Characterization method and device for carbonate rock micro-nano aperture and medium

Abstract

The invention provides a characterization method and device for carbonate rock micro-nano apertures and a medium, and relates to the technical field of carbonate rock microcosmic reservoir space characterization, reservoir multi-scale evaluation and reservoir transformation. The method comprises the steps that the target rock type and aperture type of carbonate rock are determined; under the condition that the target rock type and the aperture type are determined to be the millimeter-micron aperture type, performing qualitative analysis on the micro-nano aperture of the carbonate rock to obtain the characteristic type of the micro-nano aperture; carrying out quantitative analysis on the micro-nano aperture to obtain the structural characteristics and heterogeneity of the micro-nano aperture; and performing characterization description on the micro-nano aperture according to the feature type, the structural feature and the heterogeneity. Therefore, micro-nano-scale reservoir space fine characterization of deep ancient carbonate rocks and compact carbonate rocks is realized, so that a technical system suitable for micro reservoir space fine characterization of carbonate rocks is established.

Description

Technical Field

[0001] The present invention relates to the technical fields of carbonate rock microscopic reservoir space characterization and reservoir multi-scale evaluation, and is applied to the fine characterization research of deep ancient carbonate rocks and tight carbonate reservoirs. Specifically, it relates to a method, device and medium for characterizing micro-nano pores and fractures in carbonate rocks. Background Art

[0002] In recent years, refinement and quantification have been the trends in reservoir geology research, and reservoir research has expanded from the centimeter-millimeter-micrometer scale to the micrometer-nanometer scale.

[0003] However, related research has primarily focused on reservoirs such as shale, tight sandstone, and coal. Microscopic pore characterization of carbonate rocks, which are of great significance for oil and gas exploration, has been relatively understudied. This has severely hampered the accurate evaluation of deep, ancient carbonate and tight carbonate reservoirs. Therefore, a characterization system suitable for micro- and nano-pore characterization of carbonate rocks is urgently needed.

[0004] In response to the problems of the prior art, the present invention provides a method, device and medium for characterizing micro-nano pores in carbonate rocks. Summary of the Invention

[0005] In response to the problems of the current existing technology, the present invention provides a method, device and medium for characterizing micro-nano pores in carbonate rocks. The method comprises:

[0006] Determine the target rock type and pore type of carbonate rocks;

[0007] When the target rock type and the pore type are determined to be millimeter-micrometer pore types, a qualitative analysis is performed on the micro-nano pores of the carbonate rock to obtain characteristic types of the micro-nano pores;

[0008] Quantitatively analyzing the micro-nano pores to obtain structural characteristics and heterogeneity of the micro-nano pores;

[0009] The micro-nano pores are characterized and described according to the characteristic type, the structural characteristics, and the heterogeneity.

[0010] According to one embodiment of the present invention, the characteristic types of the micro-nano pores include the type of the micro-nano pores, the type of reservoir space, and the type of rock in which they are developed;

[0011] The characteristic type of the micro-nano pores is obtained by the following steps:

[0012] Determine the type, particle size, and geological origin of micron-sized pores;

[0013] After determining the type, particle size, and geological origin of the micropores, determine the type, particle size, and geological origin of the nanopores;

[0014] According to the particle sizes and geological causes corresponding to different pores, the reservoir space types and developed rock types corresponding to the different pores are determined. The different pores include: the micron pores and the nano pores.

[0015] According to one embodiment of the present invention, the structural characteristics of the micro-nano pores include: development characteristics, pore value and permeability, reservoir space characteristics and morphological characteristics;

[0016] The structural characteristics of the micro-nano pores are obtained by the following steps:

[0017] Selecting parallel samples of the target rock type, the parallel sample types including: plunger samples, cube samples and powder particle samples; wherein the pore diameters of the powder particle samples are smaller than the pore diameters of the cube samples and the plunger samples;

[0018] The plunger sample is subjected to low-field nuclear magnetic resonance analysis and overburden porosity analysis in sequence to obtain the development characteristics, pore value and permeability of the micro-nano pores respectively;

[0019] Performing high-pressure mercury intrusion analysis on the cubic sample to obtain reservoir space characteristics of the micro-nano pores;

[0020] The powder particle sample is subjected to low-temperature nitrogen adsorption analysis to obtain the morphological characteristics of the nanopores.

[0021] According to one embodiment of the present invention, the development characteristics of the micro-nano pores include: pore size, sorting condition, development degree and connectivity of the reservoir space;

[0022] The development characteristics of the micro-nano pores are obtained by the following steps:

[0023] Performing low-field nuclear magnetic resonance analysis on the plunger sample, and determining the development status based on the number of peaks in the T2 spectrum;

[0024] When the development of the micro-nano pores is determined, the pore size, the sorting condition, the development degree of the reservoir space and the connectivity are determined based on the interval of the left peak peak value, the left peak width, the proportion of the left peak area, the combination form between the peaks and the movable fluid saturation in the T2 spectrum.

[0025] According to one embodiment of the present invention, the reservoir space characteristics of the micro-nano pores include the development and connectivity of the reservoir space;

[0026] The reservoir space characteristics of the micro-nano pores are obtained by the following steps:

[0027] Performing high-pressure mercury injection analysis on the cubic sample to obtain the displacement pressure, mercury saturation median pressure, mercury injection saturation, pore radius, pore median radius, and pore volume of the micro-nano pores;

[0028] determining the development of the reservoir space according to the displacement pressure, the median mercury saturation pressure, the mercury injection saturation, and the median pore radius;

[0029] Draw a histogram with the pore radius as the abscissa and the pore volume as the ordinate;

[0030] The connectivity of the reservoir space is determined according to the distribution interval of the reservoir space in the histogram.

[0031] According to one embodiment of the present invention, the morphological characteristics of the nanopores include: reservoir space size, reservoir space distribution, reservoir space contribution rate and morphological structure;

[0032] The morphological characteristics of the nanopores are obtained by the following steps:

[0033] The powder particle sample is subjected to low-temperature nitrogen adsorption analysis to obtain the total specific surface area, total pore volume, pore size distribution, low-temperature nitrogen adsorption isotherm and adsorption loop of the nanopores.

[0034] Determining the size of the reservoir space according to the total specific surface area and the total pore volume;

[0035] determining the reservoir space distribution and the reservoir space contribution rate according to the pore size distribution map;

[0036] The morphological structure of the nanopore is determined based on the type of the low-temperature nitrogen adsorption isotherm and the type of the adsorption loop.

[0037] According to one embodiment of the present invention, the heterogeneity of the micro-nano pores is obtained by the following steps:

[0038] Determining the first fractal dimension of the micro-nano pores based on the displacement pressure, pore volume and Washburn model obtained by the high-pressure mercury injection analysis;

[0039] Determining the second fractal dimension of the nanopore based on the results obtained from low-temperature nitrogen adsorption and the FHH model;

[0040] The heterogeneity of the micro-nano pores is determined based on the effective fractal dimension of the first fractal dimension and the second fractal dimension.

[0041] According to one embodiment of the present invention, the first fractal dimension of the micro-nano pore is determined by the following steps:

[0042] Determining a target displacement pressure and a relative ratio of the micro-nano pores based on the displacement pressure, the pore volume, and the Washburn model, wherein the target displacement pressure is a logarithm of the displacement pressure, and the relative ratio is a logarithm of the result of dividing the pore volume by the displacement pressure;

[0043] Draw a first double logarithmic graph with the target displacement pressure as the abscissa and the relative ratio as the ordinate;

[0044] Determining a demarcation point in the first double logarithmic correlation graph and slopes corresponding to both ends of the demarcation point;

[0045] The first fractal dimension of the micro-nano pore is determined by summing the slope and the second target value.

[0046] According to one embodiment of the present invention, the results obtained from the low-temperature nitrogen adsorption include: the volume of adsorbed gas at equilibrium pressure, the volume covered by a gas monolayer, the saturated vapor pressure of nitrogen, and the equilibrium pressure;

[0047] The second fractal dimension of the micro-nano pore is determined by the following steps:

[0048] Based on the FHH model and the results obtained from the low-temperature nitrogen adsorption, the relative volume and relative pressure of the micro-nanopores are calculated; the relative volume is the logarithm of the result obtained by dividing the volume of the adsorbed gas by the volume covered by the gas monolayer, and the relative pressure is the logarithm of the result obtained by dividing the saturated vapor pressure of the nitrogen by the equilibrium pressure twice;

[0049] Draw a second double logarithmic graph with the relative pressure as the abscissa and the relative volume as the ordinate;

[0050] determining a slope in the second log-log plot;

[0051] The sum of the slope and the second target value is determined as the second fractal dimension of the micro-nanopore.

[0052] According to one embodiment of the present invention, the effective fractal dimension of the first fractal dimension and the second fractal dimension is determined by the following steps:

[0053] determining a correlation coefficient between the slopes in the first log-log plot;

[0054] If the first fractal dimension is within a first target range and the correlation coefficient is not less than a target threshold, determining that the first fractal dimension is a valid fractal dimension;

[0055] If the second fractal dimension is within a second target range, the second fractal dimension is determined to be a valid fractal dimension.

[0056] According to one embodiment of the present invention, a device for characterizing micro- and nano-pores in carbonate rocks is also provided, the device comprising:

[0057] A determination module for determining target rock types and pore types of carbonate rocks;

[0058] A first analysis module is configured to, upon determining that the target rock type and the pore type are millimeter-micrometer pore types, perform a qualitative analysis on the micro-nano pores of the carbonate rock to obtain characteristic types of the micro-nano pores;

[0059] A second analysis module is used to perform quantitative analysis on the micro-nano pores to obtain the structural characteristics and heterogeneity of the micro-nano pores;

[0060] A characterization module is used to characterize and describe the micro-nano pores according to the feature type, the structural feature, and the heterogeneity.

[0061] According to another aspect of the present invention, a storage medium is provided, which contains a series of instructions for executing the method steps described in any one of the above.

[0062] The present invention provides a method, device, and medium for characterizing micro- and nano-pores in carbonate rocks. Compared with the existing technology, the present invention has the following advantages:

[0063] This method qualitatively observes, quantitatively tests, and calculates micro- and nano-scale reservoir spaces in deep, ancient carbonate rocks and tight carbonate rocks. This enables detailed characterization of these reservoir spaces at the micro and nanoscale, establishing a technical system suitable for fine characterization of microscopic reservoir spaces in carbonate rocks. This allows for detailed characterization of micro- and nano-scale reservoir space characteristics in carbonate rocks and a new understanding of favorable reservoirs. This system is also adaptable to micro- and nano-scale pores and fractures, improving the representativeness of the characterization results.

[0064] Other features and advantages of the present invention will be described in the following description, and in part will become apparent from the description, or will be understood by practicing the present invention. The purposes and other advantages of the present invention can be realized and obtained by the structures particularly pointed out in the description, claims and drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0065] The accompanying drawings are used to provide a further understanding of the present invention and constitute a part of the specification. Together with the embodiments of the present invention, they are used to explain the present invention and do not constitute a limitation of the present invention. In the accompanying drawings:

[0066] Figure 1 A flow chart of a method for characterizing micro- and nano-pores in carbonate rocks according to one embodiment of the present invention is shown;

[0067] Figure 2 An illustration of types of micro-nano apertures according to an embodiment of the present invention is shown;

[0068] Figure 3 Shows the characteristic types of micro-nano pores according to one embodiment of the present invention;

[0069] Figure 4 shows a schematic diagram of a T2 spectrum according to one embodiment of the present invention;

[0070] Figure 5 A schematic diagram showing a capillary pressure curve and a histogram according to one embodiment of the present invention is shown;

[0071] Figure 6 A schematic diagram showing a pore size distribution diagram according to one embodiment of the present invention;

[0072] Figure 7 A schematic diagram showing a low-temperature nitrogen adsorption isotherm and an adsorption loop according to an embodiment of the present invention;

[0073] Figure 8 shows a schematic diagram of a first double logarithmic graph according to one embodiment of the present invention;

[0074] Figure 9 shows a schematic diagram of a second double logarithmic plot according to one embodiment of the present invention;

[0075] Figure 10 A block diagram of a device for characterizing micro- and nano-pores in carbonate rocks according to an embodiment of the present invention is shown.

[0076] In the accompanying drawings, the same reference numerals are used for the same parts. In addition, the accompanying drawings are not drawn according to the actual scale. DETAILED DESCRIPTION

[0077] To make the objectives, technical solutions and advantages of the present invention more clear, embodiments of the present invention are described in further detail below with reference to the accompanying drawings.

[0078] Carbonate rocks hold significant oil and gas value. Carbonate rocks can harbor numerous micro- and nanoscale pore systems, particularly deep, ancient carbonate rocks and tight carbonate rocks of immense oil and gas significance. Carbonate micro- and nanoscale reservoir spaces possess excellent preservation potential, even in deep reservoirs devoid of macropores. These micro- and nanoscale pores and fractures typically form relatively early, providing a longer window for oil and gas injection. Furthermore, carbonate micro- and nanoscale reservoir spaces are widely distributed across geological ages and lithologies, and increasing production practices are confirming their ability to effectively store natural gas and light oil.

[0079] At the same time, carbonate rocks have significant differences from shale, tight sandstone and coal reservoirs in terms of mineral composition, sedimentary structure, pore type, etc., and it is technically necessary to independently study their micro-nano pore systems.

[0080] A number of successful theories and methods have been developed for the detailed characterization of micro- and nano-reservoirs. However, these methods have not been redesigned and applied specifically to carbonate reservoirs. Micro-reservoir research primarily utilizes more precise testing methods based on conventional reservoir research, often drawing on testing methods from materials science, physical chemistry, and other disciplines to improve reservoir accuracy and provide a basis for oil and gas development. Reservoir research methods can be summarized into three categories: qualitative observation, quantitative testing, and numerical calculation. Qualitative observation primarily includes various optical microscopes, laser scanning confocal microscopy, scanning electron microscopy (SEM), field emission scanning electron microscopy (FE-SEM), and atomic force microscopy (AFM). Quantitative testing utilizes conventional mercury intrusion, high-pressure mercury intrusion, nuclear magnetic resonance, gas adsorption (N2, CO2, CH4, etc.), various porosity and permeability measurements, small-angle X-ray diffraction (SAXS), small-angle neutron scattering (SANS), CT scanning, and tomography. Numerical calculation methods primarily include fractal dimension calculation and three-dimensional reservoir space reconstruction techniques. However, the above methods have not been effectively applied to the analysis of micro-nano pores and fractures in carbonate reservoirs, and a characterization and analysis system suitable for micro-nano pores and fractures in carbonate reservoirs needs to be established urgently.

[0081] Prior art (CN2016109765192) describes a method for characterizing micro- and nanoscale reservoir spaces in continental shale. The method involves performing T2 spectral and calibration analyses on core samples using a nuclear magnetic resonance (NMR) spectrometer; analyzing and calculating the defined porosity of the core samples; performing high-precision three-dimensional scanning of the core samples using a micro- and nano-CT analyzer, and performing preliminary pore identification using manually defined grayscale thresholds; and constructing a three-dimensional model using micro- and nano-CT slices. This prior art is only applicable to the characterization and evaluation of micro- and nanoscale reservoir spaces in continental shale. While this method addresses the characterization of micro- and nanoscale reservoir spaces, it is applied to continental shale and does not address the comprehensive multi-method characterization of nanopores.

[0082] Prior art (CN2018114506252) describes a multi-scale characterization method and apparatus for carbonate pore systems, including analyzing carbonate reservoirs to determine the reservoir type and pore type; selecting reservoir samples based on the reservoir type and pore type; performing quantitative pore characterization on the reservoir samples to determine the sample pore characteristics; and determining whether the sample pore characteristics meet preset conditions. While prior art characterizes the pore system in carbonate reservoirs at multiple scales, it does not conduct targeted systematic analysis of micro- and nano-scale reservoir spaces. The analysis only utilizes field emission scanning electron microscopy and micron CT. The method is simple, primarily qualitative, and the testing cost is extremely high.

[0083] The prior art (CN201811283717.6) mentions a multi-view, multi-scale method for identifying shale reservoir micropore systems. This involves observing the surface of a shale sample and scanning it with a low-power microscope using an emission environmental scanning electron microscope. This method selects observation areas with various pore structures, scans these areas with a high-power microscope relative to the low-power microscope, and continuously photographs the pore structures to produce a multi-view shale reservoir pore structure image. The box dimension D(r) is calculated for these multi-view shale reservoir pore structure images, thereby obtaining the fractal dimension of the shale reservoir pores. Although the prior art mentions reservoir micropore system identification, the application target is shale, and the prior art is primarily based on scanning electron microscopy and image processing. It does not quantitatively characterize micro- and nanoscale pores or establish a system suitable for micro- and nanoscale pores in carbonate rocks.

[0084] The prior art (Diagenesis and Micro-Nano Reservoir Space Evolution of the Tight Sandstone of the Quan 4 Member in the Southern Songliao Basin) analyzes the impact of diagenesis on the evolution of micro-nano reservoir spaces and the occurrence and distribution of oil and gas in the reservoir, based on thin section and scanning electron microscopy observations and constant-rate mercury injection experiments. This differs from the characterization steps of the present invention.

[0085] Existing technology (High-Resolution CT-Based Research on Fractal and Multifractal Pore Systems in Porous Dolomite Reservoirs) discusses the fractal and multifractal characteristics of different pore systems, such as intergranular pores, intercrystalline pores, and mold pores, by integrating high-resolution micro- and nano-CT technology with fractal and multifractal theory for porous dolomite reservoirs. This research examines 2D CT image series slices and 3D digital core data of different pore types and sample sizes. However, existing technology only utilizes field-emission scanning electron microscopy and micro-CT, resulting in limited methods, primarily focused on qualitative description, and extremely expensive testing.

[0086] The existing technology (Study on Micropore Structure and Connectivity of Shale Reservoirs in the Longmaxi Formation of the Silurian System in Southeastern Sichuan) mentions the use of CT scanning, focused ion beam scanning electron microscopy, argon ion polishing-field emission scanning electron microscopy, and transmission electron microscopy to analyze the micropore structure and connectivity of the Longmaxi Formation shale in southeastern Sichuan. While this existing technology focuses on the identification of reservoir micropore systems, it is more focused on the characterization and evaluation of shale. The existing technology is mainly based on CT scanning, focused ion beam scanning electron microscopy, argon ion polishing-field emission scanning electron microscopy, and transmission electron microscopy, and does not specifically reflect the quantitative characterization of micro- and nanoscale pore systems or standard methods applicable to carbonate micropores.

[0087] In view of the above-mentioned defects of the prior art, the present invention provides a method, device and medium for characterizing micro-nano pores in carbonate rocks.

[0088] Figure 1 A method for characterizing micro- and nano-pores in carbonate rocks according to an embodiment of the present invention is shown, the method comprising:

[0089] S101, determining the target rock type and pore type of carbonate rock.

[0090] For example, target rock types can be determined through core observation, polarizing microscopy, and thin-section analysis using cathodoluminescence microscopy, combined with XRD mineral quantitative analysis. Conventional millimeter-scale pore and fracture types can be determined through core observation. Once the lithology and macroscopic pore and fracture characteristics are clearly defined, thin-section analysis using polarizing microscopy, combined with post-diagenetic fluid analysis using cathodoluminescence microscopy, can determine millimeter- to micrometer-scale pore and fracture types.

[0091] S102 , when the target rock type and pore type are determined to be millimeter-micrometer pore types, a qualitative analysis is performed on the micro-nano pores and fractures of the carbonate rock to obtain characteristic types of the micro-nano pores and fractures.

[0092] Millimeter-to-micrometer pores are pores with diameters between millimeters and micrometers. Micro- and nano-pores are micron and nano-pores. Once the rock type and pore type are confirmed to be millimeter-to-micrometer pores, qualitative analysis of the micro- and nano-pores can be performed using laser scanning confocal microscopy and field emission scanning electron microscopy, following a stepwise resolution analysis from large to small scales, to determine their characteristic types.

[0093] S103, quantitatively analyzing the micro-nano pores to obtain the structural characteristics and heterogeneity of the micro-nano pores;

[0094] Micro- and nano-pores can be quantitatively analyzed sequentially through low-field nuclear magnetic resonance analysis, overburden porosimetry, high-pressure mercury intrusion analysis, and low-temperature nitrogen adsorption analysis to reveal their structural characteristics. Fractal theory can be used to quantitatively calculate the fractal dimension of the micro- and nano-pores, thereby determining their heterogeneity.

[0095] S104, characterizing and describing the micro-nano pores according to characteristic types, structural characteristics, and heterogeneity.

[0096] This method qualitatively observes, quantitatively tests, and calculates micro- and nano-scale reservoir spaces in deep, ancient carbonate rocks and tight carbonate rocks. This enables detailed characterization of these reservoir spaces at the micro and nanoscale, establishing a technical system suitable for fine characterization of microscopic reservoir spaces in carbonate rocks. This allows for detailed characterization of micro- and nano-scale reservoir space characteristics in carbonate rocks and a new understanding of favorable reservoirs. This system is also adaptable to micro- and nano-scale pores and fractures, improving the representativeness of the characterization results.

[0097] In a possible embodiment, the characteristic types of micro-nano pores and fractures include the type of micro-nano pores and fractures, the type of reservoir space, and the type of rock in which they are developed;

[0098] The characteristic types of micro-nano pores are obtained by the following steps:

[0099] Determine the type, particle size, and geological origin of micron-sized pores;

[0100] Determine the type, particle size and geological origin of nanopores after determining the type, particle size and geological origin of micropores;

[0101] According to the particle size and geological origin corresponding to different pores and fractures, the reservoir space type and rock type corresponding to different pores and fractures are determined.

[0102] The different pores include micron pores and nano pores. For example, micron-scale pores can be observed by laser scanning confocal microscopy and then compared with Figure 2Comparisons were made to determine the type, particle size, and geological origin of micropores. Figure 3 As shown, the reservoir space type and the developed rock type of micron pores can be observed and determined based on the particle size and geological origin of the micron pores.

[0103] The fluorescence of oil and gas in micron-scale pores can also be analyzed to determine the effectiveness of oil and gas storage and migration. Then, when determining the type, particle size and geological origin of micron-scale pores, the analysis method of increasing resolution from large scale to small scale can be used to observe and analyze the smaller nano-scale pores through field emission scanning electron microscopy. Figure 2 Comparisons were performed to determine the type, particle size, and geological origin of the nanopores. Next, based on the particle size and geological origin of the nanopores, the reservoir type and rock type of the nanopores were determined. This comprehensive approach, using multiple scales and methods to characterize different pore types, improves the accuracy of the characteristic types and paves the way for establishing a characterization system for micro- and nanopores in carbonate rocks.

[0104] In a possible embodiment, the structural characteristics of micro-nano pores include: development characteristics, pore values ​​and permeability, reservoir space characteristics, and morphological characteristics;

[0105] The structural characteristics of micro-nano pores are obtained by the following steps:

[0106] Select parallel samples of the target rock type. The parallel sample types include: plunger samples, cube samples, and powder particle samples. The pore diameter of the powder particle sample is smaller than that of the cube sample and plunger sample.

[0107] The plug samples were subjected to low-field nuclear magnetic resonance analysis and overburden porosity analysis, respectively obtaining the development characteristics of micro- and nano-pores, pore values, and permeability.

[0108] High-pressure mercury intrusion analysis was performed on cubic samples to obtain the reservoir space characteristics of micro- and nano-pores;

[0109] The powder particle samples were subjected to low-temperature nitrogen adsorption analysis to obtain the morphological characteristics of micro-nano pores.

[0110] For example, a well or field sample of a target rock type with high homogeneity can be selected for parallel sample preparation. A plunger sample with a diameter of 25 mm and a length of 2-5 cm can be selected for low-field nuclear magnetic resonance and overburden porosity analysis. A 1 cm 3Cube samples are used for high-pressure mercury injection analysis. Powder particles with a mesh size of 30-60 and weighing no less than 1g can be used for low-temperature nitrogen adsorption analysis. The pore diameter of the powder particle sample should be less than 100nm. The pore diameter of the plunger sample and cube sample should be greater than 100nm.

[0111] Among these, low-field nuclear magnetic resonance, overburden porosity and permeability analysis, high-pressure mercury injection, and low-temperature nitrogen adsorption analysis can be performed in a stepwise manner from large to small scales to determine the development characteristics of micro- and nano-pores, pore values ​​and permeabilities, reservoir space characteristics, and morphological characteristics. This improves the precision and quantification of structural features.

[0112] For example, the porosity and permeability of the plug sample can be obtained by performing overburden porosimeter and pulse permeability analysis to characterize the pore depth and permeability characteristics of the tight reservoir under overburden conditions, thereby indicating the reservoir space size and seepage capacity characteristics.

[0113] In a possible embodiment, the development characteristics of the micro-nano pores include: pore size, sorting, development degree of reservoir space, and connectivity;

[0114] The development characteristics of micro-nano pores are obtained by the following steps:

[0115] Low-field nuclear magnetic resonance analysis was performed on the plunger samples, and the development of micro-nanopores was determined based on the number of peaks in the T2 spectrum.

[0116] When the development of micro-nano pores is determined, the pore size, sorting condition, development degree and connectivity of the reservoir space are determined based on the interval of the left peak peak, the left peak width, the proportion of the left peak area, the combination morphology between the peaks and the saturation of the movable fluid in the T2 spectrum.

[0117] like Figure 4The figure shows a T2 spectrum. For example, if the number of peaks in the T2 spectrum is greater than 1, it is determined that micro-nanopores are developed (i.e., the left peak is developed); if the number of peaks in the T2 spectrum is equal to 1, it is determined that micro-nanopores are not developed. When the development of micro-nanopores is determined, the range of the left peak in the T2 spectrum is determined, with smaller values ​​representing smaller pore diameters. The sorting of micro-nanopores is then determined based on the width of the left peak in the T2 spectrum. A larger left peak width reflects better sorting of the pores corresponding to that peak. The degree of reservoir development can then be determined based on the proportion of the left peak area (i.e., the ratio of the left peak area to the total spectrum area). A larger proportion indicates a more developed reservoir. The change in the combined morphology of the peaks, from isolated to continuous to fused, represents a trend of increasing reservoir connectivity. The greater the movable fluid saturation, the better the reservoir connectivity. In this way, low-field nuclear magnetic resonance analysis is performed on the plunger samples to quantitatively determine the developmental characteristics of the micro-nano pores, thereby improving the accuracy and quantification of the developmental characteristics.

[0118] like Figure 4 As shown, A is a three-peak development type, with well-developed pore-fracture systems at all levels and good connectivity; B is a left-peak development type, with well-developed micro-nano pore-fracture systems; C is a left-peak undeveloped type, with undeveloped micro-nano pore-fracture systems and dominated by conventional pores and fractures; D is dominated by large-scale reservoir space, with good connectivity, relatively developed reservoir space, fused morphology, and mainly dissolution-diagenetic pores.

[0119] In a possible embodiment, the reservoir space characteristics of the micro-nano pores include the development and connectivity of the reservoir space;

[0120] The reservoir space characteristics of micro-nano pores are obtained by the following steps:

[0121] High-pressure mercury injection analysis was performed on the cubic sample to obtain the displacement pressure, median mercury saturation pressure, mercury injection saturation, pore radius, median pore radius, and pore volume of the micro- and nano-pores.

[0122] The development of reservoir space can be determined based on displacement pressure, median mercury saturation pressure, mercury injection saturation and median pore radius;

[0123] Draw a histogram with the pore radius as the horizontal coordinate and the pore volume as the vertical coordinate;

[0124] The connectivity of the reservoir space is determined based on the distribution interval of the reservoir space in the histogram.

[0125] Among them, the capillary pressure curve and histogram can be obtained by performing high-pressure mercury injection analysis on the cubic sample (such as Figure 5(as shown). By searching the capillary pressure curve, the displacement pressure, the median pressure of mercury saturation, and the mercury injection saturation can be obtained. High-pressure mercury injection analysis of cubic samples can also provide the pore radius, the median radius of the pores, and the pore volume. If the displacement pressure and the median pressure of mercury saturation are large, the mercury injection saturation is small, and the median pore radius is >500nm, it is determined that micro-nano reservoir spaces are not developed. If the displacement pressure and the median pressure of mercury saturation are small, but the mercury injection saturation is large, and the median pore radius is <500nm, it is determined that micro-nano reservoir spaces are developed. If the displacement pressure and the median pressure of mercury saturation are large, the mercury injection saturation is large, and the median pore radius is <500nm, it is determined that micro-nano reservoir spaces are developed.

[0126] As shown in the figure, Type A samples (A1 and A2) have relatively low displacement pressures, median mercury saturation pressures, and high mercury injection saturations. Furthermore, pores and fractures at all scales are relatively well-developed, resulting in relatively high mercury injection saturations, reflecting the relatively well-developed microfracture-micropore reservoir characteristics. Type B samples (B1 and B2) have relatively high displacement pressures, median mercury saturation pressures, and low mercury injection saturations, reflecting more microfracture characteristics, less developed micropores, and relatively dense lithology. A histogram can then be plotted with pore radius as the abscissa and pore volume as the ordinate. Based on existing techniques, the reservoir connectivity can be determined based on the distribution intervals within the histogram. In this way, high-pressure mercury injection analysis of cubic samples quantitatively determines the reservoir characteristics of micro- and nano-pores, improving the accuracy and quantification of reservoir characteristics.

[0127] In a possible embodiment, the morphological characteristics of the nanopores include: reservoir space size, reservoir space distribution, reservoir space contribution rate and morphological structure;

[0128] The morphological characteristics of the nanopores were obtained by the following steps:

[0129] The powder particle samples were subjected to low-temperature nitrogen adsorption analysis to obtain the total specific surface area, total pore volume, pore size distribution, low-temperature nitrogen adsorption isotherm and adsorption loop of the nanopores.

[0130] Determine the size of the reservoir space based on the total specific surface area and total pore volume;

[0131] According to the pore size distribution diagram, the reservoir space distribution and reservoir space contribution rate are determined.

[0132] The morphological structure of the nanopores was determined based on the type of low-temperature nitrogen adsorption isotherm and adsorption loop.

[0133] For example, the total specific surface area, total pore volume, and pore size distribution of the nanopores (e.g., Figure 6As shown), low temperature nitrogen adsorption isotherm and adsorption loop (as shown Figure 7 The reservoir space size can be determined based on the total specific surface area and total pore volume. The reservoir space distribution in the range of 2-75 nm and the reservoir space contribution rate can be determined based on the pore size distribution diagram.

[0134] Among them, the morphological characteristics include saturated adsorption phenomenon. Figure 7 The isotherms are primarily Type II and IV, while the adsorption loops are primarily Type H3, with some H4 characteristics. Hysteresis loops are not distinct, and the adsorption-desorption isotherms overlap significantly, indicating a greater abundance of closed-end pores, closed pores, and a more complex pore structure. When P / P0 approaches the saturation pressure (i.e., between 0.9 and 1), the N2 adsorption capacity does not increase significantly due to unfavorable analytical migration of the mesopores, and saturation adsorption does not occur. The cubic sample still contains relatively large pores that cannot be measured by gas adsorption. Thus, high-pressure mercury injection analysis of the cubic sample quantitatively determined the morphological characteristics of the nanopores, improving the accuracy and quantification of the morphological characteristics.

[0135] In one possible embodiment, the heterogeneity of the micro-nano pores is obtained by the following steps:

[0136] Based on the displacement pressure, pore volume and Washburn model obtained from high-pressure mercury injection, the first fractal dimension of micro- and nano-pores is determined.

[0137] Based on the results of low-temperature nitrogen adsorption and the FHH model, the second fractal dimension of micro-nanopores was determined;

[0138] The heterogeneity of the micro-nano pores is determined based on the effective fractal dimension in the first fractal dimension and the second fractal dimension.

[0139] For example, the Washburn model can be used to calculate the first fractal dimension of the micro-nano pores on the cubic sample. For samples that cannot be effectively analyzed by the Washburn model theory (i.e., powder particle samples for nanopores), the FHH model can be used for calculation to determine the second fractal dimension of the nanopores. Then, the validity of the fractal dimension is determined, and then the effective fractal dimension is used to quantitatively evaluate the heterogeneity of the micro-nano pores. The larger the fractal dimension, the stronger the heterogeneity. In this way, the cubic sample and the powder particle sample are quantitatively analyzed respectively to quantitatively determine the heterogeneity of the micro-nano pores in the carbonate rock, thereby improving the quantification and refinement of the heterogeneity.

[0140] In a possible embodiment, the first fractal dimension of the micro-nano pore is determined by the following steps:

[0141] Based on the displacement pressure, pore volume, and Washburn model, the target displacement pressure and relative ratio of micro- and nano-pores are determined. The target displacement pressure is the logarithm of the displacement pressure, and the relative ratio is the logarithm of the pore volume divided by the displacement pressure.

[0142] The first double logarithmic graph is drawn with the target displacement pressure as the horizontal axis and the relative ratio as the vertical axis;

[0143] Determine a cutoff point in the first log-log correlation graph and the slopes corresponding to both ends of the cutoff point;

[0144] The sum of the slope and the second target value is used to determine the first fractal dimension of the micro-nanopore.

[0145] The expression of the Washburn model is as follows:

[0146]

[0147] Where Vmp is the volume of mercury pressed into the core (unit: cm 3 ), Pc is the capillary pressure (unit: MPa) or displacement pressure, V is the total pore volume of the core (unit: cm 3 ), D is the fractal dimension.

[0148] For example, the second target value may be <3. The target displacement pressure lgP may be obtained based on the volume of mercury pressed into the core, the capillary pressure, the total pore volume of the core, and the Washburn model. c and relative ratio like Figure 8 The figure shows the first logarithmic plot of the target displacement pressure versus relative ratio. The cutoff point in the first double logarithmic plot is 1 μm, and the slopes on either side of the cutoff point are -1.4886 and -1.1262. The slopes can then be added to 3 to obtain the values ​​of 1.5114 and 1.8738, which are determined as the first fractal dimensions of the micro- and nano-pores. In this way, the fractal dimension of the cubic sample can be quantitatively calculated based on the FHH model, displacement pressure, and pore volume, improving both the quantification and accuracy of the fractal dimension.

[0149] In one possible embodiment, the results obtained from the low-temperature nitrogen adsorption include: the volume of the adsorbed gas at the equilibrium pressure, the volume covered by the gas monolayer, the saturated vapor pressure of the nitrogen, and the equilibrium pressure;

[0150] The second fractal dimension of the micro-nanopores is determined by the following steps:

[0151] Based on the results obtained from the FHH model and low-temperature nitrogen adsorption, determine the relative volume and relative pressure of the micro-nano pore channels. The relative volume is the value obtained by taking the logarithm of the result of dividing the adsorbed gas volume by the volume of monolayer gas coverage. The relative pressure is the value obtained by taking the double logarithm of the result of dividing the saturated vapor pressure of nitrogen by the equilibrium pressure.

[0152] Using the relative pressure as the abscissa and the relative volume as the ordinate, plot the second double-logarithm graph.

[0153] Determine the slope in the second double-logarithm graph.

[0154] Determine the sum of the slope and the second target value as the second fractal dimension of the micro-nano pore channels.

[0155] Among them, the expression of the FHH model is as follows:

[0156]

[0157] Among them, V refers to the adsorbed gas volume at the equilibrium pressure (unit: cm 3 / g), V0 refers to the volume of monolayer gas coverage (cm 3 / g), K refers to the characteristic constant, R refers to the gas constant, T refers to the absolute temperature, P refers to the equilibrium pressure (unit: MPa), P0 refers to the saturated vapor pressure of nitrogen (unit: MPa), D is the fractal dimension, and D = K + 3.

[0158]

[0159] Among them, refers to the relative volume, refers to the relative pressure.

[0160] Exemplarily, the second target value can be <3. Based on the results obtained from the FHH model and low-temperature nitrogen adsorption, the relative volume and relative pressure can be calculated, and then, using the relative pressure as the abscissa and the relative volume as the ordinate, plot the second double-logarithm graph. As Figure 9 shown, the second double-logarithm graph can be divided into two stages: 0 < P / P0 < 0.5 and 0.5 < P / P0 < 1. Thus, determine that the pore diameter at the boundary point is 5 mm. Taking P / P0 = 0.5 as the boundary, calculate the slopes K1 = -0.4772 and K2 = -0.3861 for the two stages of 0 < P / P0 < 0.5 and 0.5 < P / P0 < 1 respectively. Then, determine the results of adding the slopes to 3 as the second fractal dimensions D1 = 2.5228 and D2 = 2.6139 of the micro-nano pore channels, which is D in the FHH model. In this way, based on the results obtained from the FHH model and low-temperature nitrogen adsorption, quantitatively calculate the fractal dimension of the nano pore channels, improving the quantification and accuracy of the fractal dimension.

[0161] In a possible embodiment, the effective fractal dimension in the first fractal dimension and the second fractal dimension is determined through the following steps:

[0162] Determine the correlation coefficient between the slopes in the first double logarithmic graph;

[0163] If the first fractal dimension is within the first target range and the correlation coefficient is not less than the target threshold, determine the first fractal dimension as the effective fractal dimension;

[0164] If the second fractal dimension is within the second target range, determine the second fractal dimension as the effective fractal dimension.

[0165] Among them, the correlation coefficient can be determined through existing formulas. As Figure 8 shown, the correlation coefficients at both ends of the demarcation point are 0.8987 and 0.939. Exemplarily, the first target range can be D >= 3 or D <= 1. The target threshold can be 0.5. Among them, if the first fractal dimension is not within the first target range, then determine that the first fractal dimension is an invalid fractal dimension (not available). Exemplarily, the second target range can be 1 < D < 3. Among them, if the second fractal dimension is within the second target range, then determine the second fractal dimension as the effective fractal dimension. In this way, by determining the effectiveness of the first fractal dimension and the second fractal dimension, the heterogeneity of the micro-nano pore fissures is determined, and in this way, the determined heterogeneity is more accurate.

[0166] A method for characterizing carbonate rock micro-nano pore fissures provided by the present invention can also cooperate with a computer-readable storage medium. A computer program is stored on the storage medium, and the computer program is executed to run a method for characterizing carbonate rock micro-nano pore fissures. The computer program can run computer instructions, and the computer instructions include computer program code. The computer program code can be in the form of source code, object code, executable file or some intermediate form, etc.

[0167] The computer-readable storage medium can include: any entity or device capable of carrying computer program code, recording medium, USB flash drive, mobile hard disk, magnetic disk, optical disc, computer memory, read-only memory (ROM, Read-Only Memory), random access memory (RAM, Random Access Memory), electrical carrier signal, telecommunication signal, and software distribution medium, etc.

[0168] It should be noted that the content included in the computer-readable storage medium can be appropriately increased or decreased according to the requirements of legislation and patent practice within the jurisdiction. For example, in some jurisdictions, according to legislation and patent practice, the computer-readable storage medium does not include electrical carrier signals and telecommunication signals.

[0169] According to another aspect of the present invention, a device for characterizing micro- and nano-pores in carbonate rocks is provided. Figure 10 This is a block diagram of a device for characterizing micro- and nano-pores in carbonate rocks provided in an embodiment of the present application, such as Figure 10 As shown, the device may include:

[0170] Determination module 510, for determining target rock type and pore type of carbonate rock;

[0171] The first analysis module 520 is configured to perform a qualitative analysis on the micro-nano pores and fractures of the carbonate rock to obtain characteristic types of the micro-nano pores and fractures when the target rock type and the pore type are determined to be millimeter-micrometer pores and fractures;

[0172] The second analysis module 530 is used to perform quantitative analysis on the micro-nano pores to obtain the structural characteristics and heterogeneity of the micro-nano pores;

[0173] The characterization module 540 is used to characterize and describe the micro-nano pores according to feature types, structural features, and heterogeneity.

[0174] In summary, the present invention provides a method for characterizing micro- and nano-pores in carbonate rocks, which has the following advantages over existing technologies:

[0175] This method qualitatively observes, quantitatively tests, and calculates micro- and nano-scale reservoir spaces in deep, ancient carbonate rocks and tight carbonate rocks. This enables detailed characterization of these reservoir spaces at the micro and nanoscale, establishing a technical system suitable for fine characterization of microscopic reservoir spaces in carbonate rocks. This allows for detailed characterization of micro- and nano-scale reservoir space characteristics in carbonate rocks and a new understanding of favorable reservoirs. This system is also adaptable to micro- and nano-scale pores and fractures, improving the representativeness of the characterization results.

[0176] It should be understood that the embodiments disclosed herein are not limited to the specific structures, processing steps, or materials disclosed herein, but should extend to equivalent substitutions of these features understood by those skilled in the relevant art. It should also be understood that the terminology used herein is for the purpose of describing specific embodiments only and is not intended to be limiting.

[0177] In the description of the present invention, unless otherwise specified, "plurality" means two or more; terms such as "upper," "lower," "left," "right," "inner," "outer," "front end," "rear end," "head," and "tail" indicate positions or relationships based on those shown in the accompanying drawings. These terms are intended solely to facilitate the description of the present invention and simplify the description. They do not indicate or imply that the devices or components referred to must have a specific orientation, be constructed, or operate in a specific orientation. Therefore, they should not be construed as limiting the present invention. Furthermore, terms such as "first," "second," and "third" are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0178] In the description of the present invention, it should be noted that, unless otherwise expressly specified or limited, the terms "connected" and "connection" should be understood in a broad sense. For example, they can refer to fixed connection, detachable connection, or integral connection; mechanical connection, electrical connection; direct connection, or indirect connection through an intermediary. Those skilled in the art will understand the specific meanings of the above terms in the present invention based on the specific circumstances.

[0179] Certain terms are used throughout this application document to indicate specific system components. As will be appreciated by those skilled in the art, different names may be used to indicate the same component, and thus this application document is not intended to distinguish between components that are only different in name but not in function. In this application document, the terms "comprise," "include," and "have" are used in an open format and should therefore be interpreted as meaning "including, but not limited to...". In addition, the terms "substantially," "substantially," or "approximately" that may be used herein refer to industry-accepted tolerances for the corresponding terms. The term "coupling," as used herein, includes direct coupling and indirect coupling via another component, element, circuit, or module, wherein for indirect coupling, the intervening component, element, circuit, or module does not change the information of the signal but can adjust its current level, voltage level, and / or power level. Inferred coupling (e.g., one element is coupled to another element by inference) includes direct and indirect coupling between two elements in the same manner as "coupling."

[0180] References in this specification to "one embodiment" or "an embodiment" mean that a particular feature, structure, or characteristic described in connection with the embodiment is included in at least one embodiment of the present invention. Therefore, appearances of the phrases "one embodiment" or "an embodiment" in various places throughout this specification do not necessarily refer to the same embodiment.

[0181] The embodiments of the present invention are presented for purposes of illustration and description and are not intended to be exhaustive or to limit the invention to the disclosed forms. Many modifications and variations will be apparent to those skilled in the art. The embodiments are chosen and described in order to better illustrate the principles of the invention and its practical application and to enable those skilled in the art to understand the invention and design various embodiments with various modifications as suited for specific applications.

[0182] Although the embodiments disclosed herein are as described above, the contents described herein are merely embodiments for facilitating understanding of the present invention and are not intended to limit the present invention. Any person skilled in the art of the present invention may make any modifications and changes in the form and details of the implementation without departing from the spirit and scope disclosed herein. However, the scope of patent protection of the present invention shall still be subject to the scope defined by the appended claims.

Claims

1. A method for characterizing micro- and nano-pores in carbonate rocks, characterized in that: The method comprises: Determine the target rock type and pore type of carbonate rocks; When the target rock type and the pore type are determined to be millimeter-micrometer pore types, a qualitative analysis is performed on the micro-nano pores of the carbonate rock to obtain characteristic types of the micro-nano pores; Quantitatively analyzing the micro-nano pores to obtain structural characteristics and heterogeneity of the micro-nano pores; The micro-nano pores are characterized and described according to the characteristic type, the structural characteristics, and the heterogeneity.

2. The method according to claim 1, wherein The characteristic types of the micro-nano pores include the types of the micro-nano pores, the types of reservoir spaces, and the types of rocks developed; The characteristic type of the micro-nano pores is obtained by the following steps: Determine the type, particle size, and geological origin of micron-sized pores; After determining the type, particle size, and geological origin of the micropores, determine the type, particle size, and geological origin of the nanopores; According to the particle sizes and geological causes corresponding to different pores, the reservoir space types and developed rock types corresponding to the different pores are determined. The different pores include: the micron pores and the nano pores.

3. The method according to claim 2, wherein The structural characteristics of the micro-nano pores include: development characteristics, pore values ​​and permeability, reservoir space characteristics and morphological characteristics; The structural characteristics of the micro-nano pores are obtained by the following steps: Selecting parallel samples of the target rock type, the parallel sample types including: plunger samples, cube samples and powder particle samples; wherein the pore diameters of the powder particle samples are smaller than the pore diameters of the cube samples and the plunger samples; The plunger sample is subjected to low-field nuclear magnetic resonance analysis and overburden porosity analysis in sequence to obtain the development characteristics, pore value and permeability of the micro-nano pores respectively; Performing high-pressure mercury intrusion analysis on the cubic sample to obtain reservoir space characteristics of the micro-nano pores; The powder particle sample is subjected to low-temperature nitrogen adsorption analysis to obtain the morphological characteristics of the nanopores.

4. The method according to claim 3, wherein The development characteristics of the micro-nano pores include: pore size, sorting, development degree of storage space and connectivity; The development characteristics of the micro-nano pores are obtained by the following steps: Performing low-field nuclear magnetic resonance analysis on the plunger sample, and determining the development status based on the number of peaks in the T2 spectrum; When the development of the micro-nano pores is determined, the pore size, the sorting condition, the development degree of the reservoir space and the connectivity are determined based on the interval of the left peak peak value, the left peak width, the proportion of the left peak area, the combination form between the peaks and the movable fluid saturation in the T2 spectrum.

5. The method according to claim 4, wherein The reservoir space characteristics of the micro-nano pores include the development and connectivity of the reservoir space; The reservoir space characteristics of the micro-nano pores are obtained by the following steps: Performing high-pressure mercury injection analysis on the cubic sample to obtain the displacement pressure, mercury saturation median pressure, mercury injection saturation, pore radius, pore median radius, and pore volume of the micro-nano pores; determining the development of the reservoir space according to the displacement pressure, the median mercury saturation pressure, the mercury injection saturation, and the median pore radius; Draw a histogram with the pore radius as the abscissa and the pore volume as the ordinate; The connectivity of the reservoir space is determined according to the distribution interval of the reservoir space in the histogram.

6. The method according to claim 5, wherein The morphological characteristics of the nanopores include: reservoir space size, reservoir space distribution, reservoir space contribution rate and morphological structure; The morphological characteristics of the nanopores are obtained by the following steps: The powder particle sample is subjected to low-temperature nitrogen adsorption analysis to obtain the total specific surface area, total pore volume, pore size distribution, low-temperature nitrogen adsorption isotherm and adsorption loop of the nanopores. Determining the size of the reservoir space according to the total specific surface area and the total pore volume; determining the reservoir space distribution and the reservoir space contribution rate according to the pore size distribution map; The morphological structure of the nanopore is determined based on the type of the low-temperature nitrogen adsorption isotherm and the type of the adsorption loop.

7. The method according to claim 6, wherein The heterogeneity of the micro-nano pores is obtained by the following steps: Determining the first fractal dimension of the micro-nano pores based on the displacement pressure, pore volume and Washburn model obtained by the high-pressure mercury injection analysis; Determining the second fractal dimension of the nanopore based on the results obtained from low-temperature nitrogen adsorption and the FHH model; The heterogeneity of the micro-nano pores is determined based on the effective fractal dimension of the first fractal dimension and the second fractal dimension.

8. The method according to claim 7, wherein The first fractal dimension of the micro-nano pore is determined by the following steps: Determining a target displacement pressure and a relative ratio of the micro-nano pores based on the displacement pressure, the pore volume, and the Washburn model, wherein the target displacement pressure is a logarithm of the displacement pressure, and the relative ratio is a logarithm of the result of dividing the pore volume by the displacement pressure; Draw a first double logarithmic graph with the target displacement pressure as the abscissa and the relative ratio as the ordinate; Determining a demarcation point in the first double logarithmic correlation graph and slopes corresponding to both ends of the demarcation point; The first fractal dimension of the micro-nano pore is determined by summing the slope and the second target value.

9. The method according to claim 8, wherein The results obtained from the low-temperature nitrogen adsorption include: the volume of adsorbed gas at equilibrium pressure, the volume covered by the gas monolayer, the saturated vapor pressure of nitrogen, and the equilibrium pressure; The second fractal dimension of the micro-nano pore is determined by the following steps: Based on the FHH model and the results obtained from the low-temperature nitrogen adsorption, the relative volume and relative pressure of the micro-nanopores are calculated; the relative volume is the logarithm of the result obtained by dividing the volume of the adsorbed gas by the volume covered by the gas monolayer, and the relative pressure is the logarithm of the result obtained by dividing the saturated vapor pressure of the nitrogen by the equilibrium pressure twice; Draw a second double logarithmic graph with the relative pressure as the abscissa and the relative volume as the ordinate; determining a slope in the second log-log plot; The sum of the slope and the second target value is determined as the second fractal dimension of the micro-nanopore.

10. The method according to claim 9, wherein The effective fractal dimension of the first fractal dimension and the second fractal dimension is determined by the following steps: determining a correlation coefficient between the slopes in the first log-log plot; If the first fractal dimension is within a first target range and the correlation coefficient is not less than a target threshold, determining that the first fractal dimension is a valid fractal dimension; If the second fractal dimension is within a second target range, the second fractal dimension is determined to be a valid fractal dimension.

11. A device for characterizing micro- and nano-pores in carbonate rocks, characterized in that: The device comprises: A determination module for determining target rock types and pore types of carbonate rocks; A first analysis module is configured to, upon determining that the target rock type and the pore type are millimeter-micrometer pore types, perform a qualitative analysis on the micro-nano pores of the carbonate rock to obtain characteristic types of the micro-nano pores; A second analysis module is used to perform quantitative analysis on the micro-nano pores to obtain the structural characteristics and heterogeneity of the micro-nano pores; A characterization module is used to characterize and describe the micro-nano pores according to the feature type, the structural feature, and the heterogeneity.

12. A storage medium, characterized in that: It comprises a series of instructions for executing the method steps according to any one of claims 1-10.

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