Analysis method for coal seam metamorphism types and combination thereof in coal mine area

Abstract

The invention relates to a coal mine area coal seam metamorphism type and combination analysis method, and belongs to the technical field of gas monitoring. The method comprises the following steps of carding coal rank distribution characteristics of a coal mine area or a mine; judging a deep metamorphic action type, and determining whether other metamorphic action types exist except the deep metamorphic action type; and further judging whether a magma deterioration effect, a hot liquid and hot water deterioration effect and a dynamic deterioration effect exist or not on the basis of the deep deterioration effect type, and judging whether the dynamic deterioration effect still exists or not. According to the method, comprehensive and effective prediction of the coal mine area or mine coal seam gas occurrence rule and the coal and gas outburst danger, comprehensive and effective evaluation of the outburst danger degree, comprehensive and effective division of the outburst danger area and effective taking of outburst prevention measures based on outburst danger main control factors are achieved from the source.

Description

Technical Field

[0001] The invention belongs to the technical field of gas monitoring, and relates to an analysis method for coal seam metamorphism types and combinations thereof in a coal mining area. Background Art

[0002] According to on-site production experience, there are often obvious differences in coal seam ranks between different mines, geological units, coal seams in a mining area, and between different parts and coal seams in the same mine. As we all know, coal seams are formed by the original coal-forming materials through peatification and coalification (diagenesis stage + coalification stage), and the coal seams are metamorphosed into different coal ranks due to the different combination characteristics of formation temperature, pressure and time during the formation process. The difference in coal rank directly affects the generation and adsorption capacity of coal seam gas, the pore structure and strength of the coal body, and other basic characteristics of coal seam gas. These basic characteristics determine the different coal seam gas occurrence characteristics and the degree of coal and gas outburst danger. At the same time, there are many sources of formation temperature and pressure that coal seams experience during their formation. At present, coal seam metamorphism is divided into four types based on the sources of formation temperature and pressure, namely, deep metamorphism, dynamic metamorphism, magmatic metamorphism (regional magmatic metamorphism + contact metamorphism), and hydrothermal hot water metamorphism. Different types of metamorphism have obvious differential control effects on coal rank and coal rank combination characteristics, coal body structure, stress environment, and occurrence characteristics (thickness + occurrence) of coal seams, and these aspects comprehensively restrict the occurrence characteristics of coal seam gas and the degree of coal and gas outburst danger. It can be seen that clarifying the types of coal seam metamorphism and their combination patterns in coal mining areas or mines is crucial to the occurrence characteristics of coal seam gas and the prediction of coal and gas outburst danger, the assessment of the degree of outburst danger, the division of outburst danger areas, and the clarification of the main control factors of outburst danger, which has practical guiding significance on the efficient control of coal seam gas and the adoption of effective measures to prevent coal and gas outburst dangers.

[0003] However, at present, for coal mining areas or mines, gas prevention and control, and coal and gas outburst prevention and control, there are few comprehensive and effective predictions of the occurrence law of coal seam gas in coal mining areas or mines and the danger of coal and gas outburst, comprehensive and effective evaluation of the degree of outburst danger, comprehensive and effective division of outburst danger areas, and comprehensive and effective clarification of the main control factors of outburst danger from the perspective of coal seam metamorphism type and its combination characteristics. Instead, based on the determination of a series of parameters such as coal seam gas content, coal seam gas pressure, and coal seam solidity coefficient at the working face, the coal and gas outburst danger of each working face is gradually predicted according to the development and production progress of the coal mining area or mine, the degree of coal and gas outburst danger of each working face is evaluated, and the coal and gas outburst danger area of ​​each working face is divided, and then anti-outburst measures are taken for each working face. In this way, the comprehensiveness, advancement, and efficiency of coal and gas outburst danger prevention and control work are lost. Summary of the invention

[0004] In view of this, the purpose of the present invention is to provide a method for analyzing the types and combinations of coal seam metamorphism in a coal mining area, so as to analyze and clarify the types and combination patterns of coal seam metamorphism in a coal mining area or a mine.

[0005] In order to achieve the above object, the present invention provides the following technical solutions:

[0006] A method for analyzing coal seam metamorphism types and combinations thereof in a coal mining area, the method comprising the following steps:

[0007] S1: Combing the coal rank distribution characteristics of coal mining areas or mines;

[0008] S2: Determine the type of deep-seated metamorphism and clarify whether there are other types of metamorphism besides deep-seated metamorphism;

[0009] S3: For the maximum metamorphic temperature T max Obviously greater than the formation temperature t at the maximum historical burial depth of the coal seam max The unit is judged on the basis of the deep metamorphism type whether there is magmatic metamorphism, hydrothermal metamorphism and dynamic metamorphism; among which, magmatic metamorphism includes regional magmatic metamorphism and contact metamorphism;

[0010] S4: On the basis of the deep metamorphism of each unit, for the units with regional magmatic metamorphism, contact metamorphism, hydrothermal and hot water metamorphism, regional magmatic metamorphism + contact metamorphism, regional magmatic metamorphism + hydrothermal and hot water metamorphism, contact metamorphism + hydrothermal and hot water metamorphism, and regional magmatic metamorphism + contact metamorphism + hydrothermal and hot water metamorphism, further determine whether they still have dynamic metamorphism.

[0011] Further, the S1 is specifically:

[0012] Based on the perspectives of different mines, different geological units or different parts of the mines in the mining area, different horizontal coal rank areas are horizontally sorted and divided, and numbered A, B, C, ... in sequence, which are the horizontal coal rank area numbers; the number of horizontal coal rank division units is consistent with the number of horizontal coal ranks;

[0013] Based on the angles of different coal seams or coal seam groups, the horizontal coal rank division units are again vertically sorted and divided one by one, and numbered a, b, c... from top to bottom according to the burial depth, which is the vertical coal rank area number, wherein the number of vertical coal rank division units divided in each horizontal coal rank division unit is consistent with the number of vertical coal ranks, the number of vertical coal rank division units divided in each horizontal coal rank division unit is ≥1, and the number of vertical coal rank division units divided in each horizontal coal rank division unit is not necessarily the same.

[0014] Further, the S2 is specifically:

[0015] Take coal samples of each coal rank unit according to industry standards and measure the maximum vitrinite reflectance Ro of each coal rank unit max ;

[0016] According to Barker's formula: T max =(lnRo max +1.2) / 0.0078), calculate the maximum metamorphic temperature T of each coal rank unit max ;

[0017] The thickness of the regional strata, the age of the regional strata, the time of structural subsidence-uplift, the number of structural subsidence-uplift, and the amount of structural uplift erosion of each coal rank unit were obtained, and the historical maximum burial depth H of the coal seam in each coal rank unit was obtained by basin simulation software. max ;

[0018] Obtain the coal seam settlement of each coal rank unit to H max The regional geothermal gradient at that time is calculated by using H max Regional geothermal gradient, calculate the formation temperature t at the historical maximum burial depth of each coal rank unit max ;

[0019] Successive comparative analysis of each coal rank unit T max With the coal seam max :

[0020] For T max -t max For units with a temperature of ≤20°C, the coal seam metamorphism type is deep metamorphism;

[0021] For T max -t max For units with a temperature greater than 20℃, the types of coal seam metamorphism include, in addition to deep-seated metamorphism, one or more of dynamic metamorphism, magmatic metamorphism, and hydrothermal metamorphism.

[0022] Further, the S3 is specifically:

[0023] Establish a combination characteristic table of comprehensive discrimination conditions for magmatic metamorphism and hydrothermal metamorphism, i.e. Table 1;

[0024] The table header includes the condition combination classification, feature details and corresponding qualitative action type;

[0025] The combination classification includes the first condition combination, the second condition combination and the third condition combination;

[0026] The characteristics of the first condition combination include: the metamorphic area where the unit is located has hydrothermal quartz veins and calcite veins; the area of ​​the metamorphic area where the unit is located is greater than a certain value, with regional characteristics, and the coal rank zoning in the metamorphic area is generally ring-shaped; the rocks in the metamorphic area where the unit is located are altered; the coal rank in the metamorphic area where the unit is located is high, with graphite belt-high metamorphic anthracite belt-medium metamorphic anthracite belt-low metamorphic anthracite belt; the unit has a high metamorphic gradient, and its Ro max The change gradient is greater than 0.1% / hm; the corresponding metamorphism type is regional magmatic metamorphism;

[0027] The characteristics of the second condition combination include: the unit develops intrusive magmatic rocks; the metamorphic area where the unit is located is centered on intrusive magmatic rocks and is local or narrow; the metamorphic area where the unit is located is centered on intrusive magmatic rocks and has coke rock mixed zone, natural coke zone, coke coal mixed zone, and thermal coal zone from the inside to the outside; the rocks in the metamorphic area where the unit is located are altered, and high-medium-low temperature alteration zones are developed from the inside to the outside with intrusive magmatic rocks as the center; the corresponding metamorphism type is contact metamorphism;

[0028] The characteristics of the third condition combination include: the metamorphic area where the unit is located has regional and boundary deep fault zones; hot springs are developed around the metamorphic area where the unit is located; the area of ​​the metamorphic area where the unit is located is less than a certain value, showing local characteristics;

[0029] The corresponding metamorphism types include magmatic metamorphism, hydrothermal metamorphism and dynamic metamorphism; the corresponding metamorphism type is hydrothermal metamorphism;

[0030] For T max -t max For units with a temperature of >20°C, geological survey and analysis are performed on Table 1:

[0031] When a coal rank unit meets the first combination of conditions, the coal rank unit has regional magmatic metamorphism superimposed on magmatic metamorphism on the basis of deep metamorphism;

[0032] When a coal rank unit meets the second combination of conditions, the coal rank unit has contact metamorphism superimposed on magmatic metamorphism on the basis of deep metamorphism;

[0033] When a coal rank unit meets the third combination of conditions, the coal rank unit is superimposed with hydrothermal metamorphism on the basis of deep metamorphism;

[0034] When a coal rank unit meets both the first and second condition combinations, the coal rank unit has both regional magmatic metamorphism and contact metamorphism superimposed on the deep metamorphism.

[0035] When a coal rank unit meets both the first and third condition combinations, the coal rank unit has both regional magmatic metamorphism and hydrothermal metamorphism superimposed on the basis of deep metamorphism.

[0036] When a coal rank unit meets both the second and third condition combinations, the coal rank unit is superimposed with both contact metamorphism of magmatic metamorphism and hydrothermal metamorphism on the basis of deep metamorphism.

[0037] When a coal rank unit meets the first condition combination, the second condition combination, and the third condition combination at the same time, then the coal rank unit is superimposed with regional magmatic metamorphism, contact metamorphism, and hydrothermal hot water metamorphism on the basis of deep metamorphism;

[0038] When a coal rank unit does not meet any of the first, second, or third condition combinations, the coal rank unit is superimposed with dynamic metamorphism on the basis of deep metamorphism.

[0039] Further, the S4 is specifically:

[0040] Establish a structural feature classification table, i.e., Table 2, the header of which includes structural feature classification and structural feature details;

[0041] The structural features of the first structural feature include: no compression faults or folds, gentle formation, i.e. dip angle ≤15°, original coal seam structure, stable coal seam occurrence, no shear slip failure inside the coal seam and between the coal seam and the rock layer, good coal seam permeability, permeability coefficient ≥3m 2 MPa -2 ·d -1 ;

[0042] The structural features of the second structural feature include: the development of wide and gentle folds or interlayer compression faults, and their scale is relatively small, the formation is relatively gentle, that is, 15°<stratum dip angle≤30, the coal seam structure is the original structure-fragmentation structure, the coal seam is relatively stable, small-scale shear slip failure occurs inside the coal seam and between the coal seam and the rock layer, the coal seam has good permeability, and 1m 2 MPa -2 ·d -1 ≤Air permeability coefficient<3m 2 MPa -2 ·d -1 ;

[0043] The structural features of the third structural feature include: the development of tight, inverted folds or compression faults, and their scale is relatively large, the coal seam structure is a granular structure-mylonitic structure, the coal seam is unstable, the formation dip is large, that is, >30°, there is a large range of shear slip failure inside the coal seam and between the coal seam and the rock layer, the coal seam has poor permeability, and the permeability coefficient is <1m 2 MPa -2 ·d -1 ;

[0044] For units with regional magmatic metamorphism, contact metamorphism, hydrothermal metamorphism, regional magmatic metamorphism + contact metamorphism, regional magmatic metamorphism + hydrothermal metamorphism, contact metamorphism + hydrothermal metamorphism, and regional magmatic metamorphism + contact metamorphism + hydrothermal metamorphism, the structural characteristics of each unit are investigated and analyzed:

[0045] When the unit structural characteristics meet the first structural characteristics or the second structural characteristics in Table 2, the external conditions for dynamic metamorphism are not met, and the unit does not experience dynamic metamorphism;

[0046] When the unit structural characteristics meet the third structural characteristics of the unit in Table 2, it has the external conditions for dynamic metamorphism, and further determines whether it has dynamic metamorphism;

[0047] ① For units with regional magmatic metamorphism, collect samples of hydrothermal quartz veins or calcite veins developed in the metamorphic area where the unit is located, and then make inclusion slices to measure the homogenization temperature T of the brine inclusions inside them. 均一 distribution characteristics and select its maximum uniform temperature T 均一max The maximum deterioration temperature of the unit is T max Conduct comparative analysis:

[0048] When T 均一max Greater than the unit T max When, or 0℃≤T max -T 均一max When the temperature is ≤20℃, there is no dynamic metamorphism in the unit;

[0049] When T max -T 均一max When the temperature is >20℃, the unit will experience dynamic metamorphism;

[0050] ② For units with contact metamorphism, collect rock samples that have undergone alteration in the metamorphic area where the unit is located and measure their alteration temperature T 蚀变 distribution range, and select its maximum alteration temperature T 蚀变max The maximum deterioration temperature of the unit is T max Conduct comparative analysis:

[0051] When T 蚀变max Greater than the unit T max When, or 0℃≤T max -T 蚀变max When the temperature is ≤20℃, there is no dynamic metamorphism in the unit;

[0052] When T max -T 蚀变max When the temperature is >20℃, the unit will experience dynamic metamorphism;

[0053] ③ For units with hydrothermal metamorphism, measure the underground fluid temperature T in or near the deep fault zone of the metamorphic area where the unit is located. 流体 distribution range, and select its maximum fluid temperature T 流体max The maximum deterioration temperature of the unit is T max Conduct comparative analysis:

[0054] When T 流体max Greater than the unit T max When, or 0℃≤T max -T 流体max When the temperature is ≤20℃, there is no dynamic metamorphism in the unit;

[0055] When T max -T 流体max When the temperature is >20℃, the unit will experience dynamic metamorphism;

[0056] ④ For units with regional magmatic metamorphism + contact metamorphism, collect samples of hydrothermal quartz veins or calcite veins developed in the metamorphic area where the unit is located, and altered rock samples, and measure the homogenization temperature T of the brine inclusions inside the veins. 均一 Distribution characteristics and rock alteration temperature T 蚀变 Distribution range, comparative analysis of its maximum uniform temperature T 均一max and the maximum alteration temperature T 蚀变max , select the larger of the two and the maximum metamorphic temperature T of the unit max Conduct comparative analysis:

[0057] When the larger of the two is greater than the unit T max When, or 0℃≤T max -When the larger of the two is ≤20℃, there is no dynamic metamorphism in the unit;

[0058] When T max -When the larger of the two is greater than 20°C, the unit is subject to dynamic metamorphism;

[0059] ⑤ For units with regional magmatic metamorphism + hydrothermal metamorphism, collect hydrothermal quartz vein or calcite vein samples developed in the metamorphic area where the unit is located, and measure the homogenization temperature T of the brine inclusions inside the vein body. 均一 distribution characteristics, and at the same time determine the underground fluid temperature T in or near the deep fault zone of the metamorphic area where the unit is located 流体 Distribution range, comparative analysis of its maximum uniform temperature T 均一max and the maximum fluid temperature T 流体max , select the larger of the two and the maximum metamorphic temperature T of the unit max Conduct comparative analysis:

[0060] When the larger of the two is greater than the unit T max When, or 0℃≤T max -When the larger of the two is ≤20℃, there is no dynamic metamorphism in the unit;

[0061] When T max -When the larger of the two is greater than 20°C, the unit is subject to dynamic metamorphism;

[0062] ⑥ For units with contact metamorphism + hydrothermal metamorphism, collect rock samples that have undergone alteration in the metamorphic area where the unit is located and measure their alteration temperature T 蚀变 distribution range, and at the same time determine the underground fluid temperature T in or near the deep fault zone of the metamorphic area where the unit is located 流体 Distribution range, comparative analysis of its maximum alteration temperature T 蚀变max and the maximum fluid temperature T 流体max , select the larger of the two and the maximum metamorphic temperature T of the unit max Conduct comparative analysis:

[0063] When the larger of the two is greater than the unit T max When, or 0℃≤T max -When the larger of the two is ≤20℃, there is no dynamic metamorphism in the unit;

[0064] When T max -When the larger of the two is greater than 20°C, the unit is subject to dynamic metamorphism;

[0065] ⑦ For units with regional magmatic metamorphism + contact metamorphism + hydrothermal hot water metamorphism, collect hydrothermal quartz vein or calcite vein samples developed in the metamorphic area where the unit is located, and altered rock samples, and measure the homogenization temperature T of the brine inclusions inside the vein body. 均一 Distribution characteristics and rock alteration temperature T 蚀变 distribution range, and at the same time determine the underground fluid temperature T in or near the deep fault zone of the metamorphic area where the unit is located 流体 Distribution range, and then compare and analyze its maximum uniform temperature T均一max , maximum alteration temperature T 蚀变max and maximum fluid temperature T 流体max , select the largest of the three and the maximum metamorphic temperature T of the unit max Conduct comparative analysis:

[0066] When the largest of the three is greater than the unit T max When, or 0℃≤T max -When the maximum of the three is ≤20℃, there is no dynamic metamorphism in the unit;

[0067] When T max -When the maximum of the three is >20°C, the unit is subject to dynamic metamorphism.

[0068] The beneficial effects of the present invention are: clarifying the types of coal seam metamorphism in coal mining areas or mines and their combination patterns, realizing comprehensive and effective prediction of coal and gas outburst hazards in coal mining areas or mines, comprehensive and effective evaluation of outburst hazard levels, comprehensive and effective division of outburst hazard areas, and effective adoption of outburst prevention measures based on the main control factors of outburst hazards. This avoids the blindness, locality, lag, and inefficiency of coal and gas outburst hazard prevention and control work in coal mining areas or mines.

[0069] Other advantages, objectives and features of the present invention will be described in the following description to some extent, and to some extent, will be obvious to those skilled in the art based on the following examination and study, or can be taught from the practice of the present invention. The objectives and other advantages of the present invention can be realized and obtained through the following description. BRIEF DESCRIPTION OF THE DRAWINGS

[0070] In order to make the purpose, technical solutions and advantages of the present invention more clear, the present invention will be described in detail below in conjunction with the accompanying drawings, wherein:

[0071] Figure 1 It is the principle diagram of the present invention;

[0072] Figure 2 It is a flow chart of the present invention. DETAILED DESCRIPTION

[0073] The following describes the embodiments of the present invention by specific examples, and those skilled in the art can easily understand other advantages and effects of the present invention from the contents disclosed in this specification. The present invention can also be implemented or applied through other different specific embodiments, and the details in this specification can also be modified or changed in various ways 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 only illustrate the basic concept of the present invention in a schematic manner, and the following embodiments and features in the embodiments can be combined with each other without conflict.

[0074] Among them, the drawings are only used for illustrative explanations, and they only represent schematic diagrams rather than actual pictures, and should not be understood as limitations on the present invention. In order to better illustrate the embodiments of the present invention, some parts of the drawings may be omitted, enlarged or reduced, and do not represent the size of actual products. For those skilled in the art, it is understandable that some well-known structures and their descriptions in the drawings may be omitted.

[0075] The same or similar numbers in the drawings of the embodiments of the present invention correspond to the same or similar parts; in the description of the present invention, it should be understood that if the terms "upper", "lower", "left", "right", "front", "rear", etc. indicate the orientation or position relationship, they are based on the orientation or position relationship shown in the drawings, which is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operate in a specific orientation. Therefore, the terms describing the position relationship in the drawings are only used for illustrative purposes and cannot be understood as limiting the present invention. For ordinary technicians in this field, the specific meanings of the above terms can be understood according to specific circumstances.

[0076] Figure 1 This is the principle diagram of the present invention. Figure 2 It is a flow chart of the present invention.

[0077] Phase 1: Sorting out the coal rank distribution characteristics of coal mining areas or mines

[0078] Based on the perspectives of different mines, different geological units or different parts of the mines in the mining area, different horizontal coal rank areas are horizontally sorted and divided, and numbered A, B, C, ... in sequence, where the number of horizontal coal rank division units is consistent with the number of horizontal coal ranks;

[0079] Based on the angles of different coal seams or coal seam groups, the horizontal coal rank division units are again vertically sorted and divided one by one, and are numbered a, b, c... from top to bottom according to the burial depth, wherein the number of vertical coal rank division units divided in each horizontal coal rank division unit is consistent with the number of vertical coal ranks, the number of vertical coal rank division units divided in each horizontal coal rank division unit is ≥1, and the number of vertical coal rank division units divided in each horizontal coal rank division unit is not necessarily the same.

[0080] Phase II: Preliminary determination of the type of deep-seated metamorphism and whether other types of metamorphism exist besides deep-seated metamorphism

[0081] 3. Take coal samples of each coal rank unit according to industry standards and determine the maximum vitrinite reflectance (Ro max ).

[0082] 4. Based on the maximum vitrinite reflectance (Ro max ) According to the existing Barker formula [T max =(lnRo max +1.2) / 0.0078)】Calculate the maximum metamorphic temperature (T max ).

[0083] 5. Obtain the thickness and age of the strata in the area where each coal rank unit is located, the time and number of structural subsidence-uplift, and the amount of uplift erosion, and then use basin simulation software to simulate and obtain the historical maximum burial depth (H) of the coal seam where each coal rank unit is located. max ).

[0084] 6. Obtain the maximum historical burial depth (H) of the coal seam where each coal rank unit is located. max ) and then based on the historical maximum burial depth (H max ) and regional geothermal gradient to obtain the formation temperature (t max ).

[0085] 7. Compare and analyze the maximum metamorphic temperature (T) of each coal rank unit one by one max ) and the formation temperature at the historical maximum burial depth of the coal seam (t max ), for the maximum metamorphic temperature (T max ) and the formation temperature at the historical maximum burial depth of the coal seam (t max ) units, the coal seam metamorphism type is deep metamorphism; for the maximum metamorphic temperature (T max ) is significantly greater than the formation temperature at the historical maximum burial depth of the coal seam (t max) units, then in addition to deep-seated metamorphism, the types of coal seam metamorphism also include dynamic metamorphism, magmatic metamorphism (regional magmatic metamorphism + contact metamorphism), and hydrothermal metamorphism.

[0086] The third stage: For the maximum metamorphic temperature (T max ) is significantly greater than the formation temperature at the historical maximum burial depth of the coal seam (t max ) units to determine whether there is magmatic metamorphism (regional magmatic metamorphism + contact metamorphism), hydrothermal metamorphism, and dynamic metamorphism based on the type of deep-seated metamorphism.

[0087] 8. Establish a combined characteristic table of comprehensive identification conditions for magmatic metamorphism (regional magmatic metamorphism + contact metamorphism) and hydrothermal and hot water metamorphism as shown in Table 1.

[0088] Table 1

[0089]

[0090] 9. For the maximum metamorphic temperature (T max ) is much greater than the formation temperature at the historical maximum burial depth of the coal seam (t max) coal rank units, a comprehensive geological survey and analysis is carried out on the detailed characteristics of magmatic metamorphism (regional magmatic metamorphism + contact metamorphism) and hydrothermal and hot water metamorphism listed in Table 1. When a coal rank unit meets the first condition combination, the coal rank unit is superimposed with regional magmatic metamorphism of magmatic metamorphism on the basis of deep-seated metamorphism; when a coal rank unit meets the second condition combination, the coal rank unit is superimposed with contact metamorphism of magmatic metamorphism on the basis of deep-seated metamorphism; when a coal rank unit meets the third condition combination, the coal rank unit is superimposed with hydrothermal and hot water metamorphism on the basis of deep-seated metamorphism; when a coal rank unit meets both the first and second condition combinations, the coal rank unit is superimposed with both regional magmatic metamorphism of magmatic metamorphism and contact metamorphism of magmatic metamorphism on the basis of deep-seated metamorphism; when a coal rank unit meets both the first and second condition combinations, the coal rank unit is superimposed with regional magmatic metamorphism of magmatic metamorphism and contact metamorphism of magmatic metamorphism on the basis of deep-seated metamorphism; When the first and third condition combinations are met, the coal rank unit is superimposed with both regional magmatic metamorphism and hydrothermal hot water metamorphism on the basis of deep-seated metamorphism; when a coal rank unit simultaneously meets the second and third condition combinations, the coal rank unit is superimposed with both contact metamorphism and hydrothermal hot water metamorphism on the basis of deep-seated metamorphism; when a coal rank unit simultaneously meets the first, second and third condition combinations, the coal rank unit is superimposed with both regional magmatic metamorphism and contact metamorphism of magmatic metamorphism and hydrothermal hot water metamorphism on the basis of deep-seated metamorphism; when a coal rank unit does not meet any of the first, second and third condition combinations, the coal rank unit is superimposed with dynamic metamorphism on the basis of deep-seated metamorphism.

[0091] The fourth stage: On the basis of the deep metamorphism of each unit, for the units with regional magmatic metamorphism, contact metamorphism, hydrothermal and hot water metamorphism, regional magmatic metamorphism + contact metamorphism, regional magmatic metamorphism + hydrothermal and hot water metamorphism, contact metamorphism + hydrothermal and hot water metamorphism, and regional magmatic metamorphism + contact metamorphism + hydrothermal and hot water metamorphism, further determine whether they still have dynamic metamorphism.

[0092] 10. Establish a structural feature classification table as shown in Table 2.

[0093] 11. For units with regional magmatic metamorphism, units with contact metamorphism, units with hydrothermal and hot water metamorphism, units with regional magmatic metamorphism + contact metamorphism, units with regional magmatic metamorphism + hydrothermal and hot water metamorphism, units with contact metamorphism + hydrothermal and hot water metamorphism, and units with regional magmatic metamorphism + contact metamorphism + hydrothermal and hot water metamorphism, a comprehensive investigation and analysis of the structural characteristics of each unit is conducted. When the structural characteristics of the unit meet the first structural characteristics or the second structural characteristics of the unit in Table 2, the external conditions for dynamic metamorphism are not met, and therefore these units do not experience dynamic metamorphism. When the structural characteristics of the unit meet the third structural characteristics of the unit in Table 2, the external conditions for dynamic metamorphism are met, and it is necessary to further determine whether dynamic metamorphism exists according to the following steps.

[0094] 12. For units with regional magmatic metamorphism, collect samples of hydrothermal quartz veins or calcite veins developed in the metamorphic area where the unit is located, and then make inclusion slices to measure the homogenization temperature of the brine inclusions inside (T 均一 ) distribution characteristics, and select its maximum uniform temperature T 均一max The maximum deterioration temperature of the unit (T max ) for comparative analysis, when the maximum uniform temperature T 均一max Greater than the maximum metamorphic temperature of the unit (T max ) or the maximum deterioration temperature of the unit (T max ) are close, then there is no dynamic metamorphism in the unit; when its maximum uniform temperature T 均一max Obviously lower than the maximum metamorphic temperature of the unit (T max ), then the unit is subject to dynamic metamorphism.

[0095] 13. For units with contact metamorphism, collect rock samples that have undergone alteration in the metamorphic area where the unit is located and measure their alteration temperature (T 蚀变 ) distribution range, and select its maximum alteration temperature T 蚀变max The maximum deterioration temperature of the unit (T max ) for comparative analysis, when the maximum alteration temperature T 蚀变max Greater than the maximum metamorphic temperature of the unit (T max ) or the maximum deterioration temperature of the unit (T max ) are close, then there is no dynamic metamorphism in the unit; when its maximum alteration temperature T 蚀变max Obviously lower than the maximum metamorphic temperature of the unit (T max ), then the unit is subject to dynamic metamorphism.

[0096] 14. For units with hydrothermal metamorphism, measure the underground fluid temperature (T 流体) distribution range, and select its maximum fluid temperature T 流体max The maximum deterioration temperature of the unit (T max ) for comparative analysis, when the maximum fluid temperature T 流体max Greater than the maximum metamorphic temperature of the unit (T max ) or the maximum deterioration temperature of the unit (T max ) are close, then there is no dynamic metamorphism in the unit; when its maximum fluid temperature T 流体max Obviously lower than the maximum metamorphic temperature of the unit (T max ), then the unit is subject to dynamic metamorphism.

[0097] 15. For units with regional magmatic metamorphism + contact metamorphism, samples of hydrothermal quartz veins or calcite veins and altered rock samples developed in the metamorphic area where the unit is located are collected, and the homogenization temperature (T 均一 ) distribution characteristics and rock alteration temperature (T 蚀变 ) distribution range, and compare and analyze its maximum uniform temperature T 均一max and the maximum alteration temperature T 蚀变max , select the larger of the two and the maximum metamorphic temperature of the unit (T max ) for comparative analysis. When it is greater than the maximum metamorphic temperature of the unit (T max ) or the maximum deterioration temperature of the unit (T max ) is close to the maximum metamorphic temperature (T max ), then the unit is subject to dynamic metamorphism.

[0098] 16. For units with regional magmatic metamorphism and hydrothermal metamorphism, collect samples of hydrothermal quartz veins or calcite veins developed in the metamorphic area where the unit is located, and measure the homogenization temperature (T 均一 ) distribution characteristics, and at the same time determine the underground fluid temperature (T 流体 ) distribution range, and compare and analyze its maximum uniform temperature T 均一max and the maximum fluid temperature T 流体max , select the larger of the two and the maximum metamorphic temperature of the unit (T max ) for comparative analysis. When it is greater than the maximum metamorphic temperature of the unit (T max ) or the maximum deterioration temperature of the unit (T max ) is close to the maximum metamorphic temperature (T max ), then the unit is subject to dynamic metamorphism.

[0099] 17. For units with contact metamorphism and hydrothermal metamorphism, collect rock samples that have undergone alteration in the metamorphic area where the unit is located and measure their alteration temperature (T 蚀变 ) distribution range, and at the same time determine the underground fluid temperature (T 流体 ) distribution range, and compare and analyze its maximum alteration temperature T 蚀变max and the maximum fluid temperature T 流体max , select the larger of the two and the maximum metamorphic temperature of the unit (T max ) for comparative analysis. When it is greater than the maximum metamorphic temperature of the unit (T max ) or the maximum deterioration temperature of the unit (T max ) is close to the maximum metamorphic temperature (T max ), then the unit is subject to dynamic metamorphism.

[0100] 18. For units with regional magmatic metamorphism, contact metamorphism, and hydrothermal metamorphism, samples of hydrothermal quartz veins or calcite veins and altered rock samples developed in the metamorphic area of ​​the unit were collected, and the homogenization temperature (T 均一 ) distribution characteristics and rock alteration temperature (T 蚀变 ) distribution range, and at the same time determine the underground fluid temperature (T 流体 ) distribution range, and then compare and analyze its maximum uniform temperature T 均一max , maximum alteration temperature T 蚀变max and maximum fluid temperature T 流体max , select the largest of the three and the maximum metamorphic temperature of the unit (T max ) for comparative analysis. When it is greater than the maximum metamorphic temperature of the unit (T max ) or the maximum deterioration temperature of the unit (T max ) is close to the maximum metamorphic temperature (T max ), then the unit is subject to dynamic metamorphism.

[0101] Table 2

[0102]

[0103] Finally, it should be noted that the above embodiments are only used to illustrate the technical solution of the present invention rather than to limit it. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solution of the present invention can be modified or replaced by equivalents without departing from the purpose and scope of the technical solution, which should be included in the scope of the claims of the present invention.

Claims

1. An analytical method for the types and combinations of coal seam metamorphism in coal mining areas, characterized by: The method comprises the following steps: S1: Combing the coal rank distribution characteristics of coal mining areas or mines; S2: Determine the type of deep-seated metamorphism and clarify whether there are other types of metamorphism besides deep-seated metamorphism; S3: For the maximum metamorphic temperature T max Obviously greater than the formation temperature t at the maximum historical burial depth of the coal seam max The unit is judged on the basis of the deep metamorphism type whether there is magmatic metamorphism, hydrothermal metamorphism and dynamic metamorphism; among which, magmatic metamorphism includes regional magmatic metamorphism and contact metamorphism; S4: On the basis of the deep metamorphism of each unit, for the units with regional magmatic metamorphism, contact metamorphism, hydrothermal and hot water metamorphism, regional magmatic metamorphism + contact metamorphism, regional magmatic metamorphism + hydrothermal and hot water metamorphism, contact metamorphism + hydrothermal and hot water metamorphism, and regional magmatic metamorphism + contact metamorphism + hydrothermal and hot water metamorphism, further determine whether they still have dynamic metamorphism.

2. The method for analyzing the types and combinations of coal seam metamorphism in coal mining areas according to claim 1, characterized in that: The S1 is specifically: Based on the perspectives of different mines, different geological units or different parts of the mines in the mining area, different horizontal coal rank areas are horizontally sorted and divided, and numbered A, B, C, ... in sequence, which are the horizontal coal rank area numbers; the number of horizontal coal rank division units is consistent with the number of horizontal coal ranks; Based on the angles of different coal seams or coal seam groups, the horizontal coal rank division units are again vertically sorted and divided one by one, and numbered a, b, c... from top to bottom according to the burial depth, which is the vertical coal rank area number, wherein the number of vertical coal rank division units divided in each horizontal coal rank division unit is consistent with the number of vertical coal ranks, the number of vertical coal rank division units divided in each horizontal coal rank division unit is ≥1, and the number of vertical coal rank division units divided in each horizontal coal rank division unit is not necessarily the same.

3. The method for analyzing the types and combinations of coal seam metamorphism in coal mining areas according to claim 1, characterized in that: The S2 is specifically: Take coal samples of each coal rank unit according to industry standards and measure the maximum vitrinite reflectance Ro of each coal rank unit max ; According to Barker's formula: T max =(lnRo max +1.2) / 0.0078), calculate the maximum metamorphic temperature T of each coal rank unit max ; The thickness of the regional strata, the age of the regional strata, the time of structural subsidence-uplift, the number of structural subsidence-uplift, and the amount of structural uplift erosion of each coal rank unit were obtained, and the historical maximum burial depth H of the coal seam in each coal rank unit was obtained by basin simulation software. max ; Obtain the coal seam settlement of each coal rank unit to H max The regional geothermal gradient at that time is calculated by using H max Regional geothermal gradient, calculate the formation temperature t at the historical maximum burial depth of each coal rank unit max ; Successive comparative analysis of each coal rank unit T max With the coal seam max : For T max -t max For units with a temperature of ≤20°C, the coal seam metamorphism type is deep metamorphism; for T max -t max For units with a temperature greater than 20℃, the coal seam metamorphism types include, in addition to deep-seated metamorphism, one or more of dynamic metamorphism, magmatic metamorphism, and hydrothermal metamorphism.

4. The method for analyzing the types and combinations of coal seam metamorphism in coal mining areas according to claim 3, characterized in that: The S3 is specifically: Establish a combination characteristic table of comprehensive discrimination conditions for magmatic metamorphism and hydrothermal metamorphism, i.e. Table 1; The table header includes the condition combination classification, feature details and corresponding qualitative action type; The combination classification includes the first condition combination, the second condition combination and the third condition combination; The characteristics of the first condition combination include: the metamorphic area where the unit is located has hydrothermal quartz veins and calcite veins; the area of ​​the metamorphic area where the unit is located is greater than a certain value, with regional characteristics, and the coal rank zoning in the metamorphic area is generally ring-shaped; the rocks in the metamorphic area where the unit is located are altered; the coal rank in the metamorphic area where the unit is located is high, with graphite belt-high metamorphic anthracite belt-medium metamorphic anthracite belt-low metamorphic anthracite belt; the unit has a high metamorphic gradient, and its Ro max The change gradient is greater than 0.1% / hm; the corresponding metamorphism type is regional magmatic metamorphism; The characteristics of the second condition combination include: the unit develops intrusive magmatic rocks; the metamorphic area where the unit is located is centered on intrusive magmatic rocks and is local or narrow; the metamorphic area where the unit is located is centered on intrusive magmatic rocks and has coke rock mixed zone, natural coke zone, coke coal mixed zone, and thermal coal zone from the inside to the outside; the rocks in the metamorphic area where the unit is located are altered, and high-medium-low temperature alteration zones are developed from the inside to the outside with intrusive magmatic rocks as the center; the corresponding metamorphism type is contact metamorphism; The characteristics of the third condition combination include: the metamorphic area where the unit is located has regional and boundary deep fault zones; hot springs are developed around the metamorphic area where the unit is located; the area of ​​the metamorphic area where the unit is located is less than a certain value, showing local characteristics; The corresponding metamorphism types include magmatic metamorphism, hydrothermal metamorphism and dynamic metamorphism; the corresponding metamorphism type is hydrothermal metamorphism; For T max -t max For units with a temperature of >20°C, geological survey and analysis are performed on Table 1: When a coal rank unit meets the first combination of conditions, the coal rank unit has regional magmatic metamorphism superimposed on magmatic metamorphism on the basis of deep metamorphism; When a coal rank unit meets the second combination of conditions, the coal rank unit has contact metamorphism superimposed on magmatic metamorphism on the basis of deep metamorphism; When a coal rank unit meets the third combination of conditions, the coal rank unit is superimposed with hydrothermal metamorphism on the basis of deep metamorphism; When a coal rank unit meets both the first and second condition combinations, the coal rank unit has both regional magmatic metamorphism and contact metamorphism superimposed on the deep metamorphism. When a coal rank unit meets both the first and third condition combinations, the coal rank unit has both regional magmatic metamorphism and hydrothermal metamorphism superimposed on the basis of deep metamorphism. When a coal rank unit meets both the second and third condition combinations, the coal rank unit is superimposed with both contact metamorphism of magmatic metamorphism and hydrothermal metamorphism on the basis of deep metamorphism. When a coal rank unit meets the first condition combination, the second condition combination, and the third condition combination at the same time, then the coal rank unit is superimposed with regional magmatic metamorphism, contact metamorphism, and hydrothermal hot water metamorphism on the basis of deep metamorphism; When a coal rank unit does not meet any of the first, second, or third condition combinations, the coal rank unit is superimposed with dynamic metamorphism on the basis of deep metamorphism.

5. The method for analyzing the types and combinations of coal seam metamorphism in coal mining areas according to claim 1, characterized in that: The S4 is specifically: Establish a structural feature classification table, i.e., Table 2, the header of which includes structural feature classification and structural feature details; The structural features of the first structural feature include: no compression faults or folds, gentle formation, i.e. dip angle ≤15°, original coal seam structure, stable coal seam occurrence, no shear slip failure inside the coal seam and between the coal seam and the rock layer, good coal seam permeability, permeability coefficient ≥3m 2 MPa -2 ·d -1 ; The structural features of the second structural feature include: the development of wide and gentle folds or interlayer compression faults, and their scale is relatively small, the formation is relatively gentle, that is, 15°<stratum dip angle≤30, the coal seam structure is the original structure-fragmentation structure, the coal seam is relatively stable, small-scale shear slip failure occurs inside the coal seam and between the coal seam and the rock layer, the coal seam has good permeability, and 1m 2 MPa -2 ·d -1 ≤Air permeability coefficient<3m 2 MPa -2 ·d -1 ; The structural features of the third structural feature include: the development of tight, inverted folds or compression faults, and their scale is relatively large, the coal seam structure is a granular structure-mylonitic structure, the coal seam is unstable, the formation dip is large, that is, >30°, there is a large range of shear slip failure inside the coal seam and between the coal seam and the rock layer, the coal seam has poor permeability, and the permeability coefficient is <1m 2 MPa -2 ·d -1 ; For units with regional magmatic metamorphism, contact metamorphism, hydrothermal metamorphism, regional magmatic metamorphism + contact metamorphism, regional magmatic metamorphism + hydrothermal metamorphism, contact metamorphism + hydrothermal metamorphism, and regional magmatic metamorphism + contact metamorphism + hydrothermal metamorphism, the structural characteristics of each unit are investigated and analyzed: When the unit structural characteristics meet the first structural characteristics or the second structural characteristics in Table 2, the external conditions for dynamic metamorphism are not met, and the unit does not experience dynamic metamorphism; When the unit structural characteristics meet the third structural characteristics of the unit in Table 2, it has the external conditions for dynamic metamorphism, and further determines whether it has dynamic metamorphism; ① For units with regional magmatic metamorphism, collect samples of hydrothermal quartz veins or calcite veins developed in the metamorphic area where the unit is located, and then make inclusion slices to measure the homogenization temperature T of the brine inclusions inside them. 均一 distribution characteristics and select its maximum uniform temperature T 均一max The maximum deterioration temperature of the unit is T max Conduct comparative analysis: When T 均一max Greater than the unit T max When, or 0℃≤T max -T 均一max When the temperature is ≤20℃, there is no dynamic metamorphism in the unit; When T max -T 均一max When the temperature is >20℃, the unit will experience dynamic metamorphism; ② For units with contact metamorphism, collect rock samples that have undergone alteration in the metamorphic area where the unit is located and measure their alteration temperature T 蚀变 distribution range, and select its maximum alteration temperature T 蚀变max The maximum deterioration temperature of the unit is T max Conduct comparative analysis: When T 蚀变max Greater than the unit T max When, or 0℃≤T max -T 蚀变max When the temperature is ≤20℃, there is no dynamic metamorphism in the unit; When T max -T 蚀变max When the temperature is >20℃, the unit will experience dynamic metamorphism; ③ For units with hydrothermal metamorphism, measure the underground fluid temperature T in or near the deep fault zone of the metamorphic area where the unit is located. 流体 distribution range, and select its maximum fluid temperature T 流体max The maximum deterioration temperature of the unit is T max Conduct comparative analysis: When T 流体max Greater than the unit T max When, or 0℃≤T max -T 流体max When the temperature is ≤20℃, there is no dynamic metamorphism in the unit; When T max -T 流体max When the temperature is >20℃, the unit will experience dynamic metamorphism; ④ For units with regional magmatic metamorphism + contact metamorphism, collect samples of hydrothermal quartz veins or calcite veins developed in the metamorphic area where the unit is located, and altered rock samples, and measure the homogenization temperature T of the brine inclusions inside the veins. 均一 Distribution characteristics and rock alteration temperature T 蚀变 Distribution range, comparative analysis of its maximum uniform temperature T 均一max and the maximum alteration temperature T 蚀变max , select the larger of the two and the maximum metamorphic temperature T of the unit max Conduct comparative analysis: When the larger of the two is greater than the unit T max When, or 0℃≤T max -When the larger of the two is ≤20℃, there is no dynamic metamorphism in the unit; When T max -When the larger of the two is greater than 20°C, the unit is subject to dynamic metamorphism; ⑤ For units with regional magmatic metamorphism + hydrothermal metamorphism, collect hydrothermal quartz vein or calcite vein samples developed in the metamorphic area where the unit is located, and measure the homogenization temperature T of the brine inclusions inside the vein body. 均一 distribution characteristics, and at the same time determine the underground fluid temperature T in or near the deep fault zone of the metamorphic area where the unit is located 流体 Distribution range, comparative analysis of its maximum uniform temperature T 均一max and the maximum fluid temperature T 流体max , select the larger of the two and the maximum metamorphic temperature T of the unit max Conduct comparative analysis: When the larger of the two is greater than the unit T max When, or 0℃≤T max -When the larger of the two is ≤20℃, there is no dynamic metamorphism in the unit; When T max -When the larger of the two is greater than 20°C, the unit is subject to dynamic metamorphism; ⑥ For units with contact metamorphism + hydrothermal metamorphism, collect rock samples that have undergone alteration in the metamorphic area where the unit is located and measure their alteration temperature T 蚀变 distribution range, and at the same time determine the underground fluid temperature T in or near the deep fault zone of the metamorphic area where the unit is located 流体 Distribution range, comparative analysis of its maximum alteration temperature T 蚀变max and the maximum fluid temperature T 流体max , select the larger of the two and the maximum metamorphic temperature T of the unit max Conduct comparative analysis: When the larger of the two is greater than the unit T max When, or 0℃≤T max -When the larger of the two is ≤20℃, there is no dynamic metamorphism in the unit; When T max -When the larger of the two is greater than 20°C, the unit is subject to dynamic metamorphism; ⑦ For units with regional magmatic metamorphism + contact metamorphism + hydrothermal hot water metamorphism, collect hydrothermal quartz vein or calcite vein samples developed in the metamorphic area where the unit is located, and altered rock samples, and measure the homogenization temperature T of the brine inclusions inside the vein body. 均一 Distribution characteristics and rock alteration temperature T 蚀变 distribution range, and at the same time determine the underground fluid temperature T in or near the deep fault zone of the metamorphic area where the unit is located 流体 Distribution range, and then compare and analyze its maximum uniform temperature T 均一max , maximum alteration temperature T 蚀变max and maximum fluid temperature T 流体max , select the largest of the three and the maximum metamorphic temperature T of the unit max Conduct comparative analysis: When the largest of the three is greater than the unit T max When, or 0℃≤T max -When the maximum of the three is ≤20℃, there is no dynamic metamorphism in the unit; When T max -When the maximum of the three is >20°C, the unit is subject to dynamic metamorphism.

Images