Construction method for draining underground goaf water through ground directional drilling

Abstract

The invention discloses a construction method for draining underground goaf water through ground directional drilling, and relates to the technical field of coal mining. The method comprises the following steps: determining a shallow goaf water target area 1; determining a deep water discharge target area 2; directional drilling construction is conducted; establishing a dynamic monitoring and early warning system; and carrying out cooperative treatment on roadway tunneling. According to the method, an upper goaf and a lower goaf are communicated through a directional drilling technology, gob water in the upper goaf is drained into the lower goaf through a drilling channel, and the gob water is drained in advance according to plans and steps by comprehensively applying various technical means such as ground directional drilling, casing pipe underneath arrangement, goaf penetrating and water level monitoring. Compared with a traditional treatment method, the method not only can effectively avoid safety risks such as water burst out-of-control and abnormal gas emission, but also can avoid resource waste caused by the fact that coal resources cannot be recovered.

Description

Technical Field

[0001] The invention relates to the technical field of coal mining, in particular to a ground directional drilling construction method for draining old underground water. Background Art

[0002] Over the long-term mining process, large amounts of groundwater often accumulate in goaf areas, forming "old goaf water accumulation areas." Mine water inrush accidents caused by this old goaf water are common, not only damaging equipment and flooding tunnels, but also seriously threatening the lives of underground workers, resulting in significant economic losses and adverse social impacts for coal companies.

[0003] In the past, traditional methods for managing old goaf water hazards mostly used underground long-distance rock tunnel centralized exploration and drainage to drain old goaf water or leave safe coal and rock pillars. However, underground drainage of old goaf water has complex construction technology and a long implementation cycle. In addition, there are safety risks such as uncontrolled water gushing and abnormal gas gushing during the underground drainage process. If the control measures are not implemented in place, it is easy to cause secondary disasters, threatening the safety of workers and mine production safety. The construction of underground floor rock tunnels and exploration and drainage projects needs to consider the temporal and spatial relationship of mine succession in advance and organize exploration and drainage in an orderly manner. Otherwise, it is easy to affect the succession of mine production and cause continuity tension. Leaving a safe coal and rock pillar will make some coal resources unable to be recovered, resulting in resource waste. For this reason, we propose a ground directional drilling construction method for draining underground old goaf water. Summary of the Invention

[0004] The purpose of the present invention is to provide a ground directional drilling construction method for draining old water in the well, so as to solve the problems raised in the above background technology.

[0005] To achieve the above-mentioned purpose, the present invention provides the following technical solution: a ground directional drilling method for draining underground old water, comprising the following steps:

[0006] Step 1: Determine shallow old goaf water target area 1: Explore the distribution location and water accumulation of the upper old goaf water in the mining area, select the low point area of ​​the old goaf water in the mining area as the shallow old goaf water target area 1 for directional drilling, and calculate parameters such as water accumulation volume and water accumulation height;

[0007] Step 2: Determine the deep drainage target area 2: Based on the geological data of the mining area, select the deep goaf or roadway as the target area 2 for directional drilling, and analyze its water level and water storage space;

[0008] Step 3: Directional Drilling: Determine the drilling location, design the directional drilling trajectory, and adopt a staged drilling process, including:

[0009] First opening section: Directional drilling is used to reach the slight leakage position at the top of the fracture zone in the shallow old goaf, and the retaining wall casing is lowered and cemented to check the water-stopping effect;

[0010] Second section: Directional drilling is used to reach target areas 1 and 2, mud wall protection is used to quickly cross the goaf, and casing is run to achieve water drainage;

[0011] Three-opening section: conventional drilling is used to reach the end hole, and a water filter flower pipe is lowered to form a double-layer structure with the second-opening water filter flower pipe to enhance the drainage effect;

[0012] Step 4: Establish a dynamic monitoring and early warning system: Use the dynamic monitoring system to monitor the water level changes and drainage effects of the old goaf in real time, and simultaneously monitor the gas composition at the wellhead to provide early warning of water disaster risks and abnormal gas outburst risks in the goaf;

[0013] Step 5. Coordinated management during tunnel excavation: During tunnel excavation in the mining area, explore the abnormal old water-rich area in front of the tunnel, arrange conventional boreholes in front of the tunnel for drilling verification. If there is no abnormality in the drilling verification, the tunnel is allowed to be excavated according to the water exploration-tunneling cycle operation mode to achieve old water management.

[0014] Furthermore, in step 1, the ground transient electromagnetic method and the ground three-dimensional seismic method are specifically used to explore the distribution position and water accumulation of the upper layer of the mining area, and the water accumulation volume and water accumulation height parameters are calculated according to the calculation formula of the water accumulation volume in the mining area, which are specifically as follows:

[0015] Q=KMS / COSα

[0016] Where M is the mining height, S is the water accumulation area, α is the coal seam inclination, Q is the calculated water accumulation volume, and K is the water filling coefficient of the goaf.

[0017] Furthermore, in step three, the first-section wall protection sleeve is of specification φ177.8mm×8.05mm, the second-section sleeve is of specification φ127mm×6.5mm solid pipe connected to the same-diameter water filter flower pipe, and the third-section water filter flower pipe is of specification φ89mm×4.5mm.

[0018] Furthermore, in the step three, the directional drilling is carried out using an XSL15 / 680 crawler drill, an MWD while drilling inclinometer, an F260 mud pump and an NBB-390 / 15 mud pump to achieve the drilling of the directional hole, ensuring successful penetration of the upper and lower goafs.

[0019] Furthermore, the dynamic monitoring and early warning system in step 4 includes:

[0020] (51) Data acquisition module, including:

[0021] The water level monitoring unit is specifically configured as a pressure-type water level sensor, which is deployed at the water accumulation point in the old empty area to collect water level data in real time and calculate the water accumulation height;

[0022] The flow monitoring unit is specifically configured as an electromagnetic flowmeter, which is installed at the outlet of the drain hole to measure the amount of water discharged and compare it with the deviation of the theoretical water volume;

[0023] Gas composition detection units, including methane sensors, carbon monoxide sensors, and oxygen sensors, are installed at the borehole wellhead and in the vicinity of the goaf to detect gas concentrations in real time;

[0024] (52) Data transmission module, using wireless communication network or optical fiber transmission protocol to transmit water level data, discharge flow and gas concentration data to the ground control computer in real time;

[0025] (53) Analysis and early warning module, integrated into the ground control computer, including:

[0026] The water level anomaly judgment unit triggers graded warnings based on preset water level drop rate thresholds and water accumulation safety height thresholds;

[0027] The gas risk warning unit sets the alarm thresholds for methane concentration ≥ 0.5% and carbon monoxide concentration ≥ 24 ppm, and associates it with abnormal oxygen concentration for comprehensive risk assessment;

[0028] The water discharge efficiency analysis unit identifies the risk of pipeline blockage or formation leakage by comparing the deviation between the actual water discharge volume and the theoretical calculated value.

[0029] Furthermore, in step five, transient electromagnetic method and high-density direct current method are used to explore the old empty water-rich abnormal area in front of the tunnel, wherein the transient electromagnetic method uses the YCS180 intrinsically safe high-power transient electromagnetic instrument, and the high-density direct current method uses the RESECSⅡ distributed high-density electrical method instrument.

[0030] Furthermore, conventional boreholes are arranged in front of the tunnel for drilling verification. If the drilling verification shows no abnormalities, the tunnel is allowed to be excavated according to the water exploration-excavation cycle operation mode, as follows:

[0031] (71) Use a light tunnel drilling rig to arrange holes in a grid pattern within the abnormal area detected by transient electromagnetic and high-density direct current methods, and make the drilling direction consistent with the tunnel excavation direction, with an elevation angle of 5°-10° to ensure that the potential water-rich area ahead is covered;

[0032] (72) The drilling rig is fixed at the head of the tunnel, and clean water or low-solids mud is used to circulate the wall. The core is taken every 10 m of drilling, and the lithology, fracture development and water inflow are recorded. If the return water is turbid, the core shows obvious fracture seepage, or the drill bit suddenly falls, or the core is broken or missing, it indicates that there is an abnormality. Otherwise, there is no abnormality.

[0033] (73) If no abnormal water-rich or empty areas are found in all boreholes, it is determined to be a safe area and excavation is allowed; if any borehole has an abnormality, excavation is stopped immediately.

[0034] Furthermore, the light tunnel drilling rig is set to be a ZLJ1200 crawler tunnel drilling rig or a KD100-4 drilling rig.

[0035] The present invention has at least the following beneficial effects:

[0036] 1. The present invention utilizes directional drilling technology to connect the upper and lower goafs, and discharges the old goaf water in the upper goaf into the lower goaf through the drilled channel. It comprehensively utilizes various technical means such as ground directional drilling, casing placement, goaf penetration, water level monitoring, etc. to carry out planned and step-by-step advance drainage of the old goaf water, so as to eliminate the threat of water hazards and achieve safe mining. Compared with traditional control methods, it can not only effectively avoid safety risks such as uncontrolled water gushing and abnormal gas gushing, but also improve the underground water drainage efficiency, and avoid the inability to recover coal resources and cause waste of resources.

[0037] 2. The present invention optimizes the drilling trajectory design through graded drilling directional drilling technology, ensures that the drilling can avoid complex geological structures, reduces construction risks, and accurately controls the drilling trajectory to ensure that the drilling can quickly penetrate the shallow old empty water area and extend to the deep goaf, so that the second opening casing can be immediately lowered to achieve the purpose of fully penetrating the upper and lower goafs.

[0038] Of course, any product implementing the present invention does not necessarily need to achieve all of the advantages described above at the same time. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] Figure 1 Schematic diagram of the construction method of the present invention; Figure 2 is a cross-sectional schematic diagram of directional drilling in an embodiment of the present invention; Figure 3 This is a planar projection diagram of the construction trajectory of the present invention; Figure 4 Schematic diagram of the change of the old empty water level over time in the present invention. DETAILED DESCRIPTION

[0040] The following will be combined with the accompanying drawings in the embodiments of the present disclosure to clearly and completely describe the technical solutions in the embodiments of the present disclosure. Obviously, the embodiments described are only part of the embodiments of the present disclosure, not all of the embodiments. Based on the embodiments of the present disclosure, all other embodiments obtained by ordinary technicians in this field without making any creative efforts are within the scope of protection of the present disclosure.

[0041] See also Figure 1 The present invention provides a technical solution: a ground directional drilling method for draining underground old empty water, comprising the following steps:

[0042] S1. Determine shallow old goaf water target area 1: Exploring the distribution and accumulation of old goaf water in the upper layers of the mining area. Target the lowest point of old goaf water in the mining area as shallow old goaf water target area 1 for directional drilling. Calculate the accumulated water volume and height parameters.

[0043] Specifically, the ground transient electromagnetic method and ground three-dimensional seismic method are used to explore the distribution position and water accumulation of the old goaf water in the upper layer of the mining area. At the same time, the water accumulation volume and water accumulation height parameters are calculated according to the calculation formula of water accumulation in the goaf. The details are as follows:

[0044] Q=KMS / COSα

[0045] Wherein, mining height M (m), water accumulation area S (m 2 ), coal seam inclination α, calculate the water accumulation Q as (m 3 ), in addition, the range of the water filling coefficient K of the goaf is as follows:

[0046] Goaf water filling coefficient table

[0047]

[0048] S2. Determine deep drainage target area 2: Based on the geological data of the mining area, select the deep goaf or roadway as the target area 2 for directional drilling, and analyze its water level and available water storage space;

[0049] S3. Directional Drilling: Determine the drilling location, design the directional drilling trajectory, and adopt a staged drilling process, including:

[0050] First opening section: Directional drilling is used to reach the slight leakage position at the top of the fracture zone in the shallow old goaf, and the retaining wall casing is lowered and cemented to check the water-stopping effect;

[0051] Second section: Directional drilling is used to reach target areas 1 and 2, mud wall protection is used to quickly cross the goaf, and casing is run (solid pipe connected to the same diameter water filter pipe) to achieve water drainage;

[0052] Three-opening section: conventional drilling is used to reach the end hole, and a water filter pipe is lowered to form a double-layer structure with the second-opening water filter pipe. The water filter pipe enhances the drainage effect;

[0053] Furthermore, the first-section wall protection casing is of φ177.8mm×8.05mm specification, the second-section casing is of φ127mm×6.5mm solid pipe connected to the same diameter flower pipe, and the third-section water filter flower pipe is of φ89mm×4.5mm structure;

[0054] Specifically, the directional drilling used an XSL15 / 680 crawler drill, an MWD inclinometer, an F260 mud pump, and an NBB-390 / 15 mud pump to drill the directional hole and ensure successful penetration of the upper and lower goafs. The details are as follows:

[0055] XSL15 / 680 crawler drill rig is a core drilling equipment used for directional drilling. It has the characteristics of high torque and large thrust and is suitable for deep hole directional drilling.

[0056] F260 mud pump provides high-pressure mud circulation for cooling the drill bit, carrying cuttings and stabilizing the hole wall.

[0057] NBB-390 / 15 mud pump, as an auxiliary mud pump, enhances mud circulation capacity, especially ensuring mud pressure in deep hole sections or complex formations.

[0058] The MWD (Measurement While Drilling) directional instrument (13 / 8") monitors the drilling trajectory parameters (hole inclination, azimuth, displacement) in real time and transmits the data to the ground control system via wired transmission to achieve dynamic trajectory adjustment.

[0059] The SWT434E diesel generator set provides power support for drilling rigs, mud pumps and other equipment, ensuring stable power supply for field construction.

[0060] Detailed construction process and technical analysis of directional drilling:

[0061] First section construction (0-260m): Use XSL15 / 680 drilling rig to drive φ216mm drill bit for directional drilling, and F260 mud pump to provide mud circulation to maintain hole wall stability;

[0062] The MWD instrument was used to monitor the hole inclination (e.g., 0.53° in the initial section) and azimuth (235.3°) in real time to ensure that the borehole was advanced according to the preset path (e.g., 0m east-west displacement and 0m north-south displacement). After drilling to the expected leakage location (260m), a φ177.8×8.05mm retaining wall casing was installed, cemented, and the water-stopping effect was checked.

[0063] Construction of the second section (260-430 m): A φ152 mm drill bit was used, and an NBB-390 / 15 mud pump was employed to enhance the mud wall protection capability. The MWD instrument continuously monitored the trajectory (e.g., at a measured depth of 206.6 m, the hole inclination was 4.31° and the azimuth was 225.19°).

[0064] Crossing the goaf: Use high-density mud to quickly pass through the old goaf and water area to prevent the hole wall from collapsing.

[0065] Installation of water filter pipe: After drilling to target area 1 (shallow old empty water) and target area 2 (deep drainage area), insert a φ127×6.5mm solid pipe and connect it to the water filter flower pipe of the same diameter, overlapping it with an open casing by 20m to form a continuous wall protection structure.

[0066] Construction of the third section (430-450m): A φ89mm drill bit was used, and the MWD instrument was used to fine-tune the final hole trajectory (for example, the hole inclination was 4.66° when the final hole depth was 216.17m).

[0067] Water filter flower pipe: φ89×4.5mm water filter flower pipe is installed in the 410-450m section to enhance the permeability and anti-clogging ability of the drainage channel;

[0068] S4. Establish a dynamic monitoring and early warning system: This system monitors water level changes and drainage effectiveness in old goaf areas in real time, while also monitoring gas composition at the wellhead to provide early warning of water hazards and abnormal gas outbursts in goaf areas.

[0069] The dynamic monitoring and early warning system includes:

[0070] Data acquisition module, including:

[0071] The water level monitoring unit is specifically configured as a pressure-type water level sensor, which is deployed at the water accumulation point in the old empty area to collect water level data in real time and calculate the water accumulation height;

[0072] The flow monitoring unit is specifically configured as an electromagnetic flowmeter, which is installed at the outlet of the drain hole to measure the amount of water discharged and compare it with the deviation of the theoretical water volume;

[0073] Gas composition detection units, including methane sensors, carbon monoxide sensors, and oxygen sensors, are installed at the borehole wellhead and in the vicinity of the goaf to detect gas concentrations in real time;

[0074] The data transmission module uses wireless communication network or optical fiber transmission protocol to transmit water level data, discharge flow and gas concentration data to the ground control computer in real time;

[0075] The analysis and warning module is integrated into the ground control computer and includes:

[0076] The water level anomaly judgment unit triggers graded warnings based on preset water level drop rate thresholds and water accumulation safety height thresholds;

[0077] The gas risk warning unit sets the alarm thresholds for methane concentration ≥ 0.5% and carbon monoxide concentration ≥ 24 ppm, and associates it with abnormal oxygen concentration for comprehensive risk assessment;

[0078] The drainage efficiency analysis unit identifies pipeline blockage or formation leakage risks by comparing the deviation between actual drainage volume and theoretically calculated values;

[0079] S5. Coordinated management during tunneling: During tunneling within the mining area, abnormally high water content in the old goaf ahead of the tunnel is detected. Conventional boreholes are drilled in front of the tunnel for verification. If the drilling verification shows no abnormalities, tunneling is allowed to proceed in a water exploration-tunneling cycle to achieve old goaf water management.

[0080] Transient electromagnetic method and high-density direct current method are used to explore the abnormal water-rich area in the old goaf ahead of the roadway. The transient electromagnetic method uses the YCS180 intrinsically safe high-power transient electromagnetic instrument to measure the attenuation characteristics of the induced current in the formation by emitting transient electromagnetic pulses, and identify the low resistivity abnormal area (water-rich area). The high-density direct current method uses the RESECSⅡ distributed high-density resistivity instrument to measure the apparent resistivity of the formation through a multi-electrode arrangement. High-density data points (such as 64 electrodes with a point spacing of 1m) are used to generate a two-dimensional / three-dimensional resistivity model to identify water-bearing fractures or goafs. The specific steps are as follows:

[0081] (S51) Transient electromagnetic method detection steps:

[0082] Arrange the survey line in front of the tunnel, and lay the transmitting coil flat on the ground or tunnel floor;

[0083] The pulse current is transmitted and the receiving sensor collects the secondary field signal;

[0084] Data processing software (such as IX1D) is used to generate resistivity profiles and delineate the water-rich anomaly area. The data processing software is integrated into the ground control computer.

[0085] (S52) High-density direct current method detection steps:

[0086] An electrode array is laid out in front of the tunnel (line spacing 5m, point spacing 1m);

[0087] Inject DC current and measure the potential difference between electrodes;

[0088] The resistivity distribution was inverted using Res2Dinv software and the abnormal areas were cross-validated in combination with TEM results.

[0089] Next, the technical solution of the present invention is further described with reference to specific embodiments:

[0090] like Figure 3 As shown in the figure, a surface drainage hole project at a certain working face in a coal mine used directional drilling technology to penetrate the goaf of the 8th and 10th coal layers, successfully draining the shallow old goaf water into the deep goaf, and lowering the shallow old goaf water level. The details are as follows:

[0091] (1) Situation of old airspace areas

[0092] 1. Shallow old empty area

[0093] According to the analysis of the mining data of a shallow working face, there is an old empty water accumulation area during the mining process of the working face. According to the observation of the old empty water long observation hole, the water level elevation is -293.5m, the lowest point is the elevation of the cut-eye lower mouth -320m, the water accumulation height is 26.5m, and the water accumulation area is 19,500 square meters.

[0094] According to the calculation formula of water accumulation in goaf: Q=KMS / COSα,

[0095] The water filling coefficient K of the goaf is 0.2, the coal seam inclination α is 9°, M = mining height 3.3m, S = water accumulation area 19,500 m 2 The calculated water volume is about 13,000 m 3 ;

[0096] 2. Deep goaf

[0097] The deep part is a certain working face goaf, with the floor elevation of -420m. There is no old water in the deep goaf, and the dynamic replenishment water is discharged through the deep goaf (monoclinic structure, lowest elevation -465m) and underground boreholes to an adjacent mining area (water level -520m), with a water storage space of about 150,000m 3 .

[0098] (2) Ground construction conditions

[0099] About 15m northwest of the shallow old empty water observation hole, the ground is relatively flat and there is no water accumulation, which meets the conditions for construction.

[0100] (3) Directional drilling design, such as Figure 2 shown

[0101] First opening: 0-260m directional drilling with a diameter of 216mm, construction to the starting point of leakage (estimated 260m, adjusted according to construction conditions), and then 177.8×8.05mm casing;

[0102] The second opening is drilled from 260 to 430 meters with a φ152mm hole. From 240 to 430 meters, a 127×6.5mm solid pipe is connected to a water filter pipe of the same diameter, overlapping with the first opening by 20 meters.

[0103] The third opening is drilled with a φ89mm hole diameter from 430 to 450m, and the 89×4.5mm water filter pipe at 410 to 450m overlaps with the second opening by 20m;

[0104] The specific directional drilling trajectory design is shown in Table 1 below:

[0105] Table 1 Directional drilling trajectory

[0106] Depth (m) Hole inclination (°) Azimuth (°) East-west displacement (m) North-south displacement (m) 34.28 0.53 235.3 0 0 44.74 0.44 210.6 -0.09 -0.13 54.23 1.49 218.16 -0.15 -0.19 63.63 1.54 213.24 -0.28 -0.29 73.06 2.42 215.79 -0.48 -0.43 82.4 3.47 202.08 -0.75 -0.62 91.8 3.78 202.50 -1.17 -0.84 101.28 3.56 203.84 -1.72 -1.06 110.82 3.56 195.97 -2.28 -1.3 120.35 3.60 202.34 -2.84 -1.5 129.89 3.78 224.23 -3.4 -1.7 139.44 4.31 229.06 -4.42 -2.47 149.07 4.00 214.91 -5.68 -4.13 158.67 4.26 230.47 -6.07 -4.68 168.23 4.00 236.79 -6.47 -5.24 177.78 4.13 233.81 -6.89 -5.78 187.33 4.13 234.77 -7.38 -6.31 196.88 4.17 229.06 -7.94 -6.8 206.6 4.31 225.19 0 0 216.17 4.66 217.72 -0.09 -0.13

[0107] During the drilling construction process, multiple digital logging, inclination measurement and gyro orientation were carried out to confirm that the hole inclination and drilling trajectory were normal, ensuring smooth penetration with the goaf. The target position of the drainage hole in the goaf was calculated to deviate by 0.59m from the designed target position. At the same time, the downhole peep instrument verified the scene of water leaking from the shallow goaf into the deep goaf.

[0108] After the connection, the water level in the upper old empty area dropped significantly: the three open holes have been drilled to 436.32m. The monitoring data shows that the old empty water level continues to drop, and the water level has dropped by 2.5m. The calculated discharge volume is about 35m 3 / h, the water level has dropped by 88 meters, and the shallow old empty water has all been discharged into the deep old empty area. Figure 4 shown.

[0109] Directional drilling, used to drain underground sludge, has proven effective in a coal mine sludge drainage project. By effectively reducing the volume and level of sludge, the project ensured safe production, improved economic efficiency, and provided valuable experience for the development of sludge prevention and control technologies. In future coal mine production, the combined above-and-below-ground sludge drainage technology should be further promoted and improved to provide strong support for the safe and efficient development of the coal industry.

[0110] It should be noted that, in this document, relational terms such as first and second, etc., are used only to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any actual relationship or order between these entities or operations. Moreover, the terms "comprises," "comprising," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that includes a list of elements includes not only those elements but also other elements not explicitly listed, or elements inherent to such process, method, article, or apparatus.

[0111] For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to the specific circumstances. When an element is referred to as being "assembled on", "installed on", "fixed on" or "set on" another element, it can be directly on the other element or there can be a central element. When an element is considered to be "connected" to another element, it can be directly connected to the other element or there can be a central element at the same time. The terms "vertical", "horizontal", "up", "down", "left", "right" and similar expressions used herein are for illustrative purposes only and are not intended to be the only embodiment.

[0112] While 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 these embodiments without departing from the principles and spirit of the invention, and that the scope of the invention is defined by the appended claims and their equivalents.

[0113] Throughout this specification, references to terms such as "one embodiment," "example," or "specific example" indicate that a specific feature, structure, material, or characteristic described in conjunction with that embodiment or example is included in at least one embodiment or example of the present disclosure. In this specification, schematic representations of these terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in any one or more embodiments or examples.

Claims

1. The ground directional drilling method for draining old water from underground wells is characterized by: The following steps are involved: Step 1: Determine shallow old goaf water target area 1: Explore the distribution location and water accumulation of the upper old goaf water in the mining area, select the low point area of ​​the old goaf water in the mining area as the shallow old goaf water target area 1 for directional drilling, and calculate parameters such as water accumulation volume and water accumulation height; Step 2: Determine the deep drainage target area 2: Based on the geological data of the mining area, select the deep goaf or abandoned roadway as the target area 2 for directional drilling, and analyze its water level and water storage space; Step 3: Directional Drilling: Determine the hole location, design the directional drilling trajectory, and adopt a staged drilling process, including: First opening section: Directional drilling is used to reach the slightly leaking layer above the fracture zone in the shallow old goaf, and the retaining wall casing is installed and cemented to check the water-stopping effect; Second section: Directional drilling is used to reach target areas 1 and 2, mud wall protection is used to quickly cross the goaf, and casing is run to achieve water drainage; Three-opening section: conventional drilling is used to reach the end hole, and a water filter flower pipe is lowered to form a double-layer structure with the second-opening water filter flower pipe to enhance the drainage effect; Step 4: Establish a dynamic monitoring and early warning system: Use the dynamic monitoring system to monitor the water level changes and drainage effects of the old goaf in real time, and simultaneously monitor the gas composition at the wellhead to provide early warning of water disaster risks and abnormal gas outburst risks in the goaf; Step 5. Coordinated management during tunnel excavation: During tunnel excavation in the mining area, explore the abnormal old water-rich area in front of the tunnel, arrange conventional boreholes in front of the tunnel for drilling verification. If there is no abnormality in the drilling verification, the tunnel is allowed to be excavated according to the water exploration-tunneling cycle operation mode to achieve old water management.

2. The method for draining underground old water by ground directional drilling according to claim 1 is characterized in that: In the step 1, the ground transient electromagnetic method and the ground three-dimensional seismic method are specifically used to explore the distribution position and water accumulation of the upper layer of the old goaf in the mining area. At the same time, the water accumulation volume and water accumulation height parameters are calculated according to the calculation formula of the water accumulation volume in the goaf, which are specifically as follows: Q=KMS / COSα Where M is the mining height, S is the water accumulation area, α is the coal seam inclination, Q is the calculated water accumulation volume, and K is the water filling coefficient of the goaf.

3. The method for draining underground old water by ground directional drilling according to claim 2 is characterized in that: In the step three, the first section of the wall protection sleeve is of φ177.8mm×8.05mm specification, the second section is of φ127mm×6.5mm solid pipe connected to the same diameter water filter flower pipe, and the third section of the water filter flower pipe is of φ89mm×4.5mm structure.

4. The method for draining underground old water by ground directional drilling according to claim 3 is characterized in that: In the step 3, the directional drilling is carried out using an XSL15 / 680 crawler drill, an MWD inclinometer, an F260 mud pump and an NBB-390 / 15 mud pump to achieve the drilling of the directional hole, ensuring successful penetration of the upper and lower goafs.

5. The method for draining underground old water by ground directional drilling according to claim 4 is characterized in that: The dynamic monitoring and early warning system in step 4 includes: (51) Data acquisition module, including: The water level monitoring unit is specifically configured as a pressure-type water level sensor, which is deployed at the water accumulation point in the old empty area to collect water level data in real time and calculate the water accumulation height; The flow monitoring unit is specifically configured as an electromagnetic flowmeter, which is installed at the outlet of the drain hole to measure the amount of water discharged and compare it with the deviation of the theoretical water volume; Gas composition detection units, including methane sensors, carbon monoxide sensors, and oxygen sensors, are installed at the borehole wellhead and in the vicinity of the goaf to detect gas concentrations in real time; (52) Data transmission module, using wireless communication network or optical fiber transmission protocol to transmit water level data, discharge flow and gas concentration data to the ground control computer in real time; (53) Analysis and warning module, integrated into the ground control computer, including: The water level anomaly judgment unit triggers graded warnings based on preset water level drop rate thresholds and water accumulation safety height thresholds; The gas risk warning unit sets the alarm thresholds for methane concentration ≥ 0.5% and carbon monoxide concentration ≥ 24 ppm, and associates it with abnormal oxygen concentration for comprehensive risk assessment; The water discharge efficiency analysis unit identifies the risk of pipeline blockage or formation leakage by comparing the deviation between the actual water discharge volume and the theoretical calculated value.

6. The method for draining underground old water by ground directional drilling according to claim 5 is characterized in that: In step five, transient electromagnetic method and high-density direct current method are used to explore the old empty water-rich abnormal area in front of the tunnel, wherein the transient electromagnetic method uses the YCS180 intrinsically safe high-power transient electromagnetic instrument, and the high-density direct current method uses the RESECSⅡ distributed high-density electrical method instrument.

7. The method for draining underground old water by ground directional drilling according to claim 6 is characterized in that: Conventional drilling holes are arranged in front of the roadway for drilling verification. If the drilling verification shows no abnormalities, the roadway is allowed to be excavated according to the water exploration-excavation cycle operation method, as follows: (71) Use a light tunnel drilling rig to arrange holes in a "grid" pattern within the abnormal area detected by transient electromagnetic and high-density direct current methods, and make the drilling direction consistent with the tunnel excavation direction, with an elevation angle of 5°-10° to ensure that the potential water-rich area ahead is covered; (72) The drilling rig is fixed at the head of the tunnel, and clean water or low-solids mud is used to circulate the wall. The core is taken every 10 m of drilling, and the lithology, fracture development and water inflow are recorded. If the return water is turbid, the core shows obvious fracture seepage, or the drill bit suddenly falls, or the core is broken or missing, it indicates that there is an abnormality. Otherwise, there is no abnormality. (73) If no abnormal water-rich or empty areas are found in all boreholes, it is determined to be a safe area and excavation is allowed; if any borehole has an abnormality, excavation is stopped immediately.

8. The method for draining underground old water by ground directional drilling according to claim 7 is characterized in that: The light tunnel drilling rig is configured as a ZLJ1200 crawler tunnel drilling rig or a KD100-4 drilling rig.

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