A method for determining the content of terrestrial-derived components of mixed-origin montmorillonite

Abstract

The invention discloses a method for determining the content of terrigenous components of mixed-origin montmorillonite, comprising: determining the authigenic and terrigenous mixed origin of the montmorillonite by scanning electron microscopy (SEM), energy dispersive spectrometer (EDS) and clay mineral X-ray diffraction; based on whole-rock and clay mineral X-ray diffraction, major element and trace element (rare earth element) analysis, fitting required parameters, determining the fitted terrigenous elements, comparing the fitting relationship function of element minerals and terrigenous clay content, and fitting the content of each component of terrigenous / autogenous montmorillonite; the method provided by the invention can more accurately calculate the total content of authigenic / terrigenous clay minerals in the limestone-marlstone interlayers commonly developed in the Permian system in South China, and can be used to promote further research on the interlayers and more economically speculate the reservoir performance of the reservoir.

Description

Technical Field

[0001] The invention relates to the technical field of geological research, and in particular to a method for distinguishing the content of terrigenous / autogenic components of mixed-genetic montmorillonite in the interlayer of limestone-marlstone in the Permian system of South China. Background Art

[0002] The Permian in South China generally has limestone-marl interlayers rich in clay minerals. The clay minerals include the "sepiolite → montmorillonite → talc mixed layer" of autogenic transformation and the "montmorillonite-illite-montmorillonite mixed layer" of terrigenous clay.

[0003] Recent studies have shown that the interlayer is a set of high-quality unconventional source rock gas reservoirs mainly controlled by clay mineral-related reservoir spaces (Hu et al., 2021; Liu et al., 2021). The most important reservoir spaces of this set of source rocks include the particle edge pores and diagenetic shrinkage pores of clay minerals. Among them, the diagenetic shrinkage pores are a pore type formed during the transformation of authigenic clay and are unique to terrigenous clay. Therefore, authigenic clay contributes more to the reservoir properties of the interlayer than terrigenous clay minerals. Distinguishing the contents of the two types of genetic clay minerals can directly reflect the reservoir properties of the interlayer. Low-field nuclear magnetic resonance is less expensive and more suitable for initial exploration work.

[0004] In addition, the proportion of terrigenous montmorillonite, illite and illite-montmorillonite mixed layers in carbonate rock formations can reflect the characteristics of their sedimentary environment. Therefore, how to separate the content of terrigenous and autogenous montmorillonite is of great significance for the subsequent research and exploration of interlayers, but it is also a difficult point, because conventional clay mineral X-ray diffraction (XRD) tests can only show the total content of montmorillonite, and cannot distinguish the content of montmorillonite of different origins.

[0005] The conventional and most direct method to distinguish between authigenic and terrigenous montmorillonite is direct observation with a scanning electron microscope (SEM). The origin of montmorillonite can be identified by using mineralogical theory through a scanning electron microscope (SEM). Non-directional and disordered flat corn flake montmorillonite is considered to be terrigenous, while honeycomb montmorillonite with flocculent edges is of authigenic origin.

[0006] However, due to the widespread development of limestone-marl interlayers in the Permian in South China, the strong compaction has changed the arrangement of montmorillonite. Therefore, we can only compare the development morphology of single montmorillonite with the sepiolite-talc-smectite mixed layer and the illite-illite-montmorillonite mixed layer. The similarity in morphology between montmorillonite and the sepiolite-talc-smectite mixed layer indicates an autogenous origin, while the similarity in morphology between montmorillonite and the illite-illite-montmorillonite mixed layer indicates a terrigenous origin.

[0007] But there are the following problems:

[0008] Scanning electron microscopy (SEM) generally uses probe pieces or sample blocks of about 1 cm3 for observation. Therefore, this method can only identify the local origin of montmorillonite in the study area, and the scope of analysis is greatly limited.

[0009] Due to the limitation of the analytical scope involved, and the fact that this method can only estimate the content of authigenic / terrigenous montmorillonite in the entire rock formation by manually identifying and counting the samples one by one, the results are unrepresentative and have errors, lacking precision;

[0010] To improve the accuracy and representativeness of this method, a scanning electron microscope (SEM) is required to observe, identify, and count a large number of samples, which is a complicated and time-consuming process. Summary of the invention

[0011] The purpose of the present invention is to provide a method for determining the content of terrestrial-derived components of mixed-origin montmorillonite, so as to solve the technical problems in the prior art of limited analysis range and lack of precision due to the simple use of scanning electron microscopy to identify the local origin of montmorillonite in the study area.

[0012] In order to solve the above technical problems, the present invention specifically provides the following technical solutions:

[0013] A method for determining the content of terrestrial-derived components of mixed-origin montmorillonite comprises the following specific steps:

[0014] Step 100: Prepare rock samples according to the location and stratum of the study area, determine the reference clay minerals of montmorillonite genesis, and determine the morphology, energy spectrum and diffraction results of montmorillonite and the reference clay minerals through various tests to obtain the terrigenous and authigenic mixed genesis of montmorillonite;

[0015] Step 200, fitting the content of each component of terrigenous and authigenic montmorillonite according to the obtained terrigenous and authigenic mixed genesis of montmorillonite, and determining the parameters required for fitting, including:

[0016] Mixed layers of montmorillonite-reference clay mineral-reference clay mineral and montmorillonite and mixed layers of reference clay mineral-reference clay mineral and montmorillonite in rock samples;

[0017] Determine the comparative element minerals in the rock samples to be compared respectively according to the main element minerals contained in the montmorillonite-reference clay mineral-reference clay mineral and the montmorillonite mixed layer and the reference clay mineral-reference clay mineral and montmorillonite mixed layer;

[0018] Calculate and obtain the average contents of montmorillonite-reference clay mineral-reference clay mineral and montmorillonite mixed layer and reference clay mineral-reference clay mineral and montmorillonite mixed layer, and comparison element minerals as the parameters required for fitting;

[0019] Step 300, by performing a linear correlation analysis on the comparison element minerals and other elements in the rock formation sample, the correlation coefficient with the comparison element minerals and elements close to the correlation coefficient are screened out, and the terrigenous elements suitable for fitting are determined;

[0020] Step 400, fitting correlations between the terrigenous elements screened out in step 300 and the comparative elements and minerals of the rock samples, and calculating the average value of the correlations;

[0021] Then, the average content of the montmorillonite-illite-montmorillonite mixed layer and the average value of the correlation of the comparative element minerals, and the average content of the illite-illite-montmorillonite mixed layer and the average value of the correlation of the comparative element minerals in step 200 are constructed as data points;

[0022] Based on two data points, a fitting relationship function between the proportion and correlation of terrigenous clay minerals was constructed;

[0023] Step 500: Calculate the average total content of terrigenous clay minerals in the sample, the average terrigenous montmorillonite content in the selected rock formation samples, and the average authigenic montmorillonite content in the selected rock formation samples according to the fitting relationship function.

[0024] As a preferred embodiment of the present invention, in step 100, the reference clay mineral of montmorillonite origin is determined, and the specific method of determining the morphology, energy spectrum and diffraction results of montmorillonite and the reference clay mineral through multiple tests includes:

[0025] Select reference clay minerals indicating authigenic origin and reference clay minerals indicating terrigenous origin, and use scanning electron microscopy to identify the similarity of the developmental morphology between montmorillonite and the selected reference clay minerals;

[0026] The selected elements of the selected reference clay mineral and montmorillonite are quantitatively analyzed by energy spectrometer, and a ternary diagram is drawn according to the quantitative analysis results. The montmorillonite scatter points that are continuously distributed with the scatter points analyzed by the energy spectrometer of the selected reference clay mineral indicate autogenous origin, and the montmorillonite scatter points that are dispersedly distributed with the scatter points analyzed by the energy spectrometer of the selected reference clay mineral indicate terrigenous origin;

[0027] The regular changes in the montmorillonite peak and the lucite mixed layer peak in the X-ray diffraction spectrum of reference clay minerals indicate an autogenic origin, while the irregular changes indicate a mixed terrigenous and autogenic origin.

[0028] As a preferred embodiment of the present invention, illite is selected as the reference clay mineral:

[0029] Montmorillonite-illite-montmorillonite mixed layer is a potential terrigenous clay mineral, in which the illite-illite-montmorillonite mixed layer is mainly K-containing minerals, and the montmorillonite-illite-montmorillonite mixed layer is mainly Al-containing minerals. Alumina and potassium oxide were selected as comparison element minerals, corresponding to the total content of montmorillonite-illite-montmorillonite mixed layer and the total content of illite-montmorillonite mixed layer, respectively.

[0030] As a preferred embodiment of the present invention, in step 300, linear correlation analysis is performed on aluminum oxide and potassium oxide in the rock formation sample and other mineral elements in the rock formation sample to screen out the correlation coefficients with aluminum oxide and potassium oxide and mineral elements with similar correlation coefficients. The specific method includes:

[0031] Screen out the correlation coefficients with aluminum oxide or potassium oxide Indicates the correlation parameters of other mineral elements, and the correlation coefficient R 2 Similar elements.

[0032] As a preferred embodiment of the present invention, in step 400, the specific method of fitting the correlation between the selected terrigenous elements and the aluminum oxide and potassium oxide of the rock sample, and calculating the average value of the correlation includes:

[0033] The selected terrigenous elements are fitted with aluminum oxide and potassium oxide respectively to obtain element correlation data sets with aluminum oxide and element correlation data sets with potassium oxide;

[0034] Calculate the average value of the element correlation of the aluminum oxide element correlation data set and the potassium oxide element correlation data set.

[0035] As a preferred embodiment of the present invention, the average proportion of montmorillonite-illite-montmorillonite mixed layer and illite-illite-montmorillonite mixed layer in the selected rock formation sample is calculated, and the average content of aluminum oxide and potassium oxide in the rock formation sample is calculated as the parameters required for fitting;

[0036] Among them, the average contents of aluminum oxide and potassium oxide are expressed as: and

[0037] The average proportion of montmorillonite-illite-montmorillonite mixed layers and illite-illite mixed layers in the selected rock samples is expressed as: and

[0038] As a preferred solution of the present invention, a specific method for constructing a fitting relationship function of the proportion and correlation of terrigenous clay minerals based on two data points includes:

[0039] Assume that the proportion of terrigenous clay minerals in the rock layer ω and the correlation coefficient R 2belongs to a quasi-normal distribution, and

[0040] According to the normal distribution function and the normal curve function, the equation group is constructed:

[0041]

[0042] Solve the equations to find A and μ, where A represents the normal distribution parameter and μ represents the average total amount of terrigenous clay minerals in the selected rock samples. Represents the average terrigenous montmorillonite content of the selected rock samples, and fits the proportion of terrigenous clay minerals in the rock layer ω and the correlation R 2 function.

[0043] As a preferred solution of the present invention, the same set of data is used Indicates the fitting accuracy value. The smaller the fitting accuracy value, the higher the accuracy of the fitting result.

[0044] Compared with the prior art, the present invention has the following beneficial effects:

[0045] The present invention determines the authigenic and terrigenous mixed origin of montmorillonite by scanning electron microscopy (SEM), energy dispersive spectrometer (EDS) and clay mineral X-ray diffraction. Based on the whole rock and clay mineral X-ray diffraction, major element and trace element (rare earth element) analysis, the built-in algorithm in MATLAB is used to fit the content of each component of terrigenous / autogenic montmorillonite. This method can more accurately calculate the total content of authigenic / terrigenous clay minerals in the limestone-marl interlayers commonly developed in the Permian in South China, which can be used to promote further research on the interlayers and more economically speculate on the reservoir performance of the reservoir. BRIEF DESCRIPTION OF THE DRAWINGS

[0046] In order to more clearly illustrate the implementation methods of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for the implementation methods or the description of the prior art. Obviously, the drawings in the following description are only exemplary, and for ordinary technicians in this field, other implementation drawings can be derived from the provided drawings without creative work.

[0047] Figure 1 A schematic flow chart of a method for identifying the content of terrigenous / autogenic components of mixed-origin montmorillonite in the interbedded limestone-marlstone layers of the Permian System in South China according to the present invention;

[0048] Figure 2Scanning electron microscope (SEM) photos of clay minerals in the interlayer of marl-limestone; (A) Talc monomers aggregate in a daisy-like shape; (B) Montmorillonite (Sme) monomers aggregate in a daisy-like shape; (C) Lamellar montmorillonite (Sme) fills the intercrystalline cracks; (D) Lamellar illite-montmorillonite mixed layers (I / S) fill the intercrystalline cracks;

[0049] Figure 3 The XRD spectrum of the representative sample of marl-limestone interlayer; Sme refers to montmorillonite, T / S refers to lubricant-smectite mixed layer, and Talc refers to talc;

[0050] Figure 4 Ternary diagram of Mg, Al and Si contents (wt%) of talc and montmorillonite measured by energy dispersive spectrometer (EDS) in marl-limestone interbed samples;

[0051] Figure 5 Schematic diagram of inferring the proportion of terrigenous clay minerals in marl-limestone interlayers, marl, and limestone by fitting the quasi-normal distribution. DETAILED DESCRIPTION

[0052] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0053] The study area is located in the central part of the Sichuan Basin. The Sichuan Basin belongs to the Upper Yangtze Block in terms of structure. It is a composite basin where a large Paleozoic craton basin overlaps with a Mesozoic and Cenozoic foreland basin. The samples were selected from the first section of the Permian Maokou Formation. The Maokou Formation in the study area is divided into sections 1-4. The first section of the Maokou Formation is in parallel unconformable contact with the Qixia Formation. The first section of the Maokou Formation mainly develops marl-limestone interlayers. Whole-rock X-ray diffraction shows that the main minerals include calcite, dolomite, clay minerals, and quartz. X-ray diffraction of clay minerals shows that the main clay minerals include talc, smectite mixed layer, montmorillonite, illite, and illite-montmorillonite mixed layer.

[0054] like Figures 1 to 5 As shown, the present invention provides a method for determining the content of terrestrial-derived components of mixed-origin montmorillonite, comprising the following specific steps:

[0055] Step 100: Prepare rock samples according to the location and stratum of the study area, determine the reference clay minerals of montmorillonite genesis, and determine the morphology, energy spectrum and diffraction results of montmorillonite and the reference clay minerals through various tests to obtain the terrigenous and authigenic mixed genesis of montmorillonite;

[0056] Step 200, fitting the content of each component of terrigenous and authigenic montmorillonite according to the obtained terrigenous and authigenic mixed genesis of montmorillonite, and determining the parameters required for fitting, including:

[0057] Mixed layers of montmorillonite-reference clay mineral-reference clay mineral and montmorillonite and mixed layers of reference clay mineral-reference clay mineral and montmorillonite in rock samples;

[0058] Determine the comparative element minerals in the rock samples to be compared respectively according to the main element minerals contained in the montmorillonite-reference clay mineral-reference clay mineral and the montmorillonite mixed layer and the reference clay mineral-reference clay mineral and montmorillonite mixed layer;

[0059] Calculate and obtain the average contents of montmorillonite-reference clay mineral-reference clay mineral and montmorillonite mixed layer and reference clay mineral-reference clay mineral and montmorillonite mixed layer, and comparison element minerals as the parameters required for fitting;

[0060] Step 300, by performing a linear correlation analysis on the comparison element minerals and other elements in the rock formation sample, the correlation coefficient with the comparison element minerals and elements close to the correlation coefficient are screened out, and the terrigenous elements suitable for fitting are determined;

[0061] Step 400, fitting correlations between the terrigenous elements screened out in step 300 and the comparative elements and minerals of the rock samples, and calculating the average value of the correlations;

[0062] Then, the average content of the montmorillonite-illite-montmorillonite mixed layer and the average value of the correlation of the comparative element minerals, and the average content of the illite-illite-montmorillonite mixed layer and the average value of the correlation of the comparative element minerals in step 200 are constructed as data points;

[0063] Based on two data points, a fitting relationship function between the proportion and correlation of terrigenous clay minerals was constructed;

[0064] Step 500: Calculate the average total content of terrigenous clay minerals in the sample, the average terrigenous montmorillonite content in the selected rock formation samples, and the average authigenic montmorillonite content in the selected rock formation samples according to the fitting relationship function.

[0065] In step 100, the specific method of determining the reference clay mineral of montmorillonite origin and determining the morphology, energy spectrum and diffraction results of montmorillonite and the reference clay mineral through various tests includes:

[0066] Select reference clay minerals indicating authigenic origin and reference clay minerals indicating terrigenous origin, and use scanning electron microscopy to identify the similarity of the developmental morphology between montmorillonite and the selected reference clay minerals;

[0067] The selected elements of the selected reference clay mineral and montmorillonite are quantitatively analyzed by energy spectrometer, and a ternary diagram is drawn according to the quantitative analysis results. The montmorillonite scatter points that are continuously distributed with the scatter points analyzed by the energy spectrometer of the selected reference clay mineral indicate autogenous origin, and the montmorillonite scatter points that are dispersedly distributed with the scatter points analyzed by the energy spectrometer of the selected reference clay mineral indicate terrigenous origin;

[0068] The regular changes in the montmorillonite peak and the lucite mixed layer peak in the X-ray diffraction spectrum of reference clay minerals indicate an autogenic origin, while the irregular changes indicate a mixed terrigenous and autogenic origin.

[0069] Illite was selected as the reference clay mineral:

[0070] Montmorillonite-illite-montmorillonite mixed layer is a potential terrigenous clay mineral, in which the illite-illite-montmorillonite mixed layer is mainly K-containing minerals, and the montmorillonite-illite-montmorillonite mixed layer is mainly Al-containing minerals. Alumina and potassium oxide were selected as comparison element minerals, corresponding to the total content of montmorillonite-illite-montmorillonite mixed layer and the total content of illite-montmorillonite mixed layer, respectively.

[0071] In step 300, linear correlation analysis is performed on aluminum oxide and potassium oxide in the rock formation sample and other mineral elements in the rock formation sample to screen out the correlation coefficients with aluminum oxide and potassium oxide and mineral elements with similar correlation coefficients. The specific method includes:

[0072] Screen out the correlation coefficients with aluminum oxide or potassium oxide Indicates the correlation parameters of other mineral elements, and the correlation coefficient R 2 Similar elements.

[0073] In step 400, the specific method of fitting the correlation between the selected terrigenous elements and the aluminum oxide and potassium oxide of the rock formation sample and calculating the average value of the correlation includes:

[0074] The selected terrigenous elements are fitted with aluminum oxide and potassium oxide respectively to obtain element correlation data sets with aluminum oxide and element correlation data sets with potassium oxide;

[0075] Calculate the average value of the element correlation of the aluminum oxide element correlation data set and the potassium oxide element correlation data set.

[0076] The alumina content of the samples in the study area has a high and similar correlation with the terrestrial elements titanium Ti, zirconium Zr, and hafnium Hf. 2 , the correlation between potassium oxide content and terrestrial elements titanium Ti, zirconium Zr, and hafnium Hf 2 As shown in the following table:

[0077] <h2 style=";text-align:left;direction:ltr"><![CDATA[R <h2 style=";text-align:left;direction:ltr"> 2 <h2 style=";text-align:left;direction:ltr"> (Al2O3-Zr)]]><h2 style=";text-align:left;direction:ltr"> <h2 style=";text-align:left;direction:ltr"><![CDATA[R <h2 style=";text-align:left;direction:ltr"> 2 <h2 style=";text-align:left;direction:ltr"> (Al2O3-Hf)]]><h2 style=";text-align:left;direction:ltr"> <h2 style=";text-align:left;direction:ltr"><![CDATA[R <h2 style=";text-align:left;direction:ltr"> 2 <h2 style=";text-align:left;direction:ltr"> (Al2O3-TiO2)]]><h2 style=";text-align:left;direction:ltr"> Marlstone-limestone interbeds 0.9305 0.944 0.9352 Marl 0.8983 0.9092 0.8966 Limestone 0.9064 0.9481 0.9389 <![CDATA[R 2 (K2O-Zr)]]> <![CDATA[R 2 (K2O-Hf)]]> <![CDATA[R 2 (K2O-TiO2)]]> Marlstone-limestone interbeds 0.5195 0.5322 0.5013 Marl 0.7630 0.7789 0.7612 Limestone 0.5572 0.6287 0.5541

[0078] Calculate and obtain the average proportion of montmorillonite-illite-montmorillonite mixed layer and illite-illite-montmorillonite mixed layer in the selected rock formation sample, and calculate the average content of aluminum oxide and potassium oxide in the rock formation sample as the parameters required for fitting;

[0079] Among them, the average contents of aluminum oxide and potassium oxide are expressed as: and

[0080] The average proportion of montmorillonite-illite-montmorillonite mixed layers and illite-illite mixed layers in the selected rock samples is expressed as: and

[0081] in,

[0082]

[0083]

[0084]

[0085] In the formula, ω i (Al2O3),ω i (K2O),ω i (Sme+It+I / S),ω i (It+I / S) are the aluminum oxide (Al2O3) content (percentage%), potassium oxide (K2O) content (percentage%), montmorillonite-illite-montmorillonite mixed layer ratio (percentage%), and illite-montmorillonite mixed layer ratio (percentage%) of the i-th sample.

[0086] The specific method of constructing the fitting relationship function of the proportion and correlation of terrigenous clay minerals based on two data points includes:

[0087] Assume that the proportion of terrigenous clay minerals in the rock layer ω and the correlation coefficient R 2 belongs to a quasi-normal distribution, and

[0088] According to the normal distribution function and the normal curve function, the equation group is constructed:

[0089]

[0090] Solve the equations to find A and μ, where A represents the normal distribution parameter and μ represents the average total amount of terrigenous clay minerals in the selected rock samples. Represents the average terrigenous montmorillonite content of the selected rock samples, and fits the proportion of terrigenous clay minerals in the rock layer ω and the correlation R 2 function.

[0091] The fitted correlation averages are shown in the following table:

[0092]

[0093] The μ value solved in step 500 is the average total content of terrigenous clay minerals in the selected sample, the average terrigenous montmorillonite content of the selected sample ω(terrigenous Sme)=μ-ω(It+I / S), the average authigenic montmorillonite content of the selected sample ω(autogenic Sme)=ω(Sme)-ω(terrigenous Sme), and the calculation results using the above formula are as follows:

[0094] Marlstone-limestone interbeds Marl Limestone Terrigenous clay minerals / total clay minerals 15.83％ 7.38％ 30.69％ (illite + illite-montmorillonite mixed layer) / total clay minerals 11.58％ 5.17％ 23.77％ Terrigenous montmorillonite / total clay minerals 4.26％ 2.21％ 6.92％ Authigenic montmorillonite / total clay minerals 1.34％ 1.38％ 2.50％

[0095] Using the same set of data Indicates the fitting accuracy value. The smaller the fitting accuracy value, the higher the accuracy of the fitting result.

[0096] The above embodiments are only exemplary embodiments of the present application and are not intended to limit the present application. The protection scope of the present application is defined by the claims. Those skilled in the art may make various modifications or equivalent substitutions to the present application within the essence and protection scope of the present application, and such modifications or equivalent substitutions shall also be deemed to fall within the protection scope of the present application.

Claims

1. A method for calculating the content of terrestrial-derived components in mixed-origin montmorillonite, characterized in that: Including specific steps: Step 100: Prepare rock samples according to the location and stratum of the study area, determine the reference clay minerals of montmorillonite genesis, and determine the morphology, energy spectrum and diffraction results of montmorillonite and the reference clay minerals through various tests to obtain the terrigenous and authigenic mixed genesis of montmorillonite; Step 200, fitting the content of each component of terrigenous and authigenic montmorillonite according to the obtained terrigenous and authigenic mixed genesis of montmorillonite, and determining the parameters required for fitting, including: Mixed layers of montmorillonite-reference clay mineral-reference clay mineral and montmorillonite and mixed layers of reference clay mineral-reference clay mineral and montmorillonite in rock samples; Determine the comparative element minerals in the rock samples to be compared respectively according to the main element minerals contained in the montmorillonite-reference clay mineral-reference clay mineral and the montmorillonite mixed layer and the reference clay mineral-reference clay mineral and montmorillonite mixed layer; Calculate and obtain the average contents of montmorillonite-reference clay mineral-reference clay mineral and montmorillonite mixed layer and reference clay mineral-reference clay mineral and montmorillonite mixed layer, and comparison element minerals as the parameters required for fitting; Among them, illite is selected as the reference clay mineral: Montmorillonite-illite-montmorillonite mixed layer is a potential terrigenous clay mineral, in which the illite-montmorillonite mixed layer is mainly K-containing minerals, and the montmorillonite-illite-montmorillonite mixed layer is mainly Al-containing minerals. Alumina and potassium oxide are selected as comparative element minerals, corresponding to the total content of montmorillonite-illite-montmorillonite mixed layer and the total content of illite-montmorillonite mixed layer, respectively. Step 300, by performing a linear correlation analysis on the comparative element minerals and other elements in the rock formation sample, screen out the terrigenous elements suitable for fitting, including: performing a linear correlation analysis on the aluminum oxide and potassium oxide in the rock formation sample and other mineral elements in the rock formation sample, and screening out the correlation coefficient with aluminum oxide or potassium oxide. And the correlation coefficient Similar elements, among which Indicates the set correlation parameters of other mineral elements; Step 400, fitting correlations between the terrigenous elements screened out in step 300 and the comparative elements and minerals of the rock samples, and calculating the average value of the correlations; Among them, the specific method of fitting the correlation between the selected terrigenous elements and the aluminum oxide and potassium oxide of the rock samples and calculating the average value of the correlation includes: The selected terrigenous elements are fitted with aluminum oxide and potassium oxide respectively to obtain element correlation data sets with aluminum oxide and element correlation data sets with potassium oxide; Calculate the element correlation average values ​​of the element correlation data set of aluminum oxide and the element correlation data set of potassium oxide; Then, the average content of the montmorillonite-illite-montmorillonite mixed layer and the average value of the correlation of the comparative element minerals, and the average content of the illite-illite-montmorillonite mixed layer and the average value of the correlation of the comparative element minerals in step 200 are constructed as data points; Based on two data points, a fitting relationship function of the proportion and correlation of terrigenous clay minerals was constructed; Step 500: Calculate the average total content of terrigenous clay minerals in the sample, the average terrigenous montmorillonite content in the selected rock formation samples, and the average authigenic montmorillonite content in the selected rock formation samples according to the fitting relationship function.

2. The method for calculating the content of terrestrial-derived components of mixed-origin montmorillonite according to claim 1, characterized in that: In step 100, the specific method of determining the reference clay mineral of montmorillonite origin and determining the morphology, energy spectrum and diffraction results of montmorillonite and the reference clay mineral through various tests includes: Select reference clay minerals indicating authigenic origin and reference clay minerals indicating terrigenous origin, and use scanning electron microscopy to identify the similarity of the developmental morphology between montmorillonite and the selected reference clay minerals; The selected elements of the selected reference clay mineral and montmorillonite are quantitatively analyzed by energy spectrometer, and a ternary diagram is drawn according to the quantitative analysis results. The montmorillonite scatter points that are continuously distributed with the scatter points analyzed by the energy spectrometer of the selected reference clay mineral indicate autogenous origin, and the montmorillonite scatter points that are dispersedly distributed with the scatter points analyzed by the energy spectrometer of the selected reference clay mineral indicate terrigenous origin; The regular changes in the montmorillonite peak and the lucite mixed layer peak in the X-ray diffraction spectrum of reference clay minerals indicate an autogenic origin, while the irregular changes indicate a mixed terrigenous and autogenic origin.

3. The method for calculating the content of terrestrial-derived components of mixed-origin montmorillonite according to claim 1, characterized in that: Calculate and obtain the average proportion of montmorillonite-illite-montmorillonite mixed layer and illite-illite-montmorillonite mixed layer in the selected rock formation sample, and calculate the average content of aluminum oxide and potassium oxide in the rock formation sample as the parameters required for fitting; Among them, the average contents of aluminum oxide and potassium oxide are expressed as: and ; The average proportion of montmorillonite-illite-montmorillonite mixed layers and illite-illite mixed layers in the selected rock samples is expressed as: and .

4. The method for calculating the content of terrestrial-derived components in mixed-origin montmorillonite according to claim 3, characterized in that: The specific method of constructing the fitting relationship function of the proportion and correlation of terrigenous clay minerals based on two data points includes: assuming that the proportion of terrigenous clay minerals in the rock formation and correlation coefficient belongs to a quasi-normal distribution, and =1; According to the normal distribution function and the normal curve function, the equation group is constructed: ； Solve the equations for A and , A represents the normal distribution parameter, where represents the average total amount of terrigenous clay minerals in the selected rock samples, (It+I / S) represents the average terrigenous montmorillonite content of the selected rock samples, and fits the proportion of terrigenous clay minerals in the rock layer and relevance function.

5. The method for calculating the content of terrestrial-derived components in mixed-origin montmorillonite according to claim 4, characterized in that: Using the same set of data Represents the fitting accuracy value. The smaller the fitting accuracy value, the higher the accuracy of the fitting result. 。

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