CN108038903B - Three-dimensional digital model generation method for building rock core model - Google Patents
Three-dimensional digital model generation method for building rock core model Download PDFInfo
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- CN108038903B CN108038903B CN201711289759.6A CN201711289759A CN108038903B CN 108038903 B CN108038903 B CN 108038903B CN 201711289759 A CN201711289759 A CN 201711289759A CN 108038903 B CN108038903 B CN 108038903B
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- G—PHYSICS
- G06—COMPUTING; CALCULATING OR COUNTING
- G06T—IMAGE DATA PROCESSING OR GENERATION, IN GENERAL
- G06T17/00—Three dimensional [3D] modelling, e.g. data description of 3D objects
- G06T17/05—Geographic models
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B33—ADDITIVE MANUFACTURING TECHNOLOGY
- B33Y—ADDITIVE MANUFACTURING, i.e. MANUFACTURING OF THREE-DIMENSIONAL [3-D] OBJECTS BY ADDITIVE DEPOSITION, ADDITIVE AGGLOMERATION OR ADDITIVE LAYERING, e.g. BY 3-D PRINTING, STEREOLITHOGRAPHY OR SELECTIVE LASER SINTERING
- B33Y50/00—Data acquisition or data processing for additive manufacturing
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- G—PHYSICS
- G06—COMPUTING; CALCULATING OR COUNTING
- G06T—IMAGE DATA PROCESSING OR GENERATION, IN GENERAL
- G06T17/00—Three dimensional [3D] modelling, e.g. data description of 3D objects
- G06T17/005—Tree description, e.g. octree, quadtree
Abstract
The invention provides a three-dimensional digital model generation method for building a core model, which comprises the following steps: step 1, obtaining an original material of a three-dimensional digital model for constructing a rock core model; step 2, carrying out binarization processing on the image obtained in the step 1; step 3, searching pore points for the image processed in the step 2, filtering tiny pores, and communicating the pores; step 4, carrying out standardization processing on the image processed in the step 3; step 5, performing size expansion on the image processed in the step 4; and 6, performing three-dimensional processing on the image processed in the step 5. According to the three-dimensional digital model generation method for building the core model, a model with a proper size can be manufactured according to research needs and the performance of a 3D printer, any plurality of core models with the same crack structure can be manufactured according to needs, transparent printing materials are used, and the manufactured model has observability.
Description
Technical Field
The invention relates to the technical field of oilfield development, in particular to a three-dimensional digital model generation method for building a rock core model.
Background
In the development process of oil and gas resources, in the method for researching displacement of the oil and gas resources in rock gaps, an experimental research method is one of common methods, and a core model is often used in experiments. According to different preparation methods, the current core models are divided into natural core models, artificial core models and glass models.
The natural rock model is obtained in nature, and the internal pore structure and distribution of the rock are most similar to those of a reservoir stratum. However, there are no two rocks with completely identical internal pore structures in nature, and even if two adjacent cores are taken from one rock, the internal pore structures and distributions of the cores are different. Therefore, it is difficult to make the initial conditions uniform when performing the comparative experiment.
The artificial rock core model is obtained by mixing sand grains with different grain sizes and adding adhesive for curing. And then preparing a core model from the artificial rock. However, the artificial core and the natural core have great difference in pore structure, and the oil-gas movement law in the artificial core is inevitably different from that of the natural core.
In addition, the natural rock core and the artificial rock core are opaque in material, so that the oil-water movement rule in a rock gap cannot be directly observed.
The glass model is formed by using hydrofluoric acid to flow on glass randomly to etch a trace, simulating a rock crack and then bonding another piece of complete glass with the crack. The glass model corroded by the method has certain randomness of corrosion traces, so that two identical glass models are difficult to manufacture, and a model with a larger size is difficult to manufacture due to the material of the glass model.
In summary, the current experimental cores are deficient in reproducibility, observability, and pore simulation. Therefore, a new three-dimensional digital model generation method for building the rock core model is invented, and the technical problems are solved.
Disclosure of Invention
The invention aims to provide a three-dimensional digital model generation method for constructing a rock core model, which can be combined with a 3D printing technology to manufacture a model for researching an oil-water periscopic motion rule experiment.
The object of the invention can be achieved by the following technical measures: the three-dimensional digital model generation method for building the core model comprises the following steps: step 1, obtaining an original material of a three-dimensional digital model for constructing a rock core model; step 2, carrying out binarization processing on the image obtained in the step 1; step 3, searching pore points for the image processed in the step 2, filtering tiny pores, and communicating the pores; step 4, carrying out standardization processing on the image processed in the step 3; step 5, performing size expansion on the image processed in the step 4; and 6, performing three-dimensional processing on the image processed in the step 5.
The object of the invention can also be achieved by the following technical measures:
in step 1, original images are scanned for core CT and used as raw materials for constructing a three-dimensional digital model of a core model.
In step 1, the obtained raw material is a gray image, that is, each pixel point has an element with a value of 0-255, white is 255, and black is 0.
In step 2, a threshold value is designated, the pixel value in the image obtained in step 1 is compared with the threshold value, and when the pixel value is smaller than the threshold value, the original pixel value is replaced by '0'; when the pixel value is larger than the threshold value, replacing the original pixel value with '1'; the pixels in the final image have only two values of "0" and "1", and two colors of "black" and "white" are presented in the image, where "0" corresponds to black and "1" corresponds to white.
In step 3, an image mask circle is extracted, a pore point is searched for the image processed in step 2, and the number of pixels at the pore is counted by using a recursive function.
In step 3, a reasonable threshold is set, the number of pore pixels is calculated, and pores with the number of pore pixels smaller than the threshold are deleted.
In step 3, for two non-connected pores, a minimum spanning tree method is used to select a pore region with the largest area as a root node, and the pores are connected by using the same color as the pores.
In step 4, the image processed in step 3 is normalized and set to be a rectangle, and the normalized image must ensure that all pores are communicated with the four sides of the rectangle.
In the step 5, the image processed in the step 4 is subjected to mirror image turning for multiple times according to the size requirement of the core to be manufactured, and the image after mirror image turning can ensure the communication between pores.
In step 6, the image processed in step 5 is stretched in a direction perpendicular to the plane to obtain a three-dimensional image.
According to the three-dimensional digital model generation method for building the rock core model, the seam texture of the three-dimensional digital model generation method takes the natural rock core texture structure as an original material, is closer to a real natural crack, can be used for manufacturing a model with a proper size according to research requirements and 3D printer performance, can be used for manufacturing any multiple rock core models with the same crack structure according to requirements, and is observable by using a transparent printing material.
Drawings
FIG. 1 is a flow diagram of one embodiment of a three-dimensional digital model generation method for constructing a core model of the present disclosure;
FIG. 2 is a core CT scan raw image in an embodiment of the present disclosure;
FIG. 3 is a diagram illustrating an exemplary image binarization process according to an embodiment of the present invention;
FIG. 4 is a schematic diagram of filtering micro-porous spots in an embodiment of the present invention;
FIG. 5 is a diagram illustrating pore communication in accordance with one embodiment of the present invention;
FIG. 6 is a diagram illustrating a graph normalization process according to an embodiment of the present invention;
FIG. 7 is a plan view of a large-scale core model in an embodiment of the present disclosure;
fig. 8 is a schematic diagram of a three-dimensional digital model used to construct a core model in an embodiment of the invention.
Detailed Description
In order to make the aforementioned and other objects, features and advantages of the present invention comprehensible, preferred embodiments accompanied with figures are described in detail below.
As shown in fig. 1, fig. 1 is a flow chart of a method for generating a three-dimensional digital model for constructing a core model according to the present invention.
Step 101: taking a real core CT end face scanning image as an original material; in general, the obtained source material is a grayscale image. Namely, each pixel point has an element with the value of 0-255, white is 255 and black is 0.
Step 102: the image in step 101 is subjected to binarization processing. The specific method comprises the following steps: specifying a threshold, comparing the pixel value in the image in the step 101 with the threshold, and replacing the original pixel value with '0' when the pixel value is smaller than the threshold; when the pixel value is greater than the threshold value, the original pixel value is replaced with a "1". The pixels in the final image have only two values of "0" and "1", and two colors of "black" and "white" are presented in the image, where "0" corresponds to black and "1" corresponds to white.
Step 103: and (4) extracting an image mask circle, searching pore points in comparison with the image in the step 102, and counting the number of pixels at the pore positions by using a recursive function. Setting a reasonable threshold, calculating the number of pore pixels, and deleting pores with the number of pore pixels smaller than the threshold.
Step 104: and for two non-connected pores, selecting a pore region with the largest area as a root node by using a minimum spanning tree method, and connecting the pores by using the same color as the pores.
Step 105: the image of step 104 is normalized and set to be rectangular, and the normalized image must ensure that all the pores are communicated with the four sides of the rectangle.
Step 106: and (3) carrying out mirror image turning on the image obtained in the step 105 for multiple times according to the size requirement of the core to be manufactured, wherein the image after mirror image turning can ensure the communication between the pores.
Step 107: and stretching the image in the step 106 along the direction vertical to the plane to obtain a three-dimensional image.
In one embodiment of the present invention, the method comprises the following steps:
Step 2, as shown in fig. 3, the image of fig. 2 is subjected to binarization processing. The specific method comprises the following steps: specifying a threshold, comparing the pixel value in the image of the step 1 with the threshold, and replacing the original pixel value with 0 when the pixel value is smaller than the threshold; when the pixel value is greater than the threshold value, the original pixel value is replaced with a "1". The pixels in the final image have only two values of "0" and "1", and two colors of "black" and "white" are presented in the image, where "0" corresponds to black and "1" corresponds to white.
Step 3, reversing the colors "black" and "white" for easy viewing. And extracting an image mask circle, searching for a pore point by comparing the image with the image in FIG. 4, and counting the number of pixels at the pore by using a recursive function. Setting a threshold value, calculating the number of pore pixels, and deleting pores with the number of pore pixels smaller than the threshold value.
And 4, selecting a pore area with the largest area as a root node for two pores which are not communicated by using a minimum spanning tree method, and communicating the pores by using the same color as the pores, as shown in fig. 5.
And 5, standardizing the images after the pores are communicated, setting the images into rectangles, wherein the standardized images must ensure that the pores are communicated with the four sides of the rectangles, as shown in FIG. 6.
And 6, carrying out mirror image turning for multiple times according to the size requirement of the core to be manufactured in the figure 7, wherein the image after mirror image turning can ensure the communication between the pores. Sidelines are respectively arranged on two sides of the image and are used for being communicated with the core gap. Two communicating holes are arranged on the outer side of the sideline and connected with the sideline, and an oil filling opening is arranged at the intersection of the communicating holes and used as an oil filling channel and an oil outflow hearing opening. The periphery of the model is provided with a black area with enough side length as a closed boundary of the model.
And 7, stereoscopically transforming the plane graph shown in the figure 7 to generate a three-dimensional digital model, as shown in the figure 8.
Claims (1)
1. The three-dimensional digital model generation method for building the core model is characterized by comprising the following steps of:
step 1, scanning an original image for a rock core CT (computed tomography) as an original material for constructing a three-dimensional digital model of a rock core model;
step 2, carrying out binarization processing on the image in the step 1; a threshold value is designated, the pixel value in the image in the step 1 is compared with the threshold value, and when the pixel value is smaller than the threshold value, the original pixel value is replaced by '0'; when the pixel value is larger than the threshold value, replacing the original pixel value with '1'; "0" corresponds to black and "1" corresponds to white;
step 3, reversing the colors of black and white for convenient observation; extracting an image mask circle, searching a pore point by comparing the image, and counting the number of pixels at the pore by using a recursive function; setting a threshold, calculating the number of pore pixels, and deleting pores with the number of pore pixels smaller than the threshold;
step 4, selecting a pore area with the largest area as a root node for two non-communicated pores by using a minimum spanning tree method, and communicating each pore by using the same color as the pore;
step 5, standardizing the images after the holes are communicated, setting the images into rectangles, wherein the standardized images are communicated with the four sides of the rectangles through the holes;
step 6, carrying out mirror image turning for multiple times according to the size requirement of the core to be manufactured, wherein the image after mirror image turning ensures the communication between the pores; side lines are respectively arranged on two sides of the image and are used for being communicated with the core gap; two communicating holes on the outer side of the sideline are connected with the sideline, and oil filling ports are arranged at the intersection of the communicating holes and are used as an oil filling channel and an oil outflow channel; setting black areas around the model as the closed boundary of the model;
and 7, performing three-dimensional processing on the image processed in the step 6 to generate a three-dimensional digital model.
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| CN108891018A (en) * | 2018-06-28 | 2018-11-27 | 西南石油大学 | The fast preparation method of microscopic seepage physical model based on 3D printing technique |
| CN109448104B (en) * | 2018-10-11 | 2020-10-30 | 中国科学院力学研究所 | Method and device for expanding and reconstructing based on core image |
| CN114379092B (en) * | 2021-12-28 | 2024-02-06 | 数岩科技股份有限公司 | Artificial core preparation method and system |
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| CN105654525A (en) * | 2014-11-10 | 2016-06-08 | 中国石油化工股份有限公司 | Two-dimensional model construction method for reflecting real rock core connectivity |
| CN106442271A (en) * | 2016-11-18 | 2017-02-22 | 杨康 | Rock core permeability simulating method and rock core permeability simulating device |
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| CN105487121B (en) * | 2015-12-03 | 2018-08-07 | 长江大学 | Multiple dimensioned digital cores method is built based on CT scan image and Electrical imaging image co-registration |
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| CN103971410A (en) * | 2014-05-23 | 2014-08-06 | 中国石油大学(华东) | Three-dimensional rock core visualization method based on CT images |
| CN105654525A (en) * | 2014-11-10 | 2016-06-08 | 中国石油化工股份有限公司 | Two-dimensional model construction method for reflecting real rock core connectivity |
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