Advanced control method for high-pressure-bearing karst water disasters of coal seam floor

Abstract

The invention provides an advanced prevention and control method for high-pressure-bearing karst water disasters of a coal seam floor, which comprises the following steps of: setting a scheme of combining parallel arrangement and pinniform arrangement along the trend of a working face according to mining planning of a treatment area, ground construction conditions, and a part of mining areas are arranged in parallel along a stratum and the trend of the working face, and the other part of mining areas are arranged in a pinniform manner; all the components obliquely intersect with the structure; the two modes are matched for use, so that the suitability is higher; a drilling project is reasonably arranged in a treatment area, full coverage of the treatment area is achieved, no blind area exists, a directional drilling technology is adopted for a treatment target layer, the development degree of a main coal mining layer bottom plate structure is explored, possible hidden water guide structures are revealed, and high-pressure grouting plugging is conducted on lime karst gaps, cracks and vertical water guide structures revealed in the drilling process. Taiyuan group limestone advanced area treatment is realized, grouting treatment effect evaluation is carried out, and a guarantee is provided for safe and efficient mining of a coal mine.

Description

Technical Field

[0001] The present invention relates to the technical field of mineral resource development, and in particular to a method for preventing and controlling high-pressure karst water hazards in coal seam floors. Background Art

[0002] As the mining of upper coal resources gradually becomes exhausted, the mining of lower coal resources often faces the threat of deep mining and high pressure water hazards. There are many mines in China that are threatened by high pressure karst water hazards in the bottom plate. The accidents of high pressure karst water hazards in the bottom plate are extremely harmful. Once water bursts, it will bring disaster to the coal mine. Therefore, the advanced prevention and control of high pressure water hazards in the coal seam bottom plate has become a hot issue at present and in the future.

[0003] Nowadays, we should promote the transformation of water prevention and control work from process control to source prevention, local control to regional control, underground control to combined control of underground and underground, preventive measures to engineering control, and water control as the main method to control and protection combined, so as to achieve "comprehensive exploration, source control, quantitative evaluation, and standard mining". When mining coal seams threatened by floor limestone pressure water, we must adhere to the principle of giving equal importance to the prevention and control of Ordovician limestone water and Taiyuan Formation limestone water, and regional advanced exploration and control.

[0004] After searching, the Chinese invention patent with application number "CN201310254224.0" discloses a method for preventing and controlling water inrush from the bottom plate of coal mining on a pressurized water body, which relates to a method for preventing and controlling water inrush from the bottom plate of coal mining. It includes the following steps: the first step is to detect the mining face; the second step is to open up drilling sites on both sides of the advance transport drift and the return air drift according to the detection results of the first step to drill holes; the third step is to install grouting casings at the drilling openings of each of the "lower three zones" of the coal seam floor, and install freezing casings at the bottom layer; the fourth step is to inject grout into the borehole after the drilling is completed, and the injection sequence starts from the bottom and proceeds upward layer by layer, and liquid nitrogen is used for quick freezing before and during the injection of grouting at the bottom layer. This invention is based on the principle of "detection first, grouting second, freezing third, and excavation last". By grouting and freezing each of the "lower three zones" layer by layer from bottom to top, it can effectively prevent and control water hazards in the process of mining deep coal seam floors with complex geological structures.

[0005] The above-mentioned method for preventing and controlling water inrush from the bottom rock strata of coal mining on pressurized water bodies utilizes grouting and freezing treatment to control the "lower three zones". It is limited to the concept of single-point exploration and control, but does not involve the concept of regional advanced prevention and control. It is impossible to reasonably arrange drilling projects in the control area to achieve full coverage of the control area without blind spots. There are hidden water-conducting structures, which affect the safe mining of coal mines.

[0006] In summary, there is an urgent need for an advanced prevention and control method for high-pressure karst water hazards in the coal seam floor to solve the above problems. Summary of the invention

[0007] In order to make up for the above shortcomings, the present invention provides a method for the advance prevention and control of high-pressure karst water hazards in the coal seam floor, which is used to solve the problems that the existing prevention and control methods for water inrush in the rock strata of coal mining on pressurized water bodies are limited to the concept of single-point exploration and management, but do not involve the concept of regional advance prevention and control, and cannot reasonably arrange drilling projects in the management area to achieve full coverage of the management area without blind spots. There are hidden water-conducting structures, which affect the safe mining of coal mines.

[0008] The present invention is achieved in that:

[0009] A method for preventing and controlling high-pressure karst water hazards in coal seam floors, comprising the following steps:

[0010] S1: drilling preparation;

[0011] S2: Drilling of the straight hole section and cementing of the pipe;

[0012] S3: drilling the deflection section and cementing the pipe;

[0013] S4: Perform water stop inspection on the drilling of the deflection section;

[0014] S5: horizontal (bedding) branch drilling;

[0015] S6: Check the water stop of horizontal (bedding) branch boreholes and perform grouting treatment on the leakage section;

[0016] S7: Branch acceptance and hole sealing;

[0017] S8: Repeat the above steps S3-S7 to operate the next branch drilling.

[0018] As a preferred solution of the method for advanced prevention and control of high-pressure karst water hazards in coal seam floors of the present invention, in step S2, the drilling process is strictly constructed according to the design parameters, and actual drilling monitoring is carried out according to the design requirements, and the construction parameters and measures are adjusted in time;

[0019] As a preferred solution of the method for advanced prevention and control of high-pressure karst water hazards in the coal seam floor of the present invention, in step S3, the wellbore azimuth is strictly controlled in the deflection section, and the azimuth is controlled within the range of ±2° of the designed azimuth, and the closing azimuth of the deflection section shall not exceed 1.5° of the designed wellbore;

[0020] As a preferred scheme of the method for advance prevention and control of high-pressure karst water hazards in the coal seam floor described in the present invention, in steps S3-S8, the layer positions are strictly controlled during the construction of all drilling groups, and the layer (depth) rate shall not be less than 80%; the actual trajectory of the horizontal branch hole shall not deviate from the designed trajectory by more than 2m, and the hole section greater than 2m shall not exceed 15% of the entire hole section.

[0021] As a preferred solution of the method for advanced prevention and control of high-pressure karst water hazards in coal seam floors described in the present invention, a gamma probe is added to the drilling instrument during the drilling process to obtain formation gamma parameters at any time.

[0022] As a preferred solution of the method for advanced prevention and control of high-pressure karst water hazards in the coal seam floor described in the present invention, in steps S2, S4, and S6, the drilling tools must be measured and the well depth must be calibrated before drilling, and the well depth error must not exceed 0.5m.

[0023] As a preferred solution of the method for advanced prevention and control of high-pressure karst water hazards in the coal seam floor described in the present invention, all the horizontal (bedding) branch drillings are arranged parallel to the formation and working face, and are at a large angle to the main structure.

[0024] As a preferred solution of the method for advanced prevention and control of high-pressure karst water hazards in the coal seam floor described in the present invention, the spacing between the horizontal (bedding) branch drilling wells is 60m.

[0025] As a preferred scheme of the method for advance prevention and control of high-pressure karst water hazards in the coal seam floor described in the present invention, a part of the horizontal (bedding) branch drilling is arranged in parallel along the direction of the stratum and the working face, with a large angle to the main structure, and the parallel spacing of the branch boreholes is 60m; the other part is arranged in feather-like parallel, all oblique to the structure.

[0026] As a preferred solution of the method for advanced prevention and control of high-pressure karst water hazards in coal seam floors of the present invention, steps S2-S8 also include a test detection method, which includes:

[0027] 1. Cuttings logging

[0028] Requirements for collecting cuttings: No sand samples are collected on the bedrock, but the bedrock interface must be determined; after entering the bedrock, 1 bag of sand is collected every 5 meters; in the inclined well section, 1 bag of cuttings is collected every 2 meters; in the horizontal section, 1 bag of cuttings is collected every 1 meter, and core verification is required when encountering special situations;

[0029] 1.1 Retrieving rock cuttings:

[0030] Accurately retrieve cuttings at the same location according to logging interval and delay time;

[0031] Add baffles in empty slots for sampling; add sample receivers in front of vibrating screens for sampling;

[0032] 1.2 Cleaning: The method depends on the rock type, and the principle is not to miss or damage the rock cuttings.

[0033] Dense and hard limestone, sandstone and some mudstone → can be washed or flushed;

[0034] Soft mudstone and loose sandstone, etc. → can only be gently rinsed in a basin;

[0035] 1.3 Dry the rock chips (or dry them naturally)

[0036] 2. Logging during drilling

[0037] 2.1 Spacing requirements: record one point every 1m from the bedrock section to well completion;

[0038] 2.2 The sudden changes during drilling should be recorded at any time so as to timely find coal seams, target limestone layers, etc., and accurately check the depth and thickness of the layers;

[0039] 2.3 Try to keep the drilling parameters relatively stable so as to improve the effectiveness of the parameters in reflecting the formation lithology during drilling and record the non-geological factors that cause the drill to get stuck;

[0040] 2.4 Check the drilling tool length and hole depth. The hole depth must be checked after each branch hole is drilled. The hole depth error shall not exceed 1.5%; the number of missed drilling points in the whole hole shall not exceed 0.5% of the total number, and no drilling points in the target layer section shall be missed;

[0041] 3. Drilling fluid logging

[0042] 3.1 Perform full performance test every 8 hours; perform general performance test (density, viscosity) every hour;

[0043] 3.2 When abnormal gas is found in the coal seam hole section, the density and viscosity of the drilling fluid should be continuously measured and recorded;

[0044] 4. Simple hydrological observation

[0045] 4.1 During the whole hole drilling process, simple hydrological observation and record work should be done strictly in accordance with the drilling requirements;

[0046] 4.2 Measure the water level (liquid level in the wellbore) once after each start of drilling and before drilling down; record the drilling fluid consumption (liquid level in the mud pool) once every hour of drilling; when drilling in leaks, karst caves, large fissures, and severely collapsed layers in the broken zone, the start and end depth records must be detailed and clear;

[0047] 4.3 Consumption observation: observe once every hour, observe once for each return of less than 1 hour, observe once every 10-30 minutes when drilling fluid leakage is found, and when all drilling fluid is lost, the pump should be turned on to measure the maximum leakage;

[0048] 4.4 Water level observation: Observe the water level once after each drilling and before each drilling, and measure the water temperature in case of abnormal conditions;

[0049] 4.5 The drilling consumption and water level observation times should reach 100% of the required times;

[0050] 5. Measurement while drilling technology

[0051] 5.1 Directional drilling is carried out using wireless inclinometers while drilling in the beveling section and horizontal section, and the borehole trajectory is accurately controlled, and geological guidance is carried out in conjunction with drilling logging, cuttings logging and other methods;

[0052] The main purpose of measurement while drilling:

[0053] ① In the vertical well section, real-time well inclination monitoring is carried out and a screw is lowered to correct the inclination when necessary.

[0054] ② In the deflection section, through directional control, the actual drilling depth trajectory is drilled according to the design, and a smooth trajectory is drilled to avoid doglegs. This is beneficial to underground safety.

[0055] ③ In the horizontal section, adjust the well inclination according to the occurrence of the target layer to ensure effective drilling in the target layer.

[0056] 5.2 Eyelet trajectory control measures:

[0057] The equipment is installed and debugged strictly according to the drilling rig standards, especially the overhead crane, turntable and hole mouth, the deviation of which is less than 10mm. It is tested according to regulations and the next step of construction can be carried out only after meeting the requirements.

[0058] Strengthen the inspection and calibration of MWD drilling monitoring equipment to ensure that the equipment is sensitive and accurate. When the mud is completely lost and cannot be returned, the MWD drilling monitoring equipment will stop working. At this time, drilling should not continue. When drilling is required, the footage should be controlled to not exceed 5m. In order to ensure that the MWD drilling monitoring equipment receives good signals, the solid content of cuttings and other solids in the mud should be controlled (less than 0.3%).

[0059] To obtain representative cuttings, the well depth and arrival time must be accurate. Accurate well depth means the drilling tools must be measured; accurate arrival time means the arrival time of cuttings must be measured at a certain interval; arrival time means the time it takes for cuttings to return from the bottom of the well to the wellhead.

[0060] Cuttings late time and determination method:

[0061] Commonly used methods for measuring lateness time include: theoretical calculation method, physical measurement method and marker layer method.

[0062] a. Theoretical calculation method

[0063]

[0064] Where: t—cuttings delay time, min;

[0065] V—the volume of the annular space between the wellbore and the drill pipe, m 3 ;

[0066] Q—drilling pump displacement, m 3 / min;

[0067] D—well diameter, i.e. drill bit diameter, m;

[0068] d—drill pipe outer diameter, m;

[0069] H—well depth, m.

[0070] The sinking of cuttings in the mud is not taken into account during the calculation (ρ cuttings > ρ mud). The theoretical calculation results are inconsistent with the actual delay time (smaller than the actual time) and are for reference only.

[0071] b. Physical measurement method

[0072] Select materials with similar size and density to the cuttings (red bricks, white porcelain fragments), and put them into the drill pipe when connecting a single pipe. Note the time when the pump is turned on after the injection, and the time when the injected material begins to return. The difference between the two times is the actual cycle period t.

[0073] t1=t-t0

[0074] Where: t1—time from well bottom to well head (delay time)

[0075] t—cycle period

[0076] t0—The time it takes for the object to descend along the drill pipe to the bottom of the well

[0077]

[0078] Where: V1, V2—the internal volume of the drill pipe and drill collar (obtained from the table), m 3 :

[0079] d1, d2—inner diameter of drill pipe and drill collar, m;

[0080] L1, L2—length of drill pipe and drill collar, m;

[0081] Q—mud displacement, m 3 / min.

[0082] Advantages of the physical object measurement method: the density of the physical object is similar or close to that of the formation, and the measured delay time is more accurate. The color is bright and easy to identify.

[0083] c. Marking layer method

[0084] When the coal seam is exposed, the drilling speed will suddenly increase and the drilling pressure will change dramatically. Start timing immediately. The time when the marker layer comes out from the vibrating screen is the delay time.

[0085] Preferably, the late time increases with the increase of the well depth, and the late time is generally measured once at a certain interval as the late time within the interval.

[0086] Compared with the prior art, the technical solution of this application has the following beneficial effects:

[0087] 1. The method for advanced prevention and control of high-pressure karst water hazards in the coal seam floor demonstrated in the present invention is to set up a scheme combining parallel arrangement and feather arrangement along the direction of the working face according to the mining plan of the treatment area and combined with the ground construction conditions, wherein some mining areas are arranged in parallel along the direction of the stratum and the working face, and the other mining areas are arranged in feather shape, both of which are oblique to the structure; the two methods are used in combination for stronger suitability; the drilling project is reasonably arranged in the treatment area to achieve full coverage of the treatment area without blind spots, and directional drilling technology is used for the treatment target layer to explore the degree of structural development of the main mining coal seam floor, reveal possible hidden water-conducting structures, and perform high-pressure grouting to seal the limestone rifts, fissures and vertical water-conducting structures revealed during the drilling process, so as to achieve advanced regional treatment of Taiyuan Group limestone, conduct grouting treatment effect evaluation, and provide guarantee for safe and efficient mining of coal mines.

[0088] 2. The method for advanced prevention and control of high-pressure karst water hazards in the coal seam floor demonstrated in the present invention is to add a gamma probe to the drilling instrument during the drilling process to obtain the gamma parameters of the formation at any time; the gamma measurement data while drilling plays an important guiding role in the construction of the horizontal section. Generally, the distance between the drill bit and the target limestone layer is judged according to the gamma amplitude of the drilled formation. When the gamma amplitude is low, the formation lithology is limestone. When the gamma amplitude is high, the drill bit is close to the coal (mudstone) layer. Therefore, according to the gamma measurement data while drilling, the drilling situation of the drill bit in the horizontal section can be judged. When the target layer is about to be drilled out, the directional data can be corrected, the wellbore trajectory can be adjusted in time, and the drill bit can be kept running in the target layer.

[0089] 3. The method for advance prevention and control of high-pressure karst water hazards in the coal seam floor demonstrated by the present invention adheres to the cross principle of "construction → layer determination → exploration → control → evaluation" by setting up ground advance area exploration and control, thereby ensuring the effect of advance exploration and control, and having a wide range of spatial control and excellent water hazard elimination effect.

[0090] 4. The method for advance prevention and control of high-pressure karst water hazards in the coal seam floor demonstrated by the present invention confirms the late arrival time of rock cuttings by adopting multiple methods such as theoretical calculation method, physical measurement method and marker layer method, so as to achieve the purpose of obtaining representative rock cuttings, accurately judge the changes in the formation, and realize the accuracy of the horizontal (bedding) branch drilling direction.

[0091] 5. The method for advanced prevention and control of high-pressure karst water hazards in the coal seam floor shown in the present invention uses the measurement while drilling technology to carry out geological guidance, combined with logging, gamma while drilling and other means to accurately judge the formation changes. The purpose of the horizontal section is to calculate the inclination and structural conditions of the target layer in real time, provide well inclination instructions for orientation, and control the well inclination changes to keep drilling in the target layer. BRIEF DESCRIPTION OF THE DRAWINGS

[0092] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings required for use in the embodiments will be briefly introduced below. It should be understood that the following drawings only show certain embodiments of the present invention and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other related drawings can be obtained based on these drawings without paying creative work.

[0093] Figure 1 A drilling construction flow chart of a method for preventing and controlling high-pressure karst water hazards in coal seam floors according to the present invention;

[0094] Figure 2 This is a diagram of the exploration and treatment engineering of the ground advance area of ​​the mining area in the first embodiment of the present invention;

[0095] Figure 3 This is a diagram of the ground advance area exploration and management engineering of the mining area in Example 2 of the present invention. DETAILED DESCRIPTION

[0096] First of all, it should be pointed out that in the different described embodiments, the same parts are provided with the same reference numerals or the same component names, wherein the disclosure contained in the entire description can be transferred to the same parts with the same reference numerals or the same component names. Selected positional descriptions in the description, such as top, bottom, lateral, etc., also refer to the directly described and shown figures and are transferred to the new positions in the case of a change in position.

[0097] Embodiment 1:

[0098] See also Figure 1-Figure 2 , the present invention provides a technical solution:

[0099] A method for preventing and controlling high-pressure karst water hazards in coal seam floors Figure 1 As shown, the following steps are included:

[0100] S1: drilling preparation;

[0101] S2: Drilling of the straight hole section and cementing of the pipe;

[0102] S3: drilling the deflection section and cementing the pipe;

[0103] S4: Perform water stop inspection on the drilling of the deflection section;

[0104] S5: horizontal (bedding) branch drilling;

[0105] S6: Check the water stop of horizontal (bedding) branch boreholes and perform grouting treatment on the leakage section;

[0106] S7: Branch acceptance and hole sealing;

[0107] S8: Repeat the above steps S3-S7 to operate the next branch drilling.

[0108] like Figure 2 As shown, all horizontal (bedding-based) branch drillings are arranged parallel to the formation and working face strike, with a large oblique angle to the main structure.

[0109] The ground advanced area exploration and treatment generally adheres to the ten-point principle of "construction → layer determination → exploration → treatment → evaluation", which ensures the effectiveness of advanced exploration and treatment, and has the characteristics of a wide range of spatial treatment and excellent effect in eliminating water hazard risks.

[0110] As a preferred solution of the method for advanced prevention and control of high-pressure karst water hazards in coal seam floors of the present invention, in step S2, the drilling process is strictly constructed according to the design parameters, and actual drilling monitoring is carried out according to the design requirements, and the construction parameters and measures are adjusted in time;

[0111] As a preferred solution of the method for advance prevention and control of high-pressure karst water hazards in the coal seam floor described in the present invention, in step S3, the wellbore azimuth is strictly controlled in the inclined section, and the azimuth is controlled within the range of ±2° of the designed azimuth, and the closing azimuth of the inclined section shall not exceed 1.5° of the designed wellbore.

[0112] As a preferred scheme of the method for advance prevention and control of high-pressure karst water hazards in the coal seam floor described in the present invention, in steps S3-S8, the layer positions are strictly controlled during the construction of all drilling groups, and the layer (depth) rate shall not be less than 80%; the actual trajectory of the horizontal branch hole shall not deviate from the designed trajectory by more than 2m, and the hole section greater than 2m shall not exceed 15% of the entire hole section.

[0113] As a preferred solution of the method for advanced prevention and control of high-pressure karst water hazards in coal seam floors of the present invention, steps S2-S8 also include a test detection method, which includes:

[0114] 1. Cuttings logging

[0115] Requirements for collecting cuttings: No sand samples are collected on the bedrock, but the bedrock interface must be determined; after entering the bedrock, 1 bag of sand is collected every 5 meters; in the inclined well section, 1 bag of cuttings is collected every 2 meters; in the horizontal section, 1 bag of cuttings is collected every 1 meter, and core verification is required when encountering special situations;

[0116] 1.1 Retrieving rock cuttings:

[0117] Accurately retrieve cuttings at the same location according to logging interval and delay time;

[0118] Add baffles in empty slots for sampling; add sample receivers in front of vibrating screens for sampling;

[0119] 1.2 Cleaning: The method depends on the rock type, and the principle is not to miss or damage the rock cuttings.

[0120] Dense and hard limestone, sandstone and some mudstone → can be washed or flushed;

[0121] Soft mudstone and loose sandstone, etc. → can only be gently rinsed in a basin;

[0122] 1.3 Dry the rock chips (or dry them naturally)

[0123] 2. Logging during drilling

[0124] 2.1 Spacing requirements: record one point every 1m from the bedrock section to well completion;

[0125] 2.2 The sudden changes during drilling should be recorded at any time so as to timely find coal seams, target limestone layers, etc., and accurately check the depth and thickness of the layers;

[0126] 2.3 Try to keep the drilling parameters relatively stable so as to improve the effectiveness of the parameters in reflecting the formation lithology during drilling and record the non-geological factors that cause the drill to get stuck;

[0127] 2.4 Check the drilling tool length and hole depth. The hole depth must be checked after each branch hole is drilled. The hole depth error shall not exceed 1.5%; the number of missed drilling points in the whole hole shall not exceed 0.5% of the total number, and no drilling points in the target layer section shall be missed;

[0128] 3. Drilling fluid logging

[0129] 3.1 Perform full performance test every 8 hours; perform general performance test (density, viscosity) every hour;

[0130] 3.2 When abnormal gas is found in the coal seam hole section, the density and viscosity of the drilling fluid should be continuously measured and recorded;

[0131] To obtain representative rock cuttings, the well depth and arrival time must be accurate. Specifically, the well depth must be accurate - the drilling tools must be measured;

[0132] Accurate late arrival time - the late arrival time of cuttings must be measured accurately at certain intervals;

[0133] Delay time - the time it takes for cuttings to return from the bottom of the well to the wellhead;

[0134] Using a specific rock cuttings determination method, the specific rock cuttings late arrival time can be calculated:

[0135] Commonly used methods for measuring lateness time include: theoretical calculation method, physical measurement method and marker layer method.

[0136] a. Theoretical calculation method

[0137]

[0138] Where: t—cuttings delay time, min;

[0139] V—the volume of the annular space between the wellbore and the drill pipe, m 3 ;

[0140] Q—drilling pump displacement, m 3 / min;

[0141] D—well diameter, i.e. drill bit diameter, m;

[0142] d—drill pipe outer diameter, m;

[0143] H—well depth, m.

[0144] The sinking of cuttings in the mud is not taken into account during the calculation (ρ cuttings > ρ mud). The theoretical calculation results are inconsistent with the actual delay time (smaller than the actual time) and are for reference only.

[0145] b. Physical measurement method

[0146] Select materials with similar size and density to the cuttings (red bricks, white porcelain fragments), and put them into the drill pipe when connecting a single pipe. Note the time when the pump is turned on after the injection, and the time when the injected material begins to return. The difference between the two times is the actual cycle period t.

[0147] t1=t-t0

[0148] Where: t1—time from well bottom to well head (delay time)

[0149] t—cycle period

[0150] t0—The time it takes for the object to descend along the drill pipe to the bottom of the well

[0151]

[0152] Where: V1, V2—the internal volume of the drill pipe and drill collar (obtained from the table), m 3 :

[0153] d1, d2—inner diameter of drill pipe and drill collar, m;

[0154] L1, L2—length of drill pipe and drill collar, m;

[0155] Q—mud displacement, m 3 / min.

[0156] Advantages of the physical object measurement method: the density of the physical object is similar or close to that of the formation, and the measured delay time is more accurate. The color is bright and easy to identify.

[0157] c. Marking layer method

[0158] When the coal seam is exposed, the drilling speed will suddenly increase and the drilling pressure will change dramatically. Start timing immediately. The time when the marker layer comes out from the vibrating screen is the delay time.

[0159] Preferably, the late time increases with the increase of the well depth, and the late time is generally measured once at a certain interval as the late time within the interval.

[0160] The cuttings arrival time is confirmed by adopting a variety of methods including theoretical calculation, physical measurement and marker layer method, so as to obtain representative cuttings, accurately judge the formation changes and realize the accuracy of horizontal (bedding) branch drilling direction.

[0161] 4. Simple hydrological observation

[0162] 4.1 During the whole hole drilling process, simple hydrological observation and record work should be done strictly in accordance with the drilling requirements;

[0163] 4.2 Measure the water level (liquid level in the wellbore) once after each start of drilling and before drilling down; record the drilling fluid consumption (liquid level in the mud pool) once every hour of drilling; when drilling in leaks, karst caves, large fissures, and severely collapsed layers in the broken zone, the start and end depth records must be detailed and clear;

[0164] 4.3 Consumption observation: observe once every hour, observe once for each return of less than 1 hour, observe once every 10-30 minutes when drilling fluid leakage is found, and when all drilling fluid is lost, the pump should be turned on to measure the maximum leakage;

[0165] 4.4 Water level observation: Observe the water level once after each drilling and before each drilling, and measure the water temperature in case of abnormal conditions;

[0166] 4.5 The drilling consumption and water level observation times should reach 100% of the required times;

[0167] 5. Measurement while drilling technology

[0168] 5.1 Directional drilling is carried out using wireless inclinometers while drilling in the beveling section and horizontal section, and the borehole trajectory is accurately controlled, and geological guidance is carried out in conjunction with drilling logging, cuttings logging and other methods;

[0169] The main purpose of measurement while drilling:

[0170] ① In the vertical well section, real-time well inclination monitoring is carried out and a screw is lowered to correct the inclination when necessary.

[0171] ② In the deflection section, through directional control, the actual drilling depth trajectory is drilled according to the design, and a smooth trajectory is drilled to avoid doglegs. This is beneficial to underground safety.

[0172] ③ In the horizontal section, adjust the well inclination according to the occurrence of the target layer to ensure effective drilling in the target layer.

[0173] During the drilling process, a gamma probe is added to the drilling instrument to obtain formation gamma parameters at any time.

[0174] By adding a gamma probe to the drilling instrument during the drilling process, the gamma parameters of the formation can be obtained at any time; the gamma measurement data while drilling plays an important guiding role in the construction of the horizontal section. Generally, the distance between the drill bit and the target limestone layer is judged according to the gamma amplitude of the formation encountered. When the gamma amplitude is low, the formation lithology is limestone, and when the gamma amplitude is high, the drill bit is close to the coal (mudstone) layer; therefore, according to the gamma measurement data while drilling, the drilling situation of the drill bit in the horizontal section can be judged. When the target layer is about to be drilled out, the directional data can be corrected, the wellbore trajectory can be adjusted in time, and the drill bit can be kept running in the target layer.

[0175] By setting up the measurement while drilling technology for geological guidance, combined with logging, gamma while drilling and other means, the formation changes can be accurately judged. The main task before entering the window is to provide the target layer change at the window entry point, provide target data for orientation, adjust the next step trajectory in time, and finally reach the appropriate well inclination angle to drill into the target layer. The purpose of the horizontal section is to calculate the inclination and structural conditions of the target layer in real time, provide well inclination instructions for orientation, and control the well inclination change to keep drilling in the target layer.

[0176] 5.2 Eyelet trajectory control measures:

[0177] The equipment is installed and debugged strictly according to the drilling rig standards, especially the overhead crane, turntable and hole mouth, the deviation of which is less than 10mm. It is tested according to regulations and the next step of construction can be carried out only after meeting the requirements.

[0178] Strengthen the inspection and calibration of MWD drilling monitoring equipment to ensure that the equipment is sensitive and accurate. When the mud is completely lost and cannot be returned, the MWD drilling monitoring equipment will stop working. At this time, drilling should not continue. When drilling is required, the footage should be controlled to not exceed 5m. In order to ensure that the MWD drilling monitoring equipment receives good signals, the solid content of cuttings and other solids in the mud should be controlled (less than 0.3%).

[0179] As a preferred solution of the method for advanced prevention and control of high-pressure karst water hazards in the coal seam floor described in the present invention, in steps S2, S4, and S6, the drilling tools must be measured and the well depth must be calibrated before drilling, and the well depth error must not exceed 0.5m.

[0180] As a preferred solution of the method for advanced prevention and control of high-pressure karst water hazards in the coal seam floor described in the present invention, the spacing between the horizontal (bedding) branch drilling wells is 60m.

[0181] Embodiment 2:

[0182] A method for preventing and controlling high-pressure karst water hazards in coal seam floors Figure 3As shown, different from Example 1, a part of the horizontal (bedding) branch drilling is arranged parallel to the formation and the working face, with a large angle to the main structure, and the parallel spacing of the branch boreholes is 60m; the other part is arranged in feather-like parallel, all oblique to the structure.

[0183] The principle of the present invention is:

[0184] Parallel arrangement and feather-like arrangement along the direction of the stratum and working face are both oblique to the structure; the two methods are used in combination for greater suitability; the drilling project is reasonably arranged in the treatment area to achieve full coverage of the treatment area without blind spots, and directional drilling technology is used for the treatment target layer to explore the degree of development of the bottom structure of the main mining coal seam, reveal possible hidden water-conducting structures, and carry out high-pressure grouting to seal the limestone karst fissures, cracks and vertical water-conducting structures revealed during the drilling process, so as to achieve advanced regional treatment of Taiyuan Group limestone, evaluate the effect of grouting treatment, and provide guarantee for safe and efficient mining of coal mines.

[0185] It should be noted that, in this article, relational terms such as first and second, etc. are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Moreover, the terms "include", "comprise" or any other variants thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or device. In the absence of further restrictions, the elements defined by the sentence "comprise a ..." do not exclude the existence of other identical elements in the process, method, article or device including the elements.

[0186] Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A method for preventing and controlling high-pressure karst water hazards in coal seam floors, characterized in that: The following steps are involved: S1: drilling preparation; S2: Drilling of the straight hole section and cementing of the pipe; S3: drilling the deflection section and cementing the pipe; S4: Perform water stop inspection on the drilling of the deflection section; S5: horizontal (bedding) branch drilling; S6: Check the water stop of horizontal (bedding) branch boreholes and perform grouting treatment on the leakage section; S7: Branch acceptance and hole sealing; S8: Repeat the above steps S3-S7 to operate the next branch drilling.

2. The method for advanced prevention and control of high-pressure karst water hazards in coal seam floors according to claim 1 is characterized in that: The horizontal (bedding-parallel) branch drillings are all arranged parallel to the formation and working surface, and are obliquely arranged at a large angle to the main structure.

3. The method for advanced prevention and control of high-pressure karst water hazards in coal seam floors according to claim 1, characterized in that: One part of the horizontal (bedding-parallel) branch drilling is arranged parallel to the formation and working face, with a large angle to the main structure, and the parallel spacing of the branch boreholes is 60m; the other part is arranged in feather-like parallel, all oblique to the structure.

4. A method for preventing and controlling high-pressure karst water hazards in coal seam floors according to claim 2 or 3, characterized in that: In step S3, the wellbore azimuth is strictly controlled in the deflection section, and the azimuth is controlled within the range of ±2° of the designed azimuth. The closing azimuth of the deflection section shall not exceed 1.5° of the designed wellbore.

5. A method for preventing and controlling high-pressure karst water hazards in coal seam floors according to claim 4, characterized in that: In steps S3-S8, all drilling groups strictly control the layer position during construction, and the layer (depth) rate shall not be less than 80%; the actual trajectory of the horizontal branch hole shall not deviate from the designed trajectory by more than 2m, and the hole section greater than 2m shall not exceed 15% of the entire hole section.

6. The method for advanced prevention and control of high-pressure karst water hazards in coal seam floors according to claim 5, characterized in that: Steps S2-S8 also include test detection methods, which include: cuttings logging, drilling logging, drilling fluid logging, simple hydrological observation and measurement while drilling technology.

7. The method for advanced prevention and control of high-pressure karst water hazards in coal seam floors according to claim 1, characterized in that: In steps S2, S4, and S6, the drilling tools must be measured and the well depth must be calibrated before drilling. The well depth error must not exceed 0.5 m.

8. The method for advanced prevention and control of high-pressure karst water hazards in coal seam floors according to claim 5, characterized in that: The spacing between the horizontal (bedding) branch drilling wells is 60m.

9. The method for advanced prevention and control of high-pressure karst water hazards in coal seam floors according to claim 6, characterized in that: The measurement while drilling technology includes: using a wireless while drilling inclinometer to perform directional drilling in the inclination section and the horizontal section, and accurately controlling the wellbore trajectory, and coordinating with drilling logging, cuttings logging and other methods for geological guidance; hole trajectory control measures: the equipment is strictly installed and debugged according to the drilling rig standards, especially the deviation of the crown block, turntable and hole mouth is less than 10mm, and the inspection and calibration of the MWD while drilling monitoring equipment is strengthened to ensure that the equipment is sensitive and accurate. When the mud is completely lost and cannot be returned, the MWD while drilling monitoring equipment will stop working, and drilling should not be continued at this time. When drilling is required, the footage should be controlled to not exceed 5m. In order to ensure that the MWD while drilling monitoring equipment receives a good signal, the solid content of cuttings and other solids in the mud should be controlled (less than 0.3%).

10. The method for advanced prevention and control of high-pressure karst water hazards in coal seam floors according to claim 5, characterized in that: During the drilling process, a gamma probe is added to the drilling instrument to obtain formation gamma parameters at any time.

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