A method and apparatus for external volume correction suitable for porosity measurements of rock samples with rough surfaces

Abstract

This application discloses an external volume correction method and apparatus suitable for measuring the porosity of rock samples with rough surfaces. The method includes: acquiring scanned raw slice data; and acquiring binary image data volume D characterizing the rock skeleton components based on the scanned raw slice data. 骨架ROI According to D 骨架ROI Obtaining the binary image data volume D after mean processing 实ROI Volume V 实 Based on the binary image data volume D after mean processing 实ROI Obtain the total pore volume V on the outer surface of the rock sample. 表孔 According to the volume V 实 and the total pore volume V on the outer surface of the rock sample 表孔 Obtain the corrected external volume V of the rock sample 外表体积 This application can provide high-precision external volume measurement results for low-porosity, dense, brittle and easily broken rocks, thereby improving the accuracy of rock helium porosity test results.

Description

Technical Field

[0001] This application relates to the field of volume measurement technology, and in particular to an external volume correction method and an external volume correction device suitable for measuring the porosity of rock samples with rough surfaces. Background Technology

[0002] The external volume of a rock sample is one of the important parameters for measuring and calculating its helium porosity. During cutting, grinding, or natural weathering, rock samples often develop an uneven, rough surface. Some of these depressions on the sample surface are man-made, resulting from the loss of rock mineral grains, while others are naturally formed pores developed during the rock's burial and diagenesis process. If the surface roughness is not considered, and the depressions left by the fallen grains are mistakenly taken as the volume of pores developed in the rock, the measured external volume will be larger than the actual value, leading to an overestimation of the helium porosity. This effect is particularly significant for low-porosity, dense rocks (such as mudstone and shale).

[0003] Determining the cause of depressions on the surface of rock samples, while removing depressions caused by missing grains and preserving the truly developed pores that are connected to the surface of the rock sample, is of great significance for accurately measuring the external volume of rock samples and correcting the measured value of helium porosity in rocks.

[0004] Currently, surface roughness is generally not considered when measuring the external volume of rock samples. To facilitate accurate determination of sample external volume, it is often necessary to prepare and use standard-sized rock samples, such as preparing plunger samples and measuring their diameter and height with vernier calipers to calculate their external volume. However, even with refined sample preparation techniques such as wire cutting, it is still impossible to avoid the phenomenon of particle breakage and loss on the rock sample surface. At the microscopic level, the surface roughness of the rock sample still affects the results of helium porosity tests.

[0005] For some brittle and fragile rock types (such as mudstone, shale, and coal), or in situations with limited sampling conditions (such as drilling cuttings or granular samples from rock fracture zones), it is difficult to prepare samples with regular shapes. In such cases, the surface roughness of the rock sample has a more significant impact on the external volume measurement and helium porosity measurement results.

[0006] Currently, commonly used methods for measuring the external volume of rock samples include: measuring rock samples with regular shapes using vernier calipers; and measuring rock samples with irregular shapes using Archimedes' principle, employing the wax sealing method or mercury removal method. In these existing methods, small depressions on the rock sample surface caused by human intervention during sampling and preparation are considered naturally developed pores during measurement. This leads to an overestimation of the measured helium porosity, especially for rock types with less developed pores and lower porosity (such as mudstone, shale, and coal). Therefore, it is necessary to correct for the influence of differences in rock sample surface roughness on the results of external volume and porosity measurements.

[0007] In summary, the measured external volume of rock samples directly affects the accuracy of helium porosity test results. Regardless of whether the rock sample has a regular or irregular shape, existing external volume measurement techniques do not correct for the volume of the missing micro-particles on the rock sample surface. Summary of the Invention

[0008] The purpose of this invention is to provide an external volume correction method suitable for measuring the porosity of rock samples with rough surfaces, which at least solves one of the above-mentioned technical problems.

[0009] This invention provides the following solution:

[0010] According to one aspect of the present invention, an external volume correction method is provided for measuring the porosity of rock samples with rough surfaces, the external volume correction method for measuring the porosity of rock samples with rough surfaces includes:

[0011] Obtain the original slice data of each scanned rock sample obtained through CT scanning;

[0012] Three-dimensional data volume reconstruction is performed on each original scanned slice data to obtain a binary image data volume D that can characterize the rock skeleton components. 骨架ROI ;

[0013] Binary image data volume D of solid skeleton of rock sample 骨架ROI The outer contour is identified, and the space inside the outer contour is averaged to obtain the averaged binary image data volume D. 实ROI And calculate the mean to obtain the binary image data volume D after mean processing. 实ROI Volume V 实 ;

[0014] Based on the binary image data volume D after mean processing 实ROI Obtain the total pore volume V on the outer surface of the rock sample. 表孔 ;

[0015] According to the volume V 实 and the total pore volume V on the outer surface of the rock sample表孔 Obtain the corrected external volume V of the rock sample 外表体积 .

[0016] Optionally, the three-dimensional data volume reconstruction of each original scanned slice data is performed to obtain a binary image data volume D that can characterize the rock skeleton components. 骨架ROI include:

[0017] The grayscale range of the solid skeleton of the rock was determined using Otsu's algorithm, and based on this, the three-dimensional image data volume of the solid part of the rock sample was segmented and extracted to obtain a binary image data volume D that can characterize the components of the rock skeleton. 骨架ROI .

[0018] Optionally, the binary image data volume D after mean processing... 实ROI Obtain the total pore volume V on the outer surface of the rock sample. 表孔 include:

[0019] The binary image data volume D after mean processing 实ROI Obtain a concave data volume D with multiple discrete units that can characterize the spatial volume of the concavity on the surface of a rock sample. 凹-multiROI ;

[0020] Based on the recessed data volume D, which has multiple discrete units and can characterize the volume of the recessed space on the surface of the rock sample. 凹-multiROI Obtain the naturally developed pores D on the outer surface of the rock 表孔-multiROI ;

[0021] Based on the naturally developed pores D on the outer surface of each rock 表孔-multiROI Obtain the total pore volume V on the outer surface of the rock sample. 表孔 .

[0022] Optionally, the binary image data volume D processed according to the mean... 实ROI Acquire a data volume D with multiple discrete units that can characterize the spatial volume of depressions on the surface of a rock sample. 凹-multiROI include:

[0023] Binary image data volume D after mean processing 实ROI Perform image morphological closing operations to obtain a binary image data volume D with a relatively smooth surface. 基准面ROI ;

[0024] The binary image data volume D with a relatively smooth surface 基准面ROI The outer surface serves as the reference plane; beyond it are the protruding parts of the rock surface, and within it are the concave parts. Based on this, D... 基准面ROI -D 实ROI Obtain the difference space data volume D 差值ROI ;

[0025] For the difference space data volume D 差值ROI Perform voxel connectivity analysis and resolve it into a difference data volume D of multiple discrete units. 差值-multiROI ;

[0026] And for the difference data volume D of each discrete unit 差值-multiROI The voxel size is measured, and data information that is insufficient in spatial resolution to characterize the reliable pore space is removed, leaving the difference data volume D of discrete units. 差值-multiROI As a concave data volume D 凹-multiROI .

[0027] Optionally, the method is based on a recessed data volume D with multiple discrete units that can characterize the volume of the recessed space on the rock sample surface. 凹-multiROI Obtain the naturally developed pores D on the outer surface of the rock 表孔-multiROI include:

[0028] Obtain standard image data volume;

[0029] Obtain the binary image data volume D based on the standard image data volume. 孔 ;

[0030] For binary image data volume D 孔 Based on the porosity voxel connectivity analysis results, a binary image data volume D of multiple discrete units was calculated. 孔-multiROI ;

[0031] Extracting binary image data volume D 孔-multiROI The pore data volume cells connected to the outer surface are used to obtain discrete binary image data volume cells, and noise cells with small voxels are removed to obtain the outer pore binary image data volume D. 外孔-multiROI ;

[0032] Based on the binary image data of each external hole D 外孔-multiROI Obtain characteristic parameters and standards for determining the origin of porosity;

[0033] Based on the characteristic parameters and standards for determining the cause of porosity, the concave data volume D is analyzed. 凹-multiROI By filtering each discrete unit, the naturally developed pores D on the outer surface of the rock can be obtained. 表孔-multiROI .

[0034] Optionally, the pores D naturally developed on the outer surface of each rock are... 表孔-multiROI Obtain the total pore volume V on the outer surface of the rock sample. 表孔 include:

[0035] Calculate and statistically analyze the naturally developed pore size D on the outer surface of each rock. 表孔-multiROI The volume of each unit space is calculated and summed to obtain the total volume V of pores developed on the outer surface of the rock sample. 表孔 .

[0036] Optionally, the step based on the volume V 实 and the total pore volume V on the outer surface of the rock sample 表孔 Obtain the corrected external volume V of the rock sample 外表体积 include:

[0037] Get volume V 实 and the total pore volume V on the outer surface of the rock sample 表孔之和 The corrected external volume of the rock sample, V 外表体积 .

[0038] Optionally, the external volume correction method for measuring the porosity of rock samples with rough surfaces further includes:

[0039] Obtain the helium porosity of the test rock sample.

[0040] Optionally, obtaining the helium porosity of the test rock sample includes:

[0041] Acquire pressure change information and known volume information obtained during the helium porosity test experiment;

[0042] Based on the gas equation, the skeletal volume V of the tested rock sample was calculated. solid ;

[0043] Based on the skeleton volume V of the rock sample being tested solid Corrected surface volume of rock sample V 外表体积 Obtain the helium porosity of the test rock sample.

[0044] This application also provides an external volume correction device suitable for measuring the porosity of rock samples with rough surfaces, the external volume correction device for measuring the porosity of rock samples with rough surfaces comprising:

[0045] The original scanned slice data acquisition module is used to acquire the original scanned slice data of each rock sample obtained by CT scanning.

[0046] D 骨架ROI The acquisition module, the D 骨架ROI The acquisition module is used to reconstruct three-dimensional data volumes from each scanned original slice data to obtain binary image data volumes D that can characterize the rock skeleton components. 骨架ROI ;

[0047] The volume acquisition module is used to process the binary image data volume D of the solid skeleton of the rock sample. 骨架ROI The outer contour is identified, and the space inside the outer contour is averaged to obtain the averaged binary image data volume D. 实ROIAnd calculate the binary image data volume D after mean processing. 实ROI Volume V 实 ;

[0048] The module for obtaining the total volume of pores developed on the outer surface is used to obtain the total volume of pores developed on the outer surface based on the binary image data volume D after mean processing. 实ROI Obtain the total pore volume V on the outer surface of the rock sample. 表孔 ;

[0049] The corrected rock sample surface volume acquisition module is used to obtain the volume V based on the volume V. 实 and the total pore volume V on the outer surface of the rock sample 表孔 Obtain the corrected external volume V of the rock sample 外表体积 .

[0050] This invention, based on CT three-dimensional scanning technology, establishes an external volume correction method suitable for measuring and calculating the porosity of rock samples with rough surfaces. This method utilizes three-dimensional image processing technology to establish a method for determining the origin of surface depressions in rock samples, correcting for the volume of missing particles in the external volume of the rock sample due to sample preparation. It enables convenient, rapid, and non-destructive measurement and calculation of the external volume of regular or irregular rock samples, providing high-precision external volume measurement results for low-porosity, dense, brittle, and easily broken rocks, thereby improving the accuracy of helium porosity testing results for rocks. Attached Figure Description

[0051] Figure 1 This is a schematic flowchart of an embodiment of the present application of an external volume correction method for measuring the porosity of rock samples with rough surfaces.

[0052] Figure 2 This is a schematic diagram of the structure of a rock sample with a rough surface according to an embodiment of this application; wherein,

[0053] 2a is a 3D rendering of the image data volume of a rock sample with a rough surface; 2b is a 2D slice rendering of the image data volume of the rock sample with a rough surface reconstructed from a CT scan; 2c is the corresponding binary image data volume D representing the rock skeleton. 骨架ROI Two-dimensional slice effect diagram; 2d is the binary image data volume D after mean processing, corresponding to 2c. 实ROI Two-dimensional slice effect diagram; 2e is the binary image data volume D after the closing operation corresponding to 2d. 基准面ROI Two-dimensional sliced ​​image; 2f is the binary image data volume D resulting from the subtraction operation between 2e and 2d. 差值ROI Two-dimensional slice effect diagram; 2g is the binary image data volume D after connectivity analysis and noise processing corresponding to 2f. 凹-multiROITwo-dimensional slice effect image; 2h is the binary image data volume D after screening naturally developed pores according to the established standards, corresponding to 2g. 表孔-multiROI Two-dimensional slice effect image; 2i is the binary image data volume D corresponding to 2a, representing the naturally developed pores on the surface. 表孔-multiROI 3D rendering.

[0054] Figure 3 This is the binary image data volume D in one embodiment of this application. 孔 A schematic diagram; 3a is in Figure 2 Data volume D, shown in figure a, is obtained by sampling in a regular cylindrical shape. 孔 3b is used to establish a criterion for judging naturally developed porosity on the surface; 3b is the binary image data volume D corresponding to 3a, representing the developed porosity. 孔 3D rendering; 3c is the data volume D of the pores corresponding to 3b and connected to the outer surface of the cylinder. 外孔-multiROI 3D porosity rendering; 3D refers to the statistical calculation data volume D. 外孔-multiROI Histogram of frequency distribution of pore structure parameters (pore volume / surface area). Detailed Implementation

[0055] The technical solution of the present invention will now be clearly and completely described with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0056] like Figure 1 The external volume correction method shown for measuring the porosity of rock samples with rough surfaces includes:

[0057] Obtain raw slice data of each rock sample obtained by CT scanning; specifically, fix the rock sample on the CT scanning bracket and scan it, and select a scanning imaging resolution that can image the larger pores inside the rock; block samples can be fixed directly, and granular samples can be placed in a container made of low-density material (such as resin), requiring that the outer volume of the container is known and its size can be placed in a helium porosimeter and CT scanner (the outer volume can be determined in advance with helium).

[0058] Three-dimensional data volume reconstruction is performed on each original scanned slice data to obtain a binary image data volume D that can characterize the rock skeleton components. 骨架ROI ;

[0059] Binary image data volume D of solid skeleton of rock sample 骨架ROI The outer contour is identified, and the space inside the outer contour is averaged to obtain the averaged binary image data volume D.实ROI And calculate the binary image data volume D after mean processing. 实ROI Volume V 实 ;

[0060] Based on the binary image data volume D after mean processing 实ROI Obtain the total pore volume V on the outer surface of the rock sample. 表孔 ;

[0061] According to the volume V 实 and the total pore volume V on the outer surface of the rock sample 表孔 Obtain the corrected external volume V of the rock sample 外表体积 .

[0062] In this embodiment, the three-dimensional data volume reconstruction of each original scanned slice data is performed to obtain a binary image data volume D that can characterize the rock skeleton components. 骨架ROI include:

[0063] The grayscale range of the solid skeleton of the rock was determined using Otsu's algorithm, and based on this, the three-dimensional image data volume of the solid part of the rock sample was segmented and extracted to obtain a binary image data volume D that can characterize the components of the rock skeleton. 骨架ROI Specifically, the original scanned slice data is reconstructed into a 3D data volume, and the reconstructed data volume is imported into a visualization software platform. The grayscale range of the rock solid skeleton is determined using the Otsu algorithm, and based on this, the 3D image data volume of the rock sample solid part is segmented and extracted to obtain a binary image data volume D that can characterize the rock skeleton components. 骨架ROI ;

[0064] In this embodiment, the binary image data volume D after mean processing... 实ROI The total pore volume Vsurface pores on the outer surface of the rock sample is obtained by calculating the total pore volume.

[0065] The binary image data volume D after mean processing 实ROI Obtain a concave data volume D with multiple discrete units that can characterize the spatial volume of the concavity on the surface of a rock sample. 凹-multiROI ;

[0066] Based on the recessed data volume D, which has multiple discrete units and can characterize the volume of the recessed space on the surface of the rock sample. 凹-multiROI Obtain the naturally developed pores D on the outer surface of the rock 表孔-multiROI ;

[0067] Based on the naturally developed pores D on the outer surface of each rock 表孔-multiROI Obtain the total pore volume V on the outer surface of the rock sample. 表孔 .

[0068] In this embodiment, the binary image data volume D processed according to the mean is... 实ROI Obtain a concave data volume D with multiple discrete units that can characterize the spatial volume of the concavity on the surface of a rock sample. 凹-multiROI include:

[0069] Binary image data volume D after mean processing 实ROI Perform image morphological closing operations to obtain a binary image data volume D with a relatively smooth surface. 基准面ROI ;

[0070] The binary image data volume D with a relatively smooth surface 基准面ROI The outer surface serves as the reference plane; beyond it are the protruding parts of the rock surface, and within it are the concave parts. Based on this, D... 基准面ROI -D 实ROI Obtain the difference space data volume D 差值ROI ;

[0071] For the difference space data volume D 差值ROI Perform voxel connectivity analysis and resolve it into a difference data volume D with multiple discrete units. 差值-multiROI ;

[0072] And for the difference data volume D of each discrete unit 差值-multiROI The voxel size is measured, and data information that is insufficient in spatial resolution to characterize the reliable pore space is removed, leaving the difference data volume D of discrete units. 差值-multiROI As a concave data volume D 凹-multiROI .

[0073] Specifically, using the binary image data volume D 实ROI For the target data volume, perform an image morphological closing operation on it (closing is a basic operation in morphological processing, consisting of two steps: dilation and erosion. In CT image processing, closing is often used to fill small holes in an image, connect adjacent objects, and smooth object edges), to obtain a binary image data volume D with a relatively smooth surface. 基准面ROI Using the outer surface of this data volume as a reference plane, the area outside the reference plane represents the protruding parts of the rock surface, and the area inside the reference plane represents the concave parts of the rock surface. Based on this, a spatial subtraction operation is performed on the two data volumes, i.e., D. 基准面ROI -D 实ROI Obtain the difference space data volume D 差值ROI The data volume was subjected to voxel connectivity analysis and resolved into a difference data volume D consisting of multiple discrete units. 差值-multiROIThe voxel size of each data unit was measured, and data units with insufficient spatial resolution to characterize reliable pore space, such as those with fewer than four voxels, were removed to obtain a recessed data volume D with multiple discrete units that can characterize the volume of the depression space on the rock sample surface. 凹-multiROI ;

[0074] In this embodiment, the recessed data volume D, which has multiple discrete units and can characterize the volume of the recessed space on the surface of the rock sample, is used. 凹-multiROI Obtain the naturally developed pores D on the outer surface of the rock 表孔-multiROI include:

[0075] Obtain standard image data volume;

[0076] Obtain the binary image data volume D based on the standard image data volume. 孔 ;

[0077] For binary image data volume D 孔 Based on the porosity voxel connectivity analysis results, a binary image data volume D of multiple discrete units was calculated. 孔-multiROI ;

[0078] Extract each binary image data volume D 孔-multiROI中 The pore data volume cells connected to the outer surface are used to obtain discrete binary image data volume cells, and noise cells with small voxels are removed to obtain the outer pore binary image data volume D. 外孔-multiROI ;

[0079] Based on the binary image data of each external hole D 外孔-multiROI Obtain characteristic parameters and standards for determining the origin of porosity;

[0080] Based on the characteristic parameters and criteria for determining the cause of porosity, the concave data volume D of each discrete unit is analyzed. 凹 -multi ROI Screening is performed to obtain the naturally developed pores D on the outer surface of the rock. 表孔-multiROI .

[0081] In this embodiment, the pores D naturally developed on the outer surface of each rock are... 表孔-multiROI Obtain the total pore volume V on the outer surface of the rock sample. 表孔 include:

[0082] Calculate and sum the volume of each unit space to obtain the total volume of pores developed on the outer surface of the rock sample, V. 表孔 .

[0083] Specifically, firstly, standard shape images (i.e., regular geometric images, such as cylinders) are used to resample the image data volume within the three-dimensional data volume of the rock sample. This yields an image data volume with a regular shape, unaffected by the actual rock surface, and relatively small in volume compared to the original analysis data volume, used to establish discrimination criteria. The grayscale thresholds for pore components are then determined, and image segmentation and extraction are performed to obtain the binary image data volume D. 孔 Furthermore, based on the porosity voxel connectivity analysis results, the binary image data volume D of multiple discrete units was calculated. 孔-multiROI Extract the pore data volume cells connected to the outer surface to obtain discrete binary image data volume cells, and remove the noise cells with small voxels to obtain a new binary image data volume D. 外孔-multiROI The structural characteristics of the rock sample were analyzed, and the pore volume / surface area parameter values ​​of each data volume unit were calculated. Statistical analysis was used to determine the distribution range of the pore volume / surface area characteristic parameters of the actual developed pores in the rock sample, which were then used as characteristic parameters and standards for judging the origin of porosity. Based on this, the concave data volume D was analyzed. 凹-multiROI The pore volume / surface area parameters are calculated, and the cause of the depression is determined based on the established characteristic parameter standards. Units outside the standard range are removed, and units that meet the standards are retained as naturally developed pores D on the outer surface of the rock. 表孔-multiROI The volume of each unit space is calculated and summed to obtain the total volume of pores developed on the outer surface of the rock sample, V. 表 hole;

[0084] In this embodiment, the step of basing the volume V 实 and the total pore volume V on the outer surface of the rock sample 表孔 Obtain the corrected external volume V of the rock sample 外表体积 include:

[0085] Get volume V 实 and the total pore volume V on the outer surface of the rock sample 表孔之和 The corrected external volume of the rock sample, V 外表体积 .

[0086] In this embodiment, the external volume correction method for measuring the porosity of rock samples with rough surfaces further includes:

[0087] Obtain the helium porosity of the test rock sample.

[0088] In this embodiment, obtaining the helium porosity of the test rock sample includes:

[0089] Obtain pressure change information and known volume information during the helium porosity test experiment (the known volume information is the volume of the reference chamber in the helium porosity test instrument, based on the measured pressure values ​​after the valve between the reference chamber and the sample chamber is closed and opened, and the volume of the reference chamber).

[0090] Based on the gas equation, the skeletal volume V of the tested rock sample was calculated. solid ;

[0091] Based on the skeleton volume V of the rock sample being tested solid Corrected surface volume of rock sample V 外表体积 Obtain the helium porosity of the test rock sample; the helium porosity of the test rock sample is Ф=(V 外表体积 -V solid ) / V 外表体积 *100%.

[0092] The following is combined Figure 2 as well as Figure 3 As this application is further elaborated, it is understood that the example does not constitute any limitation on this application.

[0093] Select an appropriate resolution to scan and image the entire rock sample. Reconstruct the original scanned projection image in three dimensions to obtain the three-dimensional data volume of the rock sample; in this example, the rock sample is a cylinder. Figure 2 a) The direction of the cylindrical cross-section is perpendicular to the direction of the natural sedimentary bedding of the rock. Figure 2 b).

[0094] By selecting an appropriate grayscale threshold, the image is segmented to identify the skeletal structure of the rock sample and obtain the data volume D. 骨架ROI In this example, the grayscale threshold of the rock sample skeleton was calculated using the Otsu method. Figure 2 b and Figure 2 Image c shows a slice of rock perpendicular to the bedding direction and a binary image of the corresponding segmented rock sample skeleton.

[0095] Data volume D of the skeleton part 骨架ROI The internal pore spaces are filled with images to obtain the corresponding solid data volume D. 实ROI The specific method used in this example is to analyze the binary image data volume D along a cross-sectional direction perpendicular to the bedding direction. 骨架ROI The outer contour of each slice is identified and its interior is filled with 1. Figure 2 d showed with Figure 2 C slice corresponds to D 实ROI Image processing results;

[0096] The reference surface data volume of the rock sample's outer surface was calculated and obtained. In this example, the image morphology closing operation function was used in the image processing software, and an appropriate structuring element size was selected (in this example, the kernel size was 15; the larger the value, the smoother the outer surface of the reference surface data volume and the lower the degree of encapsulation of the rock sample). Without changing the basic shape of the rock sample's outer contour, the concave space of the outer surface was filled, resulting in a new binary image data volume D with a relatively smooth outer surface. 基准面ROI , Figure 2 e displayed the corresponding Figure 3 D after smoothing d 基准面ROI Binary image result;

[0097] The binary image data volume D 基准面ROI and D 实ROI Perform spatial subtraction to obtain the spatial data volume D of the difference between the two. 差值ROI , Figure 2 f showed Figure 2 e and Figure 2 The binary image obtained after subtracting the data volume slices shown in d is then subjected to voxel connectivity analysis. In this example, the data volume is divided into multiple discrete data volumes D according to the six-connectivity principle. 差值-multiROI The voxel size of each unit is analyzed and statistically analyzed, and units with smaller voxels are removed. In this example, D is removed. 差值-multiROI Data volume D is obtained from units with fewer than 100 voxels. 凹-multiROI , Figure 2 g shows Figure 2 Data body D shown in f 差值 -multi ROI Data volume D of the rock sample outer surface depression unit obtained after noise removal 凹-multiROI The corresponding slice image;

[0098] Data volume resampling is performed inside the rock using regular geometric shapes to obtain data volumes with smooth surfaces and regular shapes, such as... Figure 3 a. In this example, a cylinder is used for internal resampling to obtain a data volume with a relatively small internal volume. The pore spaces within this data volume are then identified and characterized. In this example, Otsu's method is used to calculate its threshold and segment and extract the binary image data volume D. 孔 ( Figure 3 b) Further, based on the porosity voxel connectivity analysis results, it is analyzed into a binary image data volume D with multiple discrete units according to the six-connectivity principle. 孔-multiROI Extract the pore data volume units connected to the outer surface to obtain discrete binary image data volume units, and remove noise units with less than 100 voxels to obtain a new binary image data volume D. 外孔-multiROI ( Figure 3c) Calculate the pore volume / surface area parameter value for each unit, and statistically analyze to determine the distribution range of the pore volume / surface area characteristic parameters of the actual developed pores in the rock sample. Use these as characteristic parameters and standards for judging the origin of porosity. If the statistical sample data obtained from a single resampling is insufficient, this step can be repeated. By changing the sampling location or the diameter of the geometric object, multiple samplings can be performed, and the structural pore volume / surface area parameters of pores connected to the surface can be statistically analyzed. The statistical results in this example are shown in [reference needed]. Figure 3 d, the distribution range of this characteristic parameter is 0.00526 to 0.03229;

[0099] For discrete data volume element D 凹-multiROI The pore volume / surface area parameters are calculated, and the distribution range of characteristic parameters established in step 6 is used as a standard to determine the cause of the depression. Depression units outside the standard range are removed, and units that meet the standard are retained as naturally developed pores D on the outer surface of the rock. 表孔-multiROI The volume of each unit space is calculated and summed to obtain the total volume of pores developed on the outer surface of the rock sample, V. 表孔 . Figure 2 h and Figure 2 i respectively presents data volume D, which, after being screened according to standards, can characterize the porosity developed on the outer surface. 表孔-multiROI Sliced ​​binary image and 3D rendering.

[0100] Calculate the data volume D separately 实ROI and data body D 表孔-multiROI The volume of each is denoted as V. 实 With V 表孔 The volume obtained by adding the two is the corrected external surface volume V of the rock sample. 外表体积 The calculation results of the volume parameters in this example are shown in Table 1 below:

[0101] Table 1. Calculation Results of Volume Parameters

[0102] parameter <![CDATA[Value (mm 3 )]]> <![CDATA[V 实 ]]> 9958.51 <![CDATA[V 表孔 ]]> 61.54 <![CDATA[V 外表体积 ]]> 10020.05

[0103] This application also provides an external volume correction device suitable for measuring the porosity of rock samples with rough surfaces. The external volume correction device includes a scanning raw slice data acquisition module and a D... 骨架ROI The module includes a volume acquisition module, a volume acquisition module, a total volume acquisition module for pores developed on the outer surface, and a corrected volume acquisition module for the outer surface of the rock sample.

[0104] The raw scan slice data acquisition module is used to acquire raw scan slice data of rock samples obtained through CT scanning;

[0105] D 骨架ROIThe acquisition module is used to reconstruct three-dimensional data volumes from each scanned original slice data to obtain binary image data volumes D that can characterize the rock skeleton components. 骨架ROI ;

[0106] The volume acquisition module is used to process the binary image data volume D of the solid skeleton of the rock sample. 骨架ROI The outer contour is identified, and the space inside the outer contour is averaged to obtain the averaged binary image data volume D. 实ROI And calculate the binary image data volume D after mean processing. 实ROI Volume V 实 ;

[0107] The module for obtaining the total volume of pores developed on the outer surface is used to obtain the binary image data volume D after mean processing. 实ROI Obtain the total pore volume V on the outer surface of the rock sample. 表孔 ;

[0108] The corrected rock sample external surface volume acquisition module is used to obtain the volume V based on the volume V. 实 and the total pore volume V on the outer surface of the rock sample 表孔 Obtain the corrected external volume V of the rock sample 外表体积 .

[0109] This application takes into account the influence of rock sample surface roughness on helium porosity measurement and optimizes the external volume measurement method.

[0110] In the method for characterizing the outer surface and quantifying the outer surface volume of rock samples based on CT three-dimensional data, this invention removes the "artificial" pore volume formed by particle collapse caused by sampling factors, and retains the true pore volume developed by the rock itself and connected to the outer surface. The resulting outer surface volume of the rock sample can more realistically reflect the pore development of the rock when used for helium porosity testing.

[0111] This application establishes a method for determining the origin of depression space on the outer surface of rock samples based on CT scan data. It removes the volume of depression space caused by human intervention on the rock surface, while retaining the volume of naturally developed pore space on the rock surface.

[0112] Based on a characterization of the actual development of the rock sample's outer surface, a reference surface is calculated using surface smoothing techniques. The volume of the depressions on the outer surface is obtained by calculating the spatial difference between the actual outer surface and the reference surface. Further analysis of structural parameters such as pore volume / surface area within the rock sample determines their distribution range, thereby screening for the causes of the surface depressions and distinguishing which depressions are caused by human sampling and which are naturally occurring pores in the rock.

[0113] Existing techniques for determining helium porosity in irregular rock samples (such as the wax-sealing and mercury removal methods) are inherently destructive. Because the sample is contaminated with wax or mercury, it cannot be reused for subsequent analytical experiments. Furthermore, current testing standards require parallel samples for particle testing; that is, parallel block samples are used to test external volume and apparent density, meaning these are not truly the same sample as the particle sample measured by helium. In contrast, the present invention provides a completely non-destructive experiment, using the same sample throughout the entire testing process, thus maximizing sample integrity and systematic data consistency.

[0114] Traditional techniques do not detect or assess the encapsulation of irregular rock samples. For example, the wax sealing method cannot avoid or promptly detect cavities that may form during the wax encapsulation process, and the mercury removal method cannot assess the impact of intergranular space volume on the measured surface volume. Compared with existing techniques, this invention fundamentally improves the reliability of helium porosity testing results for irregular rock samples by considering the influence of surface smoothness on porosity test results. Visual inspection of surface depressions on rock samples can be performed on a visualization software platform, minimizing artificially created pore spaces due to mineral particle breakage while preserving naturally developed pores on the rock's outer surface.

[0115] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for correcting the external volume of rock samples with rough surfaces for porosity measurement, characterized in that, The external volume correction method applicable to porosity measurement of rock samples with rough surfaces includes: Obtain the original slice data of each scanned rock sample obtained through CT scanning; Three-dimensional data volume reconstruction is performed on each original scanned slice data to obtain a binary image data volume D that can characterize the rock skeleton components. 骨架ROI ; Binary image data volume D of solid skeleton of rock sample 骨架ROI The outer contour is identified, and the space inside the outer contour is averaged to obtain the averaged binary image data volume D. 实ROI And calculate the mean to obtain the binary image data volume D after mean processing. 实ROI Volume V 实 ; Based on the binary image data volume D after mean processing 实ROI Obtain the total pore volume V on the outer surface of the rock sample. 表孔 ; According to the volume V 实 and the total pore volume V on the outer surface of the rock sample 表孔 Obtain the corrected external volume V of the rock sample 外表体积 ; The binary image data volume D after mean processing 实ROI Obtain the total pore volume V on the outer surface of the rock sample. 表孔 include: The binary image data volume D after mean processing 实ROI Obtain a concave data volume D with multiple discrete units that can characterize the spatial volume of the concavity on the surface of a rock sample. 凹-multiROI ; Based on the recessed data volume D, which has multiple discrete units and can characterize the volume of the recessed space on the surface of the rock sample. 凹-multiROI Obtain the naturally developed pores D on the outer surface of the rock 表孔-multiROI ; Based on the naturally developed pores D on the outer surface of each rock 表孔-multiROI Obtain the total pore volume V on the outer surface of the rock sample. 表孔 .

2. The external volume correction method for measuring the porosity of rock samples with rough surfaces as described in claim 1, characterized in that, The binary image data volume D after processing according to the mean value 实ROI Acquire a data volume D with multiple discrete units that can characterize the spatial volume of depressions on the surface of a rock sample. 凹-multiROI include: Binary image data volume D after mean processing 实ROI Perform image morphological closing operations to obtain a binary image data volume D with a relatively smooth surface. 基准面ROI ; The binary image data volume D with a relatively smooth surface 基准面ROI The outer surface serves as the reference plane; beyond it are the protruding parts of the rock surface, and within it are the concave parts. Based on this, D... 基准面ROI - D 实ROI Obtain the difference space data volume D 差值ROI ; For the difference space data volume D 差值ROI Perform voxel connectivity analysis and resolve it into a difference data volume D of multiple discrete units. 差值-multiROI ; And for the difference data volume D of each discrete unit 差值-multiROI The voxel size is measured, and data information that is insufficient in spatial resolution to characterize the reliable pore space is removed, leaving the difference data volume D of discrete units. 差值-multiROI As a concave data volume D 凹-multiROI .

3. The external volume correction method for measuring the porosity of rock samples with rough surfaces as described in claim 2, characterized in that, The data body D, which has multiple discrete units and can characterize the volume of the depression space on the surface of the rock sample, is described. 凹-multiROI Obtain the naturally developed pores D on the outer surface of the rock 表孔-multiROI include: Obtain standard image data volume; Obtain the binary image data volume D based on the standard image data volume. 孔 ; For binary image data volume D 孔 Based on the porosity voxel connectivity analysis results, a binary image data volume D of multiple discrete units was calculated. 孔-multiROI ; Extracting binary image data volume D 孔-multiROI The pore data volume cells connected to the outer surface are used to obtain discrete binary image data volume cells, and noise cells with small voxels are removed to obtain the outer pore binary image data volume D. 外孔-multiROI ; Based on the binary image data of each external hole D 外孔-multiROI Obtain characteristic parameters and standards for determining the origin of porosity; Based on the characteristic parameters and standards for determining the cause of porosity, the concave data volume D is analyzed. 凹-multiROI By filtering each discrete unit, the naturally developed pores D on the outer surface of the rock can be obtained. 表孔-multiROI .

4. The external volume correction method for measuring the porosity of rock samples with rough surfaces as described in claim 3, characterized in that, The pores D naturally developed on the outer surface of each rock are described. 表孔-multiROI Obtain the total pore volume V on the outer surface of the rock sample. 表孔 include: Calculate and statistically analyze the naturally developed pore size D on the outer surface of each rock. 表孔-multiROI The volume of each unit space is calculated and summed to obtain the total volume V of pores developed on the outer surface of the rock sample. 表孔 .

5. The external volume correction method for measuring the porosity of rock samples with rough surfaces as described in claim 4, characterized in that, The volume V 实 and the total pore volume V on the outer surface of the rock sample 表孔 Obtain the corrected external volume V of the rock sample 外表体积 include: Get volume V 实 and the total pore volume V on the outer surface of the rock sample 表孔之和 The corrected external volume of the rock sample, V 外表体积 .

6. The external volume correction method for measuring the porosity of rock samples with rough surfaces as described in claim 5, characterized in that, The external volume correction method for measuring the porosity of rock samples with rough surfaces further includes: Obtain the helium porosity of the test rock sample.

7. The external volume correction method for measuring the porosity of rock samples with rough surfaces as described in claim 6, characterized in that, The acquisition of helium porosity of the test rock sample includes: Acquire pressure change information and known volume information obtained during the helium porosity test experiment; Based on the gas equation, the skeletal volume V of the tested rock sample was calculated. solid ; Based on the skeleton volume V of the rock sample being tested solid Corrected surface volume of rock sample V 外表体积 Obtain the helium porosity of the test rock sample.

8. An external volume correction device suitable for measuring the porosity of rock samples with rough surfaces, characterized in that, The external volume correction device suitable for measuring the porosity of rock samples with rough surfaces includes: The original scanned slice data acquisition module is used to acquire the original scanned slice data of each rock sample obtained by CT scanning. D 骨架ROI The acquisition module, the D 骨架ROI The acquisition module is used to reconstruct three-dimensional data volumes from each scanned original slice data to obtain binary image data volumes D that can characterize the rock skeleton components. 骨架ROI ; The volume acquisition module is used to process the binary image data volume D of the solid skeleton of the rock sample. 骨架ROI The outer contour is identified, and the space inside the outer contour is averaged to obtain the averaged binary image data volume D. 实ROI And calculate the binary image data volume D after mean processing. 实ROI Volume V 实 ; The module for obtaining the total volume of pores developed on the outer surface is used to obtain the total volume of pores developed on the outer surface based on the binary image data volume D after mean processing. 实ROI Obtain the total pore volume V on the outer surface of the rock sample. 表孔 ; The corrected rock sample surface volume acquisition module is used to obtain the volume V based on the volume V. 实 and the total pore volume V on the outer surface of the rock sample 表孔 Obtain the corrected external volume V of the rock sample 外表体积； The binary image data volume D after mean processing 实ROI Obtain the total pore volume V on the outer surface of the rock sample. 表孔 include: The binary image data volume D after mean processing 实ROI Obtain a concave data volume D with multiple discrete units that can characterize the spatial volume of the concavity on the surface of a rock sample. 凹-multiROI ; Based on the recessed data volume D, which has multiple discrete units and can characterize the volume of the recessed space on the surface of the rock sample. 凹-multiROI Obtain the naturally developed pores D on the outer surface of the rock 表孔-multiROI ; Based on the naturally developed pores D on the outer surface of each rock 表孔-multiROI Obtain the total pore volume V on the outer surface of the rock sample. 表孔 .

Images