Gas extraction directional drilling tool and drilling method

Abstract

The present invention discloses a gas extraction directional drilling tool, including a hollow drill rod and a drill bit, wherein the hollow drill rod is connected to a high-pressure gas circuit at the rear, and a pneumatic motor is connected to the front end of the hollow drill rod, and the output shaft of the pneumatic motor is connected to the drill bit at the front; more than three front air pressure caps are evenly arranged along the circumference at the hollow drill rod behind the pneumatic motor, and each front air pressure cap is respectively connected to the high-pressure gas circuit, and each front air pressure cap is respectively provided with a front solenoid valve for controlling the working state of the corresponding front air pressure cap at the connection between the front air pressure cap and the high-pressure gas circuit; the lifting direction of each front air pressure cap is perpendicular to the axis of the hollow drill rod; and the high-pressure gas circuit extends backward to the high-pressure gas source outside the borehole. The present invention also discloses a corresponding drilling method. The present invention realizes self-advancing drilling, lowering the pipe while drilling, and timely supporting the borehole, and there is no need to perform a separate operation of inserting a gas extraction pipe after drilling, so that the entire drilling process is safer, time-saving and efficient, reduces the difficulty of operation, and improves work efficiency.

Description

Technical Field

[0001] The invention relates to the technical field of coal mine gas extraction. Background Art

[0002] Coal mine gas disasters are the number one killer of coal mine safety production. Coal and gas outburst accidents, gas explosion accidents, gas combustion accidents, and gas asphyxiation accidents seriously threaten the lives and safety of coal miners and the property of coal mining enterprises. In particular, coal and gas outburst accidents and gas explosion accidents often cause heavy casualties, bring heavy property losses to coal mining enterprises, and cause extremely serious damage to mines. The nature is extremely bad and the social impact is extremely wide. Therefore, in order to ensure the safe and efficient production of coal mining enterprises, it is very important to control gas.

[0003] Although the prevention and control of gas disasters cannot be separated from a reliable ventilation system, it is precisely because ventilation cannot solve the gas problem or it is economically unreasonable to solve the gas problem with ventilation that we must use gas extraction to solve the gas problem. Through gas extraction, the gas content in the coal seam is reduced, and gas disasters are fundamentally controlled and prevented.

[0004] At the same time, coal mine gas (in a narrow sense, coal mine gas refers to methane) is a clean energy. If it is developed and utilized, it will be a considerable fortune. Therefore, through gas extraction, harm can be turned into treasure, the industrial chain of coal mining enterprises can be extended, and the society can be served.

[0005] At present, the drilling rigs used for coal mine gas extraction channels at home and abroad mainly have the following problems:

[0006] (I) The drill bit cannot perform directional drilling. The drill rod will experience disturbances of varying magnitudes under the action of gravity, and this disturbance becomes more pronounced as the hole depth increases. When encountering slightly more complex geological conditions, the borehole deflection becomes more obvious. In my country, the coal seam gas extraction drilling holes are designed to be arranged as straight holes, but the actual construction drilling holes are all deflected to a certain extent, resulting in the inability to evenly arrange the coal seam drilling holes. Some of the drilling holes are even too far apart, forming blank areas or blank zones for gas extraction, and failing to achieve the ideal extraction effect. It is impossible to reduce the gas content in the blank zone and eliminate the danger of gas outbursts, which can easily lead to gas disasters and accidents in coal mine production.

[0007] (ii) After drilling, the hole is easily collapsed and the gas extraction channel is blocked during the rod withdrawal process. The traditional method cannot provide timely support for the gas extraction channel during the entire drilling process.

[0008] At present, the practices at home and abroad are roughly the same, and they cannot solve these problems well. The common practice is to use a drilling rig to drill holes first, withdraw the rod after drilling the holes, and then lower the gas extraction pipe. This practice can be simply summarized as follows: if you can drill straight, you can't drill deep, and if you can drill deep, you can't drill straight.

[0009] (III) There is a lag in judging the location of the drill bit, that is, it is impossible to accurately understand the position and status of the drill rig in a timely manner. During the drilling process, when the drill rig drills very deep, the staff judges whether the drill rig hits foreign objects or other areas by observing the discharged drill cuttings. However, due to the long length of the channel, the drill rig may have passed through the area at this time, and it will not make much sense to issue instructions at this time. For this reason, research on drilling rigs that can achieve drill bit orientation, timely support drilling, smooth drilling and smooth slag discharge is in the ascendant. Solving these problems is of great significance, including ensuring construction according to design, effectively solving the technical bottleneck of borehole deviation, ensuring extraction effect, preventing gas disasters and accidents, and achieving safe production.

[0010] Traditional gas extraction methods cannot effectively solve the problems existing in the gas extraction drilling process, such as: the forward direction of the drill rig is not fixed during drilling, the gas extraction channel collapses during drilling or after drilling, and the traditional method of gas extraction faces problems such as difficult extraction, time-consuming and labor-intensive, low extraction quality, and low efficiency. Therefore, a new type of gas extraction drilling rig that can effectively solve current problems is of great significance to coal mine safety production. Summary of the invention

[0011] The purpose of the present invention is to provide a gas extraction directional drilling tool to address the defects of the prior art, which can pneumatically correct the drilling direction and reduce the probability of hole collapse.

[0012] In order to solve the above technical problems, the gas extraction directional drilling tool of the present invention comprises a hollow drill rod and a drill bit. With the drilling direction as the forward direction, the hollow drill rod is connected to a high-pressure gas circuit backward, and the front end of the hollow drill rod is connected to an air motor, and the output shaft of the air motor is connected to the drill bit forward;

[0013] More than three front air pressure tops are evenly arranged along the circumference of the hollow drill rod behind the pneumatic motor, and each front air pressure top is connected to the high-pressure gas circuit respectively. A front solenoid valve for controlling the working state of the corresponding front air pressure top is respectively arranged at the connection between each front air pressure top and the high-pressure gas circuit; the lifting direction of each front air pressure top is perpendicular to the axis of the hollow drill rod; the high-pressure gas circuit extends backward to the high-pressure gas source outside the drill hole.

[0014] The hollow drill rod is sleeved with a coaxial intermediate sleeve, and the inner wall of the intermediate sleeve is fixedly connected to the outer wall of the hollow drill rod through a connecting rod; the intermediate sleeve is located behind the pneumatic motor, and each front air pressure top is arranged on each intermediate sleeve along the circumferential direction of the intermediate sleeve and is connected to each intermediate sleeve; the front end of the intermediate sleeve is closed and the rear end is connected to a high-pressure inner tube for introducing high-pressure gas;

[0015] An outer sleeve with a coaxial line is arranged outside the middle sleeve, and the outer sleeve is located behind each front gas pressure top; a piston is arranged on the radial protrusion in the middle of the middle sleeve, and the piston is slidably and sealedly matched with the inner wall of the outer sleeve; a high-pressure outer tube is connected to the outer sleeve backward for introducing high-pressure gas; the rear end of the high-pressure inner tube is open, and the high-pressure inner tube is inserted backward into the high-pressure outer tube, and the outer diameter of the high-pressure inner tube is smaller than the inner diameter of the high-pressure outer tube, and the high-pressure inner tube and the high-pressure outer tube are slidably matched;

[0016] The front side wall of the outer sleeve is slidably sealed with the outer wall of the middle sleeve; an annular cavity is provided between the middle sleeve and the outer sleeve, the annular cavity in front of the piston is the front annular cavity, and the annular cavity behind the piston is the rear annular cavity; the front end of the outer sleeve is provided with a drill forward solenoid valve for releasing high-pressure gas into the borehole, and the drill forward solenoid valve is connected to the front annular cavity; the rear end of the outer sleeve is provided with an outer sleeve forward solenoid valve for releasing high-pressure gas into the borehole, and the outer sleeve forward solenoid valve is connected to the rear annular cavity; a through hole for connecting to the front annular cavity is provided on the middle sleeve at the rear end of the front annular cavity;

[0017] The high-pressure gas circuit includes a high-pressure outer tube, a high-pressure inner tube, an intermediate casing and a hollow drill rod; the high-pressure outer tube is connected to the high-pressure inner tube and the outer casing, and the high-pressure inner tube is connected to the intermediate casing;

[0018] The front end of the outer sleeve is evenly provided with more than three intermediate gas pressure tops along the circumferential direction, each intermediate gas pressure top is respectively connected with the outer sleeve, and the connection between each intermediate gas pressure top and the outer sleeve is respectively provided with an intermediate solenoid valve for controlling the working state of the corresponding intermediate gas pressure top, and the lifting direction of each intermediate gas pressure top is perpendicular to the axis of the outer sleeve;

[0019] The rear end of the outer sleeve is evenly provided with more than three rear air pressure tops along the circumferential direction, each rear air pressure top is connected to the outer sleeve respectively, and a rear solenoid valve for controlling the working state of the corresponding rear air pressure top is provided at the connection between each rear air pressure top and the outer sleeve respectively, and the lifting direction of each rear air pressure top is perpendicular to the axis of the outer sleeve.

[0020] The outer casing is connected to a screen pipe for supporting the borehole and extracting gas. The screen pipe extends backward to the outside of the borehole and is used to connect the gas extraction equipment.

[0021] An inclinometer is provided at the front end of the screen pipe. The connection lines of the inclinometer, each front solenoid valve, each middle solenoid valve, each rear solenoid valve, the drill bit forward solenoid valve and the outer casing forward solenoid valve are extended backward to the outside of the borehole through a high-pressure gas circuit and are connected to an electric control device arranged outside the borehole.

[0022] The present invention also discloses a drilling method using the gas extraction directional drilling tool. During drilling, the drill bit is driven to rotate by a pneumatic motor, including a steering operation. The steering operation is:

[0023] Four front air pressure caps are evenly arranged along the circumference of the hollow drill rod, namely, a front upper air pressure cap, a front lower air pressure cap, a front left air pressure cap and a front right air pressure cap;

[0024] When turning upward, the front lower air pressure top is started, when turning downward, the front upper air pressure top is started, when turning left, the front right air pressure top is started, and when turning right, the front left air pressure top is started; according to the actual steering direction, one or two air pressure tops in the opposite position to the actual steering direction are started.

[0025] It also includes the forward operation of the drill bit, the hollow drill rod and the intermediate casing, as well as the forward operation of the outer casing and the screen pipe; in the initial state, the drill bit forward solenoid valve and the outer casing forward solenoid valve are both in the closed state;

[0026] The advancement operation of the drill bit, hollow drill pipe and intermediate casing is:

[0027] First, the outer sleeve is fixed. The middle solenoid valves and the rear solenoid valves are opened to make the middle air pressure tops and the rear air pressure tops on the outer wall of the outer sleeve press against the hole wall of the drill hole, thereby fixing the outer sleeve in the drill hole.

[0028] The second is the forward operation, which makes the drill forward solenoid valve open and the outer casing forward solenoid valve closed. At this time, the drill forward solenoid valve releases pressure into the borehole, and the air pressure in the front annular cavity is lower than that in the rear annular cavity. Under the pressure difference between the rear annular cavity and the rear annular cavity, the piston drives the intermediate casing, hollow drill rod and drill bit forward.

[0029] After the drill bit moves forward, the middle solenoid valves and the rear solenoid valves are closed, thereby releasing the fixing of the outer casing; after the drill bit, the hollow drill rod and the intermediate casing move forward, the outer casing and the screen tube move forward;

[0030] The forward operation of the outer casing and screen is:

[0031] First, the intermediate casing is fixed. Each front solenoid valve is opened so that each front air pressure top on the outer wall of the intermediate casing is pressed against the hole wall of the drill hole, thereby fixing the intermediate casing in the drill hole.

[0032] The second is the forward operation, which makes the outer sleeve forward solenoid valve open and the drill bit forward solenoid valve closed. At this time, the outer sleeve forward solenoid valve releases pressure into the borehole, and the air pressure in the front annular cavity is higher than that in the rear annular cavity. Under the pressure difference between the rear annular cavity and the rear annular cavity, the outer sleeve moves forward.

[0033] After the outer sleeve moves forward, each front solenoid valve is closed, thereby releasing the fixation of the middle sleeve;

[0034] Finally, the drill bit forward solenoid valve and the outer casing forward solenoid valve are both closed to restore the initial state;

[0035] The advancing operations of the drill bit, the hollow drill pipe, the intermediate casing, and the outer casing and the screen are cyclically performed until the drilling operation is completed.

[0036] The opening of the borehole is located on the side wall of a lane; when there is a next lane ahead of the drilling, the borehole is extended to the next lane, and the drill bit and the drill rod are taken out from the next lane to complete the drilling;

[0037] When the front of the drilling is the end of the coal mining operation and there is no next tunnel, the gas extraction directional drilling tool is controlled to perform steering operations during the drilling process so that the borehole extends along an arc trajectory to another place on the side wall of the same tunnel. The drill bit and drill rod are taken out from the end opening of the borehole in the same tunnel to complete the drilling.

[0038] The present invention has the following advantages:

[0039] In the present invention, the high-pressure gas transmitted forward by the hollow drill rod is used as the power source, and the drill bit is driven to rotate by the pneumatic motor, so that the hollow drill rod does not need to be rotated during the drilling process, the vibration caused in the coal seam during the drilling process is reduced, and the probability of hole collapse is reduced.

[0040] When the drilling direction deviates from the predetermined direction, the present invention can control the opening and closing of each front solenoid valve to control each front air pressure top to be in a lifting state or a retracted state, thereby applying forces in different directions to the front of the hollow drill rod in a direction perpendicular to the axis of the hollow drill rod, thereby returning the front end of the hollow drill rod and the drill bit to the predetermined direction (or actively adjusting the direction of the hollow drill rod). In short, the present invention can adjust the direction of the drill bit by applying a force perpendicular to the axis of the hollow drill rod to the front of the hollow drill rod during the drilling process, correct the drilling direction during the drilling process, or actively adjust the drilling direction, so that the present invention has the function of directional drilling.

[0041] In the present invention, the drill rod does not need to extend backward beyond the borehole. The arrangement of the intermediate casing, the outer casing, the middle gas pressure top, the rear gas pressure top, the drill bit forward solenoid valve and the outer casing forward solenoid valve can enable the drill bit (and the hollow drill rod) and the outer casing to move forward alternately by selectively opening the drill bit forward solenoid valve or the outer casing forward solenoid valve. During the forward movement, the high-pressure gas is used as the forward driving force to stably advance the drilling work forward.

[0042] The screen is connected to the rear end of the outer casing. After the drill bit is pushed forward, the screen can immediately support the borehole and prevent the occurrence of hole collapse. After drilling, there is no need to insert a gas extraction pipe into the borehole. The gas released from the coal body around the borehole can be directly extracted through the screen, which not only prevents hole collapse, but also saves the separate insertion step, and has obvious promotion and application value.

[0043] The inclinometer can be used to understand the drilling trajectory and azimuth status in real time, so that necessary adjustments can be made to the drilling process in a timely manner.

[0044] The drilling method of the present invention flexibly and conveniently realizes the alternate advancement of the drill bit and the outer casing, and realizes the steering operation during the drilling process.

[0045] In short, the gas extraction directional drilling tool of the present invention realizes self-advancing drilling, lowers the pipe while drilling, and supports the borehole in time. There is no need to insert a separate gas extraction pipe after drilling, which makes the entire drilling process safer, time-saving and efficient, reduces the difficulty of operation, and improves work efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0046] Figure 1 It is a schematic diagram of the structure of the present invention before the drill bit, the hollow drill rod and the intermediate casing advance; at this time, the middle gas pressure top and the rear gas pressure top are lifted, and the drill bit is ready to advance;

[0047] Figure 2 It is the left side view of the drill bit;

[0048] Figure 3 yes Figure 1 A-A cross-sectional view;

[0049] Figure 4 yes Figure 1 The enlarged view of point A in the middle;

[0050] Figure 5 It is a schematic diagram of the structure of the present invention after the drill bit, the hollow drill rod and the intermediate casing have advanced; at this time, the front air pressure lifts the top, and the outer casing is ready to advance;

[0051] Figure 6 It is the electric control principle diagram of the present invention. DETAILED DESCRIPTION

[0052] like Figures 1 to 6 As shown, the gas extraction directional drilling tool of the present invention comprises a hollow drill rod 1 and a drill bit 2. With the drilling direction as the forward direction, the hollow drill rod 1 is connected to a high-pressure gas circuit backward, and the front end of the hollow drill rod 1 is connected to an air motor 3, and the output shaft of the air motor 3 is connected to the drill bit 2 forward;

[0053] At the hollow drill rod behind the pneumatic motor 3, more than three (preferably four) front air pressure tops 4 are evenly arranged along the circumferential direction, and each front air pressure top 4 is connected to a high-pressure gas circuit respectively. A front solenoid valve 5 for controlling the working state of the corresponding front air pressure top 4 is respectively arranged at the connection between each front air pressure top 4 and the high-pressure gas circuit; the lifting direction of each front air pressure top 4 is perpendicular to the axis of the hollow drill rod 1; the high-pressure gas circuit extends backward to a high-pressure gas source outside the drill hole.

[0054] The hollow drill rod 1 preferably adopts a telescopic drill rod, which is a prior art, and the specific structure is not described in detail. The solenoid valve is a conventional technology. Figure 1 and Figure 5 Not shown are the front solenoid valves 5 and the middle solenoid valves 6 and the rear solenoid valves 7 described later. The high-pressure gas source may be an air pump, an air compressor, a high-pressure gas tank or a high-pressure pipeline leading to the well, which is conventional technology and not shown in the figure.

[0055] The hollow drill rod 1 is sleeved with a coaxial intermediate sleeve 8, and the inner wall of the intermediate sleeve 8 is fixedly connected to the outer wall of the hollow drill rod 1 through a connecting rod; the connecting rod is conventional technology and is not shown in the figure. The intermediate sleeve 8 is located behind the pneumatic motor 3, and each front air pressure top 4 is arranged on each intermediate sleeve 8 along the circumferential direction of the intermediate sleeve 8 and is connected to each intermediate sleeve 8. Each front air pressure top 4 obtains high-pressure gas from the intermediate sleeve 8 as a power source through the front solenoid valve 5; the front end of the intermediate sleeve 8 is closed and the rear end is connected to a high-pressure inner tube 9 for passing high-pressure gas; each front air pressure top 4 is connected to the hollow drill rod 1 through the intermediate sleeve 8.

[0056] An outer sleeve 10 with a coaxial line is disposed outside the intermediate sleeve 8, and the outer sleeve 10 is located behind each front gas pressure top 4; a piston 11 is provided on a radial protrusion in the middle of the intermediate sleeve 8, and the piston 11 is slidably and sealedly matched with the inner wall of the outer sleeve 10; the outer sleeve 10 is connected to a high-pressure outer tube 12 for introducing high-pressure gas; the rear end of the high-pressure inner tube 9 is open, and the high-pressure inner tube 9 is inserted into the high-pressure outer tube 12 backward, and the outer diameter of the high-pressure inner tube 9 is smaller than the inner diameter of the high-pressure outer tube 12, so that there is a high-pressure gas passage leading to the outer sleeve between the two; the high-pressure inner tube 9 and the high-pressure outer tube 12 are slidably matched, which means that the high-pressure inner tube 9 can slide along the high-pressure outer tube 12, and does not mean that the outer wall of the high-pressure inner tube 9 and the high-pressure outer tube 12 are sealedly matched;

[0057] The front side wall of the outer sleeve 10 is slidably sealed with the outer wall of the middle sleeve 8; an annular cavity is provided between the middle sleeve 8 and the outer sleeve 10, the annular cavity in front of the piston 11 is the front annular cavity 13, and the annular cavity behind the piston 11 is the rear annular cavity 14; the front end of the outer sleeve 10 is provided with a drill forward solenoid valve 15 (preferably a normally open solenoid valve) for releasing high-pressure gas into the borehole, and the drill forward solenoid valve 15 is connected to the front annular cavity 13; the rear end of the outer sleeve 10 is provided with an outer sleeve forward solenoid valve 16 (preferably a normally closed solenoid valve) for releasing high-pressure gas into the borehole, and the outer sleeve forward solenoid valve 16 is connected to the rear annular cavity 14; a through hole for connecting to the front annular cavity 13 is provided on the middle sleeve 8 at the rear end of the front annular cavity 13;

[0058] The high-pressure gas circuit includes a high-pressure outer tube 12, a high-pressure inner tube 9, an intermediate casing 8 and a hollow drill rod 1; the high-pressure outer tube 12 is connected to the high-pressure inner tube 9 and the outer casing 10, the high-pressure inner tube 9 is connected to the intermediate casing 8, and the intermediate casing 8 is connected to the hollow drill rod 1 and each front gas pressure top 4;

[0059] The front end of the outer sleeve 10 is evenly provided with three or more (preferably four) intermediate gas pressure tops 17 along the circumferential direction, each intermediate gas pressure top 17 is respectively connected to the outer sleeve 10, and the connection between each intermediate gas pressure top 17 and the outer sleeve 10 is respectively provided with an intermediate solenoid valve 6 for controlling the working state of the corresponding intermediate gas pressure top 17, and the lifting direction of each intermediate gas pressure top 17 is perpendicular to the axis of the outer sleeve 10;

[0060] The rear end of the outer sleeve 10 is evenly provided with more than three (preferably four) rear air pressure tops 18 along the circumferential direction, and each rear air pressure top 18 is respectively connected to the outer sleeve 10. The connection between each rear air pressure top 18 and the outer sleeve 10 is respectively provided with a rear solenoid valve 7 for controlling the working state of the corresponding rear air pressure top 18. The lifting direction of each rear air pressure top 18 is perpendicular to the axis of the outer sleeve 10.

[0061] The outer casing 10 is connected to a screen pipe 19 for supporting the borehole and extracting gas. The screen pipe 19 extends backward to outside the borehole and is used to connect gas extraction equipment, such as a negative pressure fan and corresponding pipelines.

[0062] An inclinometer 20 is provided at the front end of the screen tube 19. The connection lines of the inclinometer 20, each front solenoid valve 5, each middle solenoid valve 6, each rear solenoid valve 7, the drill bit forward solenoid valve 15 and the outer casing forward solenoid valve 16 are all extended backward to the outside of the borehole through the high-pressure gas circuit and connected to the electric control device 21 arranged outside the borehole. The electric control device 21 is an integrated circuit or a single-chip microcomputer or a PC, and has an input device (such as a key), preferably connected to a display screen 22 and a keyboard 23.

[0063] The present invention also discloses a drilling method using the above-mentioned gas extraction directional drilling tool. During drilling, the drill bit 2 is driven to rotate by the pneumatic motor 3, including a steering operation. The steering operation is:

[0064] Four front air pressure caps 4 are evenly arranged along the circumference of the hollow drill rod 1, namely, a front upper air pressure cap, a front lower air pressure cap, a front left air pressure cap and a front right air pressure cap;

[0065] When turning upward, the lower front air pressure top is activated; when turning downward, the upper front air pressure top is activated; when turning left, the right front air pressure top is activated; when turning right, the left front air pressure top is activated; according to the actual steering direction, one or two air pressure tops in the opposite position to the actual steering direction are activated (for example, when turning to the upper left, the right front air pressure top and the lower front air pressure top are activated). The movement amplitude (pop-up amount) of the air pressure top is controlled to accurately control the steering direction.

[0066] It also includes the forward operation of the drill bit 2, the hollow drill rod 1 and the intermediate casing 8, as well as the forward operation of the outer casing 10 and the screen tube 19; in the initial state, the drill bit forward solenoid valve 15 and the outer casing forward solenoid valve 16 are both in the closed state;

[0067] The advancing operation of the drill bit 2, the hollow drill rod 1 and the intermediate casing 8 is:

[0068] First, the outer sleeve 10 is fixed, and each middle solenoid valve 6 and each rear solenoid valve 7 are opened, so that each middle air pressure top 17 and rear air pressure top 18 on the outer wall of the outer sleeve 10 are pressed against the hole wall of the drill hole, thereby fixing the outer sleeve 10 in the drill hole;

[0069] The second is the forward operation, which makes the drill forward solenoid valve 15 open, and the outer casing forward solenoid valve 16 closed. At this time, the drill forward solenoid valve 15 releases pressure into the borehole, and the air pressure in the front annular cavity 13 is lower than the air pressure in the rear annular cavity 14. Under the pressure difference between the rear annular cavity 14 and the rear annular cavity 14, the piston 11 drives the intermediate casing 8, the hollow drill rod 1 and the drill bit 2 to move forward;

[0070] After the drill bit 2 moves forward, the middle solenoid valves 6 and the rear solenoid valves 7 are closed, thereby releasing the fixing of the outer casing 10; after the drill bit 2, the hollow drill rod 1 and the intermediate casing 8 move forward, the outer casing 10 and the screen tube 19 move forward;

[0071] The forward operation of the outer casing 10 and the screen tube 19 is:

[0072] First, the intermediate sleeve 8 is fixed, and each front solenoid valve 5 is opened, so that each front air pressure top 4 on the outer wall of the intermediate sleeve 8 is pressed against the hole wall of the drill hole, thereby fixing the intermediate sleeve 8 in the drill hole;

[0073] The second is the forward operation, which makes the outer sleeve forward solenoid valve 16 open, and the drill bit forward solenoid valve 15 closed. At this time, the outer sleeve forward solenoid valve 16 releases pressure into the borehole, and the air pressure in the front annular cavity 13 is higher than the air pressure in the rear annular cavity 14. Under the pressure difference between the rear annular cavity 14 and the rear annular cavity 14, the outer sleeve 10 moves forward;

[0074] After the outer sleeve 10 moves forward, each front solenoid valve 5 is closed, thereby releasing the fixation of the middle sleeve 8;

[0075] Finally, the drill forward solenoid valve 15 and the outer casing forward solenoid valve 16 are both closed to restore the initial state;

[0076] The advancing operation of the drill bit 2, the hollow drill rod 1, the intermediate casing 8, and the advancing operation of the outer casing 10 and the screen tube 19 are cyclically performed until the drilling operation is completely completed.

[0077] The opening of the borehole is located on the side wall of a lane; when there is a next lane ahead of the drilling, the borehole is extended to the next lane, and the drill bit 2 and the drill rod are taken out from the opening of the borehole at the next lane to complete the drilling;

[0078] When the front of the drilling is the end of the coal mining operation and there is no next tunnel, the gas extraction directional drilling tool is controlled to perform steering operations during the drilling process so that the borehole extends along an arc trajectory to another part of the side wall of the same tunnel, and the drill bit 2 and the drill rod are taken out from the end opening of the borehole in the same tunnel to complete the drilling.

[0079] After drilling, the screen pipe 19 is left in the borehole, which not only supports the borehole but also can be directly used as a gas extraction pipe to extract gas from the borehole.

[0080] The above embodiments are only used to illustrate rather than limit the technical solutions of the present invention. Although the present invention is described in detail with reference to the above embodiments, those skilled in the art should understand that the present invention can still be modified or replaced by equivalents. Any modification or partial replacement that does not depart from the spirit and scope of the present invention should be included in the scope of the claims of the present invention.

Claims

1. Gas extraction directional drilling tools, including hollow drill rods and drill bits, with the drilling direction as the forward direction, are characterized by: The hollow drill rod adopts a retractable drill rod, the hollow drill rod is connected to a high-pressure air circuit at the rear, the front end of the hollow drill rod is connected to an air motor, and the output shaft of the air motor is connected to the drill bit at the front; At the hollow drill rod behind the pneumatic motor, more than three front air pressure caps are evenly arranged along the circumference, and each front air pressure cap is connected to a high-pressure gas circuit respectively. A front solenoid valve for controlling the working state of the corresponding front air pressure cap is arranged at the connection between each front air pressure cap and the high-pressure gas circuit respectively; the lifting direction of each front air pressure cap is perpendicular to the axis of the hollow drill rod; the high-pressure gas circuit extends backward to a high-pressure gas source outside the borehole; The hollow drill rod is sleeved with a coaxial intermediate sleeve, and the inner wall of the intermediate sleeve is fixedly connected to the outer wall of the hollow drill rod through a connecting rod; the intermediate sleeve is located behind the pneumatic motor, and each front air pressure top is arranged on each intermediate sleeve along the circumferential direction of the intermediate sleeve and is connected to each intermediate sleeve; the front end of the intermediate sleeve is closed and the rear end is connected to a high-pressure inner tube for introducing high-pressure gas; An outer sleeve with a coaxial line is arranged outside the middle sleeve, and the outer sleeve is located behind each front gas pressure top; a piston is arranged on the radial protrusion in the middle of the middle sleeve, and the piston is slidably and sealedly matched with the inner wall of the outer sleeve; a high-pressure outer tube is connected to the outer sleeve backward for introducing high-pressure gas; the rear end of the high-pressure inner tube is open, and the high-pressure inner tube is inserted backward into the high-pressure outer tube, and the outer diameter of the high-pressure inner tube is smaller than the inner diameter of the high-pressure outer tube, and the high-pressure inner tube and the high-pressure outer tube are slidably matched; The front side wall of the outer sleeve is slidably sealed with the outer wall of the middle sleeve; an annular cavity is provided between the middle sleeve and the outer sleeve, the annular cavity in front of the piston is the front annular cavity, and the annular cavity behind the piston is the rear annular cavity; the front end of the outer sleeve is provided with a drill forward solenoid valve for releasing high-pressure gas into the borehole, and the drill forward solenoid valve is connected to the front annular cavity; the rear end of the outer sleeve is provided with an outer sleeve forward solenoid valve for releasing high-pressure gas into the borehole, and the outer sleeve forward solenoid valve is connected to the rear annular cavity; a through hole for connecting to the front annular cavity is provided on the middle sleeve at the rear end of the front annular cavity; The high-pressure gas circuit includes a high-pressure outer tube, a high-pressure inner tube, an intermediate casing and a hollow drill rod; the high-pressure outer tube is connected to the high-pressure inner tube and the outer casing, and the high-pressure inner tube is connected to the intermediate casing; The front end of the outer sleeve is evenly provided with more than three intermediate gas pressure tops along the circumferential direction, each intermediate gas pressure top is respectively connected with the outer sleeve, and the connection between each intermediate gas pressure top and the outer sleeve is respectively provided with an intermediate solenoid valve for controlling the working state of the corresponding intermediate gas pressure top, and the lifting direction of each intermediate gas pressure top is perpendicular to the axis of the outer sleeve; The rear end of the outer sleeve is evenly provided with more than three rear air pressure tops along the circumferential direction, each rear air pressure top is connected to the outer sleeve respectively, and a rear solenoid valve for controlling the working state of the corresponding rear air pressure top is provided at the connection between each rear air pressure top and the outer sleeve respectively, and the lifting direction of each rear air pressure top is perpendicular to the axis of the outer sleeve.

2. The gas extraction directional drilling tool according to claim 1, characterized in that: The outer casing is connected to a screen pipe for supporting the borehole and extracting gas. The screen pipe extends backward to the outside of the borehole and is used to connect the gas extraction equipment.

3. The gas extraction directional drilling tool according to claim 2, characterized in that: An inclinometer is provided at the front end of the screen pipe. The connection lines of the inclinometer, each front solenoid valve, each middle solenoid valve, each rear solenoid valve, the drill bit forward solenoid valve and the outer casing forward solenoid valve are extended backward to the outside of the borehole through a high-pressure gas circuit and are connected to an electric control device arranged outside the borehole.

4. A drilling method using the gas extraction directional drilling tool as claimed in claim 3, characterized in that: During drilling, the drill bit is driven by a pneumatic motor to rotate, including steering operations. The steering operation is: Four front air pressure caps are evenly arranged along the circumference of the hollow drill rod, namely, a front upper air pressure cap, a front lower air pressure cap, a front left air pressure cap and a front right air pressure cap; When turning upward, the front lower air pressure top is started, when turning downward, the front upper air pressure top is started, when turning left, the front right air pressure top is started, and when turning right, the front left air pressure top is started; according to the actual steering direction, one or two air pressure tops in the opposite position to the actual steering direction are started.

5. The drilling method according to claim 4, characterized in that: It also includes the forward operation of the drill bit, the hollow drill rod and the intermediate casing, as well as the forward operation of the outer casing and the screen pipe; in the initial state, the drill bit forward solenoid valve and the outer casing forward solenoid valve are both in the closed state; The advancement operation of the drill bit, hollow drill pipe and intermediate casing is: First, the outer sleeve is fixed. The middle solenoid valves and the rear solenoid valves are opened to make the middle air pressure tops and the rear air pressure tops on the outer wall of the outer sleeve press against the hole wall of the drill hole, thereby fixing the outer sleeve in the drill hole. The second is the forward operation, which makes the drill forward solenoid valve open and the outer casing forward solenoid valve closed. At this time, the drill forward solenoid valve releases pressure into the borehole, and the air pressure in the front annular cavity is lower than that in the rear annular cavity. Under the pressure difference between the rear annular cavity and the rear annular cavity, the piston drives the intermediate casing, hollow drill rod and drill bit forward. After the drill bit moves forward, the middle solenoid valves and the rear solenoid valves are closed, thereby releasing the fixing of the outer casing; after the drill bit, the hollow drill rod and the intermediate casing move forward, the outer casing and the screen tube move forward; The forward operation of the outer casing and screen is: First, the intermediate casing is fixed. Each front solenoid valve is opened so that each front air pressure top on the outer wall of the intermediate casing is pressed against the hole wall of the drill hole, thereby fixing the intermediate casing in the drill hole. The second is the forward operation, which makes the outer sleeve forward solenoid valve open and the drill bit forward solenoid valve closed. At this time, the outer sleeve forward solenoid valve releases pressure into the borehole, and the air pressure in the front annular cavity is higher than that in the rear annular cavity. Under the pressure difference between the rear annular cavity and the rear annular cavity, the outer sleeve moves forward. After the outer sleeve moves forward, each front solenoid valve is closed, thereby releasing the fixation of the middle sleeve; Finally, the drill bit forward solenoid valve and the outer casing forward solenoid valve are both closed to restore the initial state; The advancing operations of the drill bit, the hollow drill pipe, the intermediate casing, and the outer casing and the screen are cyclically performed until the drilling operation is completed.

6. The drilling method according to claim 5, characterized in that: The opening of the borehole is located on the side wall of a lane; when there is a next lane ahead of the drilling, the borehole is extended to the next lane, and the drill bit and the drill rod are taken out from the next lane to complete the drilling; When the front of the drilling is the end of the coal mining operation and there is no next tunnel, the gas extraction directional drilling tool is controlled to perform steering operations during the drilling process so that the borehole extends along an arc trajectory to another place on the side wall of the same tunnel. The drill bit and drill rod are taken out from the end opening of the borehole in the same tunnel to complete the drilling.

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