A method for evaluating the supercritical CO2 fracturing capability of deep coalbed methane reservoirs

Abstract

The application discloses a kind of deep coalbed gas reservoir supercritical CO2 fracturability evaluation method, comprising the following steps: S1 coalbed gas reservoir geological occurrence environment evaluation;S2 coalbed gas reservoir tectonic geological environment analysis;S3 geological drilling well logging and lithology analysis;S4 coalbed gas reservoir and its roof and floor mechanical property analysis;S5 coalbed gas reservoir supercritical CO2 fracturing characteristics and effect experimental analysis;S6 comprehensive analysis and evaluation coalbed gas reservoir fracturability, the present application relates to unconventional natural gas resources coalbed gas development and utilization technical field.The deep coalbed gas reservoir supercritical CO2 fracturability evaluation method, according to coalbed gas reservoir occurrence geological environment and mechanical characteristics, build whether coalbed gas reservoir has the fracturability evaluation method, realize the quantitative evaluation of supercritical CO2 fracturability of coalbed gas reservoir, it is of great significance to select and reduce drilling fracturing risk of coalbed gas reservoir fracturing imbibition region.

Description

Technical Field

[0001] This invention relates to the field of unconventional natural gas resource coalbed methane development and utilization technology, specifically a method for evaluating the supercritical CO2 fracturing capability of deep coalbed methane reservoirs. Background Technology

[0002] my country possesses vast coalbed methane (CBM) reserves, but unlike conventional oil and gas resources, CBM exists primarily in an adsorbed state within the micro- and nano-pore fractures of CBM reservoirs. Exploiting CBM requires reservoir modification to increase permeability. Supercritical CO2 fracturing of deep CBM reservoirs is an effective method for modification. However, premature fracturing without sufficient fracturing assessment carries unknown risks regarding its effectiveness. Therefore, a scientifically sound method is needed to quantitatively evaluate the fracturing capacity of CBM reservoirs, providing guidance for the feasibility of supercritical CO2 fracturing in deep CBM reservoirs.

[0003] The study of the supercritical CO2 fracturing capability of deep coalbed methane reservoirs involves multiple factors, including geological structure, coalbed methane reservoir properties, and the development characteristics of the caprock. Influenced by complex geological conditions, it is necessary not only to qualitatively assess the geological factors affecting supercritical CO2 fracturing but also to quantitatively study the fracturing conditions of coalbed methane reservoirs, thereby enabling targeted fracturing operations. Currently, a large number of coalbed methane wells have been constructed in my country, but many have poor gas production, influenced by both geological conditions and construction techniques. Effectively assessing the supercritical CO2 fracturing capability of deep coalbed methane reservoirs before production is beneficial for guiding fracturing operations. Summary of the Invention

[0004] (a) Technical problems to be solved

[0005] To address the shortcomings of existing technologies, this invention provides a method for evaluating the supercritical CO2 fracturing capability of deep coalbed methane reservoirs. This method overcomes the lack of evaluation methods for the supercritical CO2 fracturing capability of deep coalbed methane reservoirs. It involves using geological factors and the mechanical properties of coalbed methane reservoirs, combined with qualitative and quantitative analysis methods, to analyze the occurrence characteristics and influencing factors of coalbed methane reservoirs, establish an evaluation system for the supercritical CO2 fracturing capability of deep coalbed methane reservoirs, and comprehensively analyze and judge whether deep coalbed methane reservoirs possess supercritical CO2 fracturing capability.

[0006] (II) Technical Solution

[0007] To achieve the above objectives, the present invention provides the following technical solution: a method for evaluating the fracturing capability of supercritical CO2 in deep coalbed methane reservoirs, comprising the following steps:

[0008] S1: Assessment of the geological environment of coalbed methane reservoirs;

[0009] S2: Structural and geological environment analysis of coalbed methane reservoirs;

[0010] S3: Geological borehole logging and lithological analysis;

[0011] S4: Analysis of the mechanical properties of coalbed methane reservoirs and their top and bottom plates;

[0012] S5: Experimental analysis of the characteristics and effects of supercritical CO2 fracturing in coalbed methane reservoirs;

[0013] S6: Comprehensive analysis and evaluation of the fracturing capability of coalbed methane reservoirs.

[0014] Preferably, the specific process of S1 is as follows: investigate the distribution characteristics of coalbed methane reservoirs in geological bodies, obtain the distribution characteristics of coalbed methane reservoirs, aquifers and top and bottom plates based on seismic data, and analyze the depositional environment of coalbed methane reservoirs.

[0015] Preferably, the seismic data consists of extracted seismic attribute parameters, including four seismic attributes: mean peak amplitude, amplitude kurtosis, maximum absolute amplitude, and instantaneous frequency slope. The seismic data serves as the basic parameter for predicting coal seam thickness.

[0016] Preferably, the distribution characteristics of the coalbed methane reservoir in the geological body include the thickness of the coalbed methane reservoir, the undulation characteristics of the coalbed methane reservoir, the thickening and pinch-out of the coalbed methane reservoir, the existence relationship of multiple coalbed methane reservoirs in the coal-bearing strata, and the distribution characteristics of the coalbed methane reservoir, aquifer, and top and bottom plates, including the distance between different aquifers and the coalbed methane reservoir, the recharge, runoff, and discharge characteristics of the aquifer, and its conduction relationship with the coalbed methane reservoir.

[0017] Preferably, the specific process of step S2 is as follows: based on three-dimensional seismic data and surface geological survey, study the distribution characteristics of geological structures such as faults, folds and collapse columns in the area where the coalbed methane reservoir is located, identify the spatial distribution patterns of different types of structures and their impact on the preservation and dissipation of coalbed methane; identify the distribution characteristics of geostress in the study area, obtain the distribution characteristics and variation patterns of vertical principal stress and horizontal principal stress, and analyze the impact of geostress on the layout of coalbed methane well network.

[0018] Preferably, the specific process of step S3 is as follows: Analyze the lithological characteristics of the coalbed methane reservoir strata using geological borehole logging data to obtain the sedimentary environment of the coalbed methane reservoir, including terrestrial and marine sedimentary environments; analyze the strata fragmentation characteristics; classify the coalbed methane reservoir structure and the top and bottom rock structures; classify the coal body structure into primary structure coal, fractured coal, granular coal, and mylonite; classify the rock structure into integral massive structure, layered structure, fractured structure, and loose structure; analyze the fragmentation characteristics of the coalbed methane reservoir and its top and bottom plates using geological borehole core data; classify the integrity of the coalbed methane reservoir structure and the top and bottom rocks; and evaluate the structural characteristics of the coal-bearing strata.

[0019] Preferably, the specific process of step S4 is as follows: Using geological borehole coring, the mechanical parameters of coalbed methane reservoir and roof / floor samples are tested indoors to quantitatively analyze the brittleness characteristics of the coalbed methane reservoir, including the compressive strength, tensile strength, elastic modulus, and Poisson's ratio of the coalbed methane reservoir and its roof / floor. The brittleness index of the coalbed methane reservoir and its roof / floor is calculated, wherein the formula for calculating the brittleness index is:

[0020]

[0021] In the formula: E is the elastic modulus, in GPa; μ is Poisson's ratio, dimensionless; B RIT The brittleness index, expressed as a percentage, is used to determine the supercritical CO2 fracturing capability of deep coalbed methane reservoirs.

[0022] Preferably, the specific process of step S5 is as follows: conduct indoor supercritical CO2 fracturing on geological borehole reservoir samples under simulated original rock stress conditions, and perform quantitative testing and analysis on the fracturing effect. If the permeability after supercritical CO2 fracturing under the same volume stress conditions is ≥20 times the permeability before fracturing, it is determined whether the sample is fracturable.

[0023] Preferably, the specific process of step S6 is as follows: combining steps S1-S5 to conduct a comprehensive factor analysis, clarify the influence and weight of different geological and mechanical factors on the fracturing capability of supercritical CO2, and comprehensively evaluate the fracturing capability of deep coalbed methane reservoirs with supercritical CO2.

[0024] (III) Beneficial Effects

[0025] This invention provides a method for evaluating the supercritical CO2 fracturing capability of deep coalbed methane reservoirs. Compared with existing technologies, it has the following advantages: This method for evaluating the supercritical CO2 fracturing capability of deep coalbed methane reservoirs includes the following steps: S1 Assessment of the geological environment of the coalbed methane reservoir; S2 Analysis of the structural geological environment of the coalbed methane reservoir; S3 Geological drilling logging and lithological analysis; S4 Analysis of the mechanical properties of the coalbed methane reservoir and its top and bottom plates; S5 Experimental analysis of the supercritical CO2 fracturing characteristics and effects of the coalbed methane reservoir; S6 Comprehensive analysis and evaluation of the fracturing capability of the coalbed methane reservoir. Based on the geological environment and mechanical characteristics of the coalbed methane reservoir, this invention constructs a method for evaluating whether a coalbed methane reservoir possesses fracturing capability, realizing a quantitative evaluation of the supercritical CO2 fracturing capability of coalbed methane reservoirs. This is of great significance for selecting fracturing and permeability enhancement areas for coalbed methane reservoirs and reducing drilling fracturing risks. Attached Figure Description

[0026] Figure 1 This is a flowchart of the present invention. Detailed Implementation

[0027] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. 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.

[0028] Please see Figure 1 The present invention provides three technical solutions: a method for evaluating the fracturing capability of supercritical CO2 in deep coalbed methane reservoirs, specifically including the following embodiments:

[0029] Example 1: A method for evaluating the fracturing capability of supercritical CO2 in deep coalbed methane reservoirs, comprising the following steps:

[0030] S1: Assessment of the geological environment of coalbed methane reservoirs;

[0031] S2: Structural and geological environment analysis of coalbed methane reservoirs;

[0032] S3: Geological borehole logging and lithological analysis;

[0033] S4: Analysis of the mechanical properties of coalbed methane reservoirs and their top and bottom plates;

[0034] S5: Experimental analysis of the characteristics and effects of supercritical CO2 fracturing in coalbed methane reservoirs;

[0035] S6: Comprehensive analysis and evaluation of the fracturing capability of coalbed methane reservoirs.

[0036] In this embodiment of the invention, the specific process of step S1 is as follows: investigate the distribution characteristics of coalbed methane reservoirs in geological bodies, obtain the distribution characteristics of coalbed methane reservoirs, aquifers and top and bottom plates based on seismic data, and analyze the depositional environment of coalbed methane reservoirs.

[0037] In this embodiment of the invention, the seismic data in step S1 mainly consists of extracted seismic attribute parameters, including four seismic attributes: average peak amplitude, amplitude kurtosis, maximum absolute amplitude, and instantaneous frequency slope, which serve as basic parameters for predicting coal seam thickness.

[0038] In this embodiment of the invention, the spatial distribution characteristics of the coal seam in step S1 include the thickness of the coalbed methane reservoir, the undulation characteristics of the coalbed methane reservoir, the thickening and pinch-out of the coalbed methane reservoir, and the relationship between the distribution of multiple coalbed methane reservoirs in coal-bearing strata. The distribution characteristics of the coalbed methane reservoir, aquifer, and roof and floor include the distance between different aquifers and the coalbed methane reservoir, the recharge, runoff, and discharge characteristics of the aquifer, and its conductivity with the coalbed methane reservoir.

[0039] If a coalbed methane reservoir has a burial depth exceeding 1500 meters, a thickness greater than 0.5 meters, and a gentle undulation, with undeveloped roof fractures and good sealing properties, then the coalbed methane reservoir is suitable for the implementation of supercritical CO2 fracturing technology. The supercritical CO2 fracturing capability of the deep coalbed methane reservoir can be further evaluated according to S2 to S6.

[0040] Example 2: The technical solution that differs from Example 1 in this embodiment is that the specific process of step S2 is as follows: Based on three-dimensional seismic data and surface geological survey, the distribution characteristics of geological structures such as faults, folds and collapse columns in the area where the coalbed methane reservoir is located are studied to identify the spatial distribution patterns of different types of structures and their impact on the preservation and dissipation of coalbed methane; the distribution characteristics of geostress in the study area are identified to obtain the distribution characteristics and variation patterns of vertical principal stress and horizontal principal stress, and the impact of geostress on the layout of coalbed methane well network is analyzed.

[0041] If the area where the coalbed methane reservoir is located contains unsealed faults, synclinal folds, or collapse columns that affect the preservation and dissipation of coalbed methane, then it does not possess supercritical CO2 fracturing capability.

[0042] If there are no geological structures in the area where the coalbed methane reservoir is located that affect the preservation and dissipation of coalbed methane, then the supercritical CO2 fracturing capability evaluation of the deep coalbed methane reservoir can continue based on S3-S6.

[0043] In this embodiment of the invention, step S3 specifically involves analyzing the lithological characteristics of the coalbed methane reservoir strata using geological borehole logging data to obtain the sedimentary environment of the coalbed methane reservoir, including terrestrial and marine sediments. The analysis includes identifying the strata fragmentation characteristics, classifying the coalbed methane reservoir structure and the top and bottom rock structures, classifying the coal body structure into primary structure coal, fractured coal, granular coal, and mylonite, and classifying the rock structure into integral massive structure, layered structure, fragmented structure, and loose structure. Geological borehole core data is used to analyze the fragmentation characteristics of the coalbed methane reservoir and its top and bottom rocks, classifying the reservoir structure and the integrity of the top and bottom rocks, and assessing the structural characteristics of the coal-bearing strata.

[0044] If the overlying strata in the area where the coalbed methane reservoir is located have a fractured or loose structure that affects the preservation and dissipation of coalbed methane, then it does not have supercritical CO2 fracturing capability; if the coal body in the area where the coalbed methane reservoir is located is fine coal or mylonite, then it also does not have supercritical CO2 fracturing capability.

[0045] If the overlying strata in the area where the coalbed methane reservoir is located have an intact structure and a weak impact on the preservation and dissipation of coalbed methane, and the coal body structure of the reservoir is either structural coal or fragmented coal, then the supercritical CO2 fracturing capability evaluation of the deep coalbed methane reservoir can continue to be carried out based on S4 to S6.

[0046] Example 3: The technical difference between this embodiment and Example 2 lies in the following: Step S4 involves using geological borehole coring to test the mechanical parameters of coalbed methane reservoir and roof / floor samples in the laboratory. This allows for a quantitative analysis of the brittleness characteristics of the coalbed methane reservoir, including compressive strength, tensile strength, elastic modulus, and Poisson's ratio of the reservoir and its roof / floor. The brittleness index of the coalbed methane reservoir and its roof / floor is then calculated, using the following formula:

[0047]

[0048] Where: E—elastic modulus, GPa;

[0049] μ — Poisson's ratio, dimensionless;

[0050] B RIT —Fragility index, %.

[0051] The fracturing capability of supercritical CO2 in deep coalbed methane reservoirs is determined based on the brittleness index values ​​in Table 1.

[0052] Table 1. Criteria for Determining the Fracturability of Supercritical CO2 in Deep Coalbed Methane Reservoirs

[0053]

[0054] If the brittleness index of the coalbed methane reservoir is >30, the supercritical CO2 fracturing capability of the deep coalbed methane reservoir can be evaluated further based on S5 to S6.

[0055] In this embodiment of the invention, step S5 specifically involves conducting indoor supercritical CO2 fracturing on geological borehole reservoir samples under simulated original rock stress conditions, and quantitatively testing and analyzing the fracturing effect. Based on the permeability after supercritical CO2 fracturing under the same volume stress conditions being ≥20 times the permeability before fracturing, it is determined whether the sample is fracturable.

[0056] If the permeability of a coalbed methane reservoir sample after supercritical CO2 fracturing is ≥20 times the permeability before fracturing, then the supercritical CO2 fracturing capability evaluation of the deep coalbed methane reservoir can continue according to S6.

[0057] In this embodiment of the invention, step S6 specifically involves conducting a comprehensive factor analysis in conjunction with S1-S5 to clarify the influence and weights of different geological and mechanical factors on the fracturing capability of supercritical CO2, and to comprehensively evaluate the fracturing capability of deep coalbed methane reservoirs using supercritical CO2.

[0058] The following case study illustrates the fracturing feasibility assessment of a location in a deep coalbed methane block where supercritical CO2 fracturing is planned:

[0059] S1: The coalbed methane reservoir is buried at a depth of 1800 meters, with a thickness of 3.0 meters. The reservoir has gentle undulations, minimal thickness variation, and no aquifer above it. The roof is composed of 5-meter-thick mudstone, exhibiting good sealing properties and supercritical CO2 fracturing capability.

[0060] S2. Based on 3D seismic data and surface geological surveys, the area where the coalbed methane reservoir is located has no normal faults, non-synclinal structures, or collapse columns that would affect the preservation and dissipation of coalbed methane. The maximum principal stress in the area is 43.6° north of east, with a maximum principal stress of approximately 45 MPa. The vertical stress is approximately 32 MPa, and the minimum horizontal stress is approximately 21 MPa, indicating that the area possesses supercritical CO2 fracturing capability.

[0061] S3. Geological borehole logging data analysis shows that the sedimentary environment of the coalbed methane reservoir is terrestrial sedimentary. The strata are relatively intact, the coal body structure is primary structure coal, and the overlying rock structure is layered. The overall structure of the reservoir and the top and bottom rocks is relatively intact, and it has supercritical CO2 fracturing capability.

[0062] S4. Using geological borehole coring, laboratory tests were conducted on the mechanical parameters of the coalbed methane reservoir: compressive strength 8.0 MPa, tensile strength 1.0 MPa, elastic modulus 2.0 GPa, and Poisson's ratio 0.25. The brittleness index of the coalbed methane reservoir was calculated using the following formula:

[0063]

[0064] The fracturing capability of supercritical CO2 in deep coalbed methane reservoirs is determined based on the brittleness index values ​​in Table 1.

[0065] Quantitative calculations show that this deep coalbed methane reservoir possesses supercritical CO2 fracturing capability.

[0066] S5. Indoor supercritical CO2 fracturing was carried out on geological borehole reservoir samples under simulated original rock stress conditions. Under the same volume stress conditions, the permeability after supercritical CO2 fracturing was 120 mD, and the permeability before fracturing was 5.5 mD. The permeability after supercritical CO2 fracturing was 21.82 times that before fracturing, indicating that it has supercritical CO2 fracturing capability.

[0067] S6. Combining the influence and weights of different geological and mechanical factors in S1-S5 on the fracturing capability of supercritical CO2, a comprehensive evaluation is made to determine whether deep coalbed methane reservoirs possess supercritical CO2 fracturing capability.

[0068] In summary, this invention constructs a method for evaluating the fracturability of coalbed methane reservoirs based on their geological environment and mechanical characteristics. This method enables a quantitative evaluation of the supercritical CO2 fracturability of coalbed methane reservoirs, which is of great significance for selecting fracturing and permeability enhancement areas for coalbed methane reservoirs and reducing drilling fracturing risks.

[0069] Furthermore, any content not described in detail in this specification is existing technology known to those skilled in the art.

[0070] It should be noted that, in this document, relational terms such as "first" and "second" are used only 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 process, method, article, or apparatus.

[0071] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A method for evaluating the fracturing capability of supercritical CO2 in deep coalbed methane reservoirs, characterized in that: Includes the following steps: S1: Evaluation of the geological environment of coalbed methane reservoir: If the coalbed methane reservoir is buried at a depth of more than 1500 meters, has a thickness of more than 0.5m, and has a gentle undulation, with no developed roof fractures and a sealing property, then the coalbed methane reservoir is suitable for the implementation of supercritical CO2 fracturing technology. Continue to evaluate the supercritical CO2 fracturing capability of the deep coalbed methane reservoir according to S2-S6. S2: Structural geological environment analysis of coalbed methane reservoir: If there are no geological structures in the area where the coalbed methane reservoir is located that affect the preservation and escape of coalbed methane, the supercritical CO2 fracturing capability evaluation of the deep coalbed methane reservoir can continue based on S3-S6. S3: Geological borehole logging and lithological analysis: If the overlying strata in the area where the coalbed methane reservoir is located have an intact structure and a weak impact on the preservation and dissipation of coalbed methane, and the coal body structure of the reservoir is raw structured coal or fragmented coal, then continue to evaluate the supercritical CO2 fracturing capability of the deep coalbed methane reservoir according to S4-S6. S4: Mechanical Properties Analysis of Coalbed Methane Reservoirs and Their Top and Bottom Plates: Using geological borehole core samples, the mechanical parameters of coalbed methane reservoir and top and bottom plate samples were tested in the laboratory. A quantitative analysis of the brittleness characteristics of the coalbed methane reservoir was conducted, including the compressive strength, tensile strength, elastic modulus, and Poisson's ratio of the coalbed methane reservoir and its top and bottom plates. The brittleness index of the coalbed methane reservoir and its top and bottom plates was calculated. The formula for calculating the brittleness index is as follows: ； In the formula: E This is the elastic modulus, expressed in GPa. μ Poisson's ratio; The brittleness index is expressed as a percentage. The fracturing capability of supercritical CO2 in deep coalbed methane reservoirs is determined based on the calculated brittleness index value. S5: Experimental analysis of the characteristics and effects of supercritical CO2 fracturing in coalbed methane reservoirs: Indoor supercritical CO2 fracturing was carried out on geological borehole reservoir samples under simulated original rock stress conditions, and the fracturing effect was quantitatively tested and analyzed. Based on the permeability after supercritical CO2 fracturing under the same volume stress conditions being ≥20 times the permeability before fracturing, it was determined whether the reservoir was fracturable. S6: Comprehensive analysis and evaluation of the fracturing capability of coalbed methane reservoirs: Combine steps S1-S5 to conduct a comprehensive factor analysis, clarify the influence and weight of different geological and mechanical factors on the fracturing capability of supercritical CO2, and comprehensively evaluate the fracturing capability of deep coalbed methane reservoirs with supercritical CO2.

2. The method for evaluating the supercritical CO2 fracturing capability of deep coalbed methane reservoirs according to claim 1, characterized in that: The specific process of S1 is as follows: investigate the distribution characteristics of coalbed methane reservoirs in geological bodies, obtain the distribution characteristics of coalbed methane reservoirs, aquifers and top and bottom plates based on seismic data, and analyze the sedimentary environment of coalbed methane reservoirs.

3. The method for evaluating the supercritical CO2 fracturing capability of deep coalbed methane reservoirs according to claim 2, characterized in that: The seismic data consists of extracted seismic attribute parameters, including four seismic attributes: mean peak amplitude, amplitude kurtosis, maximum absolute amplitude, and instantaneous frequency slope. The seismic data serves as the basic parameter for predicting coal seam thickness.

4. The method for evaluating the supercritical CO2 fracturing capability of deep coalbed methane reservoirs according to claim 2, characterized in that: The distribution characteristics of coalbed methane reservoirs in geological bodies include coalbed methane reservoir thickness, coalbed methane reservoir undulation characteristics, coalbed methane reservoir thickening and pinch-out, the existence relationship of multiple coalbed methane reservoirs in coal-bearing strata, and the distribution characteristics of coalbed methane reservoirs, aquifers, and top and bottom plates, including the distance between different aquifers and coalbed methane reservoirs, the recharge, runoff, and discharge characteristics of aquifers, and their conduction relationship with coalbed methane reservoirs.

5. The method for evaluating the supercritical CO2 fracturing capability of deep coalbed methane reservoirs according to claim 1, characterized in that: The specific process of step S2 is as follows: Based on three-dimensional seismic data and surface geological survey, study the distribution characteristics of faults, folds and collapse columns in the area where the coalbed methane reservoir is located, identify the spatial distribution patterns of different types of structures and their impact on the preservation and dissipation of coalbed methane; identify the distribution characteristics of geostress in the study area, obtain the distribution characteristics and variation patterns of vertical principal stress and horizontal principal stress, and analyze the impact of geostress on the layout of coalbed methane well network.

6. The method for evaluating the supercritical CO2 fracturing capability of deep coalbed methane reservoirs according to claim 1, characterized in that: The specific process of step S3 is as follows: Analyze the lithological characteristics of the coalbed methane reservoir strata using geological borehole logging data, obtain the sedimentary environment of the coalbed methane reservoir, including terrestrial and marine sediments, analyze the strata fragmentation characteristics, classify the coalbed methane reservoir structure and the top and bottom rock structures, classify the coal body structure into primary structure coal, fractured coal, granular coal and mylonite, and classify the rock structure into integral massive structure, layered structure, fractured structure and loose structure, analyze the fragmentation characteristics of the coalbed methane reservoir and its top and bottom plates using geological borehole core data, classify the integrity of the coalbed methane reservoir structure and the top and bottom rocks, and evaluate the structural characteristics of the coal-bearing strata.

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