Coal seam gas differential occurrence main control geological factor analysis method

Abstract

This invention belongs to the field of coal seam gas control technology. It relates to a method for analyzing the main controlling geological factors of differential coal seam gas occurrence. The method selects the main mineable coal seams in a coal mining area or the entire mine as the target coal seams for analysis and comparison. Mines or geological units within the mining area with consistent or similar coal seam gas occurrence conditions and patterns are divided into gas occurrence units. Based on the key characterization parameters corresponding to each coal seam gas occurrence capacity type obtained through measurement and calculation, and the characterization principles corresponding to the key characterization parameters and coal seam gas occurrence capacity types, the coal seam gas occurrence capacity types of each gas occurrence unit are qualitatively classified from strong to weak. This yields the main controlling capacity type of the current gas occurrence status in each gas occurrence unit. Based on the influencing geological factors corresponding to the main controlling capacity type and the corresponding influence principles between the influencing geological factors and the main controlling capacity type, digital chart analysis is performed to clarify the main controlling geological factors of the main controlling capacity type. This provides a basis for gas control and enables precise and efficient management of differential coal seam gas occurrence.

Description

Technical Field

[0001] This invention belongs to the field of coalbed methane control technology and relates to a method for analyzing the main controlling geological factors of differential occurrence of coalbed methane. Background Technology

[0002] Coal is one of my country's most important energy minerals. Coalbed methane, a byproduct of coal formation, poses a serious threat to safe and efficient mine production and the lives of frontline coal miners due to frequent methane disasters. Therefore, a series of industry regulations, standards, and norms, such as the "Interim Provisions on Coal Mine Methane Drainage Standards," require coal mining enterprises to strive for proactive coalbed methane control to ensure safe and efficient mine production.

[0003] Based on field production experience, there are often significant differences in coal seam gas occurrence between different mines or geological units within a mining area, and between different geological units or regions within a single mine. However, current mines generally adopt advanced drilling extraction for coal seam gas control, supplemented by hydraulic permeability enhancement measures such as hydraulic fracturing, hydraulic slotting, and hydraulic perforation. Targeted gas control measures based on the characteristics of coal seam gas occurrence differences between different mines or geological units within a mining area, or between different geological units or regions within a single mine, are rarely implemented. This results in a certain degree of blindness in current coal seam gas control. This is because the differences in coal seam gas occurrence between different mines or geological units within a mining area, or between different geological units or regions within a single mine, are controlled by one or more of their different generation, storage, and sealing capacities. The stronger the generation, storage, and sealing capacities, the higher the coal seam gas content and gas pressure.

[0004] Coalbed methane is formed during the geological and thermal evolution of coal seams and is stored in the pores and fissures of the coal seams in both adsorbed and free states. Its generation, storage, dissipation, and sealing are all controlled by geological structures and evolutionary processes, and are mainly reflected in many geological factors such as coalification stage, burial depth, coal seam thickness, surrounding rock lithology and thickness, coal and rock composition, magma intrusion, coal body structure, tectonic stress (geothermal stress), coal seam occurrence, structure, and pore structure. These factors mainly determine the generation capacity, storage capacity, and sealing capacity of coalbed methane.

[0005] In conclusion, to achieve precise and efficient control of coal seam gas in mines, it is necessary to accurately grasp the differential occurrence patterns and controlling capabilities of coal seam gas, thereby identifying the dominant geological factors that determine its differential occurrence and controlling capabilities, and then adopting scientific and targeted gas control measures for different gas occurrence units. Summary of the Invention

[0006] In view of this, this invention proposes a method for analyzing the main controlling geological factors of differential occurrence of coal seam gas, which clearly understands the differential occurrence law of coal seam gas and its main controlling capacity, and further clarifies the main controlling geological factors that determine its differential occurrence control capacity. Then, scientific and targeted gas control measures can be taken for different gas occurrence units, avoiding the blind selection of coal seam gas control measures, and achieving precise and efficient control of coal seam gas through a "targeted approach".

[0007] To achieve the above objectives, the present invention provides the following technical solution: A method for analyzing the main controlling geological factors of differential occurrence of coal seam gas includes the following steps: S1. Select the main mineable coal seams in the coal mining area or the entire mine area as the target coal seams for analysis and comparison. Divide mines or geological units in the mining area with consistent or similar coal seam gas occurrence and occurrence patterns into a gas occurrence unit. S2. Based on the key characterization parameters corresponding to the gas occurrence capacity types of each coal seam obtained by measurement and calculation, and the characterization principles corresponding to the key characterization parameters and the gas occurrence capacity types of each coal seam, compare the gas occurrence capacity types of the same coal seam in each gas occurrence unit to obtain the relative strength relationship of the same coal seam gas occurrence capacity types among each gas occurrence unit, and make a qualitative classification from strong to weak according to the strength level. Coal seam gas occurrence capacity types include generation capacity S a Storage capacity C a Storage capacity F a Among them, the storage capacity F a Including the coal seam's own storage capacity F am Top plate sealing capacity F at Base plate sealing capacity F ab Fracture-resistant storage capability F af Path sealing capability F al ; S3. Based on the principle that the stronger the generation capacity, the stronger the storage capacity, the stronger the sealing capacity, the higher the coal seam gas content or coal seam gas pressure, and based on the coal seam gas content or coal seam gas pressure level of each unit coal seam, comprehensively analyze and judge the main control capacity type of the gas occurrence status of each unit coal seam. Among them, the coal seam gas occurrence capacity type with the strongest intensity is the main control capacity, thereby obtaining the main control capacity type of the gas occurrence status of each gas occurrence unit. S4. Based on the influencing geological factors corresponding to the main control capacity type of each gas occurrence unit obtained by measurement, calculation, statistics and analysis, and the principle of the corresponding influence of the influencing geological factors and the main control capacity type of the gas occurrence unit, digital chart analysis is carried out. The geological factors whose distribution characteristics in the curves of various geological factors in each gas occurrence unit are consistent with the distribution characteristics of the curves of the corresponding main control capacity type are the main control geological factors of the main control capacity type of the gas occurrence unit.

[0008] Furthermore, in step S2, Generation capability S a Key characterization parameters include maximum vitrinite reflectance R. o（max） Volatile matter content V daf The coalification stage is characterized by R. o（max） The larger, V daf The smaller the size and the higher the coalification stage, the stronger the Sa generation capacity; Storage capacity C a Key characterization parameters include adsorption constants a and b. The characterization principle is that the larger the adsorption constant a and the smaller the adsorption constant b, the greater the storage capacity C. a The stronger; Coal seam self-storage capacity F am Key characterization parameters include the coal seam permeability coefficient λ and the coal seam normal thickness M. m The characterization principle is that the smaller λ is, the better M is. m The larger the coal seam, the greater its self-storage capacity F. am The stronger the value, the more λ is used as the primary characterization parameter. Top plate sealing capacity F at The key characterization parameter is the normal permeability φ of the immediate roof strata. t The characterization principle is φ t The smaller the value, the greater the top plate storage capacity F. at The stronger; Base plate sealing capacity F ab The key characterization parameter is the normal permeability φ of the direct base strata. b The characterization principle is φ b The smaller the size, the better the base plate storage capacity F. ab The stronger; Fracture storage capability F af The key characterization parameter is the open-conductivity ground fracture density ρ. The characterization principle is that the smaller ρ is, the greater the fracture storage capacity F. af The stronger; Path sealing capability F al The key characterization parameter is the maximum vertical gas escape path length L. v The characterization principle is the length L of the maximum vertical gas escape path. v The larger the value, the greater the path sealing capability F. al The stronger.

[0009] Furthermore, the qualitative classification principle is as follows: When the distribution of the corresponding coal seam gas occurrence capacity type among the gas occurrence units is consistent or similar, it is classified as "equivalent"; When the distribution of the corresponding coal seam gas occurrence capacity type among the gas occurrence units shows two levels, it is divided into "relatively strong" and "relatively weak". When the distribution of the corresponding coal seam gas occurrence capacity type among the gas occurrence units shows three levels, it is divided into "relatively strong", "medium" and "relatively weak". When the distribution of the corresponding coal seam gas occurrence capacity type among the gas occurrence units shows four levels, it is divided into "strong", "relatively strong", "relatively weak" and "weak". When the distribution of the corresponding coal seam gas occurrence capacity type among the gas occurrence units shows five levels, it is divided into "strong", "relatively strong", "medium", "relatively weak" and "weak". When the distribution of the corresponding coal seam gas occurrence capacity type among the gas occurrence units shows six levels, it is divided into "strongest", "strong", "relatively strong", "relatively weak", "weak" and "weakest". When the distribution of the corresponding coal seam gas occurrence capacity type among the gas occurrence units shows seven levels, it is divided into "strongest", "strong", "relatively strong", "medium", "relatively weak", "weak" and "weakest". Among them, the number of horizontal divisions is less than or equal to the number of gas storage units.

[0010] Furthermore, in step S4, the capability S is generated. a The influencing geological factors include tectonic compressive stress, magma intrusion, and the maximum historical burial depth of the coal seam. The principle of influence is that the greater the tectonic compressive stress, the greater the magma intrusion, and the greater the maximum historical burial depth of the coal seam, the stronger the generation capacity. Storage capacity C a Influencing geological factors include organic matter content, inert content in micro-coal and petrographic components, coalification stage, pore structure, and coal body structure type. Among these, pore structure includes the volume of small pores and micropores and specific surface area. The influencing principle is that the greater the organic matter content, the greater the inert content, the greater the coalification stage, the greater the volume of small pores and micropores, the greater the specific surface area of ​​small pores and micropores, and the greater the coal body structure type, the stronger the storage capacity. Coal seam self-storage capacity F am The influencing geological factors include coal seam thickness, tectonic compressive stress, the content of vitreous coal and bright coal in the macroscopic coal and petrographic components, the pore volume of macropores and mesopores in the pore structure, the coal body structure type, and the burial depth. The influencing principle is that the greater the coal seam thickness, the greater the tectonic compressive stress, the greater the content of vitreous coal and bright coal, the greater the pore volume of macropores and mesopores, the greater the coal body structure type, and the greater the burial depth, the stronger the coal seam's own sealing capacity. Top plate sealing capacity F at The influencing geological factors include roof lithology, tectonic compressive stress, and burial depth. The principle is that the greater the lithology, the greater the tectonic compressive stress, and the greater the burial depth, the stronger the roof sealing capacity. Base plate sealing capacity F ab The influencing geological factors include the lithology of the base plate, the tectonic compressive stress, and the burial depth. The principle is that the greater the lithology, the greater the tectonic compressive stress, and the greater the burial depth, the stronger the base plate sealing capacity. Fracture storage capability F af The influencing geological factors include tectonic compressive stress, and the principle is that the greater the tectonic compressive stress, the stronger the fracture sealing capacity. Path sealing capability F al The influencing geological factors include the coal seam burial depth, and the principle is that the greater the coal seam burial depth, the stronger the path sealing capacity. Furthermore, the textual values ​​of roof and floor lithology, coal body structure type, and magma intrusion were converted into digital values. The correspondence between roof and floor lithology values ​​is shown in Table 1, the correspondence between coal body structure type values ​​is shown in Table 2, and the correspondence between magma intrusion values ​​is shown in Table 3. Table 1. Correspondence between lithological values ​​of the top and bottom plates

[0011] Table 2. Correspondence between numerical values ​​for coal body structure types

[0012] Table 3. Correspondence between numerical values ​​of magma intrusion

[0013] Using the gas storage unit as the x-axis and the generation capacity S as the y-axis... a An analytical chart was established with the geological factors influencing the formation capacity, namely tectonic compressive stress, magmatic intrusion, and the maximum historical burial depth of the coal seam, as the vertical axis. The formation capacity S was used as the vertical axis. a As the analytical standard, the geological factors influencing the generation capacity, namely tectonic compressive stress, magma intrusion, and the historical maximum burial depth of the coal seam, are taken as the analysis objects. The effects of tectonic compressive stress, magma intrusion, and the historical maximum burial depth of the coal seam on the generation capacity S of each gas-bearing unit are analyzed unit by unit. a Geological factors whose distribution characteristics in the geological factor curves are consistent with those in the generation capacity curves are the main controlling geological factors of generation capacity. Using gas storage units as the x-axis and storage capacity C as the y-axis... a An analytical chart was established with the following parameters as the vertical axis: organic matter content, inert group content, coalification stage, pore volume of small and micropores, specific surface area of ​​small and micropores, and coal body structure type. The chart uses the storage capacity (C) as the vertical axis. aAs the analytical standard, the storage capacity was analyzed based on the geological factors influencing it, including organic matter content, inertinite content, coalification stage, pore volume (both small and micropores), specific surface area (both small and micropores), and coal body structure type. The impact of these factors on the storage capacity (C) of each gas-bearing unit was analyzed unit by unit. a Geological factors whose distribution characteristics in the geological factor curves are consistent with those in the storage capacity curves are the main controlling geological factors of storage capacity. Using the gas occurrence unit as the x-axis and the coal seam's own sequestration capacity F as the y-axis... am An analytical chart was established with the following influencing geological factors on the coal seam's self-sealing capacity: coal seam thickness, tectonic compressive stress, vitreous coal + bright coal content, macropore + mesopore volume, coal body structure type, and burial depth as the vertical axis. The chart uses the coal seam's self-sealing capacity F as the vertical axis. am As the analytical standard, the geological factors influencing the self-sealing capacity of coal seams—coal seam thickness, tectonic compressive stress, vitreous coal + bright coal content, macro- and meso-pore volume, coal body structure type, and burial depth—are analyzed unit by unit, focusing on their impact on the self-sealing capacity F of each unit coal seam. am Geological factors whose distribution characteristics in the various geological factor curves are consistent with the distribution characteristics of the coal seam's own sealing capacity curve are the main controlling geological factors of the coal seam's own sealing capacity. Using the gas storage unit as the horizontal axis and the roof sealing capacity F as the vertical axis... at and top plate sealing capacity F at Using the corresponding influencing geological factors—lithology, tectonic compressive stress, and burial depth—as the vertical axis, an analytical chart is established, with the roof sealing capacity F as the key indicator. at As the analytical standard, the geological factors influencing the roof sealing capacity Fat—lithology, tectonic compressive stress, and burial depth—are taken as the analysis objects. The effects of lithology, tectonic compressive stress, and burial depth on the roof sealing capacity Fat of each unit are analyzed unit by unit. at Geological factors whose distribution characteristics in the geological factor curves are consistent with the distribution characteristics of the roof storage capacity curve are the main controlling geological factors of roof storage capacity. Using the gas storage unit as the horizontal axis and the bottom plate sealing capacity F as the vertical axis... ab and bottom plate sealing capacity F ab Using the corresponding influencing geological factors—lithology, tectonic compressive stress, and burial depth—as the vertical axis, an analytical chart is established, with the bottom plate's sealing capacity F as the key indicator. ab As the analytical standard, the base plate sealing capacity F is used. ab The analysis focuses on the geological factors influencing lithology, tectonic compressive stress, and burial depth, analyzing the impact of lithology, tectonic compressive stress, and burial depth on the sealing capacity F of the bottom plate in each unit. abGeological factors whose distribution characteristics in the geological factor curves are consistent with those in the basement storage capacity curve are the main controlling geological factors of basement storage capacity. Using the gas storage unit as the x-axis and the fracture sealing capacity F as the y-axis... af and fracture preservation capability F af An analytical chart was established using the corresponding influencing geological factors, such as tectonic compressive stress, as the vertical axis. The chart also included the fracture retention capacity F. af As the analytical standard, the fracture storage capacity F is used. af Taking the tectonic compressive stress, a geological factor influencing the analysis, as the object of analysis, the effect of tectonic compressive stress on the fracture retention capacity F of each unit is analyzed unit by unit. af Geological factors whose distribution characteristics in the geological factor curves are consistent with those in the fault sealing capacity curves are the main controlling geological factors of fault sealing capacity. Using the gas storage unit as the x-axis and the path sealing capacity F as the y-axis... al and path sealing capability F al Using the coal seam burial depth as the vertical axis, an analysis chart is established, with the path sealing capacity F as the key geological factor. al As the analysis standard, the path sealing capability F is used. al The analysis focuses on the coal seam depth, a geological factor influencing the path sealing capacity (F) of each unit. al Geological factors whose distribution characteristics in the geological factor curves are consistent with those in the path sealing capacity curves are the main controlling geological factors of path sealing capacity.

[0014] The beneficial effects of this invention are as follows: This invention can quickly and clearly understand the differential occurrence patterns and main control capabilities of coal seam gas, and then determine the main geological factors that determine the main control capabilities of its differential occurrence, providing a basis for "targeted treatment" of gas control, thereby avoiding the blind selection of coal seam gas differential occurrence control measures and achieving precise and efficient control of coal seam gas differential occurrence.

[0015] Other advantages, objectives, and features of the invention will be set forth in part in the description which follows, and in part will be apparent to those skilled in the art from the following examination, or may be learned from practice of the invention. The objectives and other advantages of the invention can be realized and obtained through the following description. Attached Figure Description

[0016] To make the objectives, technical solutions, and advantages of the present invention clearer, the preferred embodiments of the present invention will be described in detail below with reference to the accompanying drawings, wherein: Figure 1 This is a statistical analysis chart of various characterization parameters of coal seam gas occurrence capacity in this invention.

[0017] Figure 2 Example of a statistical analysis chart for the various characterization parameters of the coal seam gas occurrence capacity after drawing.

[0018] Figure 3 This is an analysis chart of the geological factor curves and corresponding main control capability type curves in this invention. Detailed Implementation

[0019] The following specific examples illustrate the implementation of the present invention. Those skilled in the art can easily understand other advantages and effects of the present invention from the content disclosed in this specification. The present invention can also be implemented or applied through other different specific embodiments, and various details in this specification can be modified or changed based on different viewpoints and applications without departing from the spirit of the present invention. It should be noted that the illustrations provided in the following embodiments are only schematic representations of the basic concept of the present invention. Unless otherwise specified, the following embodiments and features can be combined with each other.

[0020] The accompanying drawings are for illustrative purposes only and are schematic diagrams, not actual pictures. They should not be construed as limiting the invention. To better illustrate the embodiments of the invention, some parts in the drawings may be omitted, enlarged, or reduced, and do not represent the actual product dimensions. It is understandable to those skilled in the art that some well-known structures and their descriptions may be omitted in the drawings.

[0021] In the accompanying drawings of the embodiments of the present invention, the same or similar reference numerals correspond to the same or similar components. In the description of the present invention, it should be understood that if terms such as "upper," "lower," "left," "right," "front," and "rear" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings, they are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, the terms used to describe positional relationships in the drawings are only for illustrative purposes and should not be construed as limiting the present invention. For those skilled in the art, the specific meaning of the above terms can be understood according to the specific circumstances.

[0022] A method for analyzing the main controlling geological factors of differential occurrence of coal seam gas includes the following steps: S1. Select the main mineable coal seams in the entire coal mining area or mine as the target coal seams for analysis and comparison. Statistically analyze the gas occurrence (original coal seam gas content or gas pressure) and occurrence patterns of coal seams in each mine or geological unit within the mining area. Divide mines or geological units with consistent or similar coal seam gas occurrence conditions and occurrence patterns into a gas occurrence unit, and number each gas occurrence unit sequentially according to the coal seam gas content or coal seam gas pressure from largest to smallest as A, B, C, D...

[0023] S2. Based on the key characterization parameters corresponding to the gas occurrence capacity types of each coal seam obtained by measurement and calculation, and the characterization principles corresponding to the key characterization parameters and the gas occurrence capacity types of each coal seam, compare the gas occurrence capacity types of the same coal seam in each gas occurrence unit to obtain the relative strength relationship of the same coal seam gas occurrence capacity types among each gas occurrence unit, and make a qualitative classification from strong to weak according to the strength level. Coal seam gas occurrence capacity types include generation capacity S a Storage capacity C a Storage capacity F a Among them, the storage capacity F a Including the coal seam's own storage capacity F am Top plate sealing capacity F at Base plate sealing capacity F ab Fracture-resistant storage capability F af Path sealing capability F al Key characterization parameters for each coal seam gas occurrence capacity type were established as shown in Table 1 below.

[0024] Table 1 Key Characterization Parameters of Coal Seam Gas Occurrence Capacity

[0025] Determine and calculate the generation capacity S of each gas storage unit. a Storage capacity C a Storage capacity F a The values ​​of the corresponding characterization parameters, including the maximum vertical gas escape path length L. v (Ignoring fractures) represents the vertical distance from the roof of the target coal seam at its maximum burial depth within the gas-bearing unit to the surface; the coalification stage must be based on the measured maximum vitrinite reflectance R. o（max） Volatile matter content V daf The classification is based on existing industry standards.

[0026] Establish each gas storage unit and its generation capacity S a Storage capacity C a Storage capacity F a The statistical analysis charts of the corresponding characterization parameters are attached. Figure 1As shown.

[0027] Based on the measured or calculated generation capacity S of each gas storage unit a Storage capacity C a Storage capacity F a The corresponding values ​​of each characterization parameter were used to create a graphical representation, as shown in the attached diagram. Figure 2 As shown.

[0028] Based on the completed drawing and the representation principles in Table 1, a horizontal and vertical comparative analysis was conducted to preliminarily clarify the generation capacity S of each gas occurrence unit. a Storage capacity C a Storage capacity F a The relative strength of each capability is determined, and the relative strength of each capability is qualitatively classified based on the actual horizontal distribution of each parameter. The specific principles of qualitative classification are as follows: (1) When the lateral distribution of gas occurrence capacity in each gas occurrence unit coal seam is consistent or similar, it is classified as “equivalent”. (2) When the lateral distribution of gas occurrence capacity in each gas occurrence unit coal seam is obviously two levels, it is divided into "relatively strong" and "relatively weak". (3) When the lateral distribution of gas occurrence capacity in each gas occurrence unit coal seam is obviously three levels, it is divided into “relatively strong”, “medium” and “relatively weak”. (4) When the lateral distribution of gas occurrence capacity in each gas occurrence unit coal seam is obviously manifested in four levels, it is divided into "strong", "relatively strong", "relatively weak" and "weak". (5) When the lateral distribution of gas occurrence capacity in each gas occurrence unit coal seam is obviously manifested in five levels, it is divided into "strong", "relatively strong", "medium", "relatively weak" and "weak". (6) When the horizontal distribution of gas occurrence capacity in each gas occurrence unit coal seam is obviously manifested in six levels, it is divided into "strongest", "strong", "relatively strong", "relatively weak", "weak" and "weakest". (7) When the horizontal distribution of gas occurrence capacity in each gas occurrence unit is clearly shown to be seven levels, it is divided into "strongest", "strong", "relatively strong", "medium", "relatively weak", "weak" and "weakest". At the same time, the number of qualitative level divisions is less than or equal to the number of gas occurrence units. Generally speaking, the number of coal seam gas difference occurrence units in coal mining areas rarely exceeds 5.

[0029] S3. Based on the principle that the stronger the generation capacity, storage capacity, and sealing capacity, the higher the coal seam gas content or pressure, and following the order of coal seam gas content or pressure from largest to smallest (Unit A → Unit B → Unit C → Unit D → …), and based on the coal seam gas content or pressure level of each unit, comprehensively analyze and determine the main control capacity type of the current status of coal seam gas differences in each unit, and fill in Table 2. Among them, those qualitatively evaluated as "strongest", "strong", or "relatively strong" are all main control capabilities.

[0030] Table 2. Classification of gas occurrence differences and analysis of the strength of each gas capacity and the type of dominant capacity in each coal seam.

[0031] S4. Based on the influencing geological factors corresponding to the main control capacity type of each gas occurrence unit obtained by measurement, calculation, statistics and analysis, and the principle of the corresponding influence of the influencing geological factors and the main control capacity type of the gas occurrence unit, digital chart analysis is carried out. The geological factors whose distribution characteristics in the curves of various geological factors in each gas occurrence unit are consistent with the distribution characteristics of the curves of the corresponding main control capacity type are the main control geological factors of the main control capacity type of the gas occurrence unit.

[0032] Establish the generation capability S as shown in Table 3 below. a Storage capacity C a Storage capacity F a Influencing geological factors.

[0033] Table 3. Influencing geological factors for various coal seam gas occurrence capacities.

[0034] Among them, the values ​​of roof and floor lithology, coal body structure type, and magma intrusion are textual values, which must be converted into digital values. The correspondence between roof and floor lithology is shown in Table 4, the correspondence between coal body structure type is shown in Table 5, and the correspondence between magma intrusion is shown in Table 6.

[0035] Table 4 Correspondence between lithological values ​​of the top and bottom plates

[0036] Table 5. Correspondence between numerical values ​​for coal body structure types

[0037] Table 6. Correspondence between numerical values ​​of magma intrusion

[0038] Using the gas storage unit as the horizontal axis (from unit A → unit B → unit C → unit D → ……), and the generation capacity S aAn analysis chart was established using the geological factors influencing the generation capacity (Sg) in Table 3 as the vertical axis, namely, tectonic compressive stress, magmatic intrusion, and the maximum historical burial depth of the coal seam. a As the analytical standard, the geological factors influencing the generation capacity, namely tectonic compressive stress, magma intrusion, and the maximum historical burial depth of the coal seam, are used as the analysis objects. The effects of tectonic compressive stress, magma intrusion, and the maximum historical burial depth of the coal seam on the generation capacity S of each unit are analyzed unit by unit (from unit A to unit B to unit C to unit D to...). a The geological factors whose distribution characteristics in the geological factor curves are consistent with those in the formation capacity curve are considered the dominant geological factors controlling the formation capacity. A schematic diagram of the analysis chart is attached. Figure 3 As shown in the figure, the distribution characteristics of the tectonic extrusion stress curve are consistent with the distribution characteristics of the formation capacity curve. Therefore, tectonic extrusion stress is the main controlling geological factor of formation capacity.

[0039] Using the gas storage unit as the horizontal axis (from unit A → unit B → unit C → unit D → ...), and the storage capacity C a The storage capacity is determined by the following geological factors in Table 3: organic matter content, inert group content, coalification stage, pore volume of small and micropores, specific surface area of ​​small and micropores, and coal body structure type. These factors are used as the vertical axis, similar to the attached table. Figure 3 Create an analysis panel, with storage capacity C as the key factor. a As the analytical standard, the storage capacity is analyzed based on the geological factors influencing it, including organic matter content, inertinite content, coalification stage, pore volume (both small and micropores), specific surface area (both small and micropores), and coal body structure type. The impact of these factors on the storage capacity C of each unit is analyzed unit by unit (from unit A to unit B to unit C to unit D to…). a The geological factors that control the storage capacity are those whose distribution characteristics in the geological factor curves are consistent with those in the storage capacity curves.

[0040] Using the gas occurrence unit as the horizontal axis (from unit A → unit B → unit C → unit D → …), and the coal seam's own sequestration capacity F… am The main controlling geological factors corresponding to the coal seam's self-sealing capacity in Table 3 are coal seam thickness, tectonic compressive stress, vitreous coal + bright coal content, macropore + mesopore volume, coal body structure type, and burial depth, with these factors on the vertical axis, similar to the attached table. Figure 3 Establish an analysis chart, in which the coal seam's own storage capacity F is used. amAs the analytical standard, the geological factors influencing the self-sealing capacity of the coal seam, namely coal seam thickness, tectonic compressive stress, vitreous coal + bright coal content, macro- and meso-pore volume, coal body structure type, and burial depth, are analyzed unit by unit (from unit A → unit B → unit C → unit D → ...). am The geological factors that control the self-sealing capacity of a coal seam are those whose distribution characteristics in the geological factor curves are consistent with the distribution characteristics of the coal seam's self-sealing capacity curve.

[0041] Using the gas storage unit as the horizontal axis (from unit A → unit B → unit C → unit D → …), and the roof sealing capacity F… at and the top plate sealing capacity F in Table 3 at The corresponding influencing geological factors, lithology, tectonic compressive stress, and burial depth, are plotted on the vertical axis, similar to the attached diagram. Figure 3 Establish an analysis chart, with the top plate sealing capacity F as the key element. at As the analytical standard, the top plate sealing capacity F is used. at The corresponding influencing geological factors, lithology, tectonic compressive stress, and burial depth, are the objects of analysis. The impact of lithology, tectonic compressive stress, and burial depth on the sealing capacity F of the top plate of each unit is analyzed unit by unit (from unit A to unit B to unit C to unit D to...). at The geological factors that control the roof storage capacity of a region are those whose distribution characteristics in the geological factor curves are consistent with the distribution characteristics of the roof storage capacity curve.

[0042] Using the gas storage unit as the horizontal axis (from unit A → unit B → unit C → unit D → …), and the bottom plate sealing capacity F… ab and the bottom plate sealing capacity F in Table 3 ab The corresponding influencing geological factors, lithology, tectonic compressive stress, and burial depth, are plotted on the vertical axis, similar to the attached diagram. Figure 3 Establish an analysis chart, with the base plate sealing capacity F as the key element. ab As the analytical standard, the base plate sealing capacity F is used. ab The corresponding influencing geological factors, lithology, tectonic compressive stress, and burial depth, are the objects of analysis. The impact of lithology, tectonic compressive stress, and burial depth on the sealing capacity (F) of the bottom plate of each unit is analyzed unit by unit (from unit A to unit B to unit C to unit D to...). ab The geological factors that control the base plate's storage capacity are those whose distribution characteristics in the geological factor curves are consistent with the distribution characteristics of the base plate's storage capacity curve.

[0043] Using the gas storage unit as the horizontal axis (from unit A → unit B → unit C → unit D → …), and the fracture sealing capacity F…af and its fracture retention capacity F in Table 3 af The corresponding influencing geological factors, such as tectonic compressive stress, are plotted on the ordinate, similar to the attached diagram. Figure 3 Establish an analysis chart, in which the fracture storage capacity F is used as the basis. af As the analytical standard, the fracture storage capacity F is used. af The corresponding geological influencing factor, tectonic compressive stress, is taken as the analysis object. The effect of tectonic compressive stress on the fracture retention capacity F of each unit is analyzed unit by unit (from unit A to unit B to unit C to unit D to...). af The geological factors whose distribution characteristics in the geological factor curves are consistent with the distribution characteristics of the fault sealing capacity curve are the main controlling geological factors of its sealing capacity.

[0044] Using the gas storage unit as the horizontal axis (from unit A → unit B → unit C → unit D → ...), and the path sealing capacity F al and its path sealing capability F in Table 3 al The corresponding geological factors affecting the coal seam are represented by the coal seam burial depth on the vertical axis, similar to the attached diagram. Figure 3 Establish an analysis diagram, in which the path encapsulation capability F is used. al As the analysis standard, the path sealing capability F is used. al The analysis focuses on the coal seam burial depth, a geological factor influencing the geological conditions of each unit. The impact of coal seam burial depth on the path sealing capacity F of each unit is analyzed unit by unit (from unit A to unit B to unit C to unit D to…). al The geological factors whose distribution characteristics in the geological factor curves are consistent with the distribution characteristics of the path storage capacity curve are the main controlling geological factors of their storage capacity.

[0045] Ultimately, the dominant control capacity type and the corresponding dominant geological factor type of the gas occurrence status of each gas occurrence unit were identified. For example, the high gas occurrence status of gas occurrence unit A is controlled by the high gas generation capacity caused by high compressive stress, the high gas storage capacity caused by high inertinite content, and the high gas sealing capacity caused by high coal body structure type.

[0046] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit it. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the spirit and scope of the present invention, and all such modifications or substitutions should be covered within the scope of the claims of the present invention.

Claims

1. A method for analyzing the main controlling geological factors of differential occurrence of coal seam gas, characterized in that, Includes the following steps: S1. Select the main mineable coal seams in the coal mining area or the entire mine area as the target coal seams for analysis and comparison. Divide mines or geological units in the mining area with consistent or similar coal seam gas occurrence and occurrence patterns into a gas occurrence unit. S2. Based on the key characterization parameters corresponding to the gas occurrence capacity types of each coal seam obtained by measurement and calculation, and the characterization principles corresponding to the key characterization parameters and the gas occurrence capacity types of each coal seam, compare the gas occurrence capacity types of the same coal seam in each gas occurrence unit to obtain the relative strength relationship of the same coal seam gas occurrence capacity types among each gas occurrence unit, and make a qualitative classification from strong to weak according to the strength level. Coal seam gas occurrence capacity types include generation capacity S a Storage capacity C a Storage capacity F a Among them, the storage capacity F a Including the coal seam's own storage capacity F am Top plate sealing capacity F at Base plate sealing capacity F ab Fracture-resistant storage capability F af Path sealing capability F al ; Path sealing capability F al The key characterization parameter is the maximum vertical gas escape path length L. v The characterization principle is the length L of the maximum vertical gas escape path. v The larger the value, the greater the path sealing capability F. al The stronger; S3. Based on the principle that the stronger the generation capacity, the stronger the storage capacity, the stronger the sealing capacity, the higher the coal seam gas content or coal seam gas pressure, and based on the coal seam gas content or coal seam gas pressure level of each unit coal seam, comprehensively analyze and judge the main control capacity type of the gas occurrence status of each unit coal seam. Among them, the coal seam gas occurrence capacity type with the strongest intensity is the main control capacity, thereby obtaining the main control capacity type of the gas occurrence status of each gas occurrence unit. S4. Based on the influencing geological factors corresponding to the main control capacity type of each gas occurrence unit obtained through measurement, calculation, statistics, and analysis, and the principle of the corresponding influence of the influencing geological factors on the main control capacity type of the gas occurrence unit, the textual values ​​of roof and floor lithology, coal body structure type, and magma intrusion are converted into digital values ​​and digital chart analysis is performed. Geological factors whose distribution characteristics in the curves of various geological factors in each gas occurrence unit are consistent with the distribution characteristics of the curve of the corresponding main control capacity type are the main control geological factors of the main control capacity type of the gas occurrence unit.

2. The method for analyzing the main controlling geological factors of coal seam gas difference according to claim 1, characterized in that: In step S2, Generation capability S a Key characterization parameters include maximum vitrinite reflectance R. o（max） Volatile matter content V daf The coalification stage is characterized by R. o（max） The larger, V daf The smaller the size and the higher the coalification stage, the stronger the Sa generation capacity; Storage capacity C a Key characterization parameters include adsorption constants a and b. The characterization principle is that the larger the adsorption constant a and the smaller the adsorption constant b, the greater the storage capacity C. a The stronger; Coal seam self-storage capacity F am Key characterization parameters include the coal seam permeability coefficient λ and the coal seam normal thickness M. m The characterization principle is that the smaller λ is, the better M is. m The larger the coal seam, the greater its self-storage capacity F. am The stronger the value, the more λ is used as the primary characterization parameter. Top plate sealing capacity F at The key characterization parameter is the normal permeability φ of the immediate roof strata. t The characterization principle is φ t The smaller the value, the greater the top plate storage capacity F. at The stronger; Base plate sealing capacity F ab The key characterization parameter is the normal permeability φ of the direct base strata. b The characterization principle is φ b The smaller the size, the better the base plate storage capacity F. ab The stronger; Fracture storage capability F af The key characterization parameter is the open-conductivity ground fracture density ρ. The characterization principle is that the smaller ρ is, the greater the fracture storage capacity F. af The stronger.

3. The method for analyzing the main controlling geological factors of coal seam gas difference according to claim 2, characterized in that: The qualitative classification principle is: When the distribution of the corresponding coal seam gas occurrence capacity type among the gas occurrence units is consistent or similar, it is classified as "equivalent"; When the distribution of the corresponding coal seam gas occurrence capacity type among the gas occurrence units shows two levels, it is divided into "stronger" and "weaker". When the distribution of the corresponding coal seam gas occurrence capacity type among the gas occurrence units shows three levels, it is divided into "relatively strong", "medium" and "relatively weak"; When the distribution of the corresponding coal seam gas occurrence capacity type among the gas occurrence units shows four levels, it is divided into "strong", "relatively strong", "relatively weak" and "weak". When the distribution of the corresponding coal seam gas occurrence capacity type among the gas occurrence units shows five levels, it is divided into "strong", "relatively strong", "medium", "relatively weak" and "weak". When the distribution of the corresponding coal seam gas occurrence capacity type among the gas occurrence units shows six levels, it is divided into "strongest", "strong", "relatively strong", "relatively weak", "weak" and "weakest". When the distribution of the corresponding coal seam gas occurrence capacity type among the gas occurrence units shows seven levels, it is divided into "strongest", "strong", "relatively strong", "medium", "relatively weak", "weak" and "weakest". Among them, the number of horizontal divisions is less than or equal to the number of gas storage units.

4. The method for analyzing the main controlling geological factors of coal seam gas difference according to claim 1, characterized in that: In step S4, the generation capability S a The influencing geological factors include tectonic compressive stress, magma intrusion, and the maximum historical burial depth of the coal seam. The principle of influence is that the greater the tectonic compressive stress, the greater the magma intrusion, and the greater the maximum historical burial depth of the coal seam, the stronger the generation capacity. Storage capacity C a Influencing geological factors include organic matter content, inert content in micro-coal and petrographic components, coalification stage, pore structure, and coal body structure type. Among these, pore structure includes the volume of small pores and micropores and specific surface area. The influencing principle is that the greater the organic matter content, the greater the inert content, the greater the coalification stage, the greater the volume of small pores and micropores, the greater the specific surface area of ​​small pores and micropores, and the greater the coal body structure type, the stronger the storage capacity. Coal seam self-storage capacity F am The influencing geological factors include coal seam thickness, tectonic compressive stress, the content of vitreous coal and bright coal in the macroscopic coal and petrographic components, the pore volume of macropores and mesopores in the pore structure, the coal body structure type, and the burial depth. The influencing principle is that the greater the coal seam thickness, the greater the tectonic compressive stress, the greater the content of vitreous coal and bright coal, the greater the pore volume of macropores and mesopores, the greater the coal body structure type, and the greater the burial depth, the stronger the coal seam's own sealing capacity. Top plate sealing capacity F at The influencing geological factors include roof lithology, tectonic compressive stress, and burial depth. The principle is that the greater the lithology, the greater the tectonic compressive stress, and the greater the burial depth, the stronger the roof sealing capacity. Base plate sealing capacity F ab The influencing geological factors include the lithology of the base plate, the tectonic compressive stress, and the burial depth. The principle is that the greater the lithology, the greater the tectonic compressive stress, and the greater the burial depth, the stronger the base plate sealing capacity. Fracture storage capability F af The influencing geological factors include tectonic compressive stress, and the principle is that the greater the tectonic compressive stress, the stronger the fracture sealing capacity. Path sealing capability F al The influencing geological factors include the coal seam burial depth. The principle is that the greater the burial depth of the coal seam, the stronger the path sealing capacity.

5. The method for analyzing the main controlling geological factors of coal seam gas difference according to claim 4, characterized in that: The textual values ​​of roof and floor lithology, coal body structure type, and magma intrusion were converted into digital values. The correspondence between roof and floor lithology values ​​is shown in Table 1, the correspondence between coal body structure type values ​​is shown in Table 2, and the correspondence between magma intrusion values ​​is shown in Table 3. Table 1. Correspondence between lithological values ​​of the top and bottom plates Table 2. Correspondence between numerical values ​​for coal body structure types Table 3. Correspondence between numerical values ​​of magma intrusion Using the gas storage unit as the x-axis and the generation capacity S as the y-axis... a An analytical chart was established with the geological factors influencing the formation capacity, namely tectonic compressive stress, magmatic intrusion, and the maximum historical burial depth of the coal seam, as the vertical axis. The formation capacity S was used as the vertical axis. a As the analytical standard, the geological factors influencing the generation capacity, namely tectonic compressive stress, magma intrusion, and the historical maximum burial depth of the coal seam, are taken as the analysis objects. The effects of tectonic compressive stress, magma intrusion, and the historical maximum burial depth of the coal seam on the generation capacity S of each gas-bearing unit are analyzed unit by unit. a Geological factors whose distribution characteristics in the geological factor curves are consistent with those in the generation capacity curves are the main controlling geological factors of generation capacity. Using gas storage units as the x-axis and storage capacity C as the y-axis... a An analytical chart was established with the following parameters as the vertical axis: organic matter content, inert group content, coalification stage, pore volume of small and micropores, specific surface area of ​​small and micropores, and coal body structure type. The chart uses the storage capacity (C) as the vertical axis. a As the analytical standard, the storage capacity was analyzed based on the geological factors influencing it, including organic matter content, inertinite content, coalification stage, pore volume (both small and micropores), specific surface area (both small and micropores), and coal body structure type. The impact of these factors on the storage capacity (C) of each gas-bearing unit was analyzed unit by unit. a Geological factors whose distribution characteristics in the geological factor curves are consistent with those in the storage capacity curves are the main controlling geological factors of storage capacity. Using the gas occurrence unit as the x-axis and the coal seam's own sequestration capacity F as the y-axis... am An analytical chart was established with the following influencing geological factors on the coal seam's self-sealing capacity: coal seam thickness, tectonic compressive stress, vitreous coal + bright coal content, macropore + mesopore volume, coal body structure type, and burial depth as the vertical axis. The chart uses the coal seam's self-sealing capacity F as the vertical axis. am As the analytical standard, the geological factors influencing the self-sealing capacity of coal seams—coal seam thickness, tectonic compressive stress, vitreous coal + bright coal content, macro- and meso-pore volume, coal body structure type, and burial depth—are analyzed unit by unit, focusing on their impact on the self-sealing capacity F of each unit coal seam. am Geological factors whose distribution characteristics in the various geological factor curves are consistent with the distribution characteristics of the coal seam's own sealing capacity curve are the main controlling geological factors of the coal seam's own sealing capacity. Using the gas storage unit as the horizontal axis and the roof sealing capacity F as the vertical axis... at and top plate sealing capacity F at Using the corresponding influencing geological factors—lithology, tectonic compressive stress, and burial depth—as the vertical axis, an analytical chart is established, with the roof sealing capacity F as the key indicator. at As the analytical standard, the geological factors influencing the roof sealing capacity Fat—lithology, tectonic compressive stress, and burial depth—are taken as the analysis objects. The effects of lithology, tectonic compressive stress, and burial depth on the roof sealing capacity Fat of each unit are analyzed unit by unit. at Geological factors whose distribution characteristics in the geological factor curves are consistent with the distribution characteristics of the roof storage capacity curve are the main controlling geological factors of roof storage capacity. Using the gas storage unit as the horizontal axis and the bottom plate sealing capacity F as the vertical axis... ab and bottom plate sealing capacity F ab Using the corresponding influencing geological factors—lithology, tectonic compressive stress, and burial depth—as the vertical axis, an analytical chart is established, with the bottom plate's sealing capacity F as the key indicator. ab As the analytical standard, the base plate sealing capacity F is used. ab The analysis focuses on the geological factors influencing lithology, tectonic compressive stress, and burial depth, analyzing the impact of lithology, tectonic compressive stress, and burial depth on the sealing capacity F of the bottom plate in each unit. ab Geological factors whose distribution characteristics in the geological factor curves are consistent with those in the basement storage capacity curve are the main controlling geological factors of basement storage capacity. Using the gas storage unit as the x-axis and the fracture sealing capacity F as the y-axis... af and fracture preservation capability F af An analytical chart was established using the corresponding influencing geological factors, such as tectonic compressive stress, as the vertical axis. The chart also included the fracture retention capacity F. af As the analytical standard, the fracture storage capacity F is used. af Taking the tectonic compressive stress, a geological factor influencing the analysis, as the object of analysis, the effect of tectonic compressive stress on the fracture retention capacity F of each unit is analyzed unit by unit. af Geological factors whose distribution characteristics in the geological factor curves are consistent with those in the fault sealing capacity curves are the main controlling geological factors of fault sealing capacity. Using the gas storage unit as the x-axis and the path sealing capacity F as the y-axis... al and path sealing capability F al Using the coal seam burial depth as the vertical axis, an analysis chart is established, with the path sealing capacity F as the key geological factor. al As the analysis standard, the path sealing capability F is used. al The analysis focuses on the coal seam depth, a geological factor influencing the path sealing capacity (F) of each unit. al Geological factors whose distribution characteristics in the geological factor curves are consistent with those in the path sealing capacity curves are the main controlling geological factors of path sealing capacity.

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