Well-ground combined coal mine underground directional long drill hole grouting and pipe fixing method

Abstract

The invention discloses a well-ground combined underground coal mine directional long drill hole grouting and pipe fixing method. The method comprises the following steps: constructing an orifice pressure-bearing sealing section in an annular space between an orifice section of an underground coal mine directional long drill hole and a sleeve by adopting two-blocking and one-injecting; the in-well grouting pipeline and the underground grouting pipeline are connected in a pressure-bearing and sealing mode; carrying out a pressure test on the grouting pipeline, and checking the pressure-bearing sealing connection effect of the whole grouting pipeline; carrying out orifice grouting pipe head valve pressure-bearing throttling adjustment; the grouting well cementation pump truck injects cement paste with the specific gravity required by underground directional long drill hole grouting and pipe cementation and waits for solidification under pressure; and after cementing waiting is finished, drilling is conducted into the casing pipe, plug sweeping drilling is conducted on the cement paste flowing into the casing pipe, and underground directional long drilling hole grouting pipe fixing is completed. According to the method, on the basis of the condition that the through well is used for achieving ground and underground through, the advantages of rapid slurrying and high-pressure pumping of the ground well cementation pump truck are utilized, and meanwhile underground control of the coal mine is coordinated, and grouting and pipe fixing of the annulus between the sleeve and the directional long drill hole can be efficiently achieved.

Description

Technical Field

[0001] The invention belongs to the field of underground coal mine drilling engineering and relates to a well-ground combined underground directional long drilling grouting pipe fixing method for coal mines. Background Art

[0002] As a new model for managing rock burst and gas hazards in coal mining areas, combined well-ground staged hydraulic fracturing technology combines the advantages of large-scale and wide-range surface fracturing with the mature and flexible hole layout of underground directional drilling. Using a combined well-ground approach of "underground drilling and surface fracturing," a through-hole well is constructed at a surface drilling site, connecting to several long directional boreholes at multiple working faces underground. This collaboratively manages rock burst and gas hazards in coal mines, serving as one of the key supporting technologies for ensuring safe and efficient coal mine production. The long directional boreholes implemented in this technology model can reach depths of over hundreds of meters. The grouting and pipe fixing operations after casing is run into the final hole of such boreholes are particularly demanding. If the cement slurry injected between the casing and the borehole is ineffective, crosstalk between the fracturing segments will occur during the subsequent staged hydraulic fracturing. Up to now, directional long-hole grouting and pipe-fixing in coal mines has been carried out by injecting cement slurry underground. Due to the limited underground working space, the preparation speed of the high-density cement slurry required for grouting and pipe-fixing cannot meet the requirements in time, especially for long boreholes of hundreds of meters, the density of cement slurry can reach 1.8g / cm 3 The prepared cement slurry is not only high in density and viscosity, but the existing downhole grouting pump and other equipment cannot meet the pump pressure requirements of cement slurry injection, and it is impossible to achieve the pressurized solidification of the cement slurry injected between the downhole borehole and the casing. Summary of the Invention

[0003] In view of the shortcomings of the existing technology, the purpose of the present invention is to provide a method for directional long drilling grouting and pipe fixing in coal mines. Based on the condition of connecting the ground and the underground through a through well, the advantages of rapid slurrying and high-pressure pumping of ground cementing pump trucks are utilized, and at the same time, the control of the underground coal mine is coordinated to realize directional long drilling grouting and pipe fixing.

[0004] In order to solve the above technical problems, the present invention adopts the following technical solutions:

[0005] A method for directional long drilling, grouting and pipe fixing in underground coal mines, comprising the following steps:

[0006] Step 1: constructing a pressure-bearing sealing section of the orifice by using two plugging and one grouting in the annulus between the orifice section and the inner casing of a directional long borehole in an underground coal mine; providing a grouting pipe three and a grouting pipe four penetrating the orifice pressure-bearing sealing section in the orifice section;

[0007] Step 2: The through-hole grouting pipeline and the downhole grouting pipeline are pressure-sealed and connected, and the grouting pipe head of the downhole grouting pipeline can be respectively sealed with the grouting pipe three and the grouting pipe four through two pipelines; the grouting pipe head of the downhole grouting pipeline is provided with an orifice grouting pipe head valve, and the end of the downhole grouting pipeline is provided with a blowout valve;

[0008] Step 3: Perform a pressure test on the grouting pipeline to check the pressure-bearing and sealing connection effect of the entire grouting pipeline. If the grouting pipeline passes the pressure test, proceed to the next step. Otherwise, re-perform the pressure-bearing and sealing connection of the grouting pipeline until it passes the pressure test;

[0009] Step 4: Adjust the pressure and throttling of the orifice grouting pipe head valve to prevent vacuum backflow in the grouting pipeline oil pipe in the through well;

[0010] Step 5: The grouting and cementing pump truck injects the cement slurry with the required specific gravity for directional long-hole grouting and cementing pipe in the well and waits for solidification under pressure;

[0011] Step 6: After the waiting for setting is completed, drill down into the casing to perform plug drilling on the cement slurry flowing into the casing to complete the downhole directional long hole grouting and pipe fixing.

[0012] The present invention also includes the following technical features:

[0013] Specifically, the step 1 includes:

[0014] Step 1.1: Insert two long grouting pipes, namely grouting pipe 3 and grouting pipe 4, into the annulus between the downhole directional long borehole and its inner casing, with the lower ends of grouting pipes 3 and 4 extending 1 to 2 meters beyond the downhole directional long borehole opening;

[0015] Step 1.2: Insert cotton wool into the annulus between the casing and the downhole directional long borehole to form a cotton wool filling section. The cotton wool filling section can completely seal the annulus between the casing and the downhole directional long borehole. The inserted cotton wool is soaked with water glass. The cotton wool is inserted 1 to 2 meters below the upper ends of the third and fourth grouting pipes. The length of the cotton wool filling section is at least 1 meter.

[0016] Step 1.3: Insert two short grouting pipes, grouting pipe 1 and grouting pipe 2, into the annulus between the casing and the downhole directional long borehole. The upper ends of grouting pipes 1 and 2 are 2 to 3 meters lower than the cotton filling section, and the lower ends of grouting pipes 1 and 2 extend out from the lower end of the downhole directional long borehole.

[0017] Step 1.4: Inject Marisol into the annulus between the casing and the downhole directional long drill hole to form a Marisol filling section, so as to achieve sealing and filling of the annulus between the casing at the hole end and the downhole directional long drill hole. The length of the Marisol filling section is 2 to 3 meters.

[0018] Step 1.5: Use grouting pipe 1 and grouting pipe 2 to inject cement slurry into the annulus between the cotton filling section and the Marisol filling section to form a pressure-bearing sealing section at the orifice.

[0019] Specifically, the step 1.5 includes:

[0020] The valve of grouting pipe 1 and the valve of grouting pipe 2 on grouting pipe 2 are both initially in the open state. Connect grouting pipe 2 to the downhole grouting pump pipeline, and the cement slurry enters the annulus between the casing and the downhole directional long borehole through grouting pipe 2. When cement slurry flows out of grouting pipe 1, close the valve of grouting pipe 1, and continue to inject cement slurry through grouting pipe 2. When the pressure on the grouting pump reaches 1MPa, stop grouting, close the valve of grouting pipe 2, and let the cement slurry injected into the annulus between the cotton filling section and the Malisin filling section be under a negative pressure of 1MPa and wait for 72 hours to solidify.

[0021] Specifically, in step 2, oil pipes are used to connect the grouting pipelines in the well, and the oil pipes are connected by threads. The threaded connection between the oil pipes is tightened by a ground drilling rig to achieve a pressure-bearing and sealed connection between the oil pipes.

[0022] The downhole grouting pipeline adopts the fracturing pipeline, and the fracturing pipelines are connected by oil-connected joints. The connection and fastening method between the oil-connected joints is to intermittently hammer the oil-connected joint heads with a sledgehammer to achieve pressure-bearing and sealed connections between the fracturing pipelines.

[0023] The oil pipe and the fracturing pipeline are connected via a high-pressure hose, and are connected to each other via an oil hose.

[0024] Specifically, the inner diameters of the oil pipe, high-pressure hose and fracturing pipeline are consistent and larger than the inner diameters of the grouting pipe three and the grouting pipe four, and the joints connecting them are internally flush.

[0025] Specifically, the step 3 includes:

[0026] First, connect the pipeline of the ground grouting and cementing pump truck to the oil pipeline in the ground through-hole, then close the blowout valve and the orifice grouting pipe head valve, use the grouting and cementing pump truck to pump clean water into the grouting pipeline until the pressure of the grouting and cementing pump truck reaches 30MPa, stop injecting clean water, stabilize the pressure for 10 minutes, and if the pressure drop is less than 0.5MPa, the grouting pipeline pressure test is qualified, otherwise re-connect the grouting pipeline pressure-bearing seal until the pressure test is qualified.

[0027] Specifically, the pressure throttling adjustment of the orifice grouting pipe head valve in step 4 includes:

[0028] First, ensure that the blowdown valve is in the closed state, the orifice grouting pipe head valve, the grouting pipe three valve on the grouting pipe three, and the grouting pipe four valve on the grouting pipe four are all in the open state, use the grouting and cementing pump truck to inject clean water, adjust the injection displacement of the cementing pump truck to the displacement required for normal grouting during grouting and cementing, and then slowly close the orifice grouting pipe head valve. During the process of closing the orifice grouting pipe head valve, observe the pressure changes on the grouting and cementing pump truck. When the pressure on the cementing pump truck is the same as the cement slurry specific gravity pressure required for grouting and cementing at the depth of the connection between the oil pipe and the hose, stop closing the orifice grouting pipe head valve, and the orifice grouting pipe head valve pressure throttling adjustment is successful.

[0029] Specifically, the step 5 includes:

[0030] Step 5.1: Determine the amount of cement slurry to be injected based on the volume of the annulus between the casing and the downhole directional long borehole;

[0031] At the same time, before starting to inject cement slurry, a protective cap with a drainage tube is connected to the casing head of the downhole hole through a thread. The drainage tube is equipped with a control valve. The valve of the tube is kept open during the grouting and pipe fixing period.

[0032] Step 5.2: The surface grouting and cementing pump truck begins to inject cement slurry. After the required amount of cement slurry for grouting and cementing pipes is pumped, clean water is started to be pumped in to push the cement slurry in all grouting pipelines into the annulus between the casing and the downhole directional long borehole. When the clean water displaces the cement slurry to the downhole fracturing pipeline, the capillary valve is closed.

[0033] Step 5.3: Continue to inject clean water from the ground cementing pump truck until the clean water reaches the downhole orifice. Stop injecting clean water and immediately close the grouting pipe valves 3 and 4 to keep the cement slurry injected into the annulus between the entire casing and the downhole directional long borehole under pressure and wait for solidification.

[0034] Specifically, in step 6, after the waiting for solidification is completed, the protective cap installed on the hole casing head is removed, and the drill is drilled into the casing to perform plugging drilling of the cement slurry flowing into the casing. After the plugging drilling is completed, the drill is pulled out, and the downhole directional long hole grouting and pipe fixing is completed.

[0035] Compared with the prior art, the present invention has the following technical effects:

[0036] 1. The present invention has certain applicability for both up-inclined and down-inclined near-horizontal directional long drilling. Based on the actual engineering situation, the maximum specific gravity of pure cement slurry during grouting and pipe consolidation can reach 1.85g / cm 3 At the same time, this method can effectively overcome the resistance loss along the way caused by the high specific gravity and high clay characteristics of pure cement slurry, and the grouting pump injection pressure can reach 35 to 45 MPa.

[0037] 2. The present invention can effectively realize the annular space between the pressure-bearing sealing casing and the directional long borehole. Based on actual engineering, it is known that the design spacing of the fracturing sections in the casing after grouting and fixing the pipe by this method is 50 to 60m. 3 / min, scale is 500~600m 3 During hydraulic fracturing, combined with the real-time microseismic monitoring of the fracture expansion during fracturing, no crosstalk between the fracturing segments was found, indicating that this method can efficiently achieve grouting and pipe fixing in the annulus between the casing and the directional long borehole. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] Figure 1 Schematic diagram of the borehole pressure-bearing sealing section between the borehole section and the casing of a downhole directional long drilling hole.

[0039] Figure 2 This is a schematic diagram of the pressure-bearing sealing connection of the grouting pipeline.

[0040] Figure 3 Schematic diagram of a protective cap with a drainage tube.

[0041] The meaning of each number in the figure is:

[0042] 1. Through-hole well, 2. Connection between oil pipe and hose, 3. High-pressure hose, 4. Fracturing pipeline, 5. Blowout valve, 6. Orifice grouting pipe head valve, 7. Grouting pipe three valve, 8. Downhole orifice, 9. Grouting pipe four valve, 10. Connection between fracturing pipeline and hose, 11. Oil pipe, 12. Ground, 13. Grouting pipe one valve, 14. Grouting pipe three, 15. Grouting pipe four, 16. Grouting pipe two valve, 17. Malisan filling section, 18. Grouting pipe two, 19. Cotton filling section, 20. Casing, 21. Downhole long directional drilling, 22. Grouting pipe one, 23. Orifice pressure sealing section, 24. Protective cap, 25. Drain cap, 26. Cap valve. DETAILED DESCRIPTION

[0043] Specific embodiments of the present invention are given below. It should be noted that the present invention is not limited to the following specific embodiments, and all equivalent modifications made on the basis of the technical solution of this application fall within the protection scope of the present invention.

[0044] Example:

[0045] This embodiment provides a method for directional long drilling and grouting pipe fixing in a combined underground coal mine, including the following steps:

[0046] Step 1: In the underground directional long drilling 21 implemented in the coal mine, a two-blocking and one-injection hole pressure sealing section 23 is constructed in the annulus between the borehole of a certain length and the inner casing 20. Figure 1 Specifically including:

[0047] Step 1.1: Two long grouting pipes, namely grouting pipe three 14 and grouting pipe four 15, are inserted into the annulus between the downhole directional long borehole 21 and its inner casing 20. The lower ends of grouting pipe three 14 and grouting pipe four 15 extend out of the downhole orifice pressure-bearing sealing section 23, that is, the orifice length of the downhole directional long borehole 21 is about 1 to 2 meters, so that the cement slurry injected by the ground pump 12 in the later stage can enter the annulus between the outer side of the casing 20 and the downhole directional long borehole 21.

[0048] Step 1.2: Cotton wool is stuffed into the annulus between the outer side of the casing 20 and the downhole directional long drill hole 21 at the downhole hole opening 8 to form a cotton wool filling section 19. The cotton wool filling section 19 can achieve complete sealing of the annulus between the outer side of the casing 20 and the downhole directional long drill hole 21; the stuffed cotton wool is soaked with water glass, and the depth of the cotton wool stuffing position is about 1 to 2 meters lower than the upper ends of the grouting pipe three 14 and the grouting pipe four 15; the length of the cotton wool filling section 19 reaches at least 1 meter.

[0049] Step 1.3: Insert two shorter grouting pipes, namely grouting pipe 1 22 and grouting pipe 2 18, into the annulus between the outer side of the casing 20 and the downhole directional long borehole 21. The upper ends of the inserted grouting pipes 1 22 and grouting pipe 2 18 are about 2 to 3 meters lower than the depth of the cotton filling section 19, and the lower ends of the grouting pipes 1 22 and grouting pipe 2 18 extend out of the lower end of the downhole directional long borehole 21, so as to facilitate the cement slurry injected by the downhole pump in the early stage to enter the annulus between the outer side of the casing 20 and the downhole directional long borehole 21.

[0050] Step 1.4: Marisol is injected into the annular space between the outer side of the downhole casing 20 and the downhole directional long drill hole 21 to form a Marisol filling section 17, so as to achieve sealing and filling of the annular space between the outer side of the downhole casing 20 and the downhole directional long drill hole 21. The length of the Marisol filling section 17 is designed to be about 2 to 3 meters.

[0051] Step 1.5: Use grouting pipe 1 22 and grouting pipe 2 18 to inject cement slurry into the annulus between the cotton filling section 19 and the mariscal filling section 17 to form the orifice pressure-bearing sealing section 23.

[0052] Specifically, the grouting pipe one valve 13 on the grouting pipe one 22 and the grouting pipe two valve 16 on the grouting pipe two 18 are initially in the open state. The grouting pipe two 18 is connected to the downhole grouting pump pipeline, and the cement slurry enters the annulus between the outside of the casing 20 and the downhole directional long borehole 21 through the grouting pipe two 18. When cement slurry flows out of the grouting pipe one 22, the grouting pipe one valve 13 is closed, and the cement slurry is continued to be injected through the grouting pipe two 18. When the pressure on the grouting pump is 1MPa, the grouting is stopped and the grouting pipe two valve 16 is closed, so that the cement slurry injected into the annular space between the cotton filling section 19 and the Marisan filling section 17 is placed under a negative pressure of 1MPa and waits for 72 hours to solidify. In addition, the cement slurry injected into the annular space is made of quick-setting expansive cement ash.

[0053] Step 2: The grouting pipeline in the through well 1 is connected to the downhole grouting pipeline in a pressure-bearing and sealed manner. The grouting pipe head of the downhole grouting pipeline is sealedly connected to the grouting pipe 3 14 and the grouting pipe 4 15 through two pipelines respectively; the grouting pipe head of the downhole grouting pipeline is provided with an orifice grouting pipe head valve 6, and the end of the downhole grouting pipeline is provided with a blowout valve 5; Figure 2 Specifically including:

[0054] The grouting pipeline in the through well 1 is designed to use an oil pipe 11, and the oil pipes 11 are connected by threads. The threaded connection between the oil pipes 11 is implemented by a ground drilling rig, which can effectively achieve a pressure-bearing and sealed connection between the oil pipes 11;

[0055] The design of the downhole grouting pipeline adopts a fracturing pipeline 4, and the fracturing pipelines 4 are connected by oil connection. The connection and fastening method between the oil connections can be achieved by intermittently hammering the oil connection head with a sledgehammer, which can effectively achieve a pressure-bearing and sealed connection between the fracturing pipelines 4;

[0056] The oil pipe 11 and the fracturing pipeline 4 are connected by a high-pressure hose 3 as a bridge, and the connection between them is through an oil connection.

[0057] The inner diameters of the above grouting pipelines are all consistent, and the connecting joints are internally flat; more specifically, the inner diameters of the oil pipe 11, the high-pressure hose 3 and the fracturing pipeline 4 are consistent and their inner diameters are larger than the inner diameters of the grouting pipe three 14 and the grouting pipe four 15.

[0058] Step 3: Conduct a pressure test on the grouting pipeline, which is mainly used to test the pressure-bearing and sealing connection effect of the entire grouting pipeline.

[0059] Specifically include:

[0060] First, the pipeline of the grouting and cementing pump truck 12 on the ground is connected to the oil pipe 11 in the ground through-hole 1, and then the blowout valve 5 at the end of the downhole grouting pipeline and the orifice grouting pipe head valve 6 of the grouting pipe head of the downhole grouting pipeline are closed. Finally, the grouting and cementing pump truck on the ground 12 is used to pump clean water into the grouting pipeline until the pressure of the grouting and cementing pump truck on the ground 12 reaches 30MPa, then the injection of clean water is stopped. After stabilizing the pressure for 10 minutes, if the pressure drop value is less than 0.5MPa, the grouting pipeline pressure test is qualified, otherwise the grouting pipeline pressure-bearing sealing connection is re-performed until the pressure test is qualified.

[0061] Step 4: Perform pressure throttling adjustment on the orifice grouting pipe head valve 6 to prevent vacuum backflow from forming in the oil pipe 11.

[0062] Since the inner diameters of the oil pipe 11, the high-pressure hose 3 and the fracturing pipeline 4 are the same and their inner diameters are larger than the inner diameters of the grouting pipe three 14 and the grouting pipe four 15, if the pressure throttling adjustment of the orifice grouting pipe head valve 6 is not performed, a vacuum backflow phenomenon will be formed in the oil pipe 11 during the injection of cement slurry by the ground grouting and cementing pump truck 12, which will cause the cement slurry injected into the annulus between the outside of the casing 20 and the downhole directional long borehole 21 to be in a slug state, which will seriously affect the cementing quality.

[0063] The pressure throttling adjustment of the orifice grouting pipe head valve 6 is as follows:

[0064] First, ensure that the downhole blowout valve 5 is in the closed state, the orifice grouting pipe head valve 6, the grouting pipe three valve 7 and the grouting pipe four valve 9 are all in the open state, and use the grouting and cementing pump truck to inject clean water on the ground 12. The injection displacement of the cementing pump truck is adjusted to the displacement required for normal cement injection during grouting and cementing. Then slowly close the orifice grouting pipe head valve 6. During the closing of the orifice grouting pipe head valve 6, observe the pressure changes on the grouting and cementing pump truck on the ground 12. When the pressure on the cementing pump truck is the same as the cement slurry specific gravity pressure required for equivalent grouting and cementing at the depth 2 where the oil pipe and the hose are connected, stop closing the orifice grouting pipe head valve 6. The pressure throttling adjustment of the orifice grouting pipe head valve 6 is successful.

[0065] Step 5: The ground 12 grouting and cementing pump truck begins to inject cement slurry with the required specific gravity for grouting and cementing the pipe in the downhole directional long borehole 21. Specifically including:

[0066] Step 5.1: First, determine the required cement slurry injection volume based on the volume of the annulus between the outer side of the casing 20 and the downhole directional long borehole 21. When calculating the annulus volume, the hole expansion rate of the downhole directional long borehole 21 is usually defined as 15%;

[0067] At the same time, before the start of cement slurry injection, a protective cap 24 with a drainage tube 25 is connected to the head of the casing 20 of the downhole hole 8 by threading. The drainage tube 25 is equipped with a control valve 26. During the grouting and pipe fixing, the tube valve 26 is in the open state. Figure 3 shown.

[0068] Step 5.2: The ground grouting and cementing pump truck 12 starts injecting cement slurry. After the required amount of cement slurry for grouting and cementing pipes is pumped, clean water is started to be pumped in. The cement slurry in all grouting pipelines is pushed into the annulus between the outer side of the casing 20 and the downhole directional long borehole 21 by injecting clean water. When the clean water replaces the cement slurry to the downhole fracturing pipeline 4, the capillary valve 26 is closed.

[0069] Step 5.3: The surface cementing pump truck 12 continues to inject clean water until the clean water reaches the downhole orifice 8. The surface 12 stops injecting clean water and immediately closes the grouting pipe valve 3 7 and the grouting pipe valve 4 9. This allows the cement slurry injected into the annulus between the outer side of the casing 20 and the downhole directional long borehole 21 to be pressurized and allowed to solidify for 72 hours.

[0070] Step 6: Sweep Drilling. After the waiting and setting is completed, the protective cap 24 installed on the casing head at the hole is removed underground, and the drill is lowered into the casing 20 to carry out sweep drilling of the cement slurry flowing into the casing. After the sweep drilling is completed, the drill is pulled out, and the underground directional long hole grouting and pipe fixing is completed.

[0071] The preferred embodiments of the present invention are described in detail above in conjunction with the accompanying drawings. However, the present invention is not limited to the specific details in the above embodiments. Within the technical concept of the present invention, various simple modifications can be made to the technical solution of the present invention, and these simple modifications all fall within the scope of protection of the present invention.

[0072] It should also be noted that the various specific technical features described in the above specific embodiments can be combined in any appropriate manner without contradiction. To avoid unnecessary repetition, the present invention will not further describe various possible combinations.

[0073] In addition, the various embodiments of the present invention may be arbitrarily combined, and as long as they do not violate the concept of the present invention, they should also be regarded as the contents disclosed by the present invention.

Claims

1. A method for directional long drilling and grouting pipe fixing in underground coal mines, characterized in that: The following steps are involved: Step 1: constructing a pressure-bearing sealing section of the orifice by using two plugging and one grouting in the annulus between the orifice section and the inner casing of a directional long borehole in an underground coal mine; providing a grouting pipe three and a grouting pipe four penetrating the orifice pressure-bearing sealing section in the orifice section; Step 2: The through-hole grouting pipeline and the downhole grouting pipeline are pressure-sealed and connected, and the grouting pipe head of the downhole grouting pipeline can be respectively sealed with the grouting pipe three and the grouting pipe four through two pipelines; the grouting pipe head of the downhole grouting pipeline is provided with an orifice grouting pipe head valve, and the end of the downhole grouting pipeline is provided with a blowout valve; Step 3: Perform a pressure test on the grouting pipeline to check the pressure-bearing and sealing connection effect of the entire grouting pipeline. If the grouting pipeline passes the pressure test, proceed to the next step. Otherwise, re-perform the pressure-bearing and sealing connection of the grouting pipeline until it passes the pressure test; Step 4: Adjust the pressure and throttling of the orifice grouting pipe head valve to prevent vacuum backflow in the grouting pipeline oil pipe in the through well; Step 5: The grouting and cementing pump truck injects the cement slurry with the required specific gravity for directional long-hole grouting and cementing pipe in the well and waits for solidification under pressure; Step 6: After the waiting for setting is completed, drill down into the casing to perform plug drilling on the cement slurry flowing into the casing to complete the downhole directional long hole grouting and pipe fixing.

2. The underground directional long drilling grouting and pipe fixing method for a combined well-ground coal mine according to claim 1, characterized in that: The step 1 comprises: Step 1.1: Insert two long grouting pipes, namely grouting pipe 3 and grouting pipe 4, into the annulus between the downhole directional long borehole and its inner casing, with the lower ends of grouting pipes 3 and 4 extending 1 to 2 meters beyond the downhole directional long borehole opening; Step 1.2: Insert cotton wool into the annulus between the casing and the downhole directional long borehole to form a cotton wool filling section. The cotton wool filling section can completely seal the annulus between the casing and the downhole directional long borehole. The inserted cotton wool is soaked with water glass. The cotton wool is inserted 1 to 2 meters below the upper ends of the third and fourth grouting pipes. The length of the cotton wool filling section is at least 1 meter. Step 1.3: Insert two short grouting pipes, grouting pipe 1 and grouting pipe 2, into the annulus between the casing and the downhole directional long borehole. The upper ends of grouting pipes 1 and 2 are 2 to 3 meters lower than the cotton filling section, and the lower ends of grouting pipes 1 and 2 extend out from the lower end of the downhole directional long borehole. Step 1.4: Inject Marisol into the annulus between the casing and the downhole directional long drill hole to form a Marisol filling section, so as to achieve sealing and filling of the annulus between the casing at the hole end and the downhole directional long drill hole. The length of the Marisol filling section is 2 to 3 meters. Step 1.5: Use grouting pipe 1 and grouting pipe 2 to inject cement slurry into the annulus between the cotton filling section and the Marisol filling section to form a hole pressure sealing section.

3. The underground directional long drilling grouting and pipe fixing method for a combined well-ground coal mine as claimed in claim 2, characterized in that: The step 1.5 includes: The valve of grouting pipe 1 and the valve of grouting pipe 2 on grouting pipe 2 are both initially in the open state. Connect grouting pipe 2 to the downhole grouting pump pipeline, and the cement slurry enters the annulus between the casing and the downhole directional long borehole through grouting pipe 2. When cement slurry flows out of grouting pipe 1, close the valve of grouting pipe 1, and continue to inject cement slurry through grouting pipe 2. When the pressure on the grouting pump reaches 1MPa, stop grouting, close the valve of grouting pipe 2, and let the cement slurry injected into the annulus between the cotton filling section and the Malisin filling section be under a negative pressure of 1MPa and wait for 72 hours to solidify.

4. The underground directional long drilling grouting and pipe fixing method for a combined well-ground coal mine according to claim 1, characterized in that: In step 2, oil pipes are used to connect the grouting pipelines in the well, and the oil pipes are connected by threads. The threaded connection between the oil pipes is tightened by a ground drilling rig to achieve a pressure-bearing and sealed connection between the oil pipes. The downhole grouting pipeline adopts the fracturing pipeline, and the fracturing pipelines are connected by oil-fired joints. The connection and fastening method between the oil-fired joints is to intermittently hammer the oil-fired joint heads with a sledgehammer to achieve pressure-bearing and sealed connections between the fracturing pipelines. The oil pipe and the fracturing pipeline are connected via a high-pressure hose, and are connected to each other via an oil hose.

5. The underground directional long drilling grouting and pipe fixing method for a combined well-ground coal mine as claimed in claim 4, characterized in that: The inner diameters of the oil pipe, high-pressure hose and fracturing pipeline are consistent and larger than the inner diameters of the grouting pipe three and the grouting pipe four, and the joints connecting them are internally flush.

6. The underground directional long drilling grouting and pipe fixing method for a combined well-ground coal mine as claimed in claim 4, characterized in that: The step 3 comprises: First, connect the pipeline of the ground grouting and cementing pump truck to the oil pipeline in the ground through-hole, then close the blowout valve and the orifice grouting pipe head valve, use the grouting and cementing pump truck to pump clean water into the grouting pipeline until the pressure of the grouting and cementing pump truck reaches 30MPa, stop injecting clean water, stabilize the pressure for 10 minutes, and if the pressure drop is less than 0.5MPa, the grouting pipeline pressure test is qualified, otherwise re-connect the grouting pipeline pressure-bearing seal until the pressure test is qualified.

7. The underground directional long drilling grouting and pipe fixing method for a combined well-ground coal mine according to claim 1, characterized in that: The pressure throttling adjustment of the orifice grouting pipe head valve in step 4 includes: First, ensure that the blowdown valve is in the closed state, the orifice grouting pipe head valve, the grouting pipe three valve on the grouting pipe three, and the grouting pipe four valve on the grouting pipe four are all in the open state, use the grouting and cementing pump truck to inject clean water, adjust the injection displacement of the cementing pump truck to the displacement required for normal grouting during grouting and cementing, and then slowly close the orifice grouting pipe head valve. During the process of closing the orifice grouting pipe head valve, observe the pressure changes on the grouting and cementing pump truck. When the pressure on the cementing pump truck is the same as the cement slurry specific gravity pressure required for grouting and cementing at the depth of the connection between the oil pipe and the hose, stop closing the orifice grouting pipe head valve, and the orifice grouting pipe head valve pressure throttling adjustment is successful.

8. The underground directional long drilling grouting and pipe fixing method for a combined well-ground coal mine as claimed in claim 1, characterized in that: The step 5 comprises: Step 5.1: Determine the amount of cement slurry to be injected based on the volume of the annulus between the casing and the downhole directional long borehole; At the same time, before starting to inject cement slurry, a protective cap with a drainage tube is connected to the casing head of the downhole hole through a thread. The drainage tube is equipped with a control valve. The valve of the tube is kept open during the grouting and pipe fixing period. Step 5.2: The surface grouting and cementing pump truck begins to inject cement slurry. After the required amount of cement slurry for grouting and cementing pipes is pumped, clean water is started to be pumped in to push the cement slurry in all grouting pipelines into the annulus between the casing and the downhole directional long borehole. When the clean water displaces the cement slurry to the downhole fracturing pipeline, the capillary valve is closed. Step 5.3: Continue to inject clean water from the ground cementing pump truck until the clean water reaches the downhole orifice. Stop injecting clean water and immediately close the grouting pipe valves 3 and 4 to keep the cement slurry injected into the annulus between the entire casing and the downhole directional long borehole under pressure and wait for solidification.

9. The underground directional long drilling grouting pipe fixing method for a combined well-ground coal mine as claimed in claim 8, characterized in that: In step 6, after the waiting for solidification is completed, the protective cap installed on the hole casing head is removed, and the drill is lowered into the casing to perform plugging drilling of the cement slurry flowing into the casing. After the plugging drilling is completed, the drill is pulled out, and the downhole directional long hole grouting and pipe fixing is completed.

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