CN115876668B - Petroleum reservoir porosity measuring and calculating method based on rock core - Google Patents
Petroleum reservoir porosity measuring and calculating method based on rock core Download PDFInfo
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Abstract
The invention discloses a petroleum reservoir porosity measuring and calculating method based on a rock core, which comprises the steps of drilling the rock core, manufacturing a cast sheet, scanning the cast sheet to obtain a scanned photo, calculating the porosity, correcting the porosity according to a hole-seam relation, and obtaining corrected porosity. The method has strong adaptability, realizes that the laser confocal scanning obtains a high-resolution core scanning photo, obtains more accurate porosity after correcting the scanning photo according to the geometric shape and the size of the aperture, provides more accurate information for oil gas analysis, and solves the problem of analysis errors caused by more photo details when the laser confocal scanning performs core analysis.
Description
Technical Field
The invention relates to the technical field of geophysical exploration, in particular to a petroleum reservoir porosity measuring and calculating method based on a rock core.
Background
Porosity is an inherent property of reservoir rock and is also a fundamental parameter in hydrocarbon reservoir evaluation. Porosity refers to the percentage of pore volume in the rock to the total volume of the rock, and represents an important physical parameter for controlling oil and gas reserves and energy storage, and is an important research object in the process of researching, evaluating and predicting the reservoir.
The existing method for measuring the porosity of the rock core comprises a rock core observation method, an image analysis method, a casting body slice method and a scanning electron microscope method; indirect assay: mercury-pressing capillary method and nuclear magnetic resonance measurement.
The helium method has the advantages of simple operation, low cost, short time and the like, is the most commonly used effective porosity experimental measurement method, but the pore structure of a tight reservoir is complex, the obtained measurement result cannot reflect the situation of oil gas storage, such as the Chinese patent application with publication number of CN108956422A, the effective porosity, the flowing porosity and the diffusion porosity are obtained after data are corrected by using a three-time nitrogen method test, but the data processing process is complex and difficult to adapt to different rocks. The nuclear magnetic resonance method can accurately calculate the effective porosity of the tight oil reservoir, but has long measurement period, expensive equipment and few characterization parameters, and the application effect of the method in various reservoirs is not objectively and comprehensively evaluated. Mercury-compression capillary assay results are accurate but the use of the assay is limited to laboratories.
Porosity refers to the percentage of void volume in the total volume of rock, since coarse-grained clastic particles that are not drilled are void-free, but the particles occupy the volume of the rock sample, resulting in a porosity measured using a standard core column of 25mm diameter that is too great for the actual porosity of a conglomerate reservoir, and thus may pose a risk of false positives for oil and gas exploration and development. The effective porosity is the ratio of the volume of interconnected pores in the rock to the total volume of the rock, and is an important parameter for the evaluation of hydrocarbon reservoirs.
According to the conventional porosity measurement method, a standard core column sample with the diameter of 25mm is drilled from a full-diameter core, and the porosity of the standard core column sample is measured by adopting the conventional porosity measurement method, but because coarse chip particles in the core column sample of a tight reservoir are broken and fall, the selection of the core column sample is limited, and the measured data cannot effectively reflect the storage condition of oil gas.
The confocal laser scanning microscope is an optical microscopic test method which is emerging in the 80-90 th century, and the limitations of structural observation in the pores of the traditional reservoir by using a common microscope can be overcome by high magnification and resolution. The laser confocal scanning technology can acquire more abundant information from the rock core, can more accurately measure the porosity, microporosity and throat, has obviously better measurement accuracy than a common microscope, and provides support for oil and gas exploration.
Disclosure of Invention
The invention aims to provide a petroleum reservoir porosity measuring and calculating method based on a core, which solves the problem of small measurement results caused by cracking and dropping of coarse chip particles in a core column sample in the prior art by correcting a core cast sheet photo of a tight reservoir, and at least provides a beneficial selection or creation condition.
In order to achieve the technical purpose, the technical scheme of the invention is as follows:
a method for measuring and calculating porosity of a petroleum reservoir based on a core, the method comprising the steps of:
step 1, drilling a core, and manufacturing a casting sheet;
step 2, scanning the casting body slice to obtain a scanning photo, and calculating the porosity;
step 3, correcting the porosity according to the hole-seam relation;
and 4, obtaining corrected porosity.
Further, in the step 1, the core is drilled, and the substeps of manufacturing the cast sheet are as follows:
standard core columns with a diameter of 25mm are drilled, epoxy dye dip is injected into the standard core columns, and rock flakes (typically 0.1 mm to 5 mm) are ground after the epoxy dye dip has cured.
Further, in step 2, scanning the cast body sheet to obtain a scanned photograph, and the substeps of calculating the porosity are as follows:
scanning the cast sheet of the core by using a laser confocal microscope to obtain a scanning sheet; graying treatment is carried out on the scanning sheet;
obtaining an edge curve through an edge detection operator, dividing a scanning sheet into a plurality of closed areas by the edge curve, setting a threshold value of the area of the closed areas as a gap size threshold THRS, and forming a first area set by areas of the closed areas, the area of which is larger than the gap size threshold value;
recording the total area of all the closed areas in the first area set as a first area S1, enabling the core area S0 to be the view area of the current scanning sheet, and calculating the porosity phi=S1/S0; if S1 is greater than 0, the closed area with the largest area in the first area set is MAXR, and the geometric center of gravity of the MAXR is MAXR 0 。
Preferably, the gap size threshold THRS may be set empirically or may be set based on historical data.
Further, in step 3, the substeps of correcting the porosity according to the pore-slit relation are:
the method comprises the steps of (1) ordering closed areas in MSet in descending order according to the size by using a hole seam set MSet formed by closed areas which do not belong to a first area set in each closed area of a scanning sheet, wherein MSeti is the ith closed area in the set, and i is a positive integer; initializing variable i as 2, and setting aperture set MSet as N, i E [1, N ]; setting a variable as a correction ratio CD;
step 3.1, taking the geometric gravity center point of the closed area with the largest area in the scanning sheet as a datum point PA, and increasing the value of i by 1;
and 3.2, performing corner detection on the closed area MSeti, and jumping to the step 3.2.1 if the number of the corners is less than 3, or jumping to the step 3.2.2.
The obtained scanning sheet can be divided into a plurality of areas, the size and the geometric shape of the areas can influence reservoir analysis, the further classification of the divided areas is helpful for enabling the correction process to be more accurate, and whether oil gas in the gap tends to be extracted or not is judged according to the distance from the gap to the maximum closed area.
Step 3.2.1, circle identification (i.e. hough circle detection) is performed on the closed area msi to detect a circle, the detected circle is surrounded by the closed area and the radius is maximized (because in a core of an oil and gas reservoir, a circular cavity often appears on a core slice caused by oil and gas erosion or natural storage oil and gas (a form of bubbles or oil and gas in the core is generally circular), and an oil and gas extrusion gap in the circular cavity causes a gap to generate offset on an image, so that the gap position needs to be corrected); the circle center of the circle is C, the radius is R, the geometric gravity center point of the current closed area is recorded as O, and a first gap offset distance CJ is calculated;
skipping step 3.4 if R is less than CJ and otherwise skipping step 3.4 and letting CD have a value of R/CJ;
wherein exp () is an exponential function based on natural logarithm, L () is a distance of 2 points, A () is an area of a closed region, and points P1 and P2 are the sum of the minimum distances O on the edges of the closed region MSeti, respectivelyMaximum point, MAXR 0 Is the geometric center of gravity point of MAXR.
Although the method can identify larger gaps, the method can cause misjudgment or can not identify smaller gaps, and the gaps are offset on the image due to the fact that the smaller gaps are extruded by oil gas in the circular cavity, manual correction and intervention are needed, and whether the characteristics of the gaps are classified into the gaps capable of being communicated can be determined after the characteristics of the gaps are extracted and judged.
Step 3.2.2, taking the corner point with the smallest distance to the geometric gravity point O of the closed area MSeti as P1, taking the corner point with the largest distance to the geometric gravity point O of the closed area MSeti as P2, constructing line segments PL by the P1 and P2, and calculating a second gap offset distance CH:
wherein exp () is an exponential function based on natural logarithm, L () is a distance of 2 points, A (MSeti) is an area of a closed region MSeti, and R (MSeti) is a length of an outer contour of the closed region MSeti;
if the value of the second gap offset distance CH is greater than or equal to the length of the line segment PL, step 3.3 is skipped, otherwise step 3.4 is skipped and the value of CD is L (P1, P2)/(CH).
Such gaps are generally larger, but because the size of the closed area is divided in the previous step, the smaller gaps can be further classified into effective gaps by judging whether the oil gas in the gaps tends to be extracted according to the distance from the gap to the maximum closed area.
Step 3.3, if i is smaller than N, increasing the value of i by 1 and jumping to step 3.2, otherwise jumping to step 3.5;
step 3.4, obtaining a corrected gap area:
step 3.4.1, adding Area to the value of the first Area S1, increasing the value of i by 1 if i is smaller than N, and jumping to step 3.2, otherwise jumping to step 3.5;
and 3.5, outputting the corrected first area S1.
Correcting the area of the gap can eliminate the influence of the offset of the gap on the image caused by the fact that the oil gas extrusion gap in the circular cavity frequently appears on the core slice on the area of each gap, and improve the accuracy of area calculation.
The resolution of the core scanning image obtained by laser confocal scanning is higher than that of the image obtained by scanning by a common fluorescent staining optical microscope, the obtained slit edges cannot be well distinguished due to the adsorption of the staining agent by minerals during common fluorescent staining, and the laser confocal scanning effectively avoids the problem and obtains a plurality of slit structure details which cannot be obtained by scanning by a common polarizing microscope; conventional methods for distinguishing core regions, such as gray scale methods, may suffer from the inability to identify individual gaps of poor connectivity but good yield, such as the setting of gap size thresholds, which may be obtained from historical experience and conventional observation methods, may have an impact on the calculation of porosity when using confocal laser scan photographs, whereas single-layer scan photographs obtained in view of confocal laser scans may be used for three-dimensional reconstruction to make core yield analysis more efficient, so single confocal laser scan sheet correction may make final reservoir analysis more accurate.
Further, in step 4, the substep of obtaining the corrected porosity is:
the corrected porosity is obtained by recalculating the porosity according to the porosity Φ=s1/S0, and the corrected porosity is output.
Preferably, the slit in step 3.4 is marked as an effective reservoir slit, a corrected scan slice is obtained, and a plurality of corrected scan slices are subjected to subsequent three-dimensional reconstruction.
Preferably, all undefined variables in the present invention, if not explicitly defined, may be thresholds set manually.
A core-based petroleum reservoir porosity measurement system, the system comprising:
an image acquisition module: the laser confocal scanning is used for obtaining a casting body slice to obtain a scanning slice;
an image processing module: processing a scanning sheet obtained by laser confocal scanning and outputting a plurality of closed areas;
and a data processing module: and executing the steps of the petroleum reservoir porosity measurement method based on the rock core to obtain the porosity.
In a third aspect, the present invention provides a computer readable storage medium having stored thereon a computer program which when executed by a processor implements the steps of the core-based petroleum reservoir porosity measurement method of the first aspect of the present invention.
In a fourth aspect, the present invention provides an electronic device comprising: a memory having a computer program stored thereon; and the processor is used for executing the computer program in the memory to realize the steps of the petroleum reservoir porosity measuring and calculating method based on the rock core.
Compared with the prior art, the invention has the following beneficial technical effects:
the laser confocal scanning obtains a high-resolution core scanning photo, the scanning photo is corrected according to the geometric shape and the size of the aperture to obtain more accurate porosity, more accurate information is provided for oil gas analysis, and the problem of analysis errors caused by more photo details when the laser confocal scanning performs core analysis is solved.
Drawings
FIG. 1 is a flow chart of a method for measuring and calculating porosity of a petroleum reservoir based on a core provided by the invention;
fig. 2 is a schematic block diagram of a petroleum reservoir porosity measurement system based on a core according to an embodiment of the present invention.
Detailed Description
In order to make the objects, technical solutions and advantages of the present invention more clear, the present invention will be further described in detail with reference to the accompanying drawings and examples. The specific embodiments described herein are to be considered in an illustrative sense only and are not intended to limit the invention.
It is also to be understood that the following examples are given solely for the purpose of illustration and are not to be construed as limitations upon the scope of the invention, since numerous insubstantial modifications and variations will now occur to those skilled in the art in light of the foregoing disclosure. The specific process parameters and the like described below are also merely examples of suitable ranges, i.e., one skilled in the art can make a suitable selection from the description herein and are not intended to be limited to the specific values described below.
The following illustrates an exemplary method for measuring and calculating porosity of a petroleum reservoir based on a core according to the present invention.
A flow chart of a method for measuring porosity of a core-based petroleum reservoir is shown in fig. 1, and a method for measuring porosity of a core-based petroleum reservoir according to an embodiment of the present invention is described below with reference to fig. 1, the method comprising the steps of:
step 1, drilling a core, and manufacturing a casting sheet;
step 2, scanning the casting body slice to obtain a scanning photo, and calculating the porosity;
step 3, correcting the porosity according to the hole-seam relation;
and 4, obtaining corrected porosity.
Further, in the step 1, the core is drilled, and the substeps of manufacturing the cast sheet are as follows:
and (3) drilling a standard core column sample with the diameter of 25mm, injecting an epoxy resin dip dye into the standard core column sample, and grinding the rock slice after the epoxy resin dip dye is solidified.
Further, in step 2, scanning the cast body sheet to obtain a scanned photograph, and the substeps of calculating the porosity are as follows:
scanning the cast sheet of the core by using a laser confocal microscope to obtain a scanning sheet; graying treatment is carried out on the scanning sheet;
obtaining an edge curve through an edge detection operator, dividing a scanning sheet into a plurality of closed areas by the edge curve, setting a threshold value of the area of the closed areas as a gap size threshold THRS, and forming a first area set by areas of the closed areas, the area of which is larger than the gap size threshold value;
recording the total area of all the closed areas in the first area set as a first area S1, enabling the core area S0 to be the view area of the current scanning sheet, and calculating the porosity phi=S1/S0; if S1 is greater than 0, the closed area with the largest area in the first area set is MAXR, and the geometric center of gravity of the MAXR is MAXR 0 。
Further, in step 3, the substeps of correcting the porosity according to the pore-slit relation are:
the method comprises the steps of (1) ordering closed areas in MSet in descending order according to the size by using a hole seam set MSet formed by closed areas which do not belong to a first area set in each closed area of a scanning sheet, wherein MSeti is the ith closed area in the set, and i is a positive integer; initializing variable i as 2, and setting aperture set MSet as N, i E [1, N ]; setting a variable as a correction ratio CD;
step 3.1, taking the geometric gravity center point of the closed area with the largest area in the scanning sheet as a datum point PA, and increasing the value of i by 1;
and 3.2, performing corner detection on the closed area MSeti, and jumping to the step 3.2.1 if the number of the corners is less than 3, or jumping to the step 3.2.2.
The purpose of setting the number of corner points to 3 is to classify the closed area, the gaps with the number of corner points less than 3 are generally smaller, correction is carried out after circle identification is applicable, the gaps with the number of corner points greater than 3 are generally larger, circle detection is not applicable, and the previous steps are added to divide the size of the closed area, so that the processing steps are separated.
The obtained scanning sheet can be divided into a plurality of areas, the size and the geometric shape of the areas can influence reservoir analysis, the further classification of the divided areas is helpful for enabling the correction process to be more accurate, and whether oil gas in the gap tends to be extracted or not is judged according to the distance from the gap to the maximum closed area.
Step 3.2.1, circle identification (i.e. hough circle detection) is performed on the closed area msi to detect a circle, the detected circle is surrounded by the closed area and the radius is maximized (because in a core of an oil and gas reservoir, a circular cavity often appears on a core slice caused by oil and gas erosion or natural storage oil and gas (a form of bubbles or oil and gas in the core is generally circular), and an oil and gas extrusion gap in the circular cavity causes a gap to generate offset on an image, so that the gap position needs to be corrected); the circle center of the circle is C, the radius is R, the geometric gravity center point of the current closed area is recorded as O, and a first gap offset distance CJ is calculated;
skipping step 3.4 if R is less than CJ and otherwise skipping step 3.4 and letting CD have a value of R/CJ;
wherein exp () is an exponential function based on natural logarithm, L () is a distance of 2 points, A () is an area of a closed region, points P1 and P2 are points with minimum and maximum distances O on edges of the closed region MSeti, and MAXR 0 Is the geometric center of gravity point of MAXR.
Such gaps are generally smaller, and the division of the traditional method may cause misjudgment, and require manual correction and intervention, and the characteristics of the gaps can be extracted and judged to determine whether to be classified into the gaps which can be communicated.
Step 3.2.2, taking the corner point with the smallest distance to the geometric gravity point O of the closed area MSeti as P1, taking the corner point with the largest distance to the geometric gravity point O of the closed area MSeti as P2, constructing line segments PL by the P1 and P2, and calculating a second gap offset distance CH:
wherein exp () is an exponential function based on natural logarithm, L () is a distance of 2 points, A (MSeti) is an area of a closed region MSeti, and R (MSeti) is a length of an outer contour of the closed region MSeti;
if the value of the second gap offset distance CH is greater than or equal to the length of the line segment PL, step 3.3 is skipped, otherwise step 3.4 is skipped and the value of CD is L (P1, P2)/(CH).
Such gaps are generally larger, but because the size of the closed area is divided in the previous step, the smaller gaps can be further classified into effective gaps by judging whether the oil gas in the gaps tends to be extracted according to the distance from the gap to the maximum closed area.
Step 3.3, if i is smaller than N, increasing the value of i by 1 and jumping to step 3.2, otherwise jumping to step 3.5;
step 3.4, obtaining a corrected gap area:
step 3.4.1, adding the value of Area into the first Area S1, increasing the value of i by 1 if i is smaller than N, and jumping to step 3.2, otherwise jumping to step 3.5;
and 3.5, outputting the corrected first area S1.
Correcting the area of the gap can eliminate the influence of the offset of the gap on the image caused by the fact that the oil gas extrusion gap in the circular cavity frequently appears on the core slice on the area of each gap, and improve the accuracy of area calculation.
The resolution of the core scanning image obtained by laser confocal scanning is higher than that of the image obtained by scanning by a common fluorescent staining optical microscope, the obtained slit edges cannot be well distinguished due to the adsorption of the staining agent by minerals during common fluorescent staining, and the laser confocal scanning effectively avoids the problem and obtains a plurality of slit structure details which cannot be obtained by scanning by a common polarizing microscope; conventional methods for distinguishing core regions, such as gray scale methods, may suffer from the inability to identify individual gaps of poor connectivity but good yield, such as the setting of gap size thresholds, which may be obtained from historical experience and conventional observation methods, may have an impact on the calculation of porosity when using confocal laser scan photographs, whereas single-layer scan photographs obtained in view of confocal laser scans may be used for three-dimensional reconstruction to make core yield analysis more efficient, so single confocal laser scan sheet correction may make final reservoir analysis more accurate.
Further, in step 4, the substep of obtaining the corrected porosity is:
the corrected porosity is obtained by recalculating the porosity according to the porosity Φ=s1/S0, and the corrected porosity is output.
Preferably, the slit in step 3.4 is marked as an effective reservoir slit, a corrected scan slice is obtained, and a plurality of corrected scan slices are subjected to subsequent three-dimensional reconstruction.
Preferably, all undefined variables in the present invention, if not explicitly defined, may be thresholds set manually.
Preferably, all undefined variables in the present invention, if not explicitly defined, may be thresholds set manually.
Fig. 2 is a schematic block diagram of a petroleum reservoir porosity measurement system based on a core according to an embodiment of the present invention.
A core-based petroleum reservoir porosity measurement system, the system comprising:
an image acquisition module: the laser confocal scanning is used for obtaining a casting body slice to obtain a scanning slice;
an image processing module: processing a scanning sheet obtained by laser confocal scanning and outputting a plurality of closed areas;
and a data processing module: and executing the steps of the petroleum reservoir porosity measurement method based on the rock core to obtain the porosity.
Compared with the prior art, the invention has the following beneficial technical effects:
the laser confocal scanning obtains a high-resolution core scanning photo, the scanning photo is corrected according to the geometric shape and the size of the aperture to obtain more accurate porosity, more accurate information is provided for oil gas analysis, and the problem of analysis errors caused by more photo details when the laser confocal scanning performs core analysis is solved.
The petroleum reservoir porosity measuring and calculating system based on the rock core can be operated in computing equipment such as a desktop computer, a notebook computer, a palm computer, a cloud server and the like. The core-based petroleum reservoir porosity measurement system may include, but is not limited to, a processor, a memory. It will be appreciated by those skilled in the art that the example is merely an example of a core-based oil reservoir porosity measurement system and is not limiting of a core-based oil reservoir porosity measurement system, and may include more or fewer components than examples, or may combine certain components, or different components, e.g., the core-based oil reservoir porosity measurement system may also include input and output devices, network access devices, buses, etc.
The processor may be a central processing unit (Central Processing Unit, CPU), other general purpose processors, digital signal processors (Digital Signal Processor, DSP), application specific integrated circuits (Application Specific Integrated Circuit, ASIC), field programmable gate arrays (Field-Programmable Gate Array, FPGA) or other programmable logic devices, discrete gate or transistor logic devices, discrete hardware components, or the like. The general purpose processor may be a microprocessor or the processor may be any conventional processor or the like, which is a control center of the operating system of the core-based petroleum reservoir porosity estimation system, and various interfaces and lines are used to connect various parts of the entire operating system of the core-based petroleum reservoir porosity estimation system.
The memory may be used to store the computer program and/or module, and the processor may implement various functions of the core-based petroleum reservoir porosity measurement system by running or executing the computer program and/or module stored in the memory and invoking data stored in the memory. The memory may mainly include a storage program area and a storage data area, wherein the storage program area may store an operating system, an application program (such as a sound playing function, an image playing function, etc.) required for at least one function, and the like; the storage data area may store data (e.g., audio data, phonebook, etc.) created according to the use of the handset. In addition, the memory may include high-speed random access memory, and may also include non-volatile memory, such as a hard disk, memory, plug-in hard disk, smart Media Card (SMC), secure Digital (SD) Card, flash Card (Flash Card), at least one disk storage device, flash memory device, or other volatile solid-state storage device.
Although the present invention has been described in considerable detail and with particularity with respect to several described embodiments, it is not intended to be limited to any such detail or embodiment or any particular embodiment so as to effectively cover the intended scope of the invention. Furthermore, the foregoing description of the invention has been presented in its embodiments contemplated by the inventors for the purpose of providing a useful description, and for the purposes of providing a non-essential modification of the invention that may not be presently contemplated, may represent an equivalent modification of the invention.
In the description of the present specification, reference to the terms "one embodiment," "some embodiments," "illustrative embodiments," "examples," "specific examples," or "some examples," etc., means that a particular feature, structure, material, or characteristic described in connection with the embodiment or example is included in at least one embodiment or example of the invention. In this specification, schematic representations of the above terms do not necessarily refer to the same embodiments or examples. Furthermore, the particular features, structures, materials, or characteristics described may be combined in any suitable manner in any one or more embodiments or examples.
While embodiments of the present invention have been shown and described, it will be understood by those of ordinary skill in the art that: many variations, modifications, substitutions, and alterations are possible in these embodiments without departing from the principles and spirit of the invention.
Claims (6)
1. A method for measuring and calculating porosity of a petroleum reservoir based on a rock core, which is characterized by comprising the following steps:
step 1, drilling a core, and manufacturing a casting sheet;
step 2, scanning the casting body slice to obtain a scanning photo, and calculating the porosity;
step 3, correcting the porosity according to the hole-seam relation;
step 4, obtaining corrected porosity;
in the step 2, scanning the cast body sheet to obtain a scanned photo, wherein the substeps of calculating the porosity are as follows:
scanning the cast sheet of the core by using a laser confocal microscope to obtain a scanning sheet; graying treatment is carried out on the scanning sheet;
obtaining an edge curve through an edge detection operator, dividing a scanning sheet into a plurality of closed areas by the edge curve, setting a threshold value of the area of the closed areas as a gap size threshold THRS, and forming a first area set by areas of the closed areas, the area of which is larger than the gap size threshold value;
recording the total area of all the closed areas in the first area set as a first area S1, enabling the core area S0 to be the view area of the current scanning sheet, and calculating the porosity phi=S1/S0; if S1 is greater than 0, the closed area with the largest area in the first area set is MAXR, and the geometric center of gravity of the MAXR is MAXR 0 ；
In the step 3, the substep of correcting the porosity according to the pore-seam relation is as follows:
forming a seam set MSet by using the closed areas which do not belong to the first area set in the closed areas of the scanning sheet, sorting the closed areas in the MSet in a descending order according to the size, and taking MSeti as the ith closed area in the set, wherein i is a positive integer;
initializing variable i as 2, and setting aperture set MSet as N, i E [1, N ]; setting a variable as a correction ratio CD;
step 3.1, taking the geometric gravity center point of the closed area with the largest area in the scanning sheet as a datum point PA, and increasing the value of i by 1;
step 3.2, detecting corner points in the closed area MSeti, if the number of the corner points is less than 3, jumping to step 3.2.1, otherwise jumping to step 3.2.2;
step 3.2.1, carrying out circle identification on the closed area MSeti to detect a circle, wherein the detected circle is surrounded by the closed area and the radius is maximized; the circle center of the circle is C, the radius is R, the geometric gravity center point of the current closed area is recorded as O, and a first gap offset distance CJ is calculated;
skipping step 3.4 if R is less than CJ and otherwise skipping step 3.4 and letting CD have a value of R/CJ;
wherein exp () is an exponential function based on natural logarithm, L () is a distance of 2 points, A () is an area of the closed region, points P1, P2 are points at which a distance O is minimum and maximum on edges of the closed region MSeti, MAXR, respectively 0 Is the geometric gravity center point of MAXR;
step 3.2.2, taking the corner point with the smallest distance to the geometric gravity point O of the closed area MSeti as P1, taking the corner point with the largest distance to the geometric gravity point O of the closed area MSeti as P2, constructing line segments PL by the P1 and P2, and calculating a second gap offset distance CH:
wherein exp () is an exponential function based on natural logarithm, L () is a distance of 2 points, a (msi) is an area of the closed region msi, and R (msi) is a length of an outer contour of the closed region msi;
skipping step 3.3 if the value of the second slot offset distance CH is greater than or equal to the length of the line segment PL, otherwise skipping step 3.4 and making the value of CD L (P1, P2)/(CH);
step 3.3, if i is smaller than N, increasing the value of i by 1 and jumping to step 3.2, otherwise jumping to step 3.5;
step 3.4, obtaining a corrected gap area:
step 3.4.1, adding the value of Area into the first Area S1, increasing the value of i by 1 if i is smaller than N, and jumping to step 3.2, otherwise jumping to step 3.5;
and 3.5, outputting the corrected first area S1.
2. The method for measuring and calculating porosity of a petroleum reservoir based on a rock core according to claim 1, wherein in the step 1, the rock core is drilled, and the sub-steps of manufacturing the cast sheet are as follows:
and (3) drilling a standard core column sample with the diameter of 25mm, injecting an epoxy resin dip dye into the standard core column sample, and grinding into rock slices after the epoxy resin dip dye is solidified.
3. The method for measuring and calculating porosity of a petroleum reservoir based on a rock core according to claim 1, wherein in the step 4, the substeps of obtaining corrected porosity are as follows: the corrected porosity is obtained by recalculating the porosity according to the porosity Φ=s1/S0, and the corrected porosity is output.
4. A core-based petroleum reservoir porosity measurement system, the system comprising:
an image acquisition module: a laser confocal scanning sheet for obtaining a cast sheet;
an image processing module: processing a scanning sheet obtained by laser confocal scanning and outputting a plurality of closed areas;
and a data processing module: obtaining porosity by performing the steps of a core-based petroleum reservoir porosity measurement method according to any one of claims 1-3.
5. A computer readable storage medium having stored thereon a computer program, characterized in that the program when executed by a processor realizes the steps of a core based petroleum reservoir porosity measurement method according to any of claims 1-3.
6. An electronic device, comprising: a memory having a computer program stored thereon; a processor for executing the computer program in the memory to implement the steps of a core-based petroleum reservoir porosity measurement method according to any one of claims 1 to 3.
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| US10324229B2 (en) * | 2014-10-23 | 2019-06-18 | Chevron U.S.A. Inc. | System and method of pore type classification for petrophysical rock typing |
| CN104297131B (en) * | 2014-11-04 | 2016-09-21 | 中国石油大学(华东) | A kind of gravel matter elements of sandstone porosity bearing calibration |
| CN105628580B (en) * | 2015-12-21 | 2018-04-13 | 中国石油大学(华东) | Reservoir baste identifies and physical property bearing calibration |
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| CN114112829B (en) * | 2020-08-27 | 2024-02-13 | 中国石油化工股份有限公司 | Correction method for carbonate reservoir porosity calculation |
| US20220341835A1 (en) * | 2021-04-22 | 2022-10-27 | Saudi Arabian Oil Company | Methods and Systems for Determining Reservoir and Fracture Properties |
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