Orifice blowout prevention system and construction method for soft coal seam liquid directional drilling

Abstract

The application discloses a borehole blowout prevention system and construction method for liquid directional drilling in soft coal seam, and belongs to the field of directional drilling technology.The blowout prevention system comprises a pre-warning device, a first blowout prevention device, a second blowout prevention device, a residue discharging device and a steam-water separation tank.The three-way pipe and the five-way pipe of the first blowout prevention device are combined with the directional drilling tool to block the three-phase mixture of gas, water and coal, and to make the three-phase mixture pass through the residue discharging pipe to the second blowout prevention device.The blowout prevention box of the second blowout prevention device is used as a large amount of coal and water mixture storage device and discharging device, and the telescopic cylinder connected to the blowout prevention box can contain a large amount of gas.The controller of the pre-warning device has the functions of opening the sounder and generating strong negative pressure, and can timely extract gas to prevent gas accumulation.The application can effectively prevent the three-phase mixture of gas, water and coal from being instantaneously sprayed to the drilling site, eliminate gas overrun accidents, reduce injury accidents, improve construction efficiency and gas extraction amount, and achieve efficient separation of gas, water and coal, safe, economic and efficient construction.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of underground construction of coal mines, and relates to a hole orifice blowout prevention system for liquid directional drilling in soft coal seams in underground coal mines and a construction method. BACKGROUND

[0002] At present, the most common method of gas extraction in China is to use drilling to pre-drain the coal seam gas of the mining face. When the liquid directional drilling technology is used to drill in soft coal seams, the hole may collapse, blocking the flow channels of gas, water and coal residue. When the pressure of gas and water reaches a certain value, combined with the disturbance of the directional drilling tool, the drilling hole will instantaneously spew out a large amount of gas, coal residue and water mixture, causing injuries to on-site construction personnel, gas over-limit in the drilling field, affecting construction efficiency and causing safety hazards.

[0003] At present, the existing hole orifice blowout prevention device has the shortcomings of weak blowout prevention ability, small size, poor sealing performance, low degree of automatic residue discharge, and low utilization rate of gas spewed from the hole orifice. When a large amount of gas is spewed, the advanced warning function cannot be realized. Therefore, it is mostly used in medium-hard coal seams with low gas content and small gas pressure. SUMMARY

[0004] In view of the deficiencies in the prior art, the purpose of the present application is to provide a hole orifice blowout prevention system for liquid directional drilling in soft coal seams and a construction method to solve the problems of weak blowout prevention ability of the hole orifice blowout prevention device in the prior art, safety accidents caused by instantaneous spewing of gas, water and coal three-phase mixture into the drilling field, and low utilization rate of gas.

[0005] To solve the above technical problems, the present application adopts the following technical solutions:

[0006] A hole orifice blowout prevention system for liquid directional drilling in soft coal seams, comprising a warning device, a primary blowout prevention device, a secondary blowout prevention device, a residue discharge device and a water-gas separation tank.

[0007] The primary blowout prevention device comprises a hole orifice pipe, a tee pipe, a five-way pipe, a residue discharge pipe and a weak negative pressure pipe. The hole orifice pipe is arranged in the drilling hole and extends out of the hole orifice. The three interfaces of the tee pipe are respectively connected to one end of the hole orifice pipe, one end of the weak negative pressure pipe and one interface of the five-way pipe. The other three interfaces of the five-way pipe are respectively connected to two weak negative pressure pipes and one end of the residue discharge pipe. The directional drilling tool passes through the tee pipe and the five-way pipe. The other ends of the weak negative pressure pipes connected to the tee pipe and the five-way pipe are respectively connected to the water-gas separation tank. The other end of the residue discharge pipe is connected to the blowout prevention tank of the secondary blowout prevention device.

[0008] The early warning device comprises a pressure guide pipe, a filter, a controller, a sounder and a gas concentration table; the pressure guide pipe is connected with the orifice pipe and the filter at two ends respectively, the filter is arranged below the controller, the sounder is arranged at the joint of the controller and the strong negative pressure pipe of the secondary blowout preventer, and the gas concentration table is arranged on the strong negative pressure pipe;

[0009] The secondary blowout preventer comprises a strong negative pressure pipe and a blowout preventer; one end of the strong negative pressure pipe is connected with the blowout preventer and the controller respectively, and the other end of the strong negative pressure pipe is connected with the other end of the controller and the negative pressure main pipeline respectively; when the blowout preventer is in the blowout state, the controller can drive the two strong negative pressure pipes to be in the strong negative pressure state, and can drive the sounder to alarm;

[0010] The residue discharging device comprises a spiral rod, a pneumatic motor and a transmission shaft arranged in the blowout preventer.

[0011] The application also comprises the following technical features:

[0012] Optionally, the blowout preventer is provided with a telescopic cylinder.

[0013] Optionally, the front and rear ends of the spiral rod are installed in the blowout preventer through two fixed bearings, the end of the spiral rod is connected with the pneumatic motor through the transmission shaft, a residue filtering net is arranged below the spiral rod, a residue discharging port is arranged on the side wall of the blowout preventer beside the residue filtering net, an observation window is arranged on the side wall of the blowout preventer, and a drainage port is arranged at the bottom of the blowout preventer.

[0014] Optionally, the blowout preventer and the negative pressure main pipeline are connected through a weak negative pressure pipe.

[0015] Optionally, the controller comprises a controller body, a disc, a valve rod, a spring, a pointer and a scale disc.

[0016] The controller body is of an integrated structure, comprising an upper cavity, a middle chamber and a lower two-way joint; the disc is arranged in the upper cavity of the controller body to divide the cavity into an upper disc chamber and a lower disc chamber, and the upper disc chamber is in sealed communication with the filter; the spring is sleeved on the valve rod, the upper end of the valve rod is abutted on the disc, the lower part of the valve rod penetrates through the middle chamber and extends to the lower two-way joint, the lower end of the valve rod is connected with a sealing plug, and the upper and lower ends of the spring are limited between the lower surface of the disc and the top of the middle chamber; the pointer and the scale disc are located in the middle chamber, the pointer is fixed on the valve rod, and the scale disc is fixed on the inner side wall of the middle chamber; the lower two-way joint is separated by a separation wall, the separation wall is provided with an opening, the sealing plug is located at the opening, and the two ends of the two-way joint are in communication with the strong negative pressure pipe.

[0017] When the directional drilling tool is normally drilling, the negative pressure in the borehole makes the sealing plug move upward along with the valve rod so that the sealing plug can block the opening on the partition wall, causing the strong negative pressure pipe to be unable to be conducted at the controller; when the jetting hole is drilled, the pressure guide pipe transmits the positive pressure of the gas to the disc, causing the disc to bend and move to the lower cavity of the disc chamber, the spring is in a compressed state, the valve rod moves downward to drive the sealing plug to move downward and separate from the opening, at the same time, the pointer points to the lower position, the strong negative pressure pipe is conducted at the double-way joint and the gas in the blowout preventer is extracted in time.

[0018] Optionally, the sound generator comprises a gas guide pipe, a sound cavity, a sharp nozzle, sound balls and a lattice; one end of the gas guide pipe is connected at the joint between the strong negative pressure pipe and the double-way joint, the other end of the gas guide pipe extends into the sound cavity, the sharp nozzle is arranged on the side wall of the sound cavity, the sound balls are arranged in the sound cavity, and the lattice is arranged in the sound cavity.

[0019] Optionally, the weak negative pressure pipe is arranged between the gas-water separation tank and the negative pressure main pipeline.

[0020] Optionally, the strong negative pressure pipe and the weak negative pressure pipe are each provided with a valve.

[0021] Optionally, the lower end of the gas-water separation tank is provided with a water outlet.

[0022] A construction method of the hole mouth blowout prevention system for the hydraulic directional drilling of the soft coal seam comprises the following steps:

[0023] Step 1: a hole is drilled by 12-21 m by using a hole drilling bit, then a hole is reamed by 2 m by using a reamer, the hole is ensured to be smooth after reaming, and a hole mouth pipe with a length of 1.5 m is pushed into the hole;

[0024] Step 2: the pressure guide pipe, the filter, the controller and the sound generator are sequentially installed and connected; after the directional drilling tool is sent into the hole, the hole mouth pipe is connected with the three-way pipe through a pipe clamp, the three-way pipe is connected with the five-way pipe through a pipe clamp; the upper part of the three-way pipe and the five-way pipe are connected with the gas-water separation tank through the weak negative pressure pipe, the lower side of the five-way pipe is connected with the blowout preventer through the deslagging pipe; the blowout preventer is connected with the controller through the strong negative pressure pipe, and then connected with the negative pressure main pipeline through the weak negative pressure pipe; the gas-water separation tank is connected with the negative pressure main pipeline through the weak negative pressure pipe;

[0025] Step 3: when the directional drilling is normally carried out, the controller is in a closed state, the sound generator is in a silent state, the strong negative pressure pipeline is in a state without strong negative pressure, the weak negative pressure pipe is in an open state, and the deslagging device is normally opened; when the hole is drilled, the drilling is immediately stopped, the directional drilling tool is in a stationary state, the weak negative pressure pipe is still in an open state, at the same time, the controller is in an open state, the sound generator is in a sound state, the strong negative pressure pipeline is in a strong negative pressure state, the telescopic cylinder is in an elongated state, and the deslagging device is still normally opened; after the hole is drilled, the water in the gas-water separation tank is discharged in time.

[0026] Compared with the prior art, the present application has the following technical effects:

[0027] The present application can effectively prevent the instantaneous spraying of the gas, water and coal three-phase mixture to the drilling field, reduce the injury accidents, reduce the gas over-limit accidents, improve the construction efficiency, achieve the efficient separation of the gas, water and coal, improve the gas extraction amount, realize the coal residue self-discharge, reduce the labor intensity, simultaneously improve the water recycling times, and achieve the safe, economic and efficient construction.

[0028] In the early warning device, the sound generator can realize the early warning, aims to remind the personnel that the hole spraying phenomenon will occur, and timely leaves the hole position, so as to prevent the injury accidents; the controller can realize the opening of the strong negative pressure function, strengthens the gas extraction, so as to prevent the gas over-limit accidents, simultaneously reasonably utilizes the negative pressure system, and improves the gas utilization rate.

[0029] The primary blowout preventer can prevent the direct spraying of the gas, water and coal residue mixture to the drilling hole, and can also realize the preliminary separation of the gas, water and coal residue mixture, wherein a small amount of gas enters the main pipeline through the weak negative pressure pipe, and a large amount of gas, water and coal residue mixture enters the secondary blowout preventer. The blowout preventer of the secondary blowout preventer and the telescopic cylinder can contain a large amount of instantaneous sprayed gas, especially the telescopic cylinder realizes the space and distance release of the gas pressure, and the strong negative pressure can quickly extract a large amount of gas.

[0030] After the hole spraying occurs, the residue filter net realizes the separation of the coal residue and water, the coal residue can be quickly, continuously and stably discharged through the through-hole residue discharge device, and the water reenters the water supply system through the water outlet of the blowout preventer, so as to realize the recycling of the water. BRIEF DESCRIPTION OF DRAWINGS

[0031] Fig. 1 It is the composition diagram of the blowout preventer system of the present application;

[0032] Fig. 2 It is the schematic diagram of the controller of the present application;

[0033] Fig. 3 It is the schematic diagram of the generator of the present application.

[0034] The meanings of various numbers in the figure are as follows:

[0035] 11. orifice pipe, 12. tee pipe, 13. cross pipe, 14. residue discharge pipe, 15. weak negative pressure pipe; 21. pressure guide pipe, 22. filter, 23. controller, 24. sound generator, 25. gas concentration meter; 231. controller body, 232. disc, 233. valve rod, 234. spring, 235. pointer, 236. scale, 237. sealing plug; 241. air guide pipe, 242. sound cavity, 243. sharp nozzle, 244. sound ball, 245. lattice; 31. strong negative pressure pipe, 32. blowout preventer, 33. telescopic cylinder, 34. residue discharge port, 35. observation window, 36. water discharge port; 41. screw rod, 42. pneumatic motor, 43. transmission shaft, 44. residue filter net; 51. water outlet; 10. directional drilling tool; 20. negative pressure main pipeline. DETAILED DESCRIPTION

[0036] The following specific embodiments of the present application are given, it should be noted that the present application is not limited to the following specific embodiments, any equivalent transformation based on the technical scheme of the present application falls within the protection scope of the present application.

[0037] Embodiment 1:

[0038] As shown in the figure, the present embodiment provides an orifice blowout prevention system for soft coal seam liquid directional drilling, which comprises a pre-warning device, a first blowout prevention device, a second blowout prevention device, a residue discharge device and a steam-water separation tank. Figs. 1 to 3 The first blowout prevention device comprises an orifice pipe 11, a tee pipe 12, a cross pipe 13, a residue discharge pipe 14 and a weak negative pressure pipe 15; the orifice pipe 11 is arranged in the drilling hole and extends out of the orifice, the three interfaces of the tee pipe 12 are respectively connected with one end of the orifice pipe 11, one end of the weak negative pressure pipe 15 and one interface of the cross pipe 13; the other three interfaces of the cross pipe 13 are respectively connected with two weak negative pressure pipes 15 and one end of the residue discharge pipe 14; the directional drilling tool 10 passes through the tee pipe 12 and the cross pipe 13; the other end of each weak negative pressure pipe 15 connected with the tee pipe 12 and the cross pipe 13 is respectively connected with the steam-water separation tank 5; the other end of the residue discharge pipe 14 is connected with the blowout preventer 32 of the second blowout prevention device.

[0039]

[0040] ​The early warning device comprises a pressure guide pipe 21, a filter 22, a controller 23, a sounder 24 and a gas concentration meter 25. The two ends of the pressure guide pipe 21 are connected with the orifice pipe 11 and the filter 22 respectively. The lower end of the filter 22 is arranged with the controller 23. The function of the filter is that when the orifice is formed, a large amount of gas, water and coal residue three-phase mixture is sprayed from the bottom of the orifice to the orifice. The filter plays a filtering role on the mixture of coal residue and water, which can effectively prevent the mixture from entering the controller, so that the controller remains sensitive to the change of air pressure. When the controller is blocked, it can be manually disassembled, then the controller is washed with clean water and used again. The sounder 24 is arranged at the joint of the controller 23 and the strong negative pressure pipe 31 of the secondary blowout prevention device. The gas concentration meter 25 is arranged on the strong negative pressure pipe 31. The gas concentration meter is connected with the strong negative pressure pipe, which can detect the gas concentration of the strong negative pressure pipe, so as to determine the amount of gas sprayed when the orifice is formed. The gas concentration meter can also be used as a judgment standard for the opening and closing of the controller. When the gas concentration meter is zero, it indicates that the controller is closed. Otherwise, it indicates that the controller is opened.

[0041] The secondary blowout prevention device comprises a strong negative pressure pipe 31 and a blowout prevention tank 32. One end of the strong negative pressure pipe 31 is connected with the blowout prevention tank 32 and the controller 23 respectively. The other end of the strong negative pressure pipe 31 is communicated with the other end of the controller 23 and the negative pressure main pipe 20 respectively. When the orifice is formed, the controller 23 can drive the two strong negative pressure pipes 31 to be conducted to be in a strong negative pressure state, and can drive the sounder 24 to alarm.

[0042] The residue discharging device 4 comprises a screw rod 41, a pneumatic motor 42 and a transmission shaft 43 arranged in the blowout prevention tank 32.

[0043] A copper inner sleeve is arranged in the orifice pipe to prevent sparks generated by the friction between the directional drilling tool and the orifice pipe from causing gas explosion.

[0044] The three-way pipe and the five-way pipe are connected through flanges. When the orifice is formed, the three-way pipe and the five-way pipe play a buffering role. The weak negative pressure pipe connected with the three-way pipe and the five-way pipe can preliminarily separate a small amount of gas and coal and water mixture. A large amount of gas, coal and water mixture is discharged from the residue discharging pipe to the blowout prevention tank. At this time, the strong negative pressure is opened to increase the gas extraction. The weak negative pressure pipe is in a normal open state, which can not only strengthen the gas extraction but also avoid the suction of a large amount of air to reduce the gas concentration.

[0045] The combination of the three-way pipe, the five-way pipe and the directional drilling tool can block the instantaneous spraying of the gas, water and coal three-phase mixture, and can make the gas, water and coal three-phase mixture enter the secondary blowout prevention device through the residue discharging pipe.

[0046] The steam-water separation tank is connected with the five-way weak negative pressure pipe, which can separate the gas and water and collect the water of the negative pressure main pipe. The manual valve is opened regularly to discharge the water from the water outlet.

[0047] The blowout preventer box 32 is provided with an extensible cylinder 33. The blowout preventer box can be used as a device for storing a large amount of coal-water mixture and a device for discharging the coal-water mixture; the extensible cylinder has the characteristic of extensibility, can contain a large amount of gas, and the strong negative pressure can timely extract the gas to prevent the gas from gathering in the secondary blowout preventer.

[0048] The front and rear ends of the screw rod 41 are installed in the blowout preventer box 32 through two fixed bearings, and the end of the screw rod 41 is connected with the pneumatic motor 42 through a transmission shaft 43; a residue filter net 44 is arranged below the screw rod 41, and a residue discharge port 34 is arranged on the side wall of the blowout preventer box 32 beside the residue filter net 44; an observation window 35 is arranged on the side wall of the blowout preventer box 34, and a water discharge port 36 is arranged at the bottom of the blowout preventer box 32.

[0049] The blowout preventer box is connected with the five-way pipe. In normal drilling, the strong negative pressure pipe is in a closed state, the weak negative pressure pipe is in an open state, and the extensible cylinder is in a compressed state; in blowout, a large amount of gas, coal and water mixture flows into the blowout preventer box from the residue inlet through the residue discharge pipe, the extensible cylinder and the blowout preventer box can store the gas, and the controller is opened, the strong negative pressure strengthens the gas extraction, and the gas, coal and water are completely separated. The observation window is convenient for understanding the internal condition of the blowout preventer box, the water discharge port prevents the gas from overflowing through the water seal effect, and the residue filter net filters the coal residue to separate the coal and water. The residue discharge device can realize continuous and rapid residue discharge, the pneumatic motor is connected with the screw rod through the transmission shaft to make the screw rod rotate rapidly, and the coal residue is continuously discharged from the blowout preventer box through the residue discharge port under the action of the screw rod.

[0050] The blowout preventer box 32 and the negative pressure main pipeline 20 are communicated through the weak negative pressure pipe 15.

[0051] The controller has the functions of opening the sounder and the strong negative pressure, and the controller 23 comprises a controller body 231, a disc 232, a valve rod 233, a spring 234, a pointer 235 and a scale disc 236.

[0052] The controller body 231 is of an integrated structure, comprising an upper cavity, a middle chamber and a lower two-way joint; the disc 232 is arranged in the upper cavity of the controller body to divide the cavity into an upper disc chamber and a lower disc chamber, and the upper disc chamber is in sealed communication with the filter 22; the spring 234 is sleeved on the valve rod 233, the upper end of the valve rod 233 abuts against the disc 232, the valve rod 233 penetrates through the middle chamber and extends to the lower two-way joint, the lower end of the valve rod 233 is connected with a sealing plug 237, and the upper and lower ends of the spring 234 are limited between the lower surface of the disc 232 and the top of the middle chamber; the pointer 235 and the scale disc 236 are located in the middle chamber, the pointer 235 is fixed on the valve rod 233, and the scale disc 236 is fixed on the inner side wall of the middle chamber; the lower two-way joint is separated by a separation wall, the separation wall is provided with an opening, the sealing plug 237 is located at the opening, and the two ends of the two-way joint are respectively communicated with the strong negative pressure pipe 31;

[0053] When the directional drilling tool 10 is normally drilling, the negative pressure in the borehole makes the sealing plug 237 move upward with the valve rod 233 so that the sealing plug 233 can block the opening on the partition wall, resulting in that the strong negative pressure pipe 31 cannot be connected at the controller 23. Specifically, the negative pressure of the pressure guide pipe is transmitted to the disc, making the disc bend to move to the upper cavity of the disc chamber, the spring is in a stretched state, the valve rod moves upward to drive the sealing plug to close the opening, and the pointer points to the upper position. The strong negative pressure pipe is not connected with the sounder and the blowout preventer tank. When the jet hole is drilled, the disc 232 is bent to move to the lower cavity of the disc chamber under the gas pressure transmitted by the pressure guide pipe 21, the spring 234 is in a compressed state, the valve rod 233 moves downward to drive the sealing plug 237 to move downward and separate from the opening, and the pointer 235 points to the lower position. The strong negative pressure pipe 31 is connected at the double connector and timely extracts the gas in the blowout preventer tank 32. Specifically, when the three-phase mixture of gas, water and coal ash is instantaneously jetted to the orifice, the strong negative pressure pipe is connected with the sounder and the blowout preventer tank, the negative pressure airflow drives the sounder to work and emit loud sound, thereby playing a pre-warning role. The strong negative pressure is transmitted to the blowout preventer tank through the strong negative pressure pipe, so that the gas in the blowout preventer tank is timely extracted, and the gas is prevented from being jetted out of the blowout preventer tank to cause gas overrun.

[0054] The sounder 24 includes an air guide pipe 241, a sound cavity 242, a sharp nozzle 243, sound balls 244 and a lattice 245. One end of the air guide pipe 241 is connected at the joint between the strong negative pressure pipe 31 and the double connector, the other end of the air guide pipe 241 extends into the sound cavity 242, the sharp nozzle 243 is arranged on the side wall of the sound cavity 242, the sound balls 244 are arranged in the sound cavity 242, and the lattice 245 is arranged in the sound cavity 242. The sounder can emit loud sound, thereby playing a pre-warning role. When the controller is opened, the negative pressure generated by the air guide pipe makes the airflow flow into the sound cavity from the sharp nozzle. Under the pushing action of the airflow, the sound balls move in the sound cavity, collide with the wall, return, move again, collide with the wall and return, thereby generating sound. When the airflow rapidly passes through the lattice, the lattice also generates vibration and emits sound. The two together strengthen the loudness of the sound, and the two have a relatively large frequency and can be distinguished from other sounds emitted by the surrounding environment, thereby playing a timely pre-warning role.

[0055] The steam-water separation tank 5 is connected with the negative pressure main pipe 20 through the weak negative pressure pipe 15.

[0056] Valves are arranged on the strong negative pressure pipe 31 and the weak negative pressure pipe 15.

[0057] The steam-water separation tank 5 is provided with a water outlet 51 at the lower end.

[0058] In the embodiment, the residue discharge pipe 14 is connected with a residue inlet on the side wall of the blowout preventer tank 32, and the residue inlet is higher than the spiral rod 41.

[0059] Embodiment 2:

[0060] The embodiment provides a construction method of the orifice blowout prevention system for the liquid directional drilling in the broken soft coal seam in the embodiment 1, and comprises the following steps.

[0061] Step 1, before the hole is opened, the hole position is well adjusted and the angle is adjusted, the coal wall anchor rod and anchor cable are avoided, the hole is opened by 12-21 m through the rotation of the hole opening drill bit, then the hole is expanded by 2 m through the rotation of the hole expansion drill bit, the hole is ensured to be smooth after the hole expansion, and the orifice pipe with a length of 1.5 m is pushed into the hole by manual operation;

[0062] Step 2, the pressure guide pipe, the filter, the controller and the sound generator are sequentially connected; the orifice pipe is connected with the filter through the pressure guide pipe, the filter is connected with the controller, the sound generator is connected with the controller through the air guide pipe, and the sound generator is controlled to sound; after the directional drilling tool is sent into the hole, the orifice pipe is connected with the three-way pipe through the pipe clamp, the three-way pipe is connected with the five-way pipe through the pipe clamp, the upper parts of the three-way pipe and the five-way pipe are connected with the water-gas separation tank through the weak negative pressure pipe, the lower side of the five-way pipe is connected with the blowout prevention box through the residue discharge pipe, the blowout prevention box is connected with the controller through the strong negative pressure pipe, and the controller is connected with the negative pressure main pipeline through the weak negative pressure pipe; the water-gas separation tank is connected with the negative pressure main pipeline through the weak negative pressure pipe;

[0063] Step 3, when the directional drilling is normal, the interactive precise trajectory control method of “composite drilling and inclination-keeping, sliding drilling and inclination-creating, combined direction finding” is used for drilling, so that the drilling hole can extend along the broken soft coal seam for a long distance, at the moment, the controller is in the closed state, the sound generator is in the silent state, the strong negative pressure pipeline is in the state of no strong negative pressure, the weak negative pressure pipe is in the open state, and the residue discharge device is normally opened; when the hole is blown out, the drilling is immediately stopped, the directional drilling tool is in the static state, the weak negative pressure pipe is still in the open state, the controller is in the open state, the sound generator is in the sound state, the strong negative pressure pipeline is in the strong negative pressure state, the telescopic cylinder is in the elongation state, and the residue discharge device is still normally opened; after the hole is blown out, the water in the water-gas separation tank is discharged in time.

Claims

1. A borehole blowout-prevention system for fluid-powered directional drilling of soft coal seams, characterized in that, The device comprises a pre-warning device, a first blowout preventer, a second blowout preventer, a residue discharging device and a steam-water separation tank. The first blowout preventer comprises an orifice pipe (11), a three-way pipe (12), a five-way pipe (13), a residue discharging pipe (14) and a weak negative pressure pipe (15); the orifice pipe (11) is arranged in a borehole and extends out of an orifice; three interfaces of the three-way pipe (12) are connected with one end of the orifice pipe (11), one end of the weak negative pressure pipe (15) and one interface of the five-way pipe (13) respectively; the other three interfaces of the five-way pipe (13) are connected with two weak negative pressure pipes (15) and one end of the residue discharging pipe (14) respectively; the directional drilling tool (10) passes through the three-way pipe (12) and the five-way pipe (13); the other ends of the weak negative pressure pipes (15) connected with the three-way pipe (12) and the five-way pipe (13) are communicated with the steam-water separation tank (5) respectively; the other end of the residue discharging pipe (14) is communicated with the blowout preventer tank (32) of the second blowout preventer. The pre-warning device comprises a pressure guide pipe (21), a filter (22), a controller (23), a sound generator (24) and a gas concentration meter (25); two ends of the pressure guide pipe (21) are connected with the orifice pipe (11) and the filter (22) respectively; the lower end of the filter (22) is arranged with the controller (23); the sound generator (24) is arranged at the joint of the controller (23) and the strong negative pressure pipe (31) of the second blowout preventer; the gas concentration meter (25) is arranged on the strong negative pressure pipe (31). The second blowout preventer comprises a strong negative pressure pipe (31) and a blowout preventer tank (32); one end of one section of the strong negative pressure pipe (31) is connected with the blowout preventer tank (32) and one end of the controller (23) respectively; the other end of the strong negative pressure pipe (31) is communicated with the other end of the controller (23) and the negative pressure main pipeline (20) respectively; when the blowout preventer is in operation, the controller (23) can drive the two sections of the strong negative pressure pipe (31) to be in a strong negative pressure state and drive the sound generator (24) to alarm. The residue discharging device (4) comprises a screw rod (41), a pneumatic motor (42) and a transmission shaft (43) arranged in the blowout preventer tank (32). The sound generator (24) comprises a gas guide pipe (241), a sound cavity (242), a sharp nozzle (243), sound balls (244) and a lattice (245); one end of the gas guide pipe (241) is connected with the joint of the strong negative pressure pipe (31) and a two-way joint; the other end of the gas guide pipe (241) extends into the sound cavity (242); the sharp nozzle (243) is arranged on the side wall of the sound cavity (242); the sound balls (244) are arranged in the sound cavity (242); the lattice (245) is arranged in the sound cavity (242).

2. The orifice blowout prevention system for fluid powered directional drilling of soft coal seams of claim 1, wherein, The blowout preventer tank (32) is provided with an extension cylinder (33).

3. The orifice blowout prevention system for fluid powered directional drilling of soft coal seams of claim 1, wherein, The front and rear ends of the screw rod (41) are installed in the blowout preventer tank (32) through two fixed bearings; the end of the screw rod (41) is connected with the pneumatic motor (42) through the transmission shaft (43); a residue filtering net (44) is arranged below the screw rod (41); a residue discharging port (34) is arranged on the side wall of the blowout preventer tank (32) beside the residue filtering net (44); an observation window (35) is arranged on the side wall of the blowout preventer tank (32); a drainage port (36) is arranged at the bottom of the blowout preventer tank (32).

4. The orifice blowout prevention system for fluid powered directional drilling of soft coal seams of claim 1, wherein, The blowout preventer (32) and the negative pressure main pipeline (20) are communicated through a weak negative pressure pipe (15).

5. The orifice blowout prevention system for fluid powered directional drilling of soft coal seams of claim 1, wherein, The controller (23) comprises a controller body (231), a disc (232), a valve rod (233), a spring (234), a pointer (235) and a scale dial (236). The controller body (231) is of an integrated structure, comprising an upper cavity, a middle chamber and a lower two-way joint; the disc (232) is arranged in the upper cavity of the controller body to divide the cavity into an upper disc chamber and a lower disc chamber, and the upper disc chamber is in sealed communication with the filter (22); the spring (234) is sleeved on the valve rod (233), the upper end of the valve rod (233) is abutted against the disc (232), the lower part of the valve rod (233) penetrates through the middle chamber and extends to the lower two-way joint, the lower end of the valve rod (233) is connected with a sealing plug (237), and the upper and lower ends of the spring (234) are limited between the lower surface of the disc (232) and the top of the middle chamber; the pointer (235) and the scale dial (236) are located in the middle chamber, the pointer (235) is fixed on the valve rod (233), and the scale dial (236) is fixed on the inner side wall of the middle chamber; the lower two-way joint is separated by a separation wall, the separation wall is provided with an opening, the sealing plug (237) is located at the opening, and the two ends of the two-way joint are respectively communicated with the strong negative pressure pipe (31); When the directional drilling tool (10) is normally drilled, the negative pressure in the borehole makes the sealing plug (237) vertically move upward with the valve rod (233) so that the sealing plug (237) can block the opening on the separation wall, causing the strong negative pressure pipe (31) to be unable to be conducted at the controller (23); when the borehole is jetted, the gas pressure is transmitted to the disc (232) through the pressure guide pipe (21), the disc (232) is bent to move to the lower disc chamber, the spring (234) is in a compressed state, the valve rod (233) moves downward to drive the sealing plug (237) to move downward and separate from the opening, at the same time, the pointer (235) points to the lower position, the strong negative pressure pipe (31) is conducted at the two-way joint to timely extract the gas in the blowout preventer (32).

6. The orifice blowout prevention system for fluid powered directional drilling of soft coal seams of claim 1, wherein, The gas-water separation tank (5) and the negative pressure main pipeline (20) are communicated through the weak negative pressure pipe (15).

7. The orifice blowout prevention system for fluid powered directional drilling of soft coal seams of claim 1, wherein, Valves are arranged on the strong negative pressure pipe (31) and the weak negative pressure pipe (15).

8. The orifice blowout prevention system for fluid powered directional drilling of soft coal seams of claim 1, wherein, The lower end of the gas-water separation tank (5) is provided with a water outlet (51).

9. A method for constructing the orifice blowout preventer system for fluid- powered directional drilling of soft coal seams as claimed in claim 1, characterized in that, The method comprises the following steps: Step 1: rotary hole drilling is performed by using a hole opening drill, then rotary hole expansion is performed by using a hole expanding drill, the hole is expanded to ensure smoothness, and a hole mouth pipe is pushed into the hole; Step 2: the pressure guide pipe, the filter, the controller and the sound generator are sequentially installed and connected; after the directional drilling tool is sent into the hole, the hole mouth pipe is connected with the three-way pipe, the three-way pipe is connected with the five-way pipe, the upper part of the three-way pipe and the five-way pipe is connected with the gas-water separation tank through the weak negative pressure pipe, the lower side of the five-way pipe is connected with the blowout preventer through the residue discharge pipe, the blowout preventer is connected with the controller through the strong negative pressure pipe, and the controller is connected with the negative pressure main pipeline through the weak negative pressure pipe; the gas-water separation tank is connected with the negative pressure main pipeline through the weak negative pressure pipe. Step 3, when normal directional drilling, the controller is in the closed state, the sounder is in the silent state, the strong negative pressure pipeline is in the no strong negative pressure state, the weak negative pressure pipe is in the open state, and the slag discharge device is normally opened; when jetting occurs, drilling is immediately stopped, the directional drilling tool is in a stationary state, the weak negative pressure pipe is still in the open state, the controller is in the open state, the sounder is in the sound state, the strong negative pressure pipeline is in the strong negative pressure state, the telescopic cylinder is in the extended state, and the slag discharge device is still normally opened; after jetting, the water in the water-gas separation tank is discharged in time.

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