Method for calculating the maceral content of a coal seam

Abstract

This invention provides a method for calculating the content of micro-components in coal seams, comprising the following steps: Step S1, measuring the content of micro-components, ash content (Aad), and total sulfur content (St) of the coal core; Step S2, obtaining the well logging curve values ​​for the depth segment of the coal seam where the coal core is located; Step S3, selecting sensitive well logging curves reflecting the micro-components of the coal core through mathematical statistical analysis of the correlation between the micro-component content of the coal core and the sensitive well logging curves; Step S4, performing multivariate stepwise regression analysis on the micro-component content of the coal core and the sensitive well logging curves respectively to obtain the relationship between the micro-component content of the coal core and the sensitive well logging curves; Step S5, obtaining the well logging curve values ​​corresponding to the coal seam segment for which the micro-component content of the coal core to be measured is obtained, and substituting the well logging curve values ​​into the relationship to obtain the micro-component content of that coal seam segment. The technical solution of this invention can quickly and accurately predict the content of micro-components, providing a basis for development deployment and decision-making, and reducing development risks.

Description

Technical Field

[0001] This application relates to the field of coalbed methane reservoir evaluation technology, and in particular to a method for calculating the content of microscopic components in coal seams. Background Technology

[0002] my country possesses abundant coalbed methane resources. Shallow coalbed methane resources (buried below 2000m) amount to 2.982 billion cubic meters, while deep coalbed methane resources (buried 2000-3000m) amount to 1.84 billion cubic meters, indicating enormous exploration and development potential. Due to varying temperatures, pressures, and biochemical processes, the original parent material plants or microorganisms during coal formation undergo different degrees of evolution. Some retain traces of their original parent material morphology, while others evolve into new components. Combined with coalification, these factors contribute to the complex microstructure of coal. The microstructure of coal determines the hydrocarbon generation capacity of the coal seam, the composition and relative content of coalbed methane, and also significantly influences the fracture development characteristics and adsorption capacity of the coal seam.

[0003] Different types of coal seams exhibit varying material composition and structure, with the degree of pore and fracture development, permeability, and methane adsorption capacity gradually decreasing from the vitrinite to the crustalite. Therefore, the microstructure of coal is a crucial parameter in the design of deep coalbed methane development schemes. Currently, obtaining coal microstructures through experimental testing of core samples is relatively expensive. Furthermore, this method relies heavily on the technical skill of the testing personnel, and the identification results are subjective, limiting the accuracy and efficiency of coal petrographic microstructure identification and hindering the efficient development of coalbed methane.

[0004] In existing technologies, geophysical logging techniques, which are fast, efficient, and inexpensive, are effective in analyzing and predicting coal seam structure, gas content, macroscopic coal and rock types, and rock mechanical characteristics. However, methods for quantitatively calculating coal microcomponents based on logging techniques are extremely rare. Currently, Chinese invention patent application number CN110529106B provides a method for determining the content of coal seam microcomponents using logging data. Through mathematical statistics, after determining the logging sensitivity parameters for vitrinite content in coal, the microcomponent content of the coal core is analyzed using multiple stepwise regression analysis with the sensitive logging curves to obtain the relationship between the microcomponent content of the coal core and the sensitive logging curves. However, because the selected sensitive logging curves (such as AC, DEN, CNL) are affected by physical properties and gas content, the calculated coal microcomponent content is generally higher than the experimentally tested content under conditions where free gas is prevalent in deep coalbed methane and microfractures are well-developed.

[0005] Therefore, existing methods for calculating the content of micro-components in coal seams are susceptible to the influence of sedimentary environment on the sensitive logging curves of deep coal and rock micro-components, thus affecting the accuracy and precision of the calculation results. There is an urgent need to provide a new method for calculating the content of micro-components in coal seams to address these issues. Summary of the Invention

[0006] The main objective of this invention is to provide a method for calculating the content of micro-components in coal seams, thereby solving the technical problem in existing methods for calculating the content of micro-components in coal seams where the sensitive logging curves of deep coal and rock micro-components are easily affected by the sedimentary environment, thus affecting the accuracy and precision of the calculation results.

[0007] To achieve the above objectives, according to one aspect of the present invention, a method for calculating the content of micro-components in a coal seam is provided, the method comprising the following steps: Step S1, measuring the content of micro-components, ash content Aad, and total sulfur content St of a coal core; Step S2, obtaining well logging curve values ​​for the depth range of the coal seam where the coal core is located; Step S3, selecting sensitive well logging curves reflecting the micro-components of the coal core by mathematical statistical analysis of the correlation between the content of micro-components in the coal core and the sensitive well logging curves; Step S4, performing multiple stepwise regression analysis on the content of micro-components in the coal core and the sensitive well logging curves respectively, to obtain the correlation between the content of micro-components in the coal core and the sensitive well logging curves. Relationship; Step S5, obtain the logging curve value corresponding to the coal seam segment with the content of the micro-components in the coal core to be tested, and substitute the logging curve value into the relationship to obtain the content of the micro-components in the coal seam segment; where the sensitive logging curve parameters are volumetric density DEN, uranium-free gamma CGR and sonic transit time AC; both the coal core and the coal seam are medium- to high-rank coals, and their micro-components include vitrinite, inertinite, crustitinite, minerals and others. Compared with the content of vitrinite, inertinite, minerals and crustitinite, the content of other components is negligible; among them, the content of crustitinite is less than 2%, and for ease of calculation, it is included in the inertinite group. The relationship of its volume percentage content is: V 镜质组 +V 惰质组 +V 矿物 =100, where V 镜质组 V represents the volume percentage of vitrinite in the microstructure. 惰质组 V is the sum of the volume percentages of the inertinite and the chitinite in the microstructure; 矿物 This represents the volume percentage of minerals in the inorganic micro-components within the micro-components.

[0008] Further, in step S4, the micro-component content of the coal core is subjected to multivariate stepwise regression analysis with the sensitive logging curves to obtain the relationship between the micro-component content of the coal core and the sensitive logging curves. This includes: substituting the environmentally corrected logging parameter values ​​into the logging calculation formula for ash content Aad obtained from the multivariate regression of the sensitive parameters; substituting the relationship between ash content Aad and the sensitive logging curves and the total sulfur content St into the Pail formula to obtain the relationship between the mineral content MC and the ash content Aad of the coal seam; through mathematical statistical analysis of the correlation between the demineralized vitrinite content of the coal core and the logging curves, selecting the sensitive logging curves that reflect the demineralized vitrinite content, thereby obtaining the calculation relationship for the demineralized vitrinite content; combining the demineralized vitrinite content with the calculated mineral content to obtain the calculation relationship for the vitrinite content and the inertinite content, and finally obtaining the micro-component content of the coal core.

[0009] Furthermore, the logging calculation formula for ash content Aad includes: Ash content Aad = 845.1643 × (Uranium-free gamma CGR / Acoustic transit time AC) 2 -37.57856×(Uranium-free Gamma CGR / Acoustic Transmission Time AC)+19.69697×Bulk Density DEN-16.05742.

[0010] Furthermore, the relationship between the mineral content MC and the ash content Aad of the coal seam is as follows: Mineral content MC = 1.08 × Ash content Aad + 0.55 × Total sulfur content St.

[0011] Furthermore, in the sensitive logging curves reflecting the demineralized vitrinite components, the parameters of the sensitive logging curves are the radioactive thorium content (TH) and the radioactive uranium content (U).

[0012] Furthermore, the formula for calculating the content of vitrinite without mineral matrix is: V 镜质组去矿物基 = 92.88484 - 2.65535 × radioactive thorium content TH / radioactive uranium content U.

[0013] Furthermore, the formula for calculating vitrinite content is: V 镜质组 = (100 - mineral content MC) × V 镜质组去矿物基 / 100; The relationship between the inert group content and the formula is: V 惰质组 =100-V 矿物 -V 镜质组 .

[0014] Furthermore, both the coal core and the coal seam to be tested are medium- to high-rank coal seams in the same coalbed methane block.

[0015] Furthermore, the measurement of the micro-components of the coal core was carried out in accordance with the "Methods for Determination of Micro-components and Minerals of Coal (GB / T8899-1998)".

[0016] Furthermore, in step S2, the well logging curve of the coal seam depth section where the coal core is located is measured in accordance with the "Coalfield Geophysical Well Logging Specification (DZ / T0080-93)".

[0017] The technical solution of this invention can overcome the influence of deep free gas content and microfracture development on conventional logging data such as acoustic waves, density, and neutrons. It is significantly improved compared with existing methods for calculating vitrinite content, and the calculation accuracy is significantly improved with an average relative error of less than 1%. This enables rapid and accurate prediction of micro-component content, and can obtain the differences in micro-component content in the block plane, providing a basis for development deployment and decision-making, and reducing development risks. Attached Figure Description

[0018] The accompanying drawings, which are incorporated in and form part of this specification, illustrate embodiments consistent with this application and, together with the description, serve to explain the principles of this application. In the drawings:

[0019] Figure 1 A flowchart illustrating a method for calculating the content of microscopic components in coal seams, as used in one embodiment of the present invention, is shown.

[0020] Figure 2 A schematic diagram illustrating the correlation between coal core ash content and bulk density (DEN) according to Embodiment 1 of the present invention is shown.

[0021] Figure 3 A schematic diagram illustrating the correlation between coal core ash content and uranium-free gamma (CGR) in Embodiment 1 of the present invention is shown.

[0022] Figure 4 A schematic diagram illustrating the correlation between coal core ash content and acoustic transit time (AC) according to Embodiment 1 of the present invention is shown.

[0023] Figure 5 A schematic diagram showing the correlation between the content of vitrinite in coal cores after mineral matrix removal and thorium (Th) in Embodiment 1 of the present invention is shown.

[0024] Figure 6 A schematic diagram illustrating the correlation between the content of vitrinite in coal cores after mineral matrix removal and uranium (U) in Embodiment 1 of the present invention is shown.

[0025] Figure 7 A schematic diagram illustrating the correlation between the content of vitrinite in coal cores after mineral matrix removal and the thorium / uranium (Th / U) ratio is shown in Embodiment 1 of the present invention.

[0026] Figure 8 A schematic diagram comparing the vitrinite content from coal core experiments with the vitrinite content calculated from well logging is shown in Embodiment 1 of the present invention; and

[0027] Figure 9A schematic diagram showing the comparison between the vitrinite content and ash yield of a coal core sample from a well according to Embodiment 1 of the present invention and the vitrinite content and ash yield calculated by well logging is presented. Detailed Implementation

[0028] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0029] According to the background section of this invention, the existing method for calculating the content of micro-components in coal seams suffers from the technical problem that the sensitive logging curves of deep coal and rock micro-components are easily affected by the sedimentary environment, thus affecting the accuracy and precision of the calculation results. Based on this, this invention provides a method for calculating the content of micro-components in coal seams, comprising the following steps: Step S1, measuring the content of micro-components, ash content Aad, and total sulfur content St of the coal core; Step S2, obtaining the logging curve values ​​of the depth range of the coal seam where the coal core is located; Step S3, selecting the sensitive logging curves reflecting the micro-components of the coal core through mathematical statistical analysis of the correlation between the content of micro-components in the coal core and the logging curves; Step S4, performing multivariate stepwise regression analysis on the content of micro-components in the coal core and the sensitive logging curves respectively to obtain the relationship between the content of micro-components in the coal core and the sensitive logging curves; Step S5 S5. Obtain the well logging curve values ​​corresponding to the coal seam segment for which the micro-component content of the coal core to be tested is obtained. Substitute the well logging curve values ​​into the relational formula to obtain the micro-component content of the coal seam segment. Among them, the sensitive well logging curve parameters are volumetric density (DEN), uranium-free gamma (CGR), and acoustic transit time (AC). Both the coal core and the coal seam are medium- to high-rank coals, and their micro-components include vitrinite, inertinite, crustaceanite, minerals, and others. Compared with the contents of vitrinite, inertinite, minerals, and crustaceanite, the contents of other components are negligible. Among them, the contents of crustaceanite are all less than 2%, and for ease of calculation, they are included in the inertinite group. The relationship of their volume percentage content is: V 镜质组 +V 惰质组 +V 矿物 =100, where V 镜质组 V represents the volume percentage of vitrinite in the microstructure. 惰质组 V is the sum of the volume percentages of the inertinite and the chitinite in the microstructure; 矿物 This represents the volume percentage of minerals in the inorganic micro-components within the micro-components.

[0030] This invention quantitatively calculates the micro-component content of deep coal and rock based on natural gamma-ray spectroscopy logging data. It overcomes the limitations of conventional logging data (sonic, density, neutron) which are susceptible to the influence of deep free gas content and microfracture development. By selecting a spectral logging curve sensitive only to lithology, it significantly improves upon existing methods for calculating vitrinite content. The calculation accuracy is significantly enhanced, with an average relative error of less than 1%. This enables rapid and accurate prediction of micro-component content, revealing the differences in micro-component content across a block, providing a basis for development deployment and decision-making, and reducing development risks.

[0031] In a preferred embodiment, step S4 involves performing multivariate stepwise regression analysis on the chromatographic component content of the coal core and the sensitive logging curves to obtain the relationship between the chromatographic component content of the coal core and the sensitive logging curves. This includes: substituting the environmentally corrected logging parameter values ​​into the logging calculation formula for ash content Aad obtained from the multivariate regression of the sensitive parameters; substituting the relationship between ash content Aad and the sensitive logging curves and the total sulfur content St into the Pail formula to obtain the relationship between the mineral content MC and the ash content Aad of the coal seam; through mathematical statistical analysis of the correlation between the demineralized vitrinite component content of the coal core and the logging curves, selecting the sensitive logging curves that reflect the demineralized vitrinite component, thereby obtaining the calculation relationship for the demineralized vitrinite content; combining the demineralized vitrinite content with the calculated mineral content to obtain the calculation relationship for the vitrinite content and the inertinite content, and finally obtaining the chromatographic component content of the coal core.

[0032] Further optimization yields the following logging calculation formula for ash content Aad: Ash content Aad = 845.1643 × (Uranium-free gamma CGR / Acoustic transit time AC) 2 -37.57856 × (Uranium-free Gamma CGR / Acoustic Transit AC) + 19.69697 × Bulk Density DEN - 16.05742; The relationship between mineral content MC and ash content Aad in coal seams includes: Mineral content MC = 1.08 × Ash content Aad + 0.55 × Total sulfur content St; In the sensitive logging curve reflecting the demineralized vitrinite component, the parameters of the sensitive logging curve are radioactive thorium content TH and radioactive uranium content U; The calculation relationship of demineralized vitrinite content is: V 镜质组去矿物基 = 92.88484 - 2.65535 × radioactive thorium content TH / radioactive uranium content U; the formula for calculating vitrinite content is: V 镜质组 = (100 - mineral content MC) × V 镜质组去矿物基 / 100; The relationship between the inert group content and the formula is: V 惰质组 =100-V 矿物 -V 镜质组This ultimately yields the microstructure of the coal core. In particular, the radioactive element TH and U concentration logging data used can more accurately reflect the vitrinite reservoir environment, effectively overcoming the limitations of conventional logging data (sonic, density, neutron) which are easily affected by deep free gas content and microfracture development. Energy dispersive spectroscopy logging curves, which are only sensitive to lithology, were selected, resulting in a significant improvement over existing methods for calculating vitrinite content.

[0033] In a preferred embodiment, the coal core and the coal seam to be tested are both medium- to high-rank coal seams in the same coalbed methane block; the measurement of the micro-components of the coal core is carried out in accordance with the "Methods for Determination of Micro-components and Minerals of Coal (GB / T8899-1998)"; in step S2, the measurement of the logging curve of the coal seam depth section where the coal core is located is carried out in accordance with the "Specifications for Geophysical Logging of Coalfields (DZ / T0080-93)".

[0034] The present application will be further described in detail below with reference to specific embodiments, which should not be construed as limiting the scope of protection claimed in the present application.

[0035] Example 1

[0036] Table 1 shows the data of industrial and microscopic composition analysis of seven wells in a deep coal and rock block of an oil field. The meaning of removing the mineral matrix is ​​to remove the influence of minerals and only consider the respective proportions of vitrinite and inertinite. As can be seen from the table, the vitrinite with the mineral matrix removed plus the inertinite with the mineral matrix removed equals 100%.

[0037] like Figure 1 The flowchart shown illustrates the quantitative calculation of coal and petrographic microstructures using gamma-ray spectroscopy logging data. It mainly includes:

[0038] Step S1: Analyze and test the coal core to obtain ash content (Aad) and vitrinite content (V). 镜质组 ), vitrinite content after mineral matrix removal (V 镜质组去矿物基 ), inert group content (V) 惰质组 ), content of demineralized inertinite group (V) 惰质组去矿物基 ), mineral content (V) 矿物 Experimental data, collecting total sulfur content data (St) of the region;

[0039] Core experiments on medium and high-rank coal showed that the content of the crustacean was almost entirely zero; the inorganic micro-components mainly consisted of clay minerals, carbonate minerals, sulfides, and oxides, collectively referred to as minerals, which were closely related to the ash content.

[0040] Therefore, the expression for the microstructure of medium and high-rank coal in this region is as follows:

[0041] V 镜质组 +V 惰质组 +V 矿物 =100;

[0042] The measurement area has a series that can represent the characteristics of the region. This invention conducts experiments according to the standard procedure of "Methods for Determination of Microscopic Components and Minerals of Coal (GB / T8899-1998)" to obtain the content of microscopic components of each coal core.

[0043] Step S2: Combine the coal core analysis data with the logging curve characteristics of the coal seam depth range to locate the core and obtain the logging curve values ​​of the coal core test sample, including the acoustic transit time AC, bulk density DEN, uranium-free gamma CGR, radioactive element thorium TH, uranium U content, etc., and perform environmental correction to obtain the corrected values ​​of the logging curve.

[0044] Step S3, starting from the study of well logging response mechanism, combines experimental data and statistical analysis of actual data, see [link to relevant documentation]. Figure 2 , Figure 3 , Figure 4 Three sensitive logging curves reflecting the ash content of coal seams were selected from the logging curves: density per unit volume (DEN), uranium-free gamma (CGR), and acoustic transit time (AC).

[0045] The well logging calculation formula for ash content, obtained by substituting the environmentally corrected logging parameter values ​​into the multiple regression of sensitive parameters, is as follows: Ash content Aad = 845.1643 × (Uranium-free gamma CGR / Acoustic transit time AC) 2 -37.57856×(Uranium-free Gamma CGR / Acoustic Transmission Time AC)+19.69697×Bulk Density DEN-16.05742.

[0046] Substituting the obtained relationship between ash content and sensitive logging curves and total sulfur content into the Pail formula, we obtain the relationship between mineral content and ash content for this coal seam.

[0047] Mineral content MC = 1.08 × ash content Aad + 0.55 × total sulfur content St.

[0048] Based on the study of well logging response mechanisms, and combined with experimental data and actual statistical data, see [reference needed]. Figure 5 , Figure 6 Two sensitive logging curves reflecting the content of vitrinite in the coal seam were selected from the logging curves: the content of radioactive thorium (TH) and the content of radioactive uranium (U). Figure 7 This is a schematic diagram showing the correlation between the content of mineralized vitrinite in the microstructure of coal core experiments provided by this invention and the corresponding depth-corrected logging Th / U ratio.

[0049] V from the core experiment 镜质组去矿物基 Regression was performed with the environmentally corrected logging parameters to obtain the formula for calculating the content of mineral-based vitrinite;

[0050] V 镜质组去矿物基 = 92.88484 - 2.65535 × radioactive thorium content TH / radioactive uranium content U.

[0051] The mineral content MC obtained from the vitrinite content calculation after removing the mineral matrix is ​​used to derive the formula for calculating vitrinite content:

[0052] V 镜质组 = (100 - mineral content MC) × V 镜质组去矿物基 / 100.

[0053] The relationship between inert content and other factors is then obtained as follows:

[0054] V 惰质组 =100-V 矿物 -V 镜质组 .

[0055] Step S5 involves obtaining the logging curve values ​​of coal seam segments that have undergone conventional logging but not coal core micro-component experiments. Substituting the environmentally corrected logging curve values ​​into the relational formula yields the micro-component content of the coal seam segment.

[0056] As can be seen from the above description, the embodiments of the present invention achieve the following technical effects:

[0057] Figure 8 This is a schematic diagram comparing the vitrinite content from coal core experiments with the vitrinite content calculated from well logging. The average relative error of the calculated well logging values ​​is less than 1%. Figure 9 This is a comparison chart of the content of micro-components in a coal core calculated using well logging data and the content of micro-components measured experimentally, provided by this invention. The experimentally measured micro-component content is represented by solid black dots, while the micro-component content calculated using this invention is represented by a curve. It can be seen that the black dots measured experimentally all fall on or near the curve calculated by well logging. The content of micro-components in the coal seam calculated using well logging data of this invention tends to be consistent with the actual measured values ​​of the coal core, and the application effect is obvious.

[0058] The vitrinite content of coal calculated using this invention can achieve the same test results as those obtained by laboratory coal cores through experiments and calculations according to the standard procedure of "Methods for the Determination of Microscopic Components and Minerals of Coal (GB / T 8899-1998)". Moreover, it is convenient to obtain, low in cost, and can obtain the microscopic components of coal seams in continuous well sections, showing good application effects.

[0059] While this specification contains numerous specific implementation details, these should not be construed as limiting the scope of any invention or the scope of the claims, but rather are primarily intended to describe features of specific embodiments of a particular invention. Certain features described in the various embodiments herein may also be implemented in combination in a single embodiment. Conversely, various features described in a single embodiment may also be implemented separately in various embodiments or in any suitable sub-combination. Furthermore, while features may function in certain combinations as described above and even initially claimed in this way, one or more features from a claimed combination may be removed from that combination in some cases, and a claimed combination may refer to a sub-combination or a variation thereof.

[0060] Similarly, although the operations are depicted in a specific order in the accompanying drawings, this should not be construed as requiring these operations to be performed in the specific order shown or sequentially, or requiring all illustrated operations to be performed to achieve the desired result. In some cases, multitasking and parallel processing may be advantageous. Furthermore, the separation of various system modules and components in the above embodiments should not be construed as requiring such separation in all embodiments, and it should be understood that the described program components and systems can generally be integrated together in a single software product or packaged into multiple software products.

[0061] Thus, specific embodiments of the subject matter have been described. Other embodiments are within the scope of the appended claims. In some cases, the actions recited in the claims may be performed in a different order and still achieve the desired result. Furthermore, the processes depicted in the drawings are not necessarily shown in a specific order or sequence to achieve the desired result. In some implementations, multitasking and parallel processing may be advantageous.

[0062] It should be noted that, in this document, relational terms such as "first" and "second" are used merely to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitations, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes said element.

[0063] The above description is merely a specific embodiment of this application, enabling those skilled in the art to understand or implement this application. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of this application. Therefore, this application is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features claimed herein.

Claims

1. A method for calculating the content of microscopic components in coal seams, characterized in that, The method includes the following steps: Step S1: Measure the content of microscopic components, ash content Aad, and total sulfur content St of the coal core; Step S2: Obtain the well logging curve values ​​of the coal seam depth range where the coal core is located; Step S3: Through mathematical statistical analysis of the correlation between the content of micro-components in the coal core and the logging curve, select the sensitive logging curve that reflects the micro-components of the coal core. Step S4: Perform multivariate stepwise regression analysis on the content of micro-components in the coal core and the sensitive logging curve to obtain the relationship between the content of micro-components in the coal core and the sensitive logging curve. Step S5: Obtain the well logging curve value corresponding to the coal seam segment whose microscopic component content is to be tested, and substitute the well logging curve value into the relational formula to obtain the microscopic component content of the coal seam segment; wherein, The sensitive logging curve parameters are volumetric density (DEN), uranium-free gamma (CGR), and acoustic transit time (AC). Both the coal core and the coal seam are medium- to high-rank coals. Their microscopic components include vitrinite, inertinite, chalcedony, minerals, and others. Compared to the contents of vitrinite, inertinite, minerals, and chalcedony, the contents of other components are negligible. The chalcedony component contains less than 2% of each component; for ease of calculation, it is included in the inertinite group. The volume percentage relationship is as follows: V 镜质组 +V 惰质组 +V 矿物 = 100; wherein V 镜质组 is the volume percentage content of vitrinite in the maceral; V 惰质组 is the sum of the volume percentage content of inertinite and the volume percentage content of exinite in the maceral; V 矿物 is the volume percentage content of minerals in the inorganic maceral.

2. The method according to claim 1, characterized in that, In step S4, the content of micro-components in the coal core is subjected to multiple stepwise regression analysis with the sensitive logging curves to obtain the relationship between the content of micro-components in the coal core and the sensitive logging curves, including: Substitute the environmentally corrected logging parameter values ​​into the logging calculation formula for ash content Aad obtained from the multiple regression of sensitive parameters: Substituting the relationship between ash content Aad and the sensitive logging curve and the total sulfur content St into the Pail equation, we obtain the relationship between the mineral content MC and the ash content Aad of this coal seam. By analyzing the correlation between the content of demineralized vitrinite in coal cores and the well logging curves through mathematical statistics, sensitive well logging curves reflecting the content of demineralized vitrinite are selected, thereby obtaining the formula for calculating the content of demineralized vitrinite. By combining the content of vitrinite after removing the mineral matrix with the calculated mineral content, the calculation formulas for vitrinite content and inertinite content are obtained, and finally the micro-component content of the coal core is obtained.

3. The method according to claim 2, characterized in that, The well logging calculation formula for the ash content Aad includes: Ash content Aad = 845.1643 × (uranium-free gamma CGR / acoustic transit time AC) 2 -37.57856×(Uranium-free Gamma CGR / Acoustic Transmission Time AC)+19.69697×Bulk Density DEN-16.05742.

4. The method according to claim 2, characterized in that, The relationship between the mineral content MC and the ash content Aad of the coal seam includes: Mineral content MC = 1.08 × ash content Aad + 0.55 × total sulfur content St.

5. The method according to claim 2, characterized in that, In the sensitive logging curve reflecting the demineralized vitrinite component, the parameters of the sensitive logging curve are the radioactive thorium content (TH) and the radioactive uranium content (U).

6. The method according to claim 2, characterized in that, The formula for calculating the content of demineralized vitrinite is as follows: V 镜质组去矿物基 = 92.88484 - 2.65535 × radioactive thorium content TH / radioactive uranium content U.

7. The method according to claim 2, characterized in that, The formula for calculating the vitrinite content is: V 镜质组 = (100 - mineral content MC) × V 镜质组去矿物基 / 100; The inert group content relationship is: V 惰质组 =100-V 矿物 -V vitrinoid group.

8. The method according to claim 1, characterized in that, The coal core and the coal seam to be tested are both medium- to high-rank coal seams in the same coalbed methane block.

9. The method according to claim 1, characterized in that, The measurement of the microstructure of the coal core was carried out in accordance with the "Methods for Determination of Microstructure and Minerals of Coal (GB / T8899-1998)".

10. The method for preparing the composite electrode material according to claim 6, characterized in that, In step S2, the well logging curve of the coal seam depth section where the coal core is located is measured in accordance with the "Coalfield Geophysical Well Logging Specification (DZ / T0080-93)".

Images