A method for carbonate fabric micro-area sampling based on quantized decision

Abstract

The application discloses a carbonate rock fabric micro-area sampling method based on quantitative decision, and relates to the technical field of oil and gas exploration.The application first performs stepwise grading cleaning on a core sample to remove primary pollution in the core sample, then measures the mineral fabric size, homogeneity and mineral contact index of the rock sample, quantitatively analyzes the mineral fabric and contact relationship of the rock sample, obtains the quantitative analysis result of the mineral fabric of the core sample, and formulates a sampling decision accordingly; after the sampling amount and granularity of a to-be-sampled powder sample are determined in combination with preset rock sample analysis test items, the rock sample is subjected to multi-scale collaborative sampling according to the mineral fabric size, and powder samples prepared by grinding and powdering, handheld drilling and powdering, micro-area sampling and laser micro-area sampling are obtained, so that the powder samples for subsequent geochemical analysis are obtained.The application effectively guarantees the purity and representativeness of carbonate rock fabric micro-area sampling, and lays a foundation for high-precision geochemical analysis.

Description

Technical Field

[0001] This invention relates to the field of oil and gas exploration technology, specifically to a method for micro-area sampling of carbonate rock fabrics based on quantitative decision-making. Background Technology

[0002] Carbonate rocks, as one of the most widely distributed sedimentary rocks on Earth, are key information carriers recording the evolution of the Earth's surface system, deep fluid activity, and resource formation processes. Their characteristics are extremely complex, exhibiting highly diverse lithologies (from biogenic limestone and oolitic limestone to various types of crystalline dolomite), and forming conditions that span a vast range (from warm shallow marine platforms to cold deep-sea basins and even atmospheric seepage environments). They have also undergone multiple phases and types of complex diagenetic processes (such as cementation, dissolution, dolomitization, recrystallization, and compaction / pressure solution). These processes superimpose and transform each other, ultimately resulting in the extremely heterogeneous and variable mineral composition within carbonate rocks. At the microscopic scale, a single thin section of carbonate rock may contain primitive biological skeletons, calcite or dolomite cements from different generations, solution pores filled with silica or bitumen, and later hydrothermal minerals. These micrometer- to millimeter-scale geological codes each preserve key paleoenvironmental parameters such as temperature, fluid composition, pH value, and redox state from specific geological periods.

[0003] Therefore, micro-area sampling technology for geochemical analysis has become an indispensable core means of interpreting the above information. In terms of scientific cognition, it can reveal the multi-stage geological changes that rocks have undergone, and in terms of resource exploration and practice, it can be used for engineering stability evaluation and prediction of groundwater pollutant migration behavior.

[0004] However, the prerequisite for achieving micro-area sampling technology for geochemical analysis is obtaining pure rock samples that represent the true geochemical composition of the target micro-area. Although there are various available micro-area sampling devices (such as mechanical micro-drills and laser ablation systems), there is still a lack of a pre-processing scheme from macroscopic sample handling to microscopic target decision-making. This results in a high risk of rock sample contamination during micro-area sampling, mixed mineral contamination, and a low success rate of repeated sampling, which seriously restricts the progress and depth of carbonate rock research.

[0005] Therefore, there is an urgent need to propose a micro-area sampling method for carbonate rock fabrication based on quantitative decision-making. This method should integrate rigorous geological understanding, systematic pollution control, quantitative fabrication assessment, and precise sampling execution to construct a standardized micro-area sampling scheme for carbonate rock fabrication, thereby providing technical support for carbonate rock geological research. Summary of the Invention

[0006] This invention aims to solve the above-mentioned problems and proposes a micro-area sampling method for carbonate rock texture based on quantitative decision-making. By establishing a standardized pretreatment process, the method removes primary contaminants from rock samples to the greatest extent. It combines the results of quantitative analysis of mineral texture based on mineral texture size, homogeneity, and mineral contact index to formulate sampling decisions and automatically matches the optimal sampling method for carbonate rock samples. It does not rely on the operator's personal experience and achieves precise sampling of target textures with different properties at different scales from millimeters to micrometers in carbonate rocks. This ensures the purity and representativeness of the samples and lays the foundation for high-precision geochemical analysis.

[0007] The present invention adopts the following technical solution: A micro-area sampling method for carbonate rock fabrics based on quantitative decision-making includes the following steps: Step 1: Perform a step-by-step graded cleaning of the core sample to remove the original contaminants in the core sample; Step 2: Based on the mineral composition within the rock sample, determine the mineral composition size, homogeneity, and mineral contact index of the rock sample, quantitatively analyze the mineral composition and contact relationship of the rock sample, obtain the quantitative analysis results of the mineral composition of the core sample, and formulate sampling decisions based on the quantitative analysis results of the mineral composition of the rock sample. Step 3: Determine the sampling amount and particle size of the powder sample to be taken according to the preset rock sample analysis test items; Step 4: Based on the quantitative analysis results of the mineral composition of the rock samples, combined with the sampling decision made in Step 2 and the sampling quantity determined in Step 3, large-scale rock block co-sampling is carried out on rock samples with mineral composition sizes exceeding 3 mm. Powder samples are obtained by grinding and hand drill. Step 5: Based on the quantitative analysis results of the mineral composition of the rock samples, combined with the sampling decision made in Step 2 and the sampling quantity determined in Step 3, small-scale block co-sampling is carried out on rock samples with mineral composition sizes not exceeding 3 mm, including micro-area sampling and laser micro-area sampling. Step 6: The powder samples obtained by grinding, hand-held drilling, micro-area sampling, and laser micro-area sampling are used to obtain carbonate rock texture micro-area sampling samples.

[0008] Preferably, step 1 includes the following sub-steps: Step 1.1: Pre-clean the core sample by using a rock cutting tool to remove contaminants larger than 2 mm from the surface of the core sample, so that the surface of the rock sample has a brand new and uncontaminated cross section. Nitrogen gas is used to purge the cross section to remove contact contamination from the rock cutting tool. Step 1.2: Mechanically clean the rock sample to remove dust and impurities from the surface of the rock sample. Then, place the rock sample in a beaker filled with deionized water and repeatedly clean the rock sample in an ultrasonic cleaner by changing the deionized water multiple times. Gradually peel off the micropore filling material in the rock sample until the deionized water used to clean the rock sample is clear and the conductivity does not exceed 2μS / cm. Then, stop cleaning the rock sample. Step 1.3: Remove the rock sample from the beaker, rinse the surface of the rock sample with anhydrous ethanol to remove residual moisture and impurities, and then vacuum dry the rock sample before storing it in a desiccator.

[0009] Preferably, step 2 includes the following sub-steps: Step 2.1, the mineral composition within the core sample includes matrix, cement, and fracture-filling minerals; The homogeneity of core samples was quantitatively analyzed by combining petrographic hand-drawing and RGB imaging. The area of ​​non-matrix components was measured within a square region of a preset size in the core sample. The proportion of non-matrix component area was calculated to characterize the mean. When the proportion of non-matrix component area is less than 5%, it is determined to be high mean; when the proportion of non-matrix component area is not less than 5% and not more than 15%, it is determined to be medium mean; and when the proportion of non-matrix component area is greater than 15%, it is determined to be low mean. Step 2.2: Quantify the mineral contact index (MCI) based on thin section microscopy of the core sample. The MCI is the ratio of the area to the perimeter of the mineral texture. Step 2.3: Measure the maximum width of the mineral texture at the fresh surface of the core sample as the mineral texture size; Step 2.4: Obtain the quantitative analysis results of the mineral texture of the core samples based on the mineral texture size, homogeneity, and mineral contact index. Set a sampling strategy based on these results. Specifically, when the rock sample has high homogeneity, a mineral contact index greater than 0.8, and a mineral texture size greater than 15 mm, grind and powder the mineral texture for sampling. When the rock sample has medium homogeneity, a mineral contact index not less than 0.4 and not greater than 0.8, and a mineral texture size not less than 3 mm and not greater than 15 mm, use a handheld drill for sampling. When the rock sample has low homogeneity, a mineral contact index less than 0.4, and a mineral texture size not less than 0.3 mm and less than 3 mm, use a micro-area sampler for sampling. When the mineral texture type in the rock sample is microcrystalline or a biological skeleton and the mineral texture size is less than 0.3 mm, use laser micro-area sampling.

[0010] Preferably, in step 3, the rock sample analysis and testing items include carbon and oxygen isotope determination, trace element-rare earth element content determination, strontium isotope determination, and X-ray diffraction. Specifically, the carbon and oxygen isotope determination requires a powder sample mass greater than 5 mg and a particle size of not less than 200 mesh; the trace element-rare earth element content determination requires a powder sample mass greater than 2 g and a particle size of not less than 200 mesh; the strontium isotope determination requires a powder sample mass greater than 30 mg and a particle size of not less than 200 mesh; and the X-ray diffraction requires a powder sample mass greater than 3 g and a particle size of not less than 200 mesh. When the rock sample is an ancient carbonate rock sample, the minimum sampling amount is: ; In the formula, This is the minimum sampling amount for ancient carbonate rock samples; The minimum molar amount of the target material required for rock sample testing instruments; Minimum number of tests; To test the molar mass of the species; This is the signal loss coefficient; This represents the mass fraction of the substance to be tested in the rock sample.

[0011] Preferably, step 4 includes the following sub-steps: Step 4.1: Based on the quantitative analysis results of the mineral composition of the core samples, core samples with high mean, mineral contact index greater than 0.8, and mineral composition size greater than 15 mm are ground and sampled. First, the rock samples and mortar are cleaned with deionized water, then the rock samples and mortar are rinsed with anhydrous ethanol and wiped clean. After mechanically crushing the rock samples, they are ground into a powder without particle texture in the mortar and then transferred to centrifuge tubes and sealed for later use. Step 4.2: Based on the quantitative analysis results of the mineral composition of the core samples, rock samples with moderate mean, mineral contact index of not less than 0.4 and not greater than 0.8, and mineral composition size of not less than 3 mm and not greater than 15 mm are sampled by hand drill. Fresh surfaces are first cut out in the rock samples. The fresh surfaces of the rock samples and the drill bit of the electric grinder are rinsed with deionized water and anhydrous ethanol in sequence and then dried. The speed of the electric grinder is set. The powder is then extracted from the mineral composition enrichment distribution area in the fresh surface of the rock sample by the electric grinder and transferred to a centrifuge tube for sealing and later use.

[0012] Preferably, step 5 includes the following sub-steps: Step 5.1: Based on the quantitative analysis results of the mineral composition of the core samples, rock samples with low mean, mineral contact index less than 0.4, and mineral composition size not less than 0.3 mm and less than 3 mm are sampled using a micro-area sampler. Multiple thin sections of rock are prepared using the rock samples, including one ordinary section and multiple probe sections. Each thin section of rock contains the same mineral composition. Step 5.2: Samples are taken from the ordinary sample using a micro-area sampler. First, the ordinary sample is observed under a microscope to observe its mineral composition distribution and combination characteristics. The opaque mineral components in the ordinary sample are observed using reflected light supplemented with transmitted light. Then, the probe is fixed in the sampling stage of the micro-area sampler. After generating an image of the surface area of ​​the rock sample using the micro-area sampler, the field of view under the microscope and the polarization of the polarizer are adjusted. The position, drilling speed and moving speed of the drill bit of the micro-area sampler are controlled. Powder is then extracted from the mineral composition enrichment distribution area and the edge of the mineral composition using the drill bit of the micro-area sampler. The powder is then transferred to a centrifuge tube and sealed for later use. Step 5.3: Use an ion mass spectrometer to sample the probe sheet. First, fix the probe sheet in the sampling stage of the ion mass spectrometer, set the sampling parameters of the ion mass spectrometer, use the ion mass spectrometer to sample at the selected target ablation point, and collect the collected aerosol samples into a Labco bottle and seal it for later use.

[0013] Preferably, the mineral texture enrichment distribution area is a region in the rock thin section where the width of the mineral texture is not less than 0.3 mm and extends continuously for more than 1 mm; the mineral texture edge is a region in the rock thin section where the distance from the mineral texture edge is less than 0.5 mm.

[0014] Preferably, in step 5.2, when drilling at the mineral-rich distribution area using a micro-area sampler, the drill bit of the micro-area sampler is controlled to approach the ordinary sheet, and the drilling speed is controlled to be 10 μm / s at the preset sampling point. The drilling time after the drill bit contacts the ordinary sheet is controlled not to exceed 3 seconds to prevent the drill bit from penetrating the ordinary sheet. After the sampling at the sampling point is completed, the drill bit is moved to the next sampling point along the mineral-rich distribution direction at a moving speed of 30 ~ 50 μm / s.

[0015] Preferably, the sampling parameters of the ion mass spectrometer include laser wavelength, maximum laser energy, maximum energy density, ablation frequency, spot size, sample chamber size, XYZ stage repeatability, and purge time.

[0016] The present invention has the following beneficial effects: (1) This invention proposes a micro-area sampling method for carbonate rock fabric based on quantitative decision-making, which significantly improves sampling accuracy and data quality, and fundamentally ensures the authenticity of geochemical information. This invention introduces the quantitative analysis results of mineral fabric size, homogeneity and mineral contact index, and formulates a micro-area sampling method for carbonate rock fabric based on objective and quantitative petrographic indicators. This effectively avoids improper site selection and method mismatch caused by relying on personal experience, so that the drill bit or laser beam can be accurately guided to the core part of the target area, minimizing contact between adjacent different fabrics, and minimizing the mixing and contamination between mineral fabrics in the rock sample. This effectively ensures that the data used in subsequent analysis of isotopes, trace elements and other data truly represent the original information of the target geological body. This invention uses standardized, step-by-step cleaning as a mandatory pre-processing step. Through physical, chemical, and physicochemical methods, rock samples are decontaminated step by step. This systematically removes various adhering contaminants and microporous fillers carried by rock samples from the field to the laboratory. It solves the drawbacks of arbitrary pretreatment and unverifiable effects in existing technologies, and significantly reduces the analytical background noise introduced by surface contamination of rock samples. This provides a prerequisite for obtaining high signal-to-noise ratio trace and microelement data.

[0017] (2) This invention proposes a micro-area sampling method for carbonate rock fabrication based on quantitative decision-making, optimizing the sampling process for different scales and types of mineral fabrications, and significantly improving the efficiency and automation of sampling work. This invention simplifies the decision-making process for micro-area sampling of carbonate rock fabrication, reduces the operational threshold and subjective bias, and transforms the complex petrographic judgment and tool selection process into an automated decision-making process based on quantitative parameters. This eliminates the need for operators to rely on long-term experience accumulation for trial-and-error selection during the sampling process; they only need to follow the system guidance. This greatly reduces the impact of operator technical operation and human uncertainty on micro-area sampling of carbonate rock fabrication, enabling operators of different levels to obtain stable and reliable operational results, and improving the uniformity of the overall sampling level of laboratory operators. This invention changes the inefficient mode of multiple observations and processing in the prior art, and can efficiently complete full-scale sampling from macro to micro after a single systematic sample preparation and observation, reducing the time lost in repeated processing and positioning of rock samples, and improving sampling efficiency.

[0018] (3) This invention proposes a micro-sampling method for carbonate rock fabric based on quantitative decision-making, which maximizes the protection and utilization of precious samples. This invention takes into account the special characteristics of precious, limited ancient or deep rock samples, and provides a calculation formula for the minimum powder requirement for a small number of precious rock samples. This formula is used to guide the precise micro-sampling of precious rock samples, which is sufficient for the needs of the samples. This fundamentally changes the extensive quantitative model of the existing technology, which tends to use more rather than less, and is conducive to the maximum preservation and sustainable utilization of non-renewable geological samples.

[0019] (4) This invention proposes a method for micro-area sampling of carbonate rock texture based on quantitative decision-making. By combining systematic, quantitative decision-making and standardized procedures, micro-area sampling of carbonate rock texture is carried out. This not only improves the operational accuracy, data quality and efficiency of micro-area sampling of carbonate rock texture, but also promotes the transformation of mineral texture sampling from relying on personal experience to based on objective standard and standardized procedures. It has important practical value and broad prospects for promotion. Attached Figure Description

[0020] Figure 1 This is a flowchart of a micro-area sampling method for carbonate rock fabric based on quantitative decision-making, according to the present invention.

[0021] Figure 2 A flowchart of the sampling decision-making process.

[0022] Figure 3 This is a schematic diagram for identifying multiple mineral textures; in the diagram, CD1 is fibrous dolomite, CD2 is foliated dolomite, and CD3 is granular dolomite.

[0023] Figure 4 This is a schematic diagram of the high-precision micro-area sampling results. Detailed Implementation

[0024] The specific embodiments of the present invention will be further described below with reference to the accompanying drawings.

[0025] Example 1 This invention addresses the systemic shortcomings of existing carbonate rock micro-area sampling techniques, such as fragmented steps, arbitrary method matching, weak contamination control, and a lack of multi-scale collaborative standards. It proposes a carbonate rock fabric micro-area sampling method based on quantitative decision-making, such as… Figure 1 As shown, this method is used to obtain multi-scale carbonate rock fabric samples, solving the fundamental problem of obtaining pure, accurate, and representative micro-area geochemical samples from complex rock samples. The specific steps include: Step 1: Obtain core samples or field outcrop specimens of carbonate rocks. Considering the purpose of powder sampling, the degree of contamination, and the type of contaminants, perform a stepwise graded cleaning of the core samples to remove primary contaminants such as weathering residues and biological traces, reduce interference from atmospheric precipitation and other factors on the initial geochemical signals of the rock samples, and minimize the introduction of new contaminants into the rock samples during the cleaning process. This includes the following sub-steps: Step 1.1: Pre-clean the core sample by using a rock cutting tool to remove contaminants larger than 2 mm from the surface of the core sample, such as weathering residues, biological traces, and traces of human activity, so that the surface of the rock sample has a brand new and uncontaminated cross section. Use nitrogen to purge the cross section for 1 to 2 minutes to remove contact contamination from the rock cutting tool.

[0026] Step 1.2: Mechanically clean the rock samples for 2-4 minutes using deionized water, a PTFE scraper, and a nylon brush to remove surface dust and impurities. Prepare the same number of beakers as the rock samples and fill them with deionized water, ensuring the water occupies at least 2 / 3 of the beaker's volume. This ensures the deionized water can submerge the rock samples. Place the rock samples in the corresponding beakers filled with deionized water. Then, inject deionized water into the ultrasonic cleaner, filling it to 2 / 3 of its volume. Ensure the deionized water level in the ultrasonic cleaner is higher than the deionized water level in the beakers to guarantee sufficient circulation and vibration of the water within the ultrasonic cleaner during the cleaning process. Start the ultrasonic cleaner and clean the rock sample at a frequency of 40 kHz for 40 minutes. Then replace the water with deionized water and adjust the frequency to 80 kHz to repeat the cleaning process. Gradually peel off the microporous filling material in the rock sample. During the cleaning process, closely observe the clarity of the deionized water in the beaker. If the deionized water becomes obviously turbid, replace it with new deionized water immediately. Stop cleaning the rock sample when the deionized water used to clean the rock sample is clear and the conductivity does not exceed 2 μS / cm.

[0027] Step 1.3: Remove the rock sample from the beaker and rinse the surface of the rock sample with anhydrous ethanol for 1-2 minutes to further remove residual moisture and impurities from the rock sample, while ensuring that the surface of the rock sample is dry and clean. After rinsing, vacuum dry the rock sample at 0.1 MPa and 60℃ for 2 hours to prevent the phase transformation of the thermosensitive mineral and remove moisture from the inside and surface of the rock sample. Remove the rock sample and store it in a desiccator.

[0028] Step 2: Based on the mineral composition within the rock sample, determine the mineral composition size, homogeneity, and mineral contact index of the rock sample. Quantitatively analyze the mineral composition and contact relationships of the rock sample, obtain the quantitative analysis results of the mineral composition of the core sample, and formulate sampling decisions based on the quantitative analysis results of the mineral composition of the rock sample, such as... Figure 2 As shown, it includes the following sub-steps: Step 2.1, the mineral composition within the core sample includes matrix, cement, and fracture-filling minerals.

[0029] For powder sample preparation aimed at interpreting the physicochemical parameters of paleowater bodies, the matrix was used as the target mineral composition. A combination of petrographic sketching and RGB imaging was employed to quantitatively analyze the homogeneity of the core samples. A 3cm × 3cm square region was selected within the core sample, and the area of ​​non-matrix components, including diagenetic alteration, secondary mineral cementation, impurity contamination, and fracture filling, was measured within this region. The proportion of non-matrix components was calculated to characterize the mean.

[0030] When the area of ​​non-matrix components accounts for less than 5%, it is determined to be of high mean; when the area of ​​non-matrix components accounts for not less than 5% and not more than 15%, it is determined to be of medium mean; and when the area of ​​non-matrix components accounts for more than 15%, it is determined to be of low mean.

[0031] Step 2.2 involves powder sample preparation for the study, aimed at interpreting later diagenetic alteration and fluid properties, using cement and fracture-filling minerals as target mineral textures. Thin section microscopy is used to quantify the mineral contact index (MCI), which is the ratio of the area to the perimeter of the mineral texture.

[0032] Step 2.3: Measure the maximum width of the mineral texture at the fresh surface of the core sample as the mineral texture size. The width of the mineral texture should decrease by less than 20% within a 1cm extension length.

[0033] Step 2.4: Obtain the quantitative analysis results of the mineral texture of the core samples based on the mineral texture size, homogeneity, and mineral contact index. Set a sampling strategy based on these results. Specifically, when the rock sample has high homogeneity, a mineral contact index greater than 0.8, and a mineral texture size greater than 15 mm, grind and powder the mineral texture for sampling. When the rock sample has medium homogeneity, a mineral contact index not less than 0.4 and not greater than 0.8, and a mineral texture size not less than 3 mm and not greater than 15 mm, use a handheld drill for sampling. When the rock sample has low homogeneity, a mineral contact index less than 0.4, and a mineral texture size not less than 0.3 mm and less than 3 mm, use a micro-area sampler for sampling. When the mineral texture type in the rock sample is microcrystalline or a biological skeleton and the mineral texture size is less than 0.3 mm, use laser micro-area sampling.

[0034] Step 3: Determine the sampling quantity and particle size of the powder sample to be taken according to the preset rock sample analysis test items.

[0035] Furthermore, the rock sample analysis and testing items include carbon and oxygen isotope determination, trace element-rare earth element content determination, strontium isotope determination, and X-ray diffraction.

[0036] Specifically, the carbon and oxygen isotope determination requires the powder sample to have a mass greater than 5 mg and a particle size of not less than 200 mesh; the trace element-rare earth element content determination requires the powder sample to have a mass greater than 2 g and a particle size of not less than 200 mesh; the strontium isotope determination requires the powder sample to have a mass greater than 30 mg and a particle size of not less than 200 mesh; and the X-ray diffraction requires the powder sample to have a mass greater than 3 g and a particle size of not less than 200 mesh.

[0037] Furthermore, when the rock sample is a limited number of precious ancient carbonate rock samples, the minimum sampling amount is determined using the minimum sampling amount calculation formula, which is as follows: ; In the formula, This is the minimum sample size for ancient carbonate rock samples, in units of... ; The minimum molar amount of the target material required for rock sample testing instruments, in units of... ; Minimum number of tests; To test the molar mass of a species, the unit is... ; This is the signal loss coefficient; The mass fraction of the substance to be tested in the rock sample is expressed in units of .

[0038] Step 4: Based on the quantitative analysis results of the mineral composition of the rock samples, combined with the sampling decision made in Step 2 and the sampling quantity determined in Step 3, large-scale block co-sampling is carried out on rock samples with mineral composition sizes exceeding 3 mm. Powder samples are obtained through grinding and hand drill grinding, including the following sub-steps: Step 4.1: Based on the quantitative analysis results of the mineral composition of the core samples, core samples with high mean, mineral contact index greater than 0.8, and mineral composition size greater than 15 mm are ground and sampled. First, the rock samples and mortar are cleaned with deionized water 3-5 times, then the rock samples and mortar are rinsed with anhydrous ethanol and wiped clean. The rock samples are mechanically crushed and placed in the mortar for grinding. To avoid heat generation during grinding, the grinding speed is set to less than 60 r / min, and contaminants are strictly prevented from entering the mortar during grinding. If obvious impurities or contaminants are found to have entered the mortar, they must be removed immediately with tweezers cleaned with anhydrous ethanol. After grinding the rock samples into a powder without a grainy texture using the mortar, the powder is transferred to a centrifuge tube using weighing paper and sealed for later use.

[0039] Step 4.2: Based on the quantitative analysis results of the mineral texture of the core samples, rock samples with moderate mean, mineral contact index of not less than 0.4 and not greater than 0.8, and mineral texture size of not less than 3 mm and not greater than 15 mm are sampled by hand-held drill. First, a fresh surface is cut out of the rock sample to ensure that the mineral texture is well distributed on the fresh surface. The fresh surface of the rock sample is rinsed with deionized water and anhydrous ethanol 2-3 times and then dried. Then, a diamond grinding head cone with a shank diameter of 3 mm is installed on the drill bit of the electric grinder. The drill bit is wiped with deionized water and anhydrous ethanol and dried in sequence. The speed of the electric grinder is set according to the lithology. The powder is drilled from the mineral texture enrichment distribution area in the fresh surface of the rock sample using the electric grinder. The powder is then transferred to a centrifuge tube using weighing paper and sealed for later use.

[0040] Specifically, when the lithology is limestone, the electric drill speed is set to 10000±10% RPM; when the lithology is dolomite, the electric drill speed is set to 18000±10% RPM, thereby adapting to the hardness and brittleness of the specific lithology and avoiding isotope fractionation and mineral phase transformation caused by frictional heat generation.

[0041] During the drilling process of the electric mill, in order to avoid the drill bit of the electric mill coming into contact with other components, the drilling depth of the electric mill drill bit does not exceed 3mm, which effectively avoids the impurity of components caused by the heterogeneity of mineral composition in the vertical direction.

[0042] Step 5: Based on the quantitative analysis results of the mineral fabric of the rock samples, and combined with the sampling decision made in Step 2 and the sampling quantity determined in Step 3, small-scale block co-sampling is performed on rock samples with mineral fabric sizes not exceeding 3 mm. This includes micro-area sampling and laser micro-area sampling, and includes the following sub-steps: Step 5.1: Based on the quantitative analysis results of the mineral fabric of the core samples, rock samples with low mean, mineral contact index less than 0.4, and mineral fabric size not less than 0.3 mm and less than 3 mm are sampled using a micro-area sampler. Multiple thin sections of rock are prepared from the rock samples, including one ordinary section and 3-4 probe sections. Each rock thin section contains the same mineral fabric, and the sections are sliced ​​in the same direction as much as possible. In this embodiment, the thickness of the ordinary section is 30 μm, and the thickness of the probe sections is 50-90 μm. Both sides are polished with 1000-grit sandpaper without cover plates.

[0043] Step 5.2 involves sampling the ordinary sample using a micro-area sampler. First, the ordinary sample is observed under a microscope to examine its mineral composition and distribution characteristics. Opaque mineral components within the ordinary sample are observed using reflected light supplemented with transmitted light. Then, the probe sample is fixed in the sampling stage of the ESL MicroMill micro-area sampler. Using ActiveView2 software, an image of the rock sample surface area is generated. The field of view is adjusted to 10mm~42μm, and the polarizer is used to adjust the polarized light. A full LED light is provided, and a 1 / 8'' diameter tungsten carbide drill bit is used at a 22.5° bevel angle and a rotation speed of 50000 RPM to achieve high torque and low centrifugal force. Powder is collected from the mineral-rich areas and the edges of the mineral composition using the micro-area sampler's drill bit, and then transferred to sealed centrifuge tubes for later use.

[0044] Specifically, the mineral texture enrichment distribution area is the region in the rock thin section where the width of the mineral texture is not less than 0.3 mm and extends continuously for more than 1 mm. When drilling at the mineral texture enrichment distribution area using a micro-area sampler, the drill bit of the micro-area sampler is controlled to approach the ordinary section and drill down at the preset sampling point in the vertical direction at a drilling speed of 10 μm / s. The drilling time after the drill bit contacts the ordinary section is controlled not to exceed 3 seconds to prevent the drill bit from penetrating the ordinary section. After the sampling at the sampling point is completed, the drill bit is moved to the next sampling point along the mineral texture distribution direction at a moving speed of 30 ~ 50 μm / s.

[0045] The mineral texture edge refers to the area within a rock thin section less than 0.5 mm from the edge of the mineral texture. When drilling at the edge of the mineral texture using a micro-area sampler, in order to avoid contamination caused by the drill bit contacting other components and powder loss due to airflow, it is necessary to collect powder samples in a timely manner during the sampling process. If it is planned to extract powder from multiple textures on the same thin section, the surface of the thin section should be wiped clean with anhydrous ethanol and dried after sampling of one mineral texture to prevent powder residue from entering the subsequent mineral textures and causing contamination.

[0046] Step 5.3: Sample the probe sheet using a combined system of RESOlution LR laser ablation system and Agilent 7900 inductively coupled plasma mass spectrometer. First, fix the probe sheet in the sampling stage of the ion mass spectrometer, set the sampling parameters of the ion mass spectrometer, and use the ion mass spectrometer to sample at the selected target ablation point. Collect the aerosol sample into a Labco bottle and seal it for later use.

[0047] Furthermore, the sampling parameters of the ion mass spectrometer include laser wavelength, maximum laser energy, maximum energy density, ablation frequency, spot size, sample chamber size, XYZ stage repeatability, and purge time.

[0048] Specifically, in this embodiment, the laser wavelength is set to 193nm, the maximum laser energy is set to 240mJ, and the maximum energy density is set to not less than 45J / cm². 2 The ablation frequency is set to 1~200Hz, the spot size is set to 2~380µm, the sample chamber size is set to 155mm×105mm, the repeatability of the XYZ stage does not exceed 3µm, and the purging time does not exceed 700ms.

[0049] Step 6: The powder samples obtained by grinding, hand-held drilling, micro-area sampling, and laser micro-area sampling are used to obtain carbonate rock texture micro-area sampling samples.

[0050] Example 2 The carbonate rock fabric micro-area sampling method based on quantitative decision-making described in Example 1 was applied to the sampling of deep dolomite cores in a basin to obtain powder samples of the deep dolomite cores in the basin. The specific process is as follows: Step 1: Obtain core samples or field outcrop specimens of carbonate rocks. Considering the purpose of powder sampling, the degree of contamination, and the type of contaminants, perform a stepwise graded cleaning of the core samples to remove primary contaminants such as weathering residues and biological traces, reduce interference from atmospheric precipitation and other factors on the initial geochemical signals of the rock samples, and minimize the introduction of new contaminants into the rock samples during the cleaning process. This includes the following sub-steps: Step 1.1: Pre-clean the core sample by using a rock cutting tool to remove contaminants larger than 2 mm from the surface of the core sample, such as weathering residues, biological traces, and traces of human activity, so that the surface of the rock sample has a brand new and uncontaminated cross section. Use nitrogen to purge the cross section for 2 minutes to remove contact contamination from the rock cutting tool.

[0051] Step 1.2: Mechanically clean the rock samples for 4 minutes using deionized water, a PTFE scraper, and a nylon brush to remove surface dust and impurities. Prepare the same number of beakers as the rock samples and fill them with deionized water, ensuring the water occupies at least 2 / 3 of the beaker's volume. This ensures the deionized water can submerge the rock samples. Place the rock samples in the corresponding beakers filled with deionized water. Then, fill the ultrasonic cleaner with deionized water, ensuring the water level in the ultrasonic cleaner occupies 2 / 3 of its volume. This ensures the deionized water level in the ultrasonic cleaner is higher than the deionized water level in the beakers, guaranteeing sufficient circulation and vibration of the water flow within the ultrasonic cleaner during the cleaning process. Start the ultrasonic cleaner and clean the rock sample at a frequency of 40 kHz for 40 minutes. Then replace the water with deionized water and adjust the frequency to 80 kHz to repeat the cleaning process. Gradually peel off the micropore filling material in the rock sample. During the cleaning process, closely observe the clarity of the deionized water in the beaker. If the deionized water becomes obviously turbid, replace it with new deionized water immediately. Stop cleaning the rock sample when the deionized water used to clean the rock sample is clear and the conductivity does not exceed 1.2 μS / cm.

[0052] Step 1.3: Remove the rock sample from the beaker and rinse the surface of the rock sample with anhydrous ethanol for 1 minute to further remove residual moisture and impurities from the rock sample, while ensuring that the surface of the rock sample is dry and clean. After rinsing, vacuum dry the rock sample at 0.1 MPa and 60°C for 2 hours to prevent the phase transformation of the thermosensitive mineral and remove moisture from the inside and surface of the rock sample. Remove the rock sample and store it in a desiccator.

[0053] Step 2: Based on the mineral composition within the rock sample, determine the mineral composition size, homogeneity, and mineral contact index of the rock sample; quantitatively analyze the mineral composition and contact relationships of the rock sample; obtain the quantitative analysis results of the mineral composition of the core sample; and formulate sampling decisions based on the quantitative analysis results of the mineral composition of the rock sample, including the following sub-steps: Step 2.1, the mineral composition within the core sample includes matrix, cement, and fracture-filling minerals.

[0054] For powder sample preparation aimed at interpreting the physicochemical parameters of paleowater bodies, the matrix was used as the target mineral composition. A combination of petrographic sketching and RGB imaging was employed to quantitatively analyze the homogeneity of the core sample. A 3cm × 3cm square region was selected within the core sample, and the area of ​​non-matrix components, including diagenetic alteration, secondary mineral cementation, impurity infiltration, and fracture filling, was measured within this region. The proportion of non-matrix component area was calculated to characterize the mean. In this embodiment, the mean H of the dolomite matrix in the core sample was... m It is 93.2%.

[0055] Step 2.2 involves preparing powder samples for the purpose of interpreting later diagenetic alteration and fluid properties. Using cement and fracture-filling minerals as target mineral textures, thin-section microscopy was used to identify dolomite cements with three different textures: fibrous dolomite (CD1), foliated dolomite (CD2), and granular dolomite (CD3). Figure 3 As shown, the mineral contact index (MCI) of fibrous dolomite (CD1), foliated dolomite (CD2), and granular dolomite (CD3) is quantified respectively. Among them, the MCI of fibrous dolomite is... CD1 The mineral contact index (MCI) of foliated dolomite is 0.285. CD2 The mineral contact index (MCI) of granular dolomite is 0.133. CD3 It is 0.421.

[0056] Step 2.3: Measure the maximum width of the mineral texture at the fresh surface of the core sample as the mineral texture size S. The width of the mineral texture should decrease by less than 20% within a 1cm extension length. The mineral texture size S of the fibrous dolomite is then measured. CD1 The mineral texture size S of 0.8 mm, foliated dolomite CD2 The mineral texture size S of 0.5mm granular dolomite CD3 It is 3.9mm.

[0057] Step 2.4: Obtain the quantitative analysis results of the mineral texture of the core samples based on the mineral texture size, homogeneity, and mineral contact index. Set a sampling strategy based on these results. Specifically, when the rock sample has high homogeneity, a mineral contact index greater than 0.8, and a mineral texture size greater than 15 mm, grind and powder the mineral texture for sampling. When the rock sample has medium homogeneity, a mineral contact index not less than 0.4 and not greater than 0.8, and a mineral texture size not less than 3 mm and not greater than 15 mm, use a handheld drill for sampling. When the rock sample has low homogeneity, a mineral contact index less than 0.4, and a mineral texture size not less than 0.3 mm and less than 3 mm, use a micro-area sampler for sampling. When the mineral texture type in the rock sample is microcrystalline or a biological skeleton and the mineral texture size is less than 0.3 mm, use laser micro-area sampling.

[0058] Step 3: Determine the sampling quantity and particle size of the powder sample to be taken according to the preset rock sample analysis test items.

[0059] Furthermore, the rock sample analysis and testing items include carbon and oxygen isotope determination, trace element-rare earth element content determination, strontium isotope determination, and X-ray diffraction. Specifically, the carbon and oxygen isotope determination is performed using a stable isotope ratio mass spectrometer, requiring the powder sample mass to be greater than 5 mg and the particle size to be no less than 200 mesh. The trace element-rare earth element content is determined using an X-ray fluorescence spectrometer or an inductively coupled plasma mass spectrometer, requiring the powder sample mass to be greater than 2 g and the particle size to be no less than 200 mesh. The strontium isotope determination is performed using a thermal ionization ratio mass spectrometer, requiring the powder sample mass to be greater than 30 mg and the particle size to be no less than 200 mesh. The X-ray diffraction is performed using an X-ray diffractometer, requiring the powder sample mass to be greater than 3 g and the particle size to be no less than 200 mesh.

[0060] In this embodiment, when the rock sample is a limited number of precious ancient carbonate rock samples, the minimum sampling amount of the ancient carbonate rock sample is determined to be 4.37 mg using the minimum sampling amount calculation formula.

[0061] Step 4: Based on the quantitative analysis results of the mineral composition of the rock samples, combined with the sampling decision made in Step 2 and the sampling quantity determined in Step 3, large-scale rock blocks are sampled in a coordinated manner for dolomite matrix with a maximum size greater than 3 mm and granular dolomite cementation. Powder samples are obtained through grinding and hand drill grinding, including the following sub-steps: Step 4.1: Based on the quantitative analysis results of the mineral composition of the core samples, grind and sample the dolomite matrix with high mean, mineral contact index greater than 0.8, and mineral composition size greater than 15 mm. First, wash the rock sample and mortar with deionized water 3-5 times, then rinse the rock sample and mortar with anhydrous ethanol and wipe them clean. After mechanically crushing the rock sample, place it in the mortar for grinding. To avoid heat generation during grinding, set the grinding speed to less than 60 r / min, and strictly avoid contaminants entering the mortar during grinding. If obvious impurities or contaminants are found to have entered the mortar, they must be removed immediately with tweezers cleaned with anhydrous ethanol. After grinding the rock sample into a powder without a grainy texture using the mortar, transfer it to a centrifuge tube using weighing paper and seal it for later use.

[0062] Step 4.2: Based on the quantitative analysis results of the mineral texture of the core sample, hand-held drills were used to sample the dolomite matrix with moderate mean, a mineral contact index of not less than 0.4 and not greater than 0.8, and a mineral texture size of not less than 3 mm and not greater than 15 mm. Fresh surfaces were first cut out of the rock sample to ensure that the mineral texture was well distributed on the fresh surface. The fresh surfaces of the rock sample were rinsed with deionized water and anhydrous ethanol 2-3 times and then dried. A diamond grinding head cone with a shank diameter of 3 mm was then installed on the drill bit of the electric grinder. The drill bit was wiped with deionized water and anhydrous ethanol and then dried. The electric grinder speed was set to 18000±10% RPM according to the lithology. The powder was then extracted from the mineral texture enrichment distribution area in the fresh surface of the rock sample using the electric grinder and transferred to a 5 ml centrifuge tube using weighing paper and sealed for later use.

[0063] During the drilling process of the electric mill, in order to avoid the drill bit of the electric mill coming into contact with other components, the drilling depth of the electric mill drill bit does not exceed 3mm, which effectively avoids the impurity of components caused by the heterogeneity of mineral composition in the vertical direction.

[0064] Step 5: Based on the quantitative analysis results of the mineral fabric of the rock samples, combined with the sampling decision made in Step 2 and the sampling quantity determined in Step 3, small-scale block co-sampling is carried out on fibrous dolomite cementation and foliated dolomite cementation with a mineral fabric size not exceeding 3 mm. This includes micro-area sampling and laser micro-area sampling, and includes the following sub-steps: Step 5.1: Based on the quantitative analysis results of the mineral composition of the core samples, rock samples with low mean, mineral contact index less than 0.4, and mineral composition size not less than 0.3 mm and less than 3 mm are sampled using a micro-area sampler. Multiple thin sections of rock are prepared from the rock samples, including one ordinary section with a thickness of 30 μm and 3 to 4 probe sections with a thickness of 50 to 90 μm. Each thin section contains the same mineral composition and the sections are sliced ​​in the same direction as much as possible.

[0065] Step 5.2 involves sampling the ordinary sample using a micro-area sampler. First, the ordinary sample is observed under a microscope to examine its mineral composition and distribution characteristics. Opaque mineral components within the ordinary sample are observed using reflected light supplemented with transmitted light. Then, the probe slide is fixed in the sampling stage of the ESL MicroMill micro-area sampler. Using ActiveView2 software, an image of the rock sample surface area is generated. The field of view is adjusted to 10mm~42μm, and the polarizer is used to adjust the polarized light. A full LED light is provided, and a 1 / 8'' diameter tungsten carbide drill bit is used at a 22.5° bevel angle and a rotation speed of 50000 RPM to achieve high torque and low centrifugal force. Powder is extracted from the areas enriched in fibrous dolomite cement, foliated dolomite cement, and the edges of fibrous dolomite cement, and then transferred to 5ml centrifuge tubes and sealed for later use.

[0066] In this embodiment, when drilling at the locations of fibrous dolomite cementation and foliated dolomite cementation enrichment using a micro-area sampler, the drill bit of the micro-area sampler is controlled to approach the ordinary sample at a drilling speed of 10 μm / s vertically at a preset sampling point. The drilling time after the drill bit contacts the ordinary sample is controlled to not exceed 3 seconds to prevent the drill bit from penetrating the ordinary sample. After sampling at this point is completed, the drill bit is moved to the next sampling point at a moving speed of 30-50 μm / s along the mineral fabric distribution direction for sampling, obtaining the following results: Figure 4 The results of high-precision micro-area sampling are shown.

[0067] When drilling at the edges of cemented fibrous dolomite and lamellar dolomite using a micro-area sampler, in order to avoid contamination caused by the drill bit contacting other components and powder loss due to airflow, it is necessary to collect powder samples in a timely manner during the sampling process. If it is planned to extract powder from multiple mineral structures on the same thin slice, the surface of the thin slice should be wiped clean with anhydrous ethanol and dried after sampling of one mineral structure to prevent powder residue from entering the subsequent mineral structures and causing contamination.

[0068] Step 5.3: Sample the probe sheet using a combined system of the RESOlution LR laser ablation system and the Agilent 7900 inductively coupled plasma mass spectrometer (ICP-MS). First, fix the probe sheet in the sampling stage of the ICP-MS and set the sampling parameters of the ICP-MS. In this embodiment, the laser wavelength is set to 193 nm, the maximum laser energy is set to 240 mJ, and the maximum energy density is set to not less than 45 J / cm³. 2 The ablation frequency is set to 1~200Hz, the spot size is set to 2~380µm, the sample chamber size is set to 155mm×105mm, the repeatability of the XYZ stage does not exceed 3µm, and the purging time does not exceed 700ms.

[0069] Ion mass spectrometry was used to sample the selected target ablation sites, and the collected aerosol samples were collected in Labco bottles and sealed for later use.

[0070] Step 6: The powder samples obtained by grinding, hand-held drilling, micro-area sampling, and laser micro-area sampling are used to obtain carbonate rock texture micro-area sampling samples.

[0071] Furthermore, carbon and oxygen isotope tests were performed on the four mineral composition powders collected in steps 4 and 5 to analyze the data differences and dispersion. The analysis results are shown in Table 1. In Table 1, matrix-1 and matrix-2 are matrix powders, CD1-1 and CD1-2 are fibrous dolomite powders, CD2-1 and CD2-2 are foliated dolomite powders, and CD3-1 and CD3-2 are granular dolomite powders.

[0072] Table 1. Results of carbon and oxygen isotope testing

[0073] As shown in Table 1, when the mineral texture powder obtained by the method of the present invention is tested for carbon and oxygen isotopes, the differences in carbon and oxygen isotopes of matrix, fibrous dolomite, foliated dolomite, and granular dolomite powders are significant, and the data within the texture are highly accurate. This verifies that the samples obtained by micro-area sampling of carbonate rock texture using the method of the present invention can be used to efficiently distinguish the physicochemical properties of ancient seawater and the properties of different secondary diagenetic fluids, laying the foundation for high-precision geochemical analysis.

[0074] Of course, the above description is not intended to limit the present invention, and the present invention is not limited to the examples given above. Any changes, modifications, additions or substitutions made by those skilled in the art within the scope of the present invention should also fall within the protection scope of the present invention.

Claims

1. A micro-area sampling method for carbonate rock fabrication based on quantitative decision-making, characterized in that, Includes the following steps: Step 1: Perform a step-by-step graded cleaning of the core sample to remove the original contaminants in the core sample; Step 2: Based on the mineral composition within the rock sample, determine the mineral composition size, homogeneity, and mineral contact index of the rock sample, quantitatively analyze the mineral composition and contact relationship of the rock sample, obtain the quantitative analysis results of the mineral composition of the core sample, and formulate sampling decisions based on the quantitative analysis results of the mineral composition of the rock sample. Step 3: Determine the sampling amount and particle size of the powder sample to be taken according to the preset rock sample analysis test items; Step 4: Based on the quantitative analysis results of the mineral composition of the rock samples, combined with the sampling decision made in Step 2 and the sampling quantity determined in Step 3, large-scale rock block co-sampling is carried out on rock samples with mineral composition sizes exceeding 3 mm. Powder samples are obtained by grinding and hand drill. Step 5: Based on the quantitative analysis results of the mineral composition of the rock samples, combined with the sampling decision made in Step 2 and the sampling quantity determined in Step 3, small-scale block co-sampling is carried out on rock samples with mineral composition sizes not exceeding 3 mm, including micro-area sampling and laser micro-area sampling. Step 6: The powder samples obtained by grinding, hand drilling, micro-area sampling, and laser micro-area sampling are used to obtain carbonate rock texture micro-area sampling samples. Step 2 includes the following sub-steps: Step 2.1, the mineral composition within the core sample includes matrix, cement, and fracture-filling minerals; The homogeneity of core samples was quantitatively analyzed by combining petrographic hand-drawing and RGB imaging. The area of ​​non-matrix components was measured within a square region of a preset size in the core sample. The proportion of non-matrix component area was calculated to characterize the mean. When the proportion of non-matrix component area is less than 5%, it is determined to be high mean; when the proportion of non-matrix component area is not less than 5% and not more than 15%, it is determined to be medium mean; and when the proportion of non-matrix component area is greater than 15%, it is determined to be low mean. Step 2.2: Quantify the mineral contact index (MCI) based on thin section microscopy of the core sample. The MCI is the ratio of the area to the perimeter of the mineral texture. Step 2.3: Measure the maximum width of the mineral texture at the fresh surface of the core sample as the mineral texture size; Step 2.4: Obtain the quantitative analysis results of the mineral texture of the core samples based on the mineral texture size, homogeneity, and mineral contact index. Set a sampling strategy based on these results. Specifically, when the rock sample has high homogeneity, a mineral contact index greater than 0.8, and a mineral texture size greater than 15 mm, grind and powder the mineral texture for sampling. When the rock sample has medium homogeneity, a mineral contact index not less than 0.4 and not greater than 0.8, and a mineral texture size not less than 3 mm and not greater than 15 mm, use a handheld drill for sampling. When the rock sample has low homogeneity, a mineral contact index less than 0.4, and a mineral texture size not less than 0.3 mm and less than 3 mm, use a micro-area sampler for sampling. When the mineral texture type in the rock sample is microcrystalline or a biological skeleton and the mineral texture size is less than 0.3 mm, use laser micro-area sampling.

2. The method for micro-area sampling of carbonate rock fabric based on quantitative decision-making according to claim 1, characterized in that, Step 1 includes the following sub-steps: Step 1.1: Pre-clean the core sample by using a rock cutting tool to remove contaminants larger than 2 mm from the surface of the core sample, so that the surface of the rock sample has a brand new and uncontaminated cross section. Nitrogen gas is used to purge the cross section to remove contact contamination from the rock cutting tool. Step 1.2: Mechanically clean the rock sample to remove dust and impurities from the surface of the rock sample. Then, place the rock sample in a beaker filled with deionized water and repeatedly clean the rock sample in an ultrasonic cleaner by changing the deionized water multiple times. Gradually peel off the micropore filling material in the rock sample until the deionized water used to clean the rock sample is clear and the conductivity does not exceed 2μS / cm. Then, stop cleaning the rock sample. Step 1.3: Remove the rock sample from the beaker, rinse the surface of the rock sample with anhydrous ethanol to remove residual moisture and impurities, and then vacuum dry the rock sample before storing it in a desiccator.

3. The method for micro-area sampling of carbonate rock fabric based on quantitative decision-making according to claim 1, characterized in that, In step 3, the rock sample analysis and testing items include carbon and oxygen isotope determination, trace element-rare earth element content determination, strontium isotope determination, and X-ray diffraction. Specifically, the carbon and oxygen isotope determination requires the powder sample to have a mass greater than 5 mg and a particle size of not less than 200 mesh; the trace element-rare earth element content determination requires the powder sample to have a mass greater than 2 g and a particle size of not less than 200 mesh; the strontium isotope determination requires the powder sample to have a mass greater than 30 mg and a particle size of not less than 200 mesh; and the X-ray diffraction requires the powder sample to have a mass greater than 3 g and a particle size of not less than 200 mesh. When the rock sample is an ancient carbonate rock sample, the minimum sampling amount is: ； In the formula, This is the minimum sampling amount for ancient carbonate rock samples; The minimum molar amount of the target material required for rock sample testing instruments; Minimum number of tests; To test the molar mass of the species; This is the signal loss coefficient; This represents the mass fraction of the substance to be tested in the rock sample.

4. The method for micro-area sampling of carbonate rock fabric based on quantitative decision-making according to claim 1, characterized in that, Step 4 includes the following sub-steps: Step 4.1: Based on the quantitative analysis results of the mineral composition of the core samples, core samples with high mean, mineral contact index greater than 0.8, and mineral composition size greater than 15 mm are ground and sampled. First, the rock samples and mortar are cleaned with deionized water, then the rock samples and mortar are rinsed with anhydrous ethanol and wiped clean. After mechanically crushing the rock samples, they are ground into a powder without particle texture in the mortar and then transferred to centrifuge tubes and sealed for later use. Step 4.2: Based on the quantitative analysis results of the mineral composition of the core samples, rock samples with moderate mean, mineral contact index of not less than 0.4 and not greater than 0.8, and mineral composition size of not less than 3 mm and not greater than 15 mm are sampled by hand drill. Fresh surfaces are first cut out in the rock samples. The fresh surfaces of the rock samples and the drill bit of the electric grinder are rinsed with deionized water and anhydrous ethanol in sequence and then dried. The speed of the electric grinder is set. The powder is then extracted from the mineral composition enrichment distribution area in the fresh surface of the rock sample by the electric grinder and transferred to a centrifuge tube for sealing and later use.

5. The method for micro-area sampling of carbonate rock fabric based on quantitative decision-making according to claim 1, characterized in that, Step 5 includes the following sub-steps: Step 5.1: Based on the quantitative analysis results of the mineral composition of the core samples, rock samples with low mean, mineral contact index less than 0.4, and mineral composition size not less than 0.3 mm and less than 3 mm are sampled using a micro-area sampler. Multiple thin sections of rock are prepared using the rock samples, including one ordinary section and multiple probe sections. Each thin section of rock contains the same mineral composition. Step 5.2: Samples are taken from the ordinary sample using a micro-area sampler. First, the ordinary sample is observed under a microscope to observe its mineral composition distribution and combination characteristics. The opaque mineral components in the ordinary sample are observed using reflected light supplemented with transmitted light. Then, the probe is fixed in the sampling stage of the micro-area sampler. After generating an image of the surface area of ​​the rock sample using the micro-area sampler, the field of view under the microscope and the polarization of the polarizer are adjusted. The position, drilling speed and moving speed of the drill bit of the micro-area sampler are controlled. Powder is then extracted from the mineral composition enrichment distribution area and the edge of the mineral composition using the drill bit of the micro-area sampler. The powder is then transferred to a centrifuge tube and sealed for later use. Step 5.3: Use an ion mass spectrometer to sample the probe sheet. First, fix the probe sheet in the sampling stage of the ion mass spectrometer, set the sampling parameters of the ion mass spectrometer, use the ion mass spectrometer to sample at the selected target ablation point, and collect the collected aerosol samples into a Labco bottle and seal it for later use.

6. The method for micro-area sampling of carbonate rock fabric based on quantitative decision-making according to claim 5, characterized in that, The mineral texture enrichment distribution area is the region in the rock thin section where the width of the mineral texture is not less than 0.3 mm and extends continuously for more than 1 mm; the mineral texture edge is the region in the rock thin section where the distance from the mineral texture edge is less than 0.5 mm.

7. The method for micro-area sampling of carbonate rock fabrics based on quantitative decision-making according to claim 5, characterized in that, In step 5.2, when drilling at the mineral texture enrichment distribution area using a micro-area sampler, the drill bit of the micro-area sampler is controlled to approach the ordinary sheet, and the drilling speed is controlled to be 10 μm / s at the preset sampling point. The drilling time after the drill bit contacts the ordinary sheet is controlled not to exceed 3 seconds to prevent the drill bit from penetrating the ordinary sheet. After the sampling at the sampling point is completed, the drill bit is moved to the next sampling point along the mineral texture distribution direction at a moving speed of 30 ~ 50 μm / s.

8. The method for micro-area sampling of carbonate rock fabric based on quantitative decision-making according to claim 5, characterized in that, The sampling parameters of the ion mass spectrometer include laser wavelength, maximum laser energy, maximum energy density, ablation frequency, spot size, sample chamber size, XYZ stage repeatability, and purge time.

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