lattice of a core sample of the compact sandstone is mainly obtained by a CT scanning method at home and abroad, and then a saturation model parameter is determined by a numerical simulation method, wherein the saturation model parameter comprises a saturation index. The method mainly comprises the steps of firstly carrying out micron CT scanning on a rock core sample to obtain a three-dimensional micron CT gray level image, then selecting an image gray level cut-off value, taking pixel points larger than the image gray level cut-off value as a rock framework, setting the gray level of the pixel points larger than the image gray level cut-off value as 0, assuming that the rock framework is not conductive, taking the pixel points smaller than the image gray level cut-off value as pores, setting the gray level of the pixel points smaller than the image gray level cut-off value as 1, carrying out a binarization processing process, thus obtaining a pair of three-dimensional digital rock cores only keeping pore lattice frames, and carrying out numerical simulation of parameters such as resistivity. However, because the pore size of the tight sandstone is mainly in the nanometer level, and generally accounts for 70 percent (%) or even higher proportion of the total pore volume, a connected pore cluster is often not found in the pore lattice obtained by the three-dimensional micrometer CT grayscale image through the binarization processing, that is, a connected channel is not found from one end surface to the other end surface of the core sample, so that the resistivity value of the subsequent simulation is infinite or has a few magnitude of error from the actual situation. Therefore, a new method for constructing a digital core is needed for tight sandstone reservoirs, so as to improve the accuracy of the constructed digital core.
Disclosure of Invention
An object of the embodiments of the present application is to provide a method and an apparatus for constructing a digital core, so as to improve accuracy of the established digital core.
In order to solve the above technical problem, an embodiment of the present application provides a method and an apparatus for constructing a digital core, which are implemented as follows:
a method for constructing a digital core provides a core sample of a target area, and the porosity and mineral species of the core sample; the method comprises the following steps:
performing CT scanning on the core sample to obtain a three-dimensional CT gray image of the core sample; wherein the three-dimensional CT gray-scale image comprises: a two-dimensional CT gray image corresponding to a designated area on the surface of the core sample;
scanning the designated area by using a scanning electron microscope to obtain a two-dimensional scanning electron microscope picture; determining the porosity corresponding to the specified pixel point in the two-dimensional CT gray image according to the two-dimensional scanning electron microscope picture;
testing the designated area by using an electronic probe to obtain a mineral type corresponding to a designated pixel point in the two-dimensional CT gray image;
determining the corresponding relation between the porosity and the gray distribution range based on the porosity corresponding to the specified pixel point, the specified mineral type corresponding to the specified pixel point and the gray value of the specified pixel point; wherein the gray distribution range represents a part of gray distribution range in the three-dimensional CT gray image;
and determining the porosity of the pixel points in the three-dimensional CT gray-scale image based on the corresponding relation between the porosity and the gray-scale distribution range, and establishing the four-dimensional digital core of the target area based on the porosity of the pixel points in the three-dimensional CT gray-scale image.
In a preferred embodiment, the determining, according to the two-dimensional scanning electron microscope picture, the porosity corresponding to a specified pixel point in the two-dimensional CT grayscale image includes:
counting the nanopores of the region corresponding to the specified pixel point in the two-dimensional scanning electron microscope picture;
and determining the porosity corresponding to the designated pixel point in the two-dimensional CT gray-scale image according to the statistical result.
In a preferred embodiment, the determining the corresponding relationship between the porosity and the gray scale distribution range based on the porosity corresponding to the designated pixel point, the designated mineral type corresponding to the designated pixel point, and the gray scale value of the designated pixel point includes:
determining the corresponding relation between the mineral type and the porosity of the rock core sample according to the porosity corresponding to the specified pixel point and the specified mineral type corresponding to the specified pixel point;
determining a gray distribution range corresponding to the specified mineral type according to the gray value of the specified pixel point and the specified mineral type corresponding to the specified pixel point;
and determining the corresponding relation between the porosity and the gray distribution range based on the corresponding relation between the mineral type and the porosity and the gray distribution range corresponding to the specified mineral type.
In a preferred embodiment, the determining a gray distribution range corresponding to the specified mineral type according to the gray value of the specified pixel point and the specified mineral type corresponding to the specified pixel point includes:
determining a central gray value of a gray distribution range corresponding to the specified mineral type according to the gray value of the specified pixel point, the specified mineral type corresponding to the specified pixel point and the mineral density of the specified mineral type;
and determining the gray distribution range corresponding to the specified mineral type according to the central gray value and the signal-to-noise ratio of the three-dimensional CT gray image.
In a preferred scheme, the central gray value of the gray distribution range corresponding to the specified mineral type is determined by the following formula:
Li＝a×ρi+b
b＝Lmax-a×ρmin
wherein L isiA central gray value, ρ, representing a gray distribution range corresponding to the ith mineral type of the mineral speciesiDenotes the mineral density, L, of the i-th mineral typemaxRepresenting a maximum gray value, L, in the three-dimensional CT gray imageminMinimum gray value, rho, in the three-dimensional CT gray imagemaxAnd ρminRespectively, the maximum and minimum mineral densities in the mineral species.
In a preferred scheme, the gray level distribution range corresponding to the specified mineral type is determined by the following formula:
wherein L isiminAnd LimaxRespectively representing the maximum gray value and the minimum gray value in the gray distribution range corresponding to the ith specified mineral type in the mineral species; l isiAnd representing the central gray value of the gray distribution range corresponding to the ith mineral type, and the SNR represents the signal-to-noise ratio of the three-dimensional CT gray image.
In a preferred embodiment, before the four-dimensional digital core of the target region is established based on the porosity of a pixel point in the three-dimensional CT grayscale image, the method further includes:
calculating the total porosity of the three-dimensional CT gray-scale image according to the porosity of pixel points in the three-dimensional CT gray-scale image;
calculating a relative error between the total porosity and the porosity of the core sample; wherein the relative error represents a calculation of an absolute value of a difference between the total porosity and the porosity of the core sample divided by the porosity of the core sample;
and when the relative error is greater than or equal to a preset error threshold, re-determining the corresponding relation between the mineral type and the porosity until the relative error is less than the preset error threshold, and taking the re-determined corresponding relation between the mineral type and the porosity as the final corresponding relation between the mineral type and the porosity.
In a preferred embodiment, the preset error threshold is 5%.
In a preferred scheme, the shape of the core sample is cylindrical; the diameter of the cylindrical sample ranges from: 2 cm-4 cm; the height of the cylindrical sample ranges from 1 mm to 2 cm.
An apparatus for constructing a digital core, the apparatus providing a core sample of a region of interest, and a porosity and mineral speciation of the core sample; the device comprises: the device comprises a CT scanning module, a porosity determining module, a mineral type determining module, a gray distribution range determining module and a digital core establishing module; wherein the content of the first and second substances,
the CT scanning module is used for carrying out CT scanning on the core sample to obtain a three-dimensional CT gray image of the core sample; wherein the three-dimensional CT gray-scale image comprises: a two-dimensional CT gray image corresponding to a designated area on the surface of the core sample;
the porosity determining module is used for scanning the designated area by using a scanning electron microscope to obtain a two-dimensional scanning electron microscope picture; determining the porosity corresponding to the specified pixel point in the two-dimensional CT gray image according to the two-dimensional scanning electron microscope picture;
the mineral type determining module is used for testing the specified area by using an electronic probe to obtain a mineral type corresponding to a specified pixel point in the two-dimensional CT gray image;
the gray distribution range determining module is used for determining the corresponding relation between the porosity and the gray distribution range based on the porosity corresponding to the specified pixel point, the specified mineral type corresponding to the specified pixel point and the gray value of the specified pixel point; wherein the gray distribution range represents a part of gray distribution range in the three-dimensional CT gray image;
the digital core establishing module is used for determining the porosity of the pixel points in the three-dimensional CT gray level image based on the corresponding relation between the porosity and the gray level distribution range, and establishing the four-dimensional digital core of the target area based on the porosity of the pixel points in the three-dimensional CT gray level image.
The embodiment of the application provides a method and a device for constructing a digital core, which can be used for carrying out CT scanning on a core sample to obtain a three-dimensional CT gray image of the core sample; wherein the three-dimensional CT gray-scale image comprises: a two-dimensional CT gray image corresponding to a designated area on the surface of the core sample; scanning the designated area by using a scanning electron microscope to obtain a two-dimensional scanning electron microscope picture; according to the two-dimensional scanning electron microscope picture, determining the porosity corresponding to the specified pixel point in the two-dimensional CT gray level image; testing the designated area by using an electronic probe to obtain a mineral type corresponding to a designated pixel point in the two-dimensional CT gray image; determining a corresponding relation between the porosity and a gray distribution range based on the porosity corresponding to the designated pixel point, the designated mineral type corresponding to the designated pixel point and the gray value of the designated pixel point; wherein the gray distribution range represents a part of gray distribution range in the three-dimensional CT gray image; the porosity of the pixel points in the three-dimensional CT gray-scale image can be determined based on the corresponding relation between the porosity and the gray-scale distribution range, and the four-dimensional digital core of the target area is established based on the porosity of the pixel points in the three-dimensional CT gray-scale image. Therefore, the determined pixel points in the four-dimensional digital core, which are smaller than the image gray cutoff value, have certain porosity, and the actual situation of the core sample is better met, so that the accuracy of the determined digital core can be improved.
Drawings
In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the drawings needed to be used in the description of the embodiments or the prior art will be briefly introduced below, it is obvious that the drawings in the following description are only some embodiments described in the present application, and for those skilled in the art, other drawings can be obtained according to the drawings without any creative effort.
FIG. 1 is a flow chart of an embodiment of a method of constructing a digital core according to the present application;
fig. 2 is a two-dimensional scanning electron microscope picture of a designated pixel point in a two-dimensional CT grayscale image corresponding to a designated region in the embodiment of the present application;
FIG. 3 is a diagram illustrating a relationship between porosity and a gray scale distribution range according to an embodiment of the present application;
FIG. 4 is a schematic illustration of a four-dimensional digital core in an embodiment of the present application;
fig. 5 is a structural view of the composition of the apparatus for constructing a digital core according to the present invention.
Detailed Description
The embodiment of the application provides a method and a device for constructing a digital core.
In order to make those skilled in the art better understand the technical solutions in the present application, the technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application, and it is obvious that the described embodiments are only a part of the embodiments of the present application, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present application.
The embodiment of the application provides a method for constructing a digital core. The method for constructing the digital core provides a core sample of a purposeful area, and the porosity and mineral type of the core sample.
In this embodiment, the target area may be an area where the digital core has not been determined. The target area may be an area corresponding to a tight sandstone reservoir.
In this embodiment, the core of the target area is pretreated to obtain the core sample.
In this embodiment, the core sample may be cylindrical in shape. The diameter of the cylindrical sample may range from: 2 cm to 4 cm. The height of the cylindrical sample may range from 1 mm to 2 cm.
In this embodiment, the porosity and mineral type of the core sample may be obtained by performing a physical test on the core sample.
Fig. 1 is a flow chart of an embodiment of a method of constructing a digital core according to the present application. As shown in fig. 1, the method for constructing a digital core includes the following steps.
Step S101: performing CT scanning on the core sample to obtain a three-dimensional CT gray image of the core sample; wherein the three-dimensional CT gray-scale image comprises: and the two-dimensional CT gray image corresponds to the designated area on the surface of the core sample.
In this embodiment, the core sample may be CT scanned to obtain a three-dimensional CT grayscale image of the core sample. Wherein the three-dimensional CT grayscale image may include: and the two-dimensional CT gray image corresponds to the designated area on the surface of the core sample.
In this embodiment, the resolution range of the CT scan may include: 1 micron/pixel to 9 microns/pixel.
In this embodiment, the designated area may be a square area with a side of 1 cm.
Step S102: scanning the designated area by using a scanning electron microscope to obtain a two-dimensional scanning electron microscope picture; and determining the porosity corresponding to the specified pixel point in the two-dimensional CT gray image according to the two-dimensional scanning electron microscope picture.
In this embodiment, the specified area may be scanned by a scanning electron microscope (abbreviated as SEM) to obtain a two-dimensional scanning electron microscope picture. Wherein, the resolution range scanned by the scanning electron microscope may include: 20 nm/pixel to 200 nm/pixel. For example, fig. 2 is a two-dimensional scanning electron microscope picture of a designated pixel point in a two-dimensional CT grayscale image corresponding to a designated area in the embodiment of the present application. Fig. 2 (a) and (b) are two-dimensional scanning electron microscope images of designated pixel points in a two-dimensional CT grayscale image corresponding to a designated area and a two-dimensional CT grayscale image on the surface of the core sample, respectively. In fig. 2, (a) a square area with a side length of 1 cm is the designated area. The appointed pixel point is a certain pixel point in the two-dimensional CT gray level image corresponding to the appointed area. As shown in fig. 2(b), under the resolution of the sem, a large number of nanopores such as intra-granular erosion holes, clay intercrystalline holes, etc. corresponding to a given pixel point can be seen.
In this embodiment, determining, according to the two-dimensional scanning electron microscope picture, a porosity corresponding to a specified pixel point in the two-dimensional CT grayscale image may specifically include counting nanopores in a region corresponding to the specified pixel point in the two-dimensional scanning electron microscope picture. According to the statistical result, the porosity corresponding to the designated pixel point in the two-dimensional CT gray-scale image can be determined. The designated pixel point can represent any pixel point in the two-dimensional CT gray image.
Step S103: and testing the designated area by using an electronic probe to obtain the mineral type corresponding to the designated pixel point in the two-dimensional CT gray image.
In this embodiment, the determining the corresponding relationship between the porosity and the gray scale distribution range based on the porosity corresponding to the designated pixel point, the designated mineral type corresponding to the designated pixel point, and the gray scale value of the designated pixel point may specifically include determining the corresponding relationship between the mineral type and the porosity of the core sample according to the porosity corresponding to the designated pixel point and the designated mineral type corresponding to the designated pixel point. The gray distribution range corresponding to the specified mineral type can be determined according to the gray value of the specified pixel point and the specified mineral type corresponding to the specified pixel point. The correspondence between the porosity and the gray scale distribution range may be determined based on the correspondence between the mineral type and the porosity and the gray scale distribution range corresponding to the specified mineral type.
In this embodiment, determining the gray distribution range corresponding to the specified mineral type according to the gray value of the specified pixel point and the specified mineral type corresponding to the specified pixel point may specifically include determining a central gray value of the gray distribution range corresponding to the specified mineral type according to the gray value of the specified pixel point, the specified mineral type corresponding to the specified pixel point, and the mineral density of the specified mineral type. The gray distribution range corresponding to the specified mineral type can be determined according to the central gray value and the signal-to-noise ratio of the three-dimensional CT gray image.
In this embodiment, the central gray value of the gray distribution range corresponding to the specified mineral type may be determined by using the following formula:
Li＝a×ρi+b
b＝Lmax-a×ρmin
wherein L isiA central gray value, ρ, representing a gray distribution range corresponding to the ith mineral type of the mineral speciesiDenotes the mineral density, L, of the i-th mineral typemaxRepresenting a maximum gray value, L, in the three-dimensional CT gray imageminMinimum gray value, rho, in the three-dimensional CT gray imagemaxAnd ρminRespectively, the maximum and minimum mineral densities in the mineral species.
In this embodiment, the following formula may be used to determine the gray scale distribution range corresponding to the specified mineral type:
wherein L isiminAnd LimaxRespectively representing the maximum gray value and the minimum gray value in the gray distribution range corresponding to the ith specified mineral type in the mineral species; l isiAnd representing the central gray value of the gray distribution range corresponding to the ith mineral type, and the SNR represents the signal-to-noise ratio of the three-dimensional CT gray image.
Step S104: determining the corresponding relation between the porosity and the gray distribution range based on the porosity corresponding to the specified pixel point, the specified mineral type corresponding to the specified pixel point and the gray value of the specified pixel point; wherein the gray distribution range represents a part of gray distribution range in the three-dimensional CT gray image.
In this embodiment, the corresponding relationship between the porosity and the gray scale distribution range may be determined based on the porosity corresponding to the designated pixel point, the designated mineral type corresponding to the designated pixel point, and the gray scale value of the designated pixel point. Wherein the gray distribution range may represent a partial gray distribution range in the three-dimensional CT gray image.
Fig. 3 is a schematic diagram of a relationship between porosity and a gray scale distribution range in an embodiment of the present application. The abscissa and ordinate in fig. 3 are the porosity and the gray value in the three-dimensional CT gray image, respectively. The gray value range in the three-dimensional CT gray image is 0-255. As shown in fig. 3, different gray scale distribution ranges correspond to different porosities. Each gray scale distribution range corresponds to one mineral type, for example, the gray scale distribution range corresponding to the component 1 is 0-90, and the porosity is phi1(ii) a The gray level distribution range corresponding to the component 2 is 91-120, and the corresponding porosity is phi2(ii) a The component 3 has a corresponding gray distribution range of 121-150 and a corresponding porosity of phi3(ii) a The gray distribution range corresponding to the component 4 is 151-180, and the corresponding porosity is phi4(ii) a The component 5 corresponds to a gray distribution range of 181-255 and a porosity of phi5。
Step S105: and determining the porosity of the pixel points in the three-dimensional CT gray-scale image based on the corresponding relation between the porosity and the gray-scale distribution range, and establishing the four-dimensional digital core of the target area based on the porosity of the pixel points in the three-dimensional CT gray-scale image.
In this embodiment, determining the porosity of a pixel point in the three-dimensional CT grayscale image based on the correspondence between the porosity and the grayscale distribution range may specifically include determining the grayscale distribution range in which the pixel point is located according to the grayscale value of the pixel point in the three-dimensional CT grayscale image. And determining the porosity of the pixel point in the three-dimensional CT gray image according to the gray distribution range where the pixel point is located and the corresponding relation between the porosity and the gray distribution range.
In this embodiment, establishing the four-dimensional digital core of the target area based on the porosity of the pixel point in the three-dimensional CT grayscale image may specifically include calculating the resistivity of the pixel point based on the porosity of the pixel point in the three-dimensional CT grayscale image by using the following formula:
wherein R is0jRepresenting the resistivity, R, of the jth pixel point in the three-dimensional CT gray level imagewRepresents the water resistivity, phi, of the target regioniIndicating the porosity of the jth pixel. The resistivity of the pixel points in the three-dimensional CT gray level image can be normalized, and the normalized result is used as the resistivity coefficient of the pixel points.
Based on the resistivity coefficient of the pixel points in the three-dimensional CT gray level image, the target area can be establishedFour-dimensional digital cores. The four-dimensional digital core not only comprises the three-dimensional coordinates of the pixel points in the three-dimensional CT gray level image, but also comprises the resistivity coefficient of the pixel points, namely, each pixel point in the four-dimensional digital core has four-dimensional coordinates (x, y, z, k)0). And x, y and z respectively represent the space coordinates of the pixel points in the four-dimensional digital core, namely the space coordinates of the pixel points in the three-dimensional CT gray level image. k is a radical of0And representing the resistivity coefficients of the pixel points in the four-dimensional digital core.
Fig. 4 is a schematic diagram of a four-dimensional digital core in an example of the present application. The grey values in fig. 4 represent the resistivity coefficients of the pixels.
In an embodiment, before the four-dimensional digital core of the target region is established based on the porosity of the pixel points in the three-dimensional CT grayscale image, the method for establishing the digital core may further include calculating the total porosity of the three-dimensional CT grayscale image according to the porosity of the pixel points in the three-dimensional CT grayscale image. A relative error between the total porosity and the porosity of the core sample may be calculated. Wherein the relative error represents a calculation of an absolute value of a difference between the total porosity and the porosity of the core sample divided by the porosity of the core sample. When the relative error is greater than or equal to the preset error threshold, the corresponding relationship between the mineral type and the porosity may be re-determined according to the method of step S104 until the relative error is less than the preset error threshold, and the re-determined corresponding relationship between the mineral type and the porosity is used as the final corresponding relationship between the mineral type and the porosity.
In this embodiment, the preset error threshold may be 5 percent.
According to the embodiment of the method for constructing the digital core, CT scanning can be carried out on the core sample to obtain a three-dimensional CT gray image of the core sample; wherein the three-dimensional CT gray-scale image comprises: a two-dimensional CT gray image corresponding to a designated area on the surface of the core sample; scanning the designated area by using a scanning electron microscope to obtain a two-dimensional scanning electron microscope picture; according to the two-dimensional scanning electron microscope picture, determining the porosity corresponding to the specified pixel point in the two-dimensional CT gray level image; testing the designated area by using an electronic probe to obtain a mineral type corresponding to a designated pixel point in the two-dimensional CT gray image; determining a corresponding relation between the porosity and a gray distribution range based on the porosity corresponding to the designated pixel point, the designated mineral type corresponding to the designated pixel point and the gray value of the designated pixel point; wherein the gray distribution range represents a part of gray distribution range in the three-dimensional CT gray image; the porosity of the pixel points in the three-dimensional CT gray-scale image can be determined based on the corresponding relation between the porosity and the gray-scale distribution range, and the four-dimensional digital core of the target area is established based on the porosity of the pixel points in the three-dimensional CT gray-scale image. Therefore, the determined pixel points in the four-dimensional digital core, which are smaller than the image gray cutoff value, have certain porosity, and the actual situation of the core sample is better met, so that the accuracy of the determined digital core can be improved.
Fig. 5 is a structural view of the composition of the apparatus for constructing a digital core according to the present invention. The device for constructing the digital core provides a core sample of a target area, and the porosity and the mineral type of the core sample. As shown in fig. 5, the apparatus for constructing a digital core may include: a CT scanning module 100, a porosity determination module 200, a mineral type determination module 300, a gray scale distribution range determination module 400, and a digital core creation module 500.
The CT scanning module 100 may be configured to perform CT scanning on the core sample to obtain a three-dimensional CT grayscale image of the core sample; wherein the three-dimensional CT gray-scale image comprises: and the two-dimensional CT gray image corresponds to the designated area on the surface of the core sample.
The porosity determination module 200 may be configured to scan the designated area by using a scanning electron microscope to obtain a two-dimensional scanning electron microscope picture; determining the porosity corresponding to the specified pixel point in the two-dimensional CT gray image according to the two-dimensional scanning electron microscope picture;
the mineral type determining module 300 may be configured to perform a test on the designated area by using an electronic probe, so as to obtain a mineral type corresponding to a designated pixel point in the two-dimensional CT grayscale image.
The gray scale distribution range determining module 400 may be configured to determine a corresponding relationship between the porosity and the gray scale distribution range based on the porosity corresponding to the designated pixel point, the designated mineral type corresponding to the designated pixel point, and the gray scale value of the designated pixel point; wherein the gray distribution range represents a part of gray distribution range in the three-dimensional CT gray image.
The digital core establishing module 500 may be configured to determine the porosity of a pixel point in the three-dimensional CT grayscale image based on a correspondence between the porosity and a grayscale distribution range, and establish the four-dimensional digital core of the target region based on the porosity of the pixel point in the three-dimensional CT grayscale image.
The embodiment of the device for constructing the digital core corresponds to the embodiment of the method for constructing the digital core, so that the technical scheme of the embodiment of the method for constructing the digital core can be realized, and the technical effect of the embodiment of the method can be obtained.
In the 90 s of the 20 th century, improvements in a technology could clearly distinguish between improvements in hardware (e.g., improvements in circuit structures such as diodes, transistors, switches, etc.) and improvements in software (improvements in process flow). However, as technology advances, many of today's process flow improvements have been seen as direct improvements in hardware circuit architecture. Designers almost always obtain the corresponding hardware circuit structure by programming an improved method flow into the hardware circuit. Thus, it cannot be said that an improvement in the process flow cannot be realized by hardware physical modules. For example, a Programmable Logic Device (PLD), such as a Field Programmable Gate Array (FPGA), is an integrated circuit whose Logic functions are determined by programming the Device by a user. A digital system is "integrated" on a PLD by the designer's own programming without requiring the chip manufacturer to design and fabricate application-specific integrated circuit chips. Furthermore, nowadays, instead of manually making an integrated Circuit chip, such Programming is often implemented by "logic compiler" software, which is similar to a software compiler used in program development and writing, but the original code before compiling is also written by a specific Programming Language, which is called Hardware Description Language (HDL), and HDL is not only one but many, such as abel (advanced Boolean Expression Language), ahdl (alternate Language Description Language), traffic, pl (core unified Programming Language), HDCal, JHDL (Java Hardware Description Language), langue, Lola, HDL, laspam, hardsradware (Hardware Description Language), vhjhd (Hardware Description Language), and vhigh-Language, which are currently used in most popular applications. It will also be apparent to those skilled in the art that hardware circuitry that implements the logical method flows can be readily obtained by merely slightly programming the method flows into an integrated circuit using the hardware description languages described above.
Those skilled in the art will also appreciate that, in addition to implementing the controller as pure computer readable program code, the same functionality can be implemented by logically programming method steps such that the controller is in the form of logic gates, switches, application specific integrated circuits, programmable logic controllers, embedded microcontrollers and the like. Such a controller may thus be considered a hardware component, and the means included therein for performing the various functions may also be considered as a structure within the hardware component. Or even means for performing the functions may be regarded as being both a software module for performing the method and a structure within a hardware component.
The apparatuses and modules illustrated in the above embodiments may be implemented by a computer chip or an entity, or by a product with certain functions.
For convenience of description, the above devices are described as being divided into various modules by functions, and are described separately. Of course, the functionality of the various modules may be implemented in the same one or more software and/or hardware implementations as the present application.
From the above description of the embodiments, it is clear to those skilled in the art that the present application can be implemented by software plus necessary general hardware platform. With this understanding in mind, the present solution, or portions thereof that contribute to the prior art, may be embodied in the form of a software product, which in a typical configuration includes one or more processors (CPUs), input/output interfaces, network interfaces, and memory. The computer software product may include instructions for causing a computing device (which may be a personal computer, a server, or a network device, etc.) to perform the methods described in the various embodiments or portions of embodiments of the present application. The computer software product may be stored in a memory, which may include forms of volatile memory in a computer readable medium, Random Access Memory (RAM) and/or non-volatile memory, such as Read Only Memory (ROM) or flash memory (flash RAM). Memory is an example of a computer-readable medium. Computer-readable media, including both non-transitory and non-transitory, removable and non-removable media, may implement information storage by any method or technology. The information may be computer readable instructions, data structures, modules of a program, or other data. Examples of computer storage media include, but are not limited to, phase change memory (PRAM), Static Random Access Memory (SRAM), Dynamic Random Access Memory (DRAM), other types of Random Access Memory (RAM), Read Only Memory (ROM), Electrically Erasable Programmable Read Only Memory (EEPROM), flash memory or other memory technology, compact disc read only memory (CD-ROM), Digital Versatile Discs (DVD) or other optical storage, magnetic cassettes, magnetic tape magnetic disk storage or other magnetic storage devices, or any other non-transmission medium that can be used to store information that can be accessed by a computing device. As defined herein, computer readable media does not include transitory computer readable media (transient media), such as modulated data signals and carrier waves.
The embodiments in the present specification are described in a progressive manner, and the same and similar parts among the embodiments are referred to each other, and each embodiment focuses on the differences from the other embodiments. In particular, as for the apparatus embodiment, since it is substantially similar to the method embodiment, the description is relatively simple, and for the relevant points, reference may be made to the partial description of the method embodiment.
The application is operational with numerous general purpose or special purpose computing system environments or configurations. For example: personal computers, server computers, hand-held or portable devices, tablet-type devices, multiprocessor systems, microprocessor-based systems, set top boxes, programmable consumer electronics, network PCs, minicomputers, mainframe computers, distributed computing environments that include any of the above systems or devices, and the like.
The application may be described in the general context of computer-executable instructions, such as program modules, being executed by a computer. Generally, program modules include routines, programs, objects, components, data structures, etc. that perform particular tasks or implement particular abstract data types. The application may also be practiced in distributed computing environments where tasks are performed by remote processing devices that are linked through a communications network. In a distributed computing environment, program modules may be located in both local and remote computer storage media including memory storage devices.
While the present application has been described with examples, those of ordinary skill in the art will appreciate that there are numerous variations and permutations of the present application without departing from the spirit of the application, and it is intended that the appended claims encompass such variations and permutations without departing from the spirit of the application.
Claims (10)
1. A method for constructing a digital core provides a core sample of a target area, and the porosity and mineral species of the core sample; characterized in that the method comprises:
performing CT scanning on the core sample to obtain a three-dimensional CT gray image of the core sample; wherein the three-dimensional CT gray-scale image comprises: a two-dimensional CT gray image corresponding to a designated area on the surface of the core sample;
scanning the designated area by using a scanning electron microscope to obtain a two-dimensional scanning electron microscope picture; determining the porosity corresponding to the specified pixel point in the two-dimensional CT gray image according to the two-dimensional scanning electron microscope picture;
testing the designated area by using an electronic probe to obtain a mineral type corresponding to a designated pixel point in the two-dimensional CT gray image;
determining the corresponding relation between the porosity and the gray distribution range based on the porosity corresponding to the specified pixel point, the specified mineral type corresponding to the specified pixel point and the gray value of the specified pixel point; wherein the gray distribution range represents a part of gray distribution range in the three-dimensional CT gray image;
and determining the porosity of the pixel points in the three-dimensional CT gray-scale image based on the corresponding relation between the porosity and the gray-scale distribution range, and establishing the four-dimensional digital core of the target area based on the porosity of the pixel points in the three-dimensional CT gray-scale image.
2. The method for constructing the digital core according to claim 1, wherein the determining the porosity corresponding to the specified pixel point in the two-dimensional CT grayscale image according to the two-dimensional scanning electron microscope image comprises:
counting the nanopores of the region corresponding to the specified pixel point in the two-dimensional scanning electron microscope picture;
and determining the porosity corresponding to the designated pixel point in the two-dimensional CT gray-scale image according to the statistical result.
3. The method for constructing a digital core according to claim 1, wherein the determining the corresponding relationship between the porosity and the gray scale distribution range based on the porosity corresponding to the designated pixel point, the designated mineral type corresponding to the designated pixel point, and the gray scale value of the designated pixel point comprises:
determining the corresponding relation between the mineral type and the porosity of the rock core sample according to the porosity corresponding to the specified pixel point and the specified mineral type corresponding to the specified pixel point;
determining a gray distribution range corresponding to the specified mineral type according to the gray value of the specified pixel point and the specified mineral type corresponding to the specified pixel point;
and determining the corresponding relation between the porosity and the gray distribution range based on the corresponding relation between the mineral type and the porosity and the gray distribution range corresponding to the specified mineral type.
4. The method for constructing a digital core according to claim 3, wherein the determining a gray scale distribution range corresponding to the specified mineral type according to the gray scale value of the specified pixel point and the specified mineral type corresponding to the specified pixel point comprises:
determining a central gray value of a gray distribution range corresponding to the specified mineral type according to the gray value of the specified pixel point, the specified mineral type corresponding to the specified pixel point and the mineral density of the specified mineral type;
and determining the gray distribution range corresponding to the specified mineral type according to the central gray value and the signal-to-noise ratio of the three-dimensional CT gray image.
5. The method for constructing the digital core according to claim 4, wherein the central gray value of the gray distribution range corresponding to the specified mineral type is determined by using the following formula:
Li＝a×ρi+b
b＝Lmax-a×ρmin
wherein L isiA central gray value, ρ, representing a gray distribution range corresponding to the ith mineral type of the mineral speciesiDenotes the mineral density, L, of the i-th mineral typemaxTo representMaximum gray value, L, in the three-dimensional CT gray imageminMinimum gray value, rho, in the three-dimensional CT gray imagemaxAnd ρminRespectively, the maximum and minimum mineral densities in the mineral species.
6. The method for constructing the digital core according to claim 4, wherein the gray scale distribution range corresponding to the specified mineral type is determined by using the following formula:
wherein L isiminAnd LimaxRespectively representing the maximum gray value and the minimum gray value in the gray distribution range corresponding to the ith specified mineral type in the mineral species; l isiAnd representing the central gray value of the gray distribution range corresponding to the ith mineral type, and the SNR represents the signal-to-noise ratio of the three-dimensional CT gray image.
7. The method for constructing the digital core according to claim 1, wherein before the four-dimensional digital core of the target region is established based on the porosity of the pixel points in the three-dimensional CT grayscale image, the method further comprises:
calculating the total porosity of the three-dimensional CT gray-scale image according to the porosity of pixel points in the three-dimensional CT gray-scale image;
calculating a relative error between the total porosity and the porosity of the core sample; wherein the relative error represents a calculation of an absolute value of a difference between the total porosity and the porosity of the core sample divided by the porosity of the core sample;
and when the relative error is greater than or equal to a preset error threshold, re-determining the corresponding relation between the mineral type and the porosity until the relative error is less than the preset error threshold, and taking the re-determined corresponding relation between the mineral type and the porosity as the final corresponding relation between the mineral type and the porosity.
8. The method for constructing a digital core as claimed in claim 7, wherein the predetermined error threshold is 5 percent.
9. The method for constructing a digital core as claimed in claim 1, wherein the core sample is cylindrical in shape; the diameter of the cylindrical sample ranges from: 2 cm-4 cm; the height of the cylindrical sample ranges from 1 mm to 2 cm.
10. An apparatus for constructing a digital core, the apparatus providing a core sample of a region of interest, and a porosity and mineral speciation of the core sample; the device comprises: the device comprises a CT scanning module, a porosity determining module, a mineral type determining module, a gray distribution range determining module and a digital core establishing module; wherein the content of the first and second substances,
the CT scanning module is used for carrying out CT scanning on the core sample to obtain a three-dimensional CT gray image of the core sample; wherein the three-dimensional CT gray-scale image comprises: a two-dimensional CT gray image corresponding to a designated area on the surface of the core sample;
the porosity determining module is used for scanning the designated area by using a scanning electron microscope to obtain a two-dimensional scanning electron microscope picture; determining the porosity corresponding to the specified pixel point in the two-dimensional CT gray image according to the two-dimensional scanning electron microscope picture;
the mineral type determining module is used for testing the specified area by using an electronic probe to obtain a mineral type corresponding to a specified pixel point in the two-dimensional CT gray image;
the gray distribution range determining module is used for determining the corresponding relation between the porosity and the gray distribution range based on the porosity corresponding to the specified pixel point, the specified mineral type corresponding to the specified pixel point and the gray value of the specified pixel point; wherein the gray distribution range represents a part of gray distribution range in the three-dimensional CT gray image;
the digital core establishing module is used for determining the porosity of the pixel points in the three-dimensional CT gray level image based on the corresponding relation between the porosity and the gray level distribution range, and establishing the four-dimensional digital core of the target area based on the porosity of the pixel points in the three-dimensional CT gray level image.
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