Quantitative method for content of dolomite isomorph

Abstract

The invention discloses a method for quantifying the content of dolomite plasm isomers, and relates to the technical field of exploration and research of oil and gas reservoirs. Rock mineral identification, a scanning electron microscope experiment, an energy spectrum analysis experiment, an X-ray fluorescence spectrum experiment and an X-ray diffraction experiment are carried out on rock slices and rock powder respectively, whether dolomite, ferrodolomite and manganese dolomite exist or not is judged, and the percentage contents of the dolomite, the ferrodolomite and the manganese dolomite are determined; carrying out peak separation treatment on diffraction peaks of the ferrodolomite and the manganese dolomite; and finally, carrying out full-spectrum fitting on the fitted diffraction peaks of the three, fitting the sequence peaks of the three in a diffraction spectrogram, and calculating the mass fraction of each mineral in the sample by using the finally fitted theoretical diffraction spectrogram so as to quantify the content of the dolomite plasmon. The method provided by the invention overcomes the deficiency of quantitative accuracy of traditional methods such as rock slice identification and elemental analysis, realizes accurate quantification of the content of dolomite plasmon, and improves the accuracy and reliability of analysis.

Description

Technical Field

[0001] This invention relates to the field of oil and gas reservoir exploration and research technology, and more specifically to a method for quantitatively analyzing the content of dolomite isomorphous bodies. Background Technology

[0002] Dolomite, a common type of carbonate rock oil and gas reservoir with dolomite as its main mineral, exhibits diverse types, a long formation time span, and complex genesis. In deep and ancient marine strata, dolomite is more likely than limestone to form high-quality oil and gas reservoirs. Taking the Sichuan Basin as an example, the Maokou Formation and Dengying Formation in this region are the main oil and gas resource reservoirs. Dolomite in these strata has excellent reservoir properties and is an important location for oil and gas resources. Dolomite is the main mineral constituting dolomite. Marine sedimentary dolomite often occurs interbedded with siderite and limestone layers, while lacustrine sedimentary dolomite often coexists with gypsum, anhydrite, halite, and other minerals. Dolomite isomorphous bodies mainly consist of two types: iron dolomite and manganese dolomite. Analyzing the isomorphous relationships between trace and major elements in dolomite and analyzing the content characteristics of dolomite isomorphous bodies helps to gain a deeper understanding of the formation mechanism and evolution characteristics of dolomite reservoirs, and provides a scientific basis for the genetic analysis of dolomite.

[0003] Currently, domestic and international methods for analyzing isomorphous dolomite formations mainly rely on thin section analysis, scanning electron microscopy (SEM), and elemental analysis. Thin section analysis can distinguish dolomite from ferrodolomite based on color variations, but its optical resolution limits its ability to accurately quantify the content. SEM can analyze the microscopic morphology and structure of minerals, and combined with energy dispersive spectroscopy (EDS) analysis of elemental composition, enabling the identification of isomorphous formations. However, because elements are difficult to accurately reconstruct the true mineral content, quantitative analysis is also impossible. Elemental analysis, also known as chemical analysis, determines the presence of isomorphous formations by analyzing the differences in elemental composition and content.

[0004] Chinese invention patent document CN116935982A, published on October 24, 2023, discloses a semi-quantitative analysis method for mineral content in debris flow samples. The method involves sieving the debris flow sample to a size no larger than 0.075 mm, performing XRD and XRF elemental analysis on the sieved sample, matching the diffraction peaks obtained from the XRD test according to X-ray diffraction standard cards, selecting minerals corresponding to the XRF elements, and determining the types of minerals in the debris flow based on the degree of matching of elements and diffraction angles. Based on the chemical formulas of the mineral types determined in step S2 and the XRF data, the relative content of each mineral is calculated. The obtained relative contents of each mineral are normalized, and finally, the relative proportion of each mineral is obtained. This invention's determination method includes X-ray fluorescence spectroscopy and X-ray diffraction experiments, and calculates the relative content of each mineral. However, the above technical solutions cannot distinguish the same elements in different mineral phases and cannot achieve accurate quantification of the content of dolomite isomorphous bodies. On the other hand, the error caused by matching analysis of only a single peak is relatively large. Summary of the Invention

[0005] To overcome the defects and shortcomings of the existing technology, this invention provides a method for quantitatively analyzing the content of dolomite isomorphs. The purpose of this invention is to solve the problem that existing methods can only identify dolomite isomorphs but cannot quantify them. This invention identifies dolomite isomorphs, uses scanning electron microscopy, energy dispersive spectroscopy, and X-ray fluorescence spectroscopy to obtain the morphology and elemental information of dolomite, uses X-ray diffraction peak-splitting and full-spectrum fitting techniques to obtain the structural information of dolomite isomorphs, and combines mathematical and physical calculation methods to quantify the content of dolomite isomorphs, thus providing a fundamental solution to the problem of quantifying the content of dolomite isomorphs.

[0006] To address the problems existing in the prior art, the present invention is achieved through the following technical solution: This invention provides a method for quantitatively analyzing the content of dolomite isomorphous particles, comprising the following steps: S1. Select a dolomite sample and obtain rock thin sections and rock powder; S2. Perform rock and mineral identification on the thin rock section to determine whether dolomite and ferrodolomite are present simultaneously. S3. Perform scanning electron microscopy and energy dispersive spectroscopy on thin sections of rock to obtain the contents of dolomite, ferro-dolomite and manganese dolomite based on mineral morphology and energy dispersive spectroscopy element distribution characteristics. S4. Divide the rock powder from S1 into two parts. Perform X-ray fluorescence spectroscopy on one part to determine whether there is iron dolomite and manganese dolomite, and obtain the content of dolomite, iron dolomite and manganese dolomite in it. S5. Conduct an X-ray diffraction experiment on another sample of rock powder from S4; S6. Based on the diffraction pattern tested in the X-ray diffraction experiment in S5, perform transverse peak separation on the diffraction peaks of iron dolomite and manganese dolomite. S7. Take the weighted average of the percentage contents of dolomite, ferro-dolomite and manganese dolomite obtained in S3 and S4 above as the true area percentage contents of dolomite, ferro-dolomite and manganese dolomite, and use it as the diffraction peak intensity relationship of the three. Determine the peak positions of dolomite, ferro-dolomite and manganese dolomite according to the diffraction peak intensity relationship of the three and perform vertical peak separation processing. S8. Perform full-spectrum fitting on the fitted diffraction peaks of dolomite, ferro-dolomite, and manganese-dolomite, and fit the sequence peaks of the three in the diffraction patterns. Use the final fitted theoretical diffraction patterns to calculate the mass fraction of each mineral in the sample, and use this result as the quantitative result of the dolomite isomorphic content.

[0007] In S6, the lateral peak splitting process refers to splitting the peaks based on twice the diffraction angle of the characteristic diffraction peaks of iron dolomite and manganese dolomite, thus separating the diffraction peaks of the two in the X-axis direction of the diffraction pattern.

[0008] In S7, determining the peak positions of dolomite, ferro-dolomite, and manganese dolomite based on the intensity relationship of the three diffraction peaks and performing longitudinal peak division processing means that since the main peak positions of dolomite, ferro-dolomite, and manganese dolomite overlap in the X-ray diffraction pattern, the peak positions are determined in the diffraction pattern based on twice the diffraction angle and diffraction intensity of the three main diffraction peaks. Then, based on the diffraction intensity of the characteristic diffraction peaks of dolomite, ferro-dolomite, and manganese-dolomite, the diffraction peaks of the three are separated along the Y-axis of the diffraction pattern.

[0009] In step S1, rock thin sections are obtained through rock slide preparation. The rock slide preparation should meet the technical requirements of "Rock Slide Preparation Method: SY / T 5913-2004". During the slide preparation process, a mixed solution is used for staining. The mixed solution is prepared by mixing Alizarin Red S solution and potassium ferricyanide solution at a volume ratio of 3:2.

[0010] In step S1, the rock powder is obtained by rock grinding. The rock grinding should meet the technical requirements of "X-ray diffraction analysis method for clay minerals and common non-clay minerals in sedimentary rocks: SY / T 5163-2018". The crushed rock sample is ground to a particle size of less than 200 mesh, with uniform size and no grainy feel when rubbed between the fingers.

[0011] In S2, rock and mineral identification refers to determining the area where dolomite is located based on the optical properties of dolomite under a polarizing microscope, and then determining whether it is dolomite or iron dolomite based on the mineral staining in that area.

[0012] The mineral staining conditions include unstained, light blue, and dark blue, where unstained is dolomite, light blue is iron-bearing dolomite, and dark blue is iron-bearing dolomite; wherein, the iron content of iron-bearing dolomite is less than 25%, and the iron content of iron-bearing dolomite is greater than 25%.

[0013] In S3, the scanning electron microscopy experiment should meet the technical requirements of "Analysis Methods for Rock Samples by Scanning Electron Microscopy: SY / T 5162-2021".

[0014] In S3, the energy dispersive spectroscopy (EDS) analysis experiment should meet the technical requirements of "Quantitative Analysis Methods for Rocks and Minerals by Energy Dispersive Spectroscopy: SY / T 6189-2018".

[0015] In S4, the X-ray fluorescence spectroscopy experiment should meet the technical requirements of "General Rules for Fluorescence Spectroscopy Analysis Methods: JY / T 0571-2020".

[0016] In S4, if the iron content in the X-ray fluorescence spectroscopy experiment is less than 25%, it is determined that there is iron-containing dolomite; if the iron content is greater than 25%, it is determined that there is iron-containing dolomite; if the manganese content is less than 25%, it is determined that there is manganese-containing dolomite; if the manganese content is greater than 25%, it is determined that there is manganese-containing dolomite.

[0017] In step S4, the step of obtaining the percentage content of dolomite, ferrodolomite, and manganese dolomite in the sample includes: calculating the percentage content of dolomite, ferrodolomite, and manganese dolomite in the sample based on the percentage content relationship of calcium, magnesium, iron, and manganese elements in the X-ray fluorescence spectroscopy experimental results, combined with the percentage content relationship of calcium, magnesium, iron, and manganese elements in the standard minerals of dolomite, ferrodolomite, and manganese dolomite.

[0018] In S5, the X-ray diffraction experiment should meet the technical requirements of "X-ray diffraction analysis method for clay minerals and common non-clay minerals in sedimentary rocks: SY / T 5163-2018".

[0019] In S8, the full spectrum fitting should meet the technical requirements of the Ritwald graphical fitting correction method.

[0020] Compared with the prior art, the beneficial technical effects of the present invention are as follows: 1. This invention breaks through the limitations of traditional technologies. By employing advanced physical calculation and analysis techniques, it overcomes the shortcomings in quantitative accuracy of traditional methods such as rock thin section identification and X-ray fluorescence spectroscopy. Traditional rock thin section identification relies on manual observation, which is greatly affected by subjective factors and makes it difficult to identify mineral isomorphs. X-ray fluorescence spectroscopy can only test the total elemental content in rock samples and cannot distinguish mineral isomorphs based on elemental composition. This invention performs multi-level analysis from three aspects: image statistics, elemental analysis, and crystal structure analysis, achieving precise quantification of dolomite isomorphic content and improving the accuracy and reliability of the analysis.

[0021] 2. This invention integrates multiple technologies, achieving technological integration and innovation. This method not only employs isomorphic identification and quantification methods, enabling the identification of various dolomite isomorphs at different scales (two-dimensional area and three-dimensional volume) and the quantification of some dolomite isomorphs, but also innovatively applies the peak-splitting method of X-ray diffraction patterns to the quantitative analysis of dolomite isomorphs, improving testing efficiency and accuracy.

[0022] 3. This invention innovatively utilizes modern rock and mineral testing techniques and mathematical and physical calculation methods. By employing the X-ray diffraction full-spectrum fitting method to refine the X-ray diffraction pattern, the content of dolomite isomorphous particles can be determined more accurately. This method considers all possible diffraction peaks, thereby reducing the errors that may be introduced by single-peak analysis.

[0023] 4. This invention has broad applicability and significant economic and social benefits. This method is not only applicable to the testing of isomorphous content in dolomite, but can also be extended to the testing of isomorphous content in other minerals. This broad applicability means that this method can play a role in multiple fields such as geological exploration, materials science, and environmental monitoring, thereby bringing significant economic and social benefits.

[0024] 5. This invention provides a novel solution to the quantitative analysis of isomorphous bodies in dolomite. This method effectively addresses the challenges of inaccurate quantification in image-based methods due to human experience and sample representativeness, and the difficulty in quantification in X-ray diffraction methods due to overlapping main peaks and the lack of peak differentiation standards. By employing various experimental techniques such as scanning electron microscopy, energy dispersive spectroscopy, and X-ray fluorescence spectroscopy, and utilizing advanced software analysis methods and algorithms, this invention fundamentally provides a completely new approach to the quantitative analysis of isomorphous structures in rocks and minerals, thus promoting technological progress in the fields of mineralogy and materials science. Attached Figure Description

[0025] Figure 1 This is a flowchart of the method of the present invention; Figure 2 This is a schematic diagram before peak splitting in this invention; Figure 3 This is a schematic diagram after peak separation according to the present invention. Detailed Implementation

[0026] The technical solution of the present invention will be clearly and completely described below with reference to specific embodiments. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0027] Example 1 As a preferred embodiment of the present invention, this embodiment discloses a method for quantitatively analyzing the content of dolomite isomorphous particles, the method comprising the following steps: S1. Select a dolomite sample and obtain rock thin sections and rock powder; S2. Perform rock and mineral identification on the thin rock section to determine whether dolomite and ferrodolomite are present simultaneously. S3. Perform scanning electron microscopy and energy dispersive spectroscopy on thin sections of rock to obtain the contents of dolomite, ferro-dolomite and manganese dolomite based on mineral morphology and energy dispersive spectroscopy element distribution characteristics. S4. Divide the rock powder from S1 into two parts. Perform X-ray fluorescence spectroscopy on one part to determine whether there is iron dolomite and manganese dolomite, and obtain the content of dolomite, iron dolomite and manganese dolomite in it. S5. Conduct an X-ray diffraction experiment on another sample of rock powder from S4; S6. Based on the diffraction pattern tested in the X-ray diffraction experiment in S5, perform transverse peak separation on the diffraction peaks of iron dolomite and manganese dolomite. S7. Take the weighted average of the percentage contents of dolomite, ferro-dolomite and manganese dolomite obtained in S3 and S4 above as the true area percentage contents of dolomite, ferro-dolomite and manganese dolomite, and use it as the diffraction peak intensity relationship of the three. Determine the peak positions of dolomite, ferro-dolomite and manganese dolomite according to the diffraction peak intensity relationship of the three and perform vertical peak separation processing. S8. Perform full-spectrum fitting on the fitted diffraction peaks of dolomite, ferro-dolomite, and manganese-dolomite, and fit the sequence peaks of the three in the diffraction patterns. Use the final fitted theoretical diffraction patterns to calculate the mass fraction of each mineral in the sample, and use this result as the quantitative result of the dolomite isomorphic content.

[0028] This embodiment overcomes the shortcomings of traditional methods such as rock thin section identification and X-ray fluorescence spectroscopy in terms of quantitative accuracy. Traditional rock thin section identification relies on manual observation, which is greatly affected by subjective factors and makes it difficult to identify mineral isomorphs. X-ray fluorescence spectroscopy can only test the total element content in rock samples and cannot distinguish mineral isomorphs by element. This embodiment performs multi-level analysis from three aspects: image statistics, elements, and crystal structure, to achieve precise quantification of dolomite isomorphic content, thereby improving the accuracy and reliability of the analysis.

[0029] Example 2 As another preferred embodiment of the present invention, this embodiment discloses a method for quantitatively analyzing the content of dolomite isomorphous particles, the method comprising the following steps: S1. Select a portion of the dolomite sample, prepare a rock section to obtain a thin rock section, and grind the remaining portion into powder. The rock section preparation shall be performed in accordance with the relevant requirements of "Rock Section Preparation Method: SY / T 5913-2004", which requires the use of "mixed solution" staining during the section preparation process. The mixed solution shall be a mixture of Alizarin Red S solution and potassium ferricyanide solution at a volume ratio of 3:2. The rock powder grinding shall be performed in accordance with the relevant requirements of "X-ray Diffraction Analysis Method for Clay Minerals and Common Non-Clay Minerals in Sedimentary Rocks: SY / T 5163-2018", which requires that the pulverized rock sample be ground to a particle size of less than 200 mesh, uniform in size, and without a grainy feel when rubbed between the fingers. S2. Identify the rock and minerals in the thin sections prepared in S1. Determine the area containing dolomite based on the optical properties of dolomite under a polarizing microscope. Within that area, determine whether it is dolomite or ferrodolomite based on the mineral staining, and whether both dolomite and ferrodolomite are present simultaneously. Unstained areas are dolomite, light blue areas are ferrodolomite, and dark blue areas are ferrodolomite. Ferrodolomite contains less than 25% iron, while ferrodolomite contains more than 25% iron. S3. The rock thin sections from S2 were subjected to scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS) analysis. Based on the mineral morphology and EDS elemental distribution characteristics, the contents of dolomite, ferro-dolomite, and manganese-dolomite were obtained using the Maps Mineralogy automated mineralogical analysis system software. The SEM experiments were performed in accordance with the relevant requirements of "Analysis Methods for Rock Samples by Scanning Electron Microscopy: SY / T5162-2021"; the EDS analysis experiments were performed in accordance with the relevant requirements of "Quantitative Analysis Methods for Rocks and Minerals by Energy Dispersive Spectroscopy: SY / T 6189-2018". S4. Divide the rock powder ground in S1 into two portions. Perform X-ray fluorescence spectroscopy on one portion to determine the presence of ferrodolomite and manganese dolomite. Specifically, if the iron content in the X-ray fluorescence spectroscopy results is less than 25%, it is determined that the sample contains ferrodolomite; if the iron content is greater than 25%, it is determined that the sample contains ferrodolomite. If the manganese content is less than 25%, it is determined that the sample contains manganese dolomite; if the manganese content is greater than 25%, it is determined that the sample contains manganese dolomite. After confirming that the sample contains ferrodolomite and manganese dolomite, obtain the percentage content of dolomite, ferrodolomite, and manganese dolomite in the sample. The X-ray fluorescence spectroscopy experiment shall be performed in accordance with the relevant requirements of "General Rules for Fluorescence Spectroscopic Analysis: JY / T 0571-2020". S5. Conduct an X-ray diffraction experiment on another sample of rock powder from S4; S6. Based on the diffraction pattern tested in the X-ray diffraction experiment in S5, perform transverse peak separation on the diffraction peaks of iron dolomite and manganese dolomite. S7. Take the weighted average of the percentage contents of dolomite, ferro-dolomite and manganese dolomite obtained in S3 and S4 above as the true area percentage contents of dolomite, ferro-dolomite and manganese dolomite, and use it as the diffraction peak intensity relationship of the three. Determine the peak positions of dolomite, ferro-dolomite and manganese dolomite according to the diffraction peak intensity relationship of the three and perform vertical peak separation processing. S8. Perform full-spectrum fitting on the fitted diffraction peaks of dolomite, ferro-dolomite, and manganese-dolomite, and fit the sequence peaks of the three in the diffraction patterns. Use the final fitted theoretical diffraction patterns to calculate the mass fraction of each mineral in the sample, and use this result as the quantitative result of the dolomite isomorphic content.

[0030] This embodiment not only employs methods for isomorphic identification and quantification, enabling the identification of various dolomite isomorphs at different scales of two-dimensional area and three-dimensional volume, but also innovatively applies the peak-splitting method of X-ray diffraction patterns to the quantitative analysis of dolomite isomorphs. This method combines the advantages of multiple technologies, improving the efficiency and accuracy of testing through integrated innovation.

[0031] Example 3 As another preferred embodiment of the present invention, this embodiment discloses a method for quantitatively analyzing the content of dolomite isomorphous particles, the method comprising the following steps: S1. Select a portion of the dolomite sample, prepare a rock section to obtain a thin rock section, and grind the remaining portion into powder. The rock section preparation shall be performed in accordance with the relevant requirements of "Rock Section Preparation Method: SY / T 5913-2004", which requires the use of "mixed solution" staining during the section preparation process. The mixed solution shall be a mixture of Alizarin Red S solution and potassium ferricyanide solution at a volume ratio of 3:2. The rock powder grinding shall be performed in accordance with the relevant requirements of "X-ray Diffraction Analysis Method for Clay Minerals and Common Non-Clay Minerals in Sedimentary Rocks: SY / T 5163-2018", which requires that the pulverized rock sample be ground to a particle size of less than 200 mesh, uniform in size, and without a grainy feel when rubbed between the fingers. S2. Perform rock and mineral identification on the thin rock sections prepared in S1. Determine the area containing dolomite based on the optical properties of dolomite under a polarizing microscope. In this area, determine whether it is dolomite or ferrodolomite based on the mineral staining, and determine whether both dolomite and ferrodolomite are present simultaneously. Unstained dolomite is dolomite, light blue is ferrodolomite, and dark blue is ferrodolomite. Ferrodolomite has an iron content of less than 25%, while ferrodolomite has an iron content of more than 25%. S3. The rock thin sections from S2 were subjected to scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS) analysis. Based on the mineral morphology and EDS elemental distribution characteristics, the contents of dolomite, ferro-dolomite, and manganese-dolomite were obtained using the Maps Mineralogy automated mineralogical analysis system software. The SEM experiments were performed in accordance with the relevant requirements of "Analysis Methods for Rock Samples by Scanning Electron Microscopy: SY / T5162-2021"; the EDS analysis experiments were performed in accordance with the relevant requirements of "Quantitative Analysis Methods for Rocks and Minerals by Energy Dispersive Spectroscopy: SY / T 6189-2018". S4. Divide the rock powder ground in S1 into two portions. Perform X-ray fluorescence spectroscopy on one portion to determine the presence of ferrodolomite and manganese dolomite. Specifically, if the iron content in the X-ray fluorescence spectroscopy results is less than 25%, it is determined to contain ferrodolomite; if the iron content is greater than 25%, it is determined to contain ferrodolomite. Similarly, if the manganese content is less than 25%, it is determined to contain manganese dolomite; if the manganese content is greater than 25%, it is determined to contain manganese dolomite. After confirming the presence of ferrodolomite and manganese dolomite in the sample, based on the X-ray fluorescence spectroscopy results... The percentage content of calcium, magnesium, iron, and manganese elements was determined by combining the percentage content of calcium, magnesium, iron, and manganese elements in the standard minerals of dolomite, iron dolomite, and manganese dolomite. The percentage content of dolomite, iron dolomite, and manganese dolomite in the sample was calculated. Among them, iron dolomite and manganese dolomite cannot be distinguished by X-ray diffraction experiments because their crystal structures are basically the same as those of dolomite. Therefore, only the content of dolomite, iron dolomite, and manganese dolomite was analyzed. The X-ray fluorescence spectroscopy experiment was performed in accordance with the relevant requirements of "General Rules for Fluorescence Spectroscopy Analysis: JY / T 0571-2020". S5. Conduct an X-ray diffraction experiment on another sample of rock powder from S4; S6. Based on the diffraction pattern tested in the X-ray diffraction experiment in S5, use software such as Jade, Tops, and HighScore, which can perform peak segmentation and full-spectrum fitting on the X-ray diffraction pattern, to perform lateral peak segmentation on the diffraction peaks of iron dolomite and manganese dolomite. The lateral peak segmentation refers to segmenting the peaks according to twice the diffraction angle of the characteristic diffraction peaks of iron dolomite and manganese dolomite, thus separating the diffraction peaks of the two in the X-axis direction of the diffraction pattern. S7. The weighted average of the percentage contents of dolomite, ferro-dolomite, and manganese dolomite obtained in S3 and S4 above is taken as the true area percentage contents of dolomite, ferro-dolomite, and manganese dolomite. This is used as the relationship of the diffraction peak intensities of the three. The peak positions of dolomite, ferro-dolomite, and manganese dolomite are determined according to the relationship of the diffraction peak intensities of the three and vertical peak separation is performed. Determining the peak positions of dolomite, ferro-dolomite, and manganese dolomite according to the relationship of the diffraction peak intensities of the three means that since the main peak positions of dolomite, ferro-dolomite, and manganese dolomite overlap in the X-ray diffraction pattern, the peak positions are determined in the diffraction pattern according to twice the diffraction angle and diffraction intensity of the three main diffraction peaks. Then, based on the diffraction intensity of the characteristic diffraction peaks of dolomite, ferro-dolomite, and manganese-dolomite, the diffraction peaks of the three are separated along the Y-axis of the diffraction pattern.

[0032] S8. Perform full-spectrum fitting on the fitted diffraction peaks of dolomite, ferro-dolomite, and manganese-dolomite, fitting the sequence peaks of all three in the diffraction patterns. Use the final fitted theoretical diffraction pattern to calculate the mass fraction of each mineral in the sample, and use this result as the quantitative result of the dolomite isomorphic content. The full-spectrum fitting is performed in accordance with the relevant requirements of the Ritwald pattern fitting correction method. According to the principle of full-spectrum fitting, the diffraction peaks of all minerals in the diffraction pattern are fitted to obtain the theoretical diffraction pattern. The percentage content of all minerals in the diffraction pattern is calculated using the theoretical diffraction pattern, thereby obtaining the content of dolomite, ferro-dolomite, and manganese-dolomite.

[0033] In this embodiment, by employing the X-ray diffraction full-spectrum fitting method to refine the X-ray diffraction pattern, the content of dolomite isomorphous particles can be determined more accurately. This method considers all possible diffraction peaks, thereby reducing the errors that may be introduced by single-peak analysis.

Claims

1. A method for quantitatively analyzing the content of dolomite isomorphous particles, comprising: S1. Select a dolomite sample and obtain rock thin sections and rock powder; S2. Perform rock mineral identification on the rock thin sections to determine whether dolomite and ferrodolithite are present simultaneously; S3. Perform scanning electron microscopy and energy dispersive spectroscopy on the rock thin sections, and obtain the contents of dolomite, ferrodolithite, and manganese dolomite based on the mineral morphology characteristics and energy dispersive spectroscopy element distribution characteristics; S4. Divide the rock powder from S1 into two parts, and perform X-ray fluorescence spectroscopy on one part to determine whether ferrodolithite and manganese dolomite are present, and obtain the contents of dolomite, ferrodolithite, and manganese dolomite therein. The method is characterized by further including the following steps: S5. Conduct an X-ray diffraction experiment on another sample of rock powder from S4; S6. Based on the diffraction pattern tested in the X-ray diffraction experiment in S5, perform transverse peak separation on the diffraction peaks of iron dolomite and manganese dolomite. S7. Take the weighted average of the percentage contents of dolomite, ferro-dolomite and manganese dolomite obtained in S3 and S4 above as the true area percentage contents of dolomite, ferro-dolomite and manganese dolomite, and use it as the diffraction peak intensity relationship of the three. Determine the peak positions of dolomite, ferro-dolomite and manganese dolomite according to the diffraction peak intensity relationship of the three and perform vertical peak separation processing. S8. Perform full-spectrum fitting on the fitted diffraction peaks of dolomite, ferro-dolomite, and manganese-dolomite, and fit the sequence peaks of the three in the diffraction patterns. Use the final fitted theoretical diffraction patterns to calculate the mass fraction of each mineral in the sample, and use this as the quantitative result of the dolomite isomorphic content.

2. The method for quantitatively analyzing the content of dolomite isomorphous particles according to claim 1, characterized in that: In S6, the lateral peak splitting process refers to splitting the peaks based on twice the diffraction angle of the characteristic diffraction peaks of iron dolomite and manganese dolomite, thus separating the diffraction peaks of the two in the X-axis direction of the diffraction pattern.

3. The method for quantitatively analyzing the content of dolomite isomorphous particles according to claim 1, characterized in that: In S7, determining the peak positions of dolomite, ferro-dolomite, and manganese dolomite based on the intensity relationship of the three diffraction peaks and performing longitudinal peak division processing means that since the main peak positions of dolomite, ferro-dolomite, and manganese dolomite overlap in the X-ray diffraction pattern, the peak positions are determined in the diffraction pattern based on twice the diffraction angle and diffraction intensity of the three main diffraction peaks. Then, based on the diffraction intensity of the characteristic diffraction peaks of dolomite, ferro-dolomite, and manganese-dolomite, the diffraction peaks of the three are separated along the Y-axis of the diffraction pattern.

4. The method for quantitatively analyzing the content of dolomite isomorphous particles according to claim 1, characterized in that: In step S1, rock thin sections are obtained through rock slide preparation. The rock slide preparation should meet the technical requirements of "Rock Slide Preparation Method: SY / T 5913-2004". During the slide preparation process, a mixed solution is used for staining. The mixed solution is prepared by mixing Alizarin Red S solution and potassium ferricyanide solution at a volume ratio of 3:

2.

5. The method for quantitatively analyzing the content of dolomite isomorphous particles according to claim 1, characterized in that: In step S1, the rock powder is obtained by rock grinding. The rock grinding should meet the technical requirements of "X-ray diffraction analysis method for clay minerals and common non-clay minerals in sedimentary rocks: SY / T 5163-2018". The crushed rock sample is ground to a particle size of less than 200 mesh, with uniform size and no grainy feel when rubbed between the fingers.

6. The method for quantitatively analyzing the content of dolomite isomorphous particles according to claim 1, characterized in that: In S2, rock and mineral identification refers to determining the area where dolomite is located based on the optical properties of dolomite under a polarizing microscope, and then determining whether it is dolomite or iron dolomite based on the mineral staining in that area.

7. The method for quantitatively analyzing the content of dolomite isomorphous particles according to claim 6, characterized in that: The mineral staining conditions include unstained, light blue, and dark blue, where unstained is dolomite, light blue is iron-bearing dolomite, and dark blue is iron-bearing dolomite; wherein, the iron content of iron-bearing dolomite is less than 25%, and the iron content of iron-bearing dolomite is greater than 25%.

8. The method for quantitatively analyzing the content of dolomite isomorphous particles according to claim 1, characterized in that: In S3, the scanning electron microscopy experiment should meet the technical requirements of "Analysis Methods for Rock Samples by Scanning Electron Microscopy: SY / T 5162-2021".

9. The method for quantitatively analyzing the content of dolomite isomorphous particles according to claim 1, characterized in that: In S3, the energy dispersive spectroscopy (EDS) analysis experiment should meet the technical requirements of "Quantitative Analysis Methods for Rocks and Minerals by Energy Dispersive Spectroscopy: SY / T 6189-2018".

10. The method for quantitatively analyzing the content of dolomite isomorphous particles according to claim 1, characterized in that: In S4, the X-ray fluorescence spectroscopy experiment should meet the technical requirements of "General Rules for Fluorescence Spectroscopy Analysis Methods: JY / T 0571-2020".

11. The method for quantitatively analyzing the content of dolomite isomorphous particles according to claim 1, characterized in that: In S4, if the iron content in the X-ray fluorescence spectroscopy experiment is less than 25%, it is determined that there is iron-containing dolomite; if the iron content is greater than 25%, it is determined that there is iron-containing dolomite; if the manganese content is less than 25%, it is determined that there is manganese-containing dolomite; if the manganese content is greater than 25%, it is determined that there is manganese-containing dolomite.

12. The method for quantitatively analyzing the content of dolomite isomorphous particles according to claim 1, characterized in that: In step S4, the step of obtaining the percentage content of dolomite, ferrodolomite, and manganese dolomite in the sample includes: calculating the percentage content of dolomite, ferrodolomite, and manganese dolomite in the sample based on the percentage content relationship of calcium, magnesium, iron, and manganese elements in the X-ray fluorescence spectroscopy experimental results, combined with the percentage content relationship of calcium, magnesium, iron, and manganese elements in the standard minerals of dolomite, ferrodolomite, and manganese dolomite.

13. The method for quantitatively analyzing the content of dolomite isomorphous particles according to claim 1, characterized in that: In S5, the X-ray diffraction experiment should meet the technical requirements of "X-ray diffraction analysis method for clay minerals and common non-clay minerals in sedimentary rocks: SY / T5163-2018".

14. The method for quantitatively analyzing the content of dolomite isomorphous particles according to claim 1, characterized in that: In S8, the full spectrum fitting should meet the technical requirements of the Ritwald graphical fitting correction method.

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