An annular space back pressure release device and method for directional drilling stuck drill accident in coal mine

Abstract

The present invention discloses an annular back pressure release device and method for directional drilling of a drill stuck in underground coal mines. The device and method can overcome the serious drill stuck accident in underground coal mine directional drilling, which causes the drill string in the hole to be "stuck", and can be successfully handled in a timely and efficient manner, thereby avoiding economic losses caused by delays in production schedules; in addition, the technical solution of the present invention is used to solve the drill stuck accident, and there is no need to prepare "milling" to salvage the drill tool, which can reduce production costs, the occurrence of secondary accidents in the hole, and the risk of handling accidents.

Description

Technical Field

[0001] The invention belongs to the technical field of underground tunnel drilling in coal mines, and relates to an annular space back pressure release device and method for a drill stuck accident in a directional drilling in a coal mine. Background Art

[0002] Near-horizontal directional drilling technology in underground coal mines is widely used in the fields of gas prevention and control, water exploration and drainage, grouting transformation, geological structure detection, etc., which has greatly improved the safety and technical level of coal mining and made great contributions to the safe production of coal mines. With the continuous expansion of the application field of near-horizontal directional drilling technology, from coal seam drilling to rock formation drilling, and then to the current complex rock formation and hard rock formation drilling, as well as ultra-deep holes and large-diameter drilling, the development of near-horizontal directional drilling technology is increasingly restricted by in-hole accidents, especially in complex rock formations, mudstone necking, hole collapse and other phenomena are very likely to cause directional drilling difficulties. At present, the methods of handling drill stuck accidents in near-horizontal directional drilling mainly include "active drill tool + mud pump punching", "forced pulling" and "milling". Among them, "active drill tool + mud pump punching" and "forced pulling" have a higher probability of successfully solving the accident when the drill is not completely "stuck". In the case of a serious drill stuck accident leading to "stuck", the "milling" method is currently mainly used to try to solve it. However, it is necessary to specially match the milling drill rod and milling drill bit according to the drill tool grade used. The problem is that the preparation time of the drill tool is long, and the best time node for solving the accident in the hole may be missed. In addition, during the milling process, since the milling drill tool needs to pass through the accident drill tool and realize sweeping drilling, if the actual drilling trajectory of the directional drilling is complex, the feed force and torque required for milling are large, secondary accidents may occur, which will further increase the difficulty of handling directional drilling accidents. Summary of the invention

[0003] In view of the problems or shortcomings of the prior art, the present invention combines the needs of safe and efficient drilling of near-horizontal directional drilling in coal mines, integrates the long-term experience and achievements in underground coal mine drilling, and studies and invents an annulus back-pressure and jam-release device and method for directional drilling drill jam accidents in coal mines to overcome the above-mentioned shortcomings.

[0004] The purpose of the present invention is to provide an annular space back pressure release device and method for a drill stuck accident in a directional drilling in a coal mine, so as to solve the problems existing in the prior art.

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

[0006] A device for releasing stuck drill holes in an annulus in underground directional drilling in a coal mine comprises a mud pump and a directional drilling casing. The mud pump is connected to a shallow annulus at an accident point through a back-pressure grouting nipple and the directional drilling casing. A drill string in the hole is radially penetrated through the directional drilling casing. The mud pump delivers high-pressure water to the shallow annulus at the accident point through the back-pressure grouting nipple, and pressure agitation is generated in the shallow annulus at the accident point, so that a rock block at the accident point moves or the position of a collapsed rock block is adjusted. The back-pressure release of the annulus in the directional drilling accident is achieved by pulling out or twisting the drill string in the hole by utilizing the pressure transient in the shallow annulus at the accident point.

[0007] Furthermore, the in-hole drilling tool string includes a drill bit, a screw motor, a non-magnetic drilling tool, an inclinometer, a directional drill rod and a one-way check valve connected in sequence; the mud pump outlet is connected to the tail of the in-hole drilling tool string, and high-pressure water is sent to the screw motor through the directional drill rod and the non-magnetic drilling tool, driving the screw motor to rotate, thereby driving the drill bit.

[0008] A stop valve is installed on the water injection pipe of the counter-pressure grouting pup joint, and a drain valve is installed on the drain pipe of the counter-pressure grouting pup joint.

[0009] The back-pressure grouting nipple is also connected to a blowout preventer to create high pressure in the shallow annulus near the failure point.

[0010] A flange joint is connected to the directional drilling casing, and an orifice pressure gauge is installed on the flange joint.

[0011] The present invention further provides a method for unblocking the annulus of a directional drilling drill stuck in a coal mine using the device, the method comprising the following steps:

[0012] Step A: Determine the location of the drill stuck accident point and the hole depth of the drill stuck accident point, then use a mud pump to pump high-pressure water to the shallow annulus of the drill stuck accident point through a back pressure grouting nipple, and directly apply the back pressure water force to the rock block at the drill stuck accident point, so that pressure is generated in the shallow annulus of the accident point, forcing the rock block at the drill stuck accident point to move or adjust the position of the rock block in the collapsed hole;

[0013] Step B: In the absence of formation leakage, increase the water injection pressure, select an appropriate pressure to maintain the pressure, stop water injection, close the stop valve, observe the pressure change in the annulus behind the drilling through the orifice pressure gauge, and when the pressure suddenly changes, quickly open the drain valve to release the water, so that the water pressure in the annulus behind the drilling is instantly reduced to 0MPa; at this time, use a directional drilling rig to pull out or twist the drill string in the active hole to release the jam;

[0014] Step C, repeat steps A and B until the jam is successfully resolved, and the drill string in the hole is removed. The drill jam accident is now resolved.

[0015] In the step A, the calculation formula for determining the hole depth L at the drill sticking accident point is as follows:

[0016]

[0017] Where, L is the hole depth at the accident point, m; K is the correction coefficient, which is 0.95~1 for downward-inclined drilling and 0.9~0.95 for upward-inclined drilling; e is the average elongation of the drill pipe during continuous pulling out, m; P is the average tension during continuous pulling out of the drill pipe, N; E is the elastic modulus of the drill pipe, which is 2.1×10 11 N / m 2 ; D is the outer diameter of the drill pipe, m 2 ; d is the inner diameter of the drill pipe, m 2 .

[0018] In step A, the mud pump pumps high-pressure water to the drill stuck accident point in a shallow annulus through the back pressure grouting pup joint 7, and directly applies the back pressure water force on the rock block at the drill stuck accident point; wherein the generated back pressure water force is configured in the following manner:

[0019]

[0020] In the formula, F r is the back pressure force, N; P is the injection pressure, N / m 2 ; D is the borehole diameter, mm; d is the drill rod diameter, mm.

[0021] Furthermore, step A specifically includes the following steps:

[0022] 1) Close the BOP and hold the drill string tightly in the hole;

[0023] 2) Open the stop valve and close the drain valve;

[0024] 3) Use a mud pump to pump high-pressure water to the shallow annulus at the accident point through a back-pressure grouting nipple, directly apply the back-pressure water force to the rock block at the drill stuck accident point, generate pressure excitement in the shallow annulus at the accident point, and cause the rock block at the drill stuck accident point to move or adjust the position of the collapsed rock block.

[0025] Preferably, step B specifically comprises the following steps:

[0026] 1) Continue to inject water into the shallow annulus near the accident point, select an appropriate pressure to maintain pressure, stop injecting water, close the stop valve, and observe the pressure change in the annulus after drilling through the orifice pressure gauge;

[0027] 2) In case of sudden pressure changes, quickly open the drain valve to release the water, so that the water pressure in the shallow annulus at the accident point drops to 0 instantly;

[0028] 3) Open the blowout preventer;

[0029] 4) Use a directional drill to pull or twist the drill string in the movable hole to release the jam.

[0030] Compared with the prior art, the present invention has the following beneficial effects: in the event of a serious drill-stuck accident during directional drilling in a coal mine, which causes the drill string in the hole to be "stuck", the accident in the hole can be handled by the technical solution of the present invention, and it can be successfully handled in a timely and efficient manner, thereby avoiding economic losses caused by delays in production schedules; in addition, by adopting the technical solution of the present invention to solve the drill-stuck accident, there is no need to prepare a "milling" salvage drill tool, thereby reducing production costs, the occurrence of secondary accidents in the hole, and the risk of handling accidents. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 It is a schematic diagram of an annular back pressure release device for drill stuck accidents in directional drilling in coal mines;

[0032] Figure 2 It is a schematic diagram of the drilling string in the hole.

[0033] Reference numerals:

[0034] 1. Drill bit 2. Drill string in the hole 21. Screw motor 22. Non-magnetic drilling tool 23. Inclinometer 24. Directional drill pipe 3. Drilling accident point 4. Directional drilling casing 5. Flange joint 6. Orifice pressure gauge 7. Back pressure grouting short joint 8. Blowout preventer 9. One-way check valve 10. Stop valve 11. Drain valve 12. Shallow annulus at the accident point 13. Deep annulus at the accident point. DETAILED DESCRIPTION

[0035] The present invention is described in detail below with reference to the accompanying drawings and specific embodiments.

[0036] See also Figure 1 A device for releasing stuck drill holes in underground directional drilling in coal mines by back pressure and annulus pressure, comprising a mud pump and a directional drilling casing 4. The mud pump is connected to a shallow annulus 12 at an accident point through a back pressure grouting nipple 7 and the directional drilling casing 4. An in-hole drill string 2 is radially penetrated through the directional drilling casing 4. The mud pump delivers high pressure water to the shallow annulus 12 at the accident point through the back pressure grouting nipple 7, and pressure agitation is generated in the shallow annulus 12 at the accident point, so that the rock block at the accident point moves or the position of the collapsed rock block is adjusted; by utilizing the pressure transient in the shallow annulus 12 at the accident point, the in-hole drill string 2 is pulled out or twisted to realize back pressure release of the annulus of the directional drilling accident.

[0037] The in-hole drilling tool string 2 of the present invention comprises a drill bit 1, a screw motor 21, a non-magnetic drilling tool 22, an inclinometer 23, a directional drill rod 24 and a one-way check valve 9 which are connected in sequence; the water outlet of the mud pump is connected to the tail of the in-hole drilling tool string 2, and high-pressure water is sent to the screw motor 21 through the directional drill rod 24 and the non-magnetic drilling tool 22, driving the screw motor 21 to rotate, thereby driving the drill bit 1 to break the rock, and the drill bit water is all returned from the hole mouth through the borehole annulus. The back pressure effect is the reverse water supply relative to the positive pressure effect. After the high-pressure water is sent into the back pressure grouting short section 7, high pressure is established in the shallow annulus 12 at the accident point, and the back pressure water acts on the rock block at the drill stuck accident point 3.

[0038] The one-way check valve 9 is a one-way water supply and reverse flow interception short joint, which can be directly connected to the drill pipe through a threaded connection to prevent high pressure from being built up in the shallow annulus 12 near the accident point, and the pressure is transmitted to the deep borehole annulus 13 near the drill sticking accident point 3, and then acts on the screw motor 21, causing the screw motor to reverse and enter slag and be damaged.

[0039] A stop valve 10 is installed on the water injection pipe of the back pressure grouting pup joint 7, and a drain valve 11 is installed on the drain pipe of the back pressure grouting pup joint 7. A rubber hose with a larger diameter can be selected for the drain pipe to facilitate the release of the drain valve.

[0040] The directional drilling casing 4 must be completed before directional drilling. The directional drilling casing 4 can be consolidated with the drilled stratum through processes such as hole opening, hole expansion, casing installation, grouting, etc., and 30 cm is reserved in the hole mouth section to connect the flange joint 5 during accident handling.

[0041] The back pressure grouting nipple 7 is also connected to a blowout preventer 8, which is a through hole structure with an inner through hole larger than the outer diameter of the drill bit when opened. When closed, the internal gate holds the drill pipe tightly to prevent water from being unloaded from the hole, and high pressure can be established in the shallow annulus 12 at the accident point.

[0042] A flange joint 5 is connected to the directional drilling casing 4, and an orifice pressure gauge 6 is installed on the flange joint 5. The stop valve 10 is connected to the high-pressure water outlet of the mud pump through a high-pressure hose.

[0043] The device of the present invention is further used to realize a method for releasing the stuck drill in an annulus caused by drill jam in directional drilling in coal mines. The method comprises the following steps:

[0044] Step A: Determine the location of the drill stuck accident point and the hole depth of the drill stuck accident point, then use a mud pump to pump high-pressure water to the shallow annulus of the drill stuck accident point through a back pressure grouting nipple, and directly apply the back pressure water force to the rock block at the drill stuck accident point, so that pressure is generated in the shallow annulus of the accident point, forcing the rock block at the drill stuck accident point to move or adjust the position of the rock block in the collapsed hole;

[0045] Step B: In the absence of formation leakage, increase the water injection pressure, select an appropriate pressure to maintain the pressure, stop water injection, close the stop valve, observe the pressure change in the annulus behind the drilling through the orifice pressure gauge, and when the pressure suddenly changes, quickly open the drain valve to release the water, so that the water pressure in the annulus behind the drilling is instantly reduced to 0MPa; at this time, use a directional drilling rig to pull out or twist the drill string in the active hole to release the jam;

[0046] Step C, repeat steps A and B until the jam is successfully resolved, and the drill string in the hole is removed. The drill jam accident is now resolved.

[0047] In the step A, the calculation formula for determining the hole depth L at the drill sticking accident point is as follows:

[0048]

[0049] Where, L is the hole depth at the accident point, m; K is the correction coefficient, which is 0.95~1 for downward-inclined drilling and 0.9~0.95 for upward-inclined drilling; e is the average elongation of the drill pipe during continuous pulling out, m; P is the average tension during continuous pulling out of the drill pipe, N; E is the elastic modulus of the drill pipe, which is 2.1×10 11 N / m 2 ; D is the outer diameter of the drill pipe, m 2 ; d is the inner diameter of the drill pipe, m 2 .

[0050] The location of the drill sticking accident point 3 may be any location among the drill bit 1 , the screw motor 21 , the non-magnetic drilling tool 22 , and the directional drill rod 24 .

[0051] In the step A, the mud pump pumps high-pressure water to the drill stuck accident point in a shallow annulus through the back pressure grouting pup joint 7, and directly applies the back pressure water force on the rock block at the drill stuck accident point; wherein the generated back pressure water force is configured in the following manner:

[0052]

[0053] In the formula, F r is the back pressure force, N; P is the injection pressure, N / m 2 ; D is the borehole diameter, mm; d is the drill rod diameter, mm.

[0054] Following the above technical steps, the present invention provides a specific embodiment.

[0055] refer to Figure 2The embodiment of the present invention discloses a method for unblocking the annulus in a directional drilling accident in a coal mine. The 1 is a 120mm directional drill bit, 21 is an 89mm five-stage screw motor, 22 is a non-magnetic drill tool including an 89mm lower non-magnetic drill rod, an 89mm measuring outer tube and an 89mm upper non-magnetic drill rod, 23 is a hole power supply measuring probe, 24 is an 89mm cable drill rod, 9 is an 89mm cable one-way check valve, and the connection group is composed of a 2-hole drilling tool string.

[0056] Figure 1 Before starting directional drilling with the drill string 2 in the hole, use conventional drilling technology to open and expand the hole, insert a 146mm casing into the hole mouth, reserve 30cm at the hole mouth, and use cement grouting to fix the casing.

[0057] When the directional drilling of the accident string 2 in the hole reached 500m, the drill encountered a broken zone and the drill bit was stuck. According to the previous treatment, when the average tension reached 250kN, the average elongation of the drill bit was 30cm, the borehole was tilted downward, and the correction coefficient K was taken as 0.97. After calculation:

[0058]

[0059] The calculated stuck point was at a hole depth of 440m. Analysis of the actual drilling formation conditions during drilling showed that the stuck drill point was in the sandy mudstone formation section between 430m and 450m. When drilling into the sandy mudstone formation in this hole section, the amount of slag returned from the hole mouth increased, large rock blocks were returned, and the mud pump was blocked. Therefore, combined with the handling situation after the drill was stuck, it was determined that the drill stuck accident was difficult to handle by the drilling rig, so the annulus back pressure release method was used to quickly handle it.

[0060] The specific steps for handling drill stuck accidents are as follows:

[0061] A 146mm flange joint is connected to the 146mm orifice casing in a threaded manner, and a pressure gauge is installed on the flange joint. The pressure gauge range is greater than 15MPa;

[0062] The flange joint is connected with the back-pressure grouting nipple in the form of a flange. A stop valve and a drain valve are installed on the back-pressure grouting nipple. The stop valve is connected to the high-pressure outlet end of the mud pump with a high-pressure hose;

[0063] The drain valve is installed on the drain pipe. The drain pipe should be a larger diameter hose, which is conducive to the release of the drain valve.

[0064] The single gate type BOP is connected to the back pressure grouting nipple in flange form. The through hole diameter of the BOP is 140mm, and the gate closing diameter is 89mm. In the open state, a 120mm directional drill bit can pass through. In the closed state, the drill string in the hole of 89mm can be tightly held to prevent water leakage from the orifice during back pressure water injection.

[0065] Before the annular space back pressure release, after analyzing the previous treatment situation, the residual water pressure in the deep annulus at the accident point under the positive pressure was estimated to be 6MPa:

[0066]

[0067] The calculated positive water pressure force is about 30.5 kN;

[0068] Close the blowout preventer, close the drain valve, and open the stop valve;

[0069] Use a mud pump to pump high-pressure water to the drill stuck accident point in the shallow annulus through the back-pressure grouting short joint, directly apply the back-pressure water force to the rock block at the drill stuck accident point, generate pressure excitement in the annulus after drilling, and make the rock block at the drill stuck accident point move or adjust the position of the rock block at the collapsed hole;

[0070] In the absence of formation leakage, the water injection pressure is increased, and water is continuously injected into the annulus (12) behind the borehole until the water injection pressure reaches 8 MPa;

[0071] Calculate the back pressure water force at this time:

[0072]

[0073] That is, at this time, the reverse water pressure force applied to the rock block is about 40.7 kN, which is greater than the positive water pressure force;

[0074] Stop water injection, close the stop valve, observe the pressure change in the annulus behind the drilling hole through the orifice pressure gauge, maintain the pressure for 10 minutes, and if the pressure basically does not change, open the drain valve to release the water, so that the water pressure in the annulus behind the drilling hole (12) drops to 0 MPa instantly, open the blowout preventer, and use the directional drilling rig to pull or twist the drill string in the active hole to try to unblock it, but to no avail;

[0075] Close the blowout preventer, close the drain valve, open the stop valve, and inject high-pressure water into the annulus (12) behind the borehole again. The injection pressure reaches 10 MPa. It is calculated that the back pressure force applied to the rock block at this time is about 51 kN.

[0076] Stop water injection, close the stop valve, and observe the pressure change in the annulus behind the borehole through the orifice pressure gauge. If the pressure gauge swings suddenly, quickly open the drain valve to release the water, so that the water pressure in the annulus behind the borehole (12) drops to 0 MPa instantly;

[0077] Open the blowout preventer;

[0078] Use a directional drill to pull or twist the drill string in the hole to try to unblock it. If the unblocking is successful, the drill string in the hole can be moved and quickly pulled out.

[0079] In this drilling accident, if the "milling" method is used, the preparation of the milling drill tool will take a certain amount of time, which will extend the construction time of the drilling project and cause a tight schedule; in addition, after the milling drill tool is prepared, during the milling process, because the drill stuck accident point is at 440m, the accident point is deep, the borehole is in the rock, and the rock is hard. The torque of the drill tool rises rapidly during deep hole milling. When the torque exceeds the construction capacity of the drilling rig, the milling construction cannot be continued, or a secondary accident may occur during forced milling, that is, while the original drill stuck accident is not successfully handled, there is a greater risk of secondary accidents, which may increase the difficulty of handling drilling accidents and economic losses. The "counter-pressure" treatment method can be used to timely unblock the drill tool in the borehole and pull it out of the hole after the drill stuck accident cannot be successfully handled through measures such as active drilling tools and strong pulling, reducing the time cost of accident handling and the economic loss of lost drilling tools.

Claims

1. A method for releasing stuck drill in directional drilling accidents in coal mines by reverse pressure in the annulus, characterized in that: The method performs the following steps through an annular space back pressure release device: Step A: Determine the location of the drill stuck accident point and the hole depth of the drill stuck accident point, then use a mud pump to pump high-pressure water to the shallow annulus of the drill stuck accident point through a back pressure grouting nipple, and directly apply the back pressure water force to the rock block at the drill stuck accident point, so that pressure is generated in the shallow annulus of the accident point, forcing the rock block at the drill stuck accident point to move or adjust the position of the rock block in the collapsed hole; In the step A, the calculation formula for determining the hole depth L at the drill sticking accident point is as follows: Where, L is the hole depth at the accident point, m; K is the correction coefficient, which is 0.95~1 for downward-inclined drilling and 0.9~0.95 for upward-inclined drilling; e is the average elongation of the drill pipe during continuous pulling out, m; P is the average tension during continuous pulling out of the drill pipe, N; E is the elastic modulus of the drill pipe, which is 2.1×10 11 N / m 2 ; D is the outer diameter of the drill pipe, m 2 ; d is the inner diameter of the drill pipe, m 2 ; In the step A, the mud pump pumps high-pressure water to the drill stuck accident point in a shallow annulus through the back pressure grouting pup joint 7, and directly applies the back pressure water force on the rock block at the drill stuck accident point; wherein the generated back pressure water force is configured in the following manner: In the formula, F r is the back pressure force, N; P is the injection pressure, N / m 2 ; D is the borehole diameter, mm; d is the drill rod diameter, mm; Step B: In the absence of formation leakage, increase the water injection pressure, select an appropriate pressure to maintain the pressure, stop water injection, close the stop valve, observe the pressure change in the annulus behind the drilling through the orifice pressure gauge, and when the pressure suddenly changes, quickly open the drain valve to release the water, so that the water pressure in the annulus behind the drilling is instantly reduced to 0MPa; at this time, use a directional drilling rig to pull out or twist the drill string in the active hole to release the jam; Step C, repeat steps A and B until the jam is successfully released, the drill string in the hole is taken out, and the drill jam accident is handled; The annulus backpressure unblocking device comprises a mud pump and a directional drilling casing (4), and is characterized in that: the mud pump is connected to the shallow annulus (12) at the accident point through a backpressure grouting short section (7) and the directional drilling casing (4), and an in-hole drill string (2) is arranged along the radial direction of the directional drilling casing (4); the mud pump delivers high-pressure water to the shallow annulus (12) at the accident point through the backpressure grouting short section (7), and pressure is generated in the shallow annulus (12) at the accident point, so that the rock block at the drill stuck accident point moves or the position of the collapsed rock block is adjusted; the in-hole drill string (2) comprises a drill bit (1), a screw motor (21), a non-magnetic drilling tool (22), an inclinometer (23), a directional drill pipe (24), and the like which are connected in sequence. 24) and a one-way check valve (9); the water outlet of the mud pump is connected to the tail of the drill string (2) in the hole, and high-pressure water is sent to the screw motor (21) through the directional drill rod (24) and the non-magnetic drill tool (22), driving the screw motor (21) to rotate, thereby driving the drill bit (1) to break the rock, and the water discharged from the drill bit is all returned from the hole mouth through the borehole annulus. The back pressure effect is the reverse water supply relative to the positive pressure effect. After the high-pressure water is sent from the back pressure grouting short joint (7), high pressure is established in the shallow annulus (12) at the accident point. The back pressure water acts on the rock block at the drill stuck accident point (3). By utilizing the pressure transient of the shallow annulus (12) at the accident point, the drill string (2) in the hole is pulled out or twisted to realize the back pressure release of the directional drilling drill stuck accident annulus; The back pressure grouting nipple (7) is also connected to a blowout preventer (8) for establishing high pressure in a shallow annulus (12) around the dead point.

2. The method for releasing stuck drill in underground directional drilling in coal mines according to claim 1, characterized in that: The step A specifically comprises the following steps: 1) Close the BOP and hold the drill string tightly in the hole; 2) Open the stop valve and close the drain valve; 3) Use a mud pump to pump high-pressure water to the shallow annulus at the accident point through a back-pressure grouting nipple, directly apply the back-pressure water force to the rock block at the drill stuck accident point, generate pressure excitement in the shallow annulus at the accident point, and cause the rock block at the drill stuck accident point to move or adjust the position of the collapsed rock block.

3. The method for releasing stuck drill in underground directional drilling in coal mine according to claim 2, characterized in that: The step B specifically comprises the following steps: 1) Continue to inject water into the shallow annulus near the accident point, select an appropriate pressure to maintain pressure, stop injecting water, close the stop valve, and observe the pressure change in the annulus after drilling through the orifice pressure gauge; 2) In case of sudden pressure changes, quickly open the drain valve to release the water, so that the water pressure in the shallow annulus at the accident point drops to 0 instantly; 3) Open the blowout preventer; 4) Use a directional drill to pull or twist the drill string in the movable hole to release the jam.

4. The method for releasing stuck drill in coal mine directional drilling accident by reverse pressure in the annulus as claimed in claim 1, characterized in that: A stop valve (10) is installed on the water injection pipe of the counter-pressure grouting pup joint (7), and a water discharge valve (11) is installed on the water discharge pipe of the counter-pressure grouting pup joint (7).

5. The method for releasing stuck drill in underground directional drilling in coal mines according to claim 4, characterized in that: The directional drilling casing (4) is connected to a flange joint (5), and an orifice pressure gauge (6) is installed on the flange joint (5).

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