Internal deslagging drilling equipment and method for drilling and extracting gas by using internal deslagging drilling equipment

Abstract

The invention discloses the technical field of drilling equipment, and particularly relates to internal deslagging drilling equipment which comprises a drilling machine, a flexible drilling rod and the like. The output end of the drilling machine is connected with a brake which is connected with a flexible drill rod, the far end of the flexible drill rod is connected with a directional corrector which is connected with a hole bottom motor, and the hole bottom motor is connected with a drill bit. The flexible drill rod comprises an outer-layer drill rod, and the outer-layer drill rod is provided with an outer-layer connecting male buckle, an outer-layer connecting female buckle, a plurality of connecting rod assemblies and a connecting ring. Each connecting rod assembly comprises a plurality of connecting rods distributed along the circumference, every two adjacent connecting rods are movably connected to the connecting ring, and the connecting rod at the outermost end is fixedly connected to the outer-layer connecting male buckle and the outer-layer connecting female buckle. And the outer walls and the inner walls of the connecting rod assembly and the connecting ring are coated with wear-resistant elastic bodies. Supporting frames are fixedly connected in the outer-layer connecting male buckle and the outer-layer connecting female buckle, gaps are reserved, the supporting frames are fixedly connected with the inner-layer connecting male buckle and the inner-layer connecting female buckle respectively, and a deformable inner-layer drill rod is connected between the inner-layer connecting male buckle and the inner-layer connecting female buckle to form an inner-layer closed channel. According to the drilling equipment, the problem of gas control in the drilling process can be effectively solved.

Description

Technical Field

[0001] The present invention belongs to the technical field of drilling equipment, and particularly relates to an inner slag discharge drilling equipment and a method for drilling and gas drainage thereof. Background Art

[0002] Coal seams under complex geological conditions such as steeply inclined coal seams, loose coal seams of roof and floor, and high-gas mines mostly have characteristics such as high gas content, soft coal quality, and low gas permeability. Serious problems such as hole spraying, hole collapse, and drill sticking often occur during the gas control construction process, resulting in a low hole formation rate and great difficulty in drilling construction. In addition, the in-situ discharge of drill cuttings during drilling operations increases the labor intensity of workers, and the high adsorption of coal seam gas and poor compact permeability of the formation limit the gas drainage rate, which has a significant impact on the effective utilization of gas and the safe and efficient mining of subsequent coal.

[0003] In response to this situation, flexible drill pipes or rigid double-channel drill pipes are generally used to solve the problem at present. For example, patents such as the published numbers "CN114412369A", "CN108104737A", and the authorized announcement number "CN217538604U" disclose double-channel drill pipes. These drill pipes use double-channel inner slag-discharging drill pipes to isolate gas from the medium, keep the borehole unexposed, and use sandwich or reverse circulation systems to avoid geological disasters. However, all of the above drill pipes are rigid. When used for borehole drilling and external gas drainage in coal seams under complex conditions such as soft coal seams, multi-fault seams, coal-gangue cementation, steeply inclined coal seams, and high-gas mines, the following problems exist: 1. In soft coal seams, rigid drill pipes lack flexibility and are difficult to follow the soft deformation of the coal seam, which easily leads to further fragmentation of the coal body around the borehole, not only increasing the risk of borehole collapse, but also expanding the damaged range of the coal body structure during the drilling process, affecting the stability and integrity of the borehole. 2. For multi-fault coal seams, the geological structure at the fault is complex and stress is concentrated. When the rigid drill pipe crosses the fault, due to its inability to flexibly adapt to the angular changes and geological differences at the fault, sticking of the drill pipe often occurs, and in severe cases, the drill pipe may even break. 3. In coal seams with coal-gangue cementation, the rigid drill pipe has limited ability to break and drill through the cementation, making it difficult to effectively penetrate the hard cementation layer, resulting in low drilling efficiency, and the cementation is easy to accumulate around the drill pipe, affecting the normal operation of the inner slag-discharging system. 4. In steeply inclined coal seams, under the combined action of gravity and the inclination angle of the coal seam, it is difficult to accurately control the borehole trajectory of the rigid drill pipe, and borehole deviation is likely to occur, making it impossible to accurately reach the target position according to the design requirements, thus affecting the gas drainage effect. 5. Since it is difficult to ensure the quality and stability of the borehole with rigid drill pipes under complex geological conditions, the effective contact area between the borehole and the coal seam gas occurrence area is reduced, lowering the gas drainage range. 6. The vibration and impact generated by the rigid drill pipe during construction will cause an increase in the desorption amount of coal seam gas. However, due to problems such as fragmentation and collapse of the coal body around the borehole, some of the desorbed gas cannot be effectively discharged through the drill pipe, but accumulates around the borehole, increasing the safety hazard of gas overrun and being unfavorable for the safe management of gas and subsequent coal mining operations.

[0004] The current flexible drill pipe generally includes two drill pipe joints and multiple drill pipe short sections connected end to end. The free ends of the two outermost drill pipe short sections are respectively fixedly connected to the two drill pipe joints. Compared with the rigid drill pipe, the flexible drill pipe can better adapt to complex geological conditions and borehole trajectory requirements during drilling. It can achieve directional drilling through a smaller bending radius, reduce the occurrence of accidents such as drill sticking and drill breaking, and improve the success rate and efficiency of borehole drilling. However, the existing flexible drill pipes generally have the following problems: 1. After the borehole is completed, it is necessary to remove the flexible drill pipe and seal the borehole mouth before gas collection can be carried out. This makes it impossible to collect gas during the borehole drilling and drill pipe removal process, consuming a large amount of time. 2. When drilling in soft coal seams, factors such as ground stress and coal body structure make the coal body around the borehole prone to fragmentation. The drilling process of the flexible drill pipe disturbs the borehole wall, destroys the original stress balance of the borehole wall, reduces the stability of the borehole wall, and causes the inner wall of the slag discharge channel (i.e., the borehole wall) to easily collapse, blocking the slag discharge channel and affecting the slag discharge effect. 3. Inside the borehole, affected by factors such as coal seam stress and its own bending, the contact state between the flexible drill pipe and the borehole wall is constantly changing, and the gap between the two is of different sizes. A smaller gap hinders the discharge of slag powder, while a larger gap slows down the slag discharge speed and is also prone to the accumulation of slag powder in the borehole. 4. For the commonly used air or hydraulic slag discharge methods, when discharging slag on the surface of the flexible drill pipe, due to the irregular annular space between the drill pipe and the borehole wall, the fluid flow resistance is large, and it is difficult to form a stable and efficient slag discharge flow field. As the borehole depth increases, the fluid pressure loss is large, and the pressure and flow rate may not be able to effectively discharge the slag powder when reaching the bottom of the borehole. 5. The particle size of the slag powder is uneven and may contain more viscous substances, which are prone to form local blockages in parts such as the spiral grooves and grooved sections of the drill pipe. Once a local blockage is formed, the effective cross-sectional area of the slag discharge channel decreases, affecting the overall slag discharge efficiency and even possibly causing the pressure in the borehole to increase.

[0005] Therefore, designing a new type of drilling equipment suitable for coal seams under complex conditions such as soft coal seams, multiple faults, coal-gangue cementation, steeply inclined coal seams, and high-gas mines has positive significance for effectively solving the gas control problem. Summary of the Invention

[0006] The present invention aims to provide an internal slag discharge drilling equipment to solve the technical problems mentioned in the above background art.

[0007] An inner slag-discharging drilling device in this solution includes a drilling rig and a flexible drill pipe. A brake is connected to the output end of the drilling rig, the brake is connected to the flexible drill pipe, a directional corrector is connected to the end of the flexible drill pipe away from the drilling rig, a downhole motor is connected to the directional corrector, and a drill bit is connected to the downhole motor; the flexible drill pipe includes an outer drill pipe, the outer drill pipe includes an outer connecting male thread, an outer connecting female thread, and a movable skeleton movably connected between the two. The axis direction of the movable skeleton is penetrated, and both the outer wall and the inner wall of the movable skeleton are coated with a first sealing layer that is wear-resistant, pressure-resistant, corrosion-resistant and has toughness; the axis directions of the outer connecting male thread and the outer connecting female thread are penetrated and both are fixedly connected with a support frame inside. There is a gap between the support frame and the outer connecting male thread and the outer connecting female thread respectively; an inner connecting male thread and an inner connecting female thread are respectively fixedly connected to the two support frames, and the same deformable inner drill pipe is fixedly connected between the inner connecting female thread and the inner connecting male thread. An inner closed channel with a penetrated axis direction is formed among the inner connecting female thread, the inner connecting male thread and the inner drill pipe; an outer closed channel with a penetrated axis direction is formed among the outer connecting male thread, the outer connecting female thread and the inner first sealing layer; the inner connecting female thread is connected with a high-pressure water and air device, and the directional corrector is connected with the inner connecting male thread.

[0008] The working principle of this solution:

[0009] When drilling operations are carried out, the flexible drill pipe can perform normal circulation and reverse circulation drilling operations through the high-pressure water and air device.

[0010] During normal circulation operation, the high-pressure water and air device pumps the drilling medium (such as high-pressure water, mud, high-pressure liquid fireproof foam / high-pressure gas) into the inner closed channel of the flexible drill pipe. The drilling medium drives the downhole motor to work, enters the bottom of the hole through the drill bit, and returns to the hole mouth through the annulus of the outer closed channel after carrying the drill cuttings, forming a positive cycle of "inward into the hole and outward out of the hole".

[0011] During reverse circulation operation, the high-pressure water and air device pumps the drilling medium (such as high-pressure water, mud, high-pressure liquid fireproof foam / high-pressure gas) into the outer closed channel of the flexible drill pipe. The drilling medium drives the downhole motor to work, enters the bottom of the hole through the drill bit, and returns to the hole mouth through the inner closed channel of the flexible drill pipe after carrying the drill cuttings, forming a reverse cycle of "outward into the hole and inward out of the hole".

[0012] The beneficial effects of this solution: 1. The overall design of the flexible drill pipe, especially the flexible structure of the outer drill pipe and the buffering effect of the first sealing layer, reduces the disturbance to the hole wall during the drilling process. Compared with rigid drill pipes, in soft coal seams, it can better adapt to the soft deformation of the coal seam, reduce the risk of further fragmentation of the coal body around the hole, improve the stability of the hole wall, and reduce the occurrence of hole collapse phenomena.

[0013] 2. During the positive cycle, the outer closed channel (i.e., the annulus between the outer drill pipe and the inner drill pipe) is relatively regular, reducing the resistance of fluid flow. Compared with traditional flexible drill pipes, it is easier to form a stable and efficient slag discharge flow field. Even when the drilling depth increases, due to the improved stability of the flow field, the fluid pressure loss is controlled to a certain extent, ensuring that there is still sufficient pressure and flow rate when reaching the bottom of the hole to effectively discharge the slag powder.

[0014] 3. Under complex geological conditions such as steeply inclined coal seams, the flexible drill pipe can more flexibly adjust the drilling trajectory under the combined action of gravity and the inclination angle of the coal seam. Combining with the precise correction function of the directional corrector, it can effectively avoid drilling deviation, enabling the drill hole to accurately reach the target position according to the design requirements and improving the gas drainage effect.

[0015] 4. During the reverse cycle, since the aperture of the inner closed channel remains unchanged, stable slag discharge can be ensured, guaranteeing the quality and stability of the drill hole, enabling the drill hole to maintain good contact with the coal seam gas occurrence area, increasing the effective contact area, and expanding the gas drainage range. At the same time, it reduces the gas accumulation caused by the fragmentation and caving of the coal body around the drill hole, reduces the safety hazard of gas overrun, and is conducive to the safe management of gas and subsequent coal mining operations.

[0016] 5. For multi-fault coal seams, the flexible drill pipe can flexibly adapt to the angle changes and geological differences at the fault, reducing the occurrence of sticking and drill pipe breakage accidents; in coal-gangue cemented coal seams, relying on its flexibility and high-pressure gas-assisted slag discharge, it can more effectively penetrate the hard cemented layer, improve the drilling efficiency, and ensure the normal operation of the inner slag discharge system.

[0017] Furthermore, the outer wall of the movable skeleton is fixedly sleeved with an outer steel wire mesh tube, and the outer first sealing layer covers the outer wall of the outer steel wire mesh tube. The outer steel wire mesh tube enhances the overall structural strength of the outer drill pipe, making it not easily deformed or damaged under external forces in complex geological conditions. The first sealing layer covers the outer wall of the outer steel wire mesh tube. On the one hand, it can protect the outer steel wire mesh tube from abrasion, and on the other hand, using its toughness characteristics, it can better adapt to deformation when the flexible drill pipe bends, maintaining the stability of the slag discharge channel. At the same time, the outer steel wire mesh tube forms an overall constraint on the movable skeleton, preventing the structure from collapsing when a local overload fracture occurs.

[0018] Furthermore, the inner drill pipe includes an inner steel wire mesh pipe and a second sealing layer covering the inner and outer surfaces of the inner steel wire mesh pipe and having toughness, wear resistance, pressure resistance, and corrosion resistance. The inner steel wire mesh pipe provides a certain structural strength, enabling the inner drill pipe to maintain its shape when subjected to external forces, not being easily flattened or overly deformed, and ensuring the normal use of the inner closed channel. The second sealing layer not only enhances the wear resistance of the inner drill pipe, reducing the wear on the inner wall of the inner drill pipe during the transportation of high-pressure liquid fire foam and gas, but also, due to its toughness, can adapt to the bending deformation of the flexible drill pipe during the drilling process, avoiding damage caused by stress concentration due to a rigid structure, and improving the service life of the inner drill pipe.

[0019] Furthermore, the first sealing layer and / or the second sealing layer is a rubber layer, a special plastic layer, or a thermoplastic elastomer layer. The rubber layer, special plastic layer, or thermoplastic elastomer layer all have good toughness, wear resistance, pressure resistance, and corrosion resistance.

[0020] Furthermore, both the first sealing layer and the second sealing layer are rubber layers. The first sealing layer is fixedly bonded to the outer steel wire mesh pipe and the movable skeleton by vulcanization; the second sealing layer is fixedly connected to the inner steel wire mesh pipe by vulcanization bonding. Through the vulcanization bonding fixation method, the gaps between the outer steel wire mesh pipe and the movable skeleton are filled and cured with fluid rubber, greatly improving the sealing performance, connection strength, structural stability, wear resistance, and corrosion resistance of the outer drill pipe; and the elasticity of the rubber layer enables the entire structure to adapt to a certain degree of deformation and displacement. When affected by external factors such as vibration, impact, or temperature change, the rubber layer can play a buffering and shock-absorbing role, and at the same time, the firmness of the vulcanization bonding ensures that the components do not undergo relative sliding or detachment during the deformation process, so that the structure can work normally under complex and variable working conditions. The vulcanization process enables the molecular-level combination of the steel wire mesh and the rubber, eliminating the weak interface points of traditional glue bonding. The inner steel wire mesh is embedded in the rubber layer to form a "reinforced concrete"-type structure. When the flexible drill pipe bends, the interface stress is evenly dispersed, avoiding delamination and cracking, and is particularly suitable for frequent bending working conditions.

[0021] Furthermore, on the inner wall of the second sealing layer of the inner layer, there are spiral blades made of rubber material with toughness, wear resistance, pressure resistance, and corrosion resistance. The spiral blades are integrally formed on the second sealing layer by vulcanization bonding fixation. The spiral blades generate a swirling effect when transporting drill cuttings, causing the fluid to advance along the axial direction of the flexible drill pipe rather than being driven solely by pressure. This active transportation method can reduce the fluid pressure loss, especially suitable for long-distance drilling. At the same time, the rotational flow energy can prevent slag powder from depositing on the inner wall of the flexible drill pipe, avoiding blockage of the inner channel. When the reverse circulation slag discharge is blocked or the drill pipe is stuck, the drilling rig drives the flexible drill pipe to rotate, and the spiral blades can clear the slag and prevent the drill pipe from getting stuck.

[0022] Furthermore, spiral grooves are provided on the outer wall of the outer first sealing layer. The spiral grooves can change the fluid flow state between the outer drill pipe and the hole wall, enabling the gas carrying drill cuttings during the slag discharge process to form a more orderly spiral flow under the guidance of the spiral grooves, enhancing the slag discharge capacity. At the same time, the spiral grooves can also increase the friction force between the outer drill pipe and the hole wall to a certain extent, making the flexible drill pipe less likely to undergo relative sliding due to the action of coal seam stress, etc. during the drilling process, and improving the stability of the flexible drill pipe in the borehole. When the slag discharge is blocked or the drill pipe is stuck, the drilling rig drives the flexible drill pipe to rotate, and the slag is discharged smoothly and the drill pipe is prevented from being stuck through the spiral grooves.

[0023] Furthermore, the movable framework includes multiple groups of connecting rod assemblies and connecting rings located between adjacent connecting rod assemblies. Each group of connecting rod assemblies includes multiple connecting rods. The multiple connecting rods in the same group are distributed circumferentially. The connecting rods of adjacent two groups of connecting rod assemblies are movably connected through the connecting rings. The ends of the outermost connecting rods away from the connecting rings are respectively movably connected to the outer connecting male joint and the outer connecting female joint. The movable framework is composed of multiple groups of connecting rod assemblies and multiple connecting rings. During the drilling process, when a certain connecting rod is impacted and broken, the wire mesh can temporarily bear the load and maintain the shape of the slag discharge channel until the current drilling cycle is completed, significantly improving the fault tolerance rate of the flexible drill pipe.

[0024] Furthermore, through holes penetrating in the thickness direction are provided at both ends of the connecting rod. The through holes at both ends of the multiple connecting rods in the same group are respectively strung together by a fixing rope. The head and tail ends of the fixing rope are fixedly connected; multiple connecting blocks are circumferentially distributed on both sides of the connecting ring. The end of the connecting rod is located between adjacent connecting blocks, and the fixing rope is connected in series between the multiple connecting rods and the connecting blocks in the same circumferential direction. Using the fixing rope to connect the connecting rods in series allows a deflection angle of 0° to 30° between adjacent connecting rings and maintains the circumferential stiffness through the rope tension. Compared with a pure hinge structure, this design can provide the necessary anti-torsion stiffness during vertical drilling to prevent the flexible drill pipe from spinning out of control in the borehole.

[0025] Furthermore, the number of connecting blocks on the same side of the connecting ring is not less than the number of connecting rods in the same group. Through grooves and / or connection holes are provided on the connecting blocks on both sides of the connecting ring; the fixing rope is connected in the through grooves and / or through holes of the corresponding connecting blocks, and the connecting rod is located between adjacent connecting blocks on the connecting ring. Through the setting of the through grooves and / or connection holes, the connection between the connecting rod and the connecting ring is realized in cooperation with the fixing rope, and the operation is simple.

[0026] Furthermore, both the outer connecting male buckle and the outer connecting female buckle have necked - in portions on the outer walls of their opposite ends, and there are also a plurality of connecting blocks distributed along the circumference at the ends. The number of connecting blocks is not less than the number of connecting rods in the same group, and the connecting blocks are also provided with through - grooves and / or connecting holes; the fixing ropes on the connecting rod assemblies at both ends are connected in the through - grooves and / or through - holes of the corresponding connecting blocks, and the connecting rods are located between adjacent connecting blocks on the connecting ring; both ends of the outer steel wire mesh tube are respectively sleeved at the necked - in portions on the outer walls of the outer connecting male buckle and the outer connecting female buckle, and the first sealing layer on the outer layer is fixed on the outer walls of the outer connecting male buckle and the outer connecting female buckle. The necked - in design on the outer connecting male buckle and the outer connecting female buckle facilitates the installation and fixation of the outer steel wire mesh tube, enabling it to fit tightly with the outer connecting male buckle and the outer connecting female buckle, enhancing the stability of the overall structure. The setting of the connecting blocks, through - grooves, and connecting holes, in cooperation with the fixing ropes on the connecting rod assembly, realizes the flexible connection between the outer drill pipe and the outer connecting male buckle and the outer connecting female buckle, enabling the flexible drill pipe to flexibly adapt to different drilling trajectories during the drilling process. At the same time, the first sealing layer is fixed on the outer walls of the outer connecting male buckle and the outer connecting female buckle, further protecting the connection part and improving the wear resistance and sealing performance of the connection part.

[0027] Furthermore, the notch directions of the through - grooves on the connecting blocks on both sides of the connecting ring respectively face the inside and outside of the connecting block, or the notch directions of the through - grooves on multiple connecting blocks on the same side alternately face the inside and outside of the connecting block. This distribution of the through - grooves makes the connection positions of the fixing ropes on the connecting blocks more flexible and diverse. When the flexible drill pipe undergoes bending deformation, the fixing ropes at different positions can better cooperate with each other to adapt to the deformation requirements of the flexible drill pipe, avoiding damage to the connection part due to uneven stress on the fixing ropes. At the same time, this design increases the redundancy of the connection structure and improves the reliability and stability of the outer drill pipe under complex working conditions.

[0028] Furthermore, there is also a necked - in portion inside the end of the outer connecting female buckle far from the outer connecting male buckle. There is a retaining ring at this necked - in portion, and a plurality of grooves are evenly distributed on the retaining ring. There are a plurality of stepped grooves on the outer wall of the outer connecting female buckle that cooperate with the grooves, and wedge blocks are provided in the stepped grooves and extend into the corresponding grooves. The cooperation between the retaining ring and the wedge blocks at the necked - in portion plays a role in locking and sealing.

[0029] Furthermore, friction pads are sleeved on both the inner connecting male buckle and the inner connecting female buckle, and the friction pads are located at the connection between the inner connecting male buckle, the inner connecting female buckle and the support frame. The friction pads can increase the friction force between the inner connecting male buckle, the inner connecting female buckle and the support frame, preventing the inner drill pipe from undergoing relative displacement due to vibration or force during operation. At the same time, the friction pads can also play a buffering role, reducing the impact force transmitted from the inner drill pipe to the support frame, protecting the connection part between the support frame and the inner drill pipe, extending the service life of the connection components, and ensuring the stability and reliability of the inner closed channel.

[0030] Furthermore, a pulse generator is connected between the downhole motor and the drill bit. The pulse generator can generate periodic pulse impact forces during the drilling process. When the downhole motor drives the drill bit to drill, the pulse generator transmits additional impact forces to the drill bit according to the set frequency and intensity. The combination of such pulse impact forces and the rotary cutting force of the drill bit itself can more effectively break coal and rock.

[0031] Furthermore, the drill rig includes a driving motor and a reduction gearbox. The driving motor is connected to the input gear of the reduction gearbox, and the brake is connected to the output gear of the reduction gearbox. The driving motor provides the original power, and the high-speed rotational power output by it is decelerated and torque-increased through the reduction gearbox. The reduction gearbox reduces the rotational speed of the driving motor to a suitable range according to different requirements and increases the torque to drive the flexible drill pipe to rotate to solve the problems of chip blockage and sticking of the flexible drill pipe.

[0032] Furthermore, a gripper is connected to the flexible hose. The gripper is installed on the flexible drill pipe at one end close to the drill rig. It can fix and support the flexible drill pipe according to the drilling depth and actual needs. The gripper can automatically adjust the clamping force according to the stress condition of the flexible drill pipe during the drilling process to ensure that the flexible drill pipe maintains a stable posture during the drilling process.

[0033] The method for using the inner-removal slag drilling equipment for drilling and gas drainage is as follows:

[0034] For the working conditions of deep-hole hard rock drilling, high-gas mines, steeply inclined coal seams, accurate core sampling and / or protecting the borehole wall, reverse circulation drilling operations are adopted throughout the whole layer; or forward circulation drilling operations are adopted in the upper formation and reverse circulation drilling operations are adopted in the lower formation; for shallow holes, loose formations, limited budgets and / or low requirements for drilling speed, forward circulation drilling operations are adopted;

[0035] During forward circulation drilling operations, the following steps are included:

[0036] (1) Start the high-pressure water and air device. The high-pressure water and air device pumps the drilling medium into the inner closed channel of the flexible drill pipe. The drilling medium drives the downhole motor to work, and the downhole motor drives the drill bit to perform drilling operations;

[0037] (2) The drill cuttings generated during the drilling process are discharged out of the hole through the outer closed channel of the flexible drill pipe;

[0038] (3) When sticking and / or drill cuttings blockage occur, the drill rig drives the flexible drill pipe to rotate to release the sticking or drill cuttings blockage;

[0039] During reverse circulation drilling operations, the following steps are included:

[0040] (4) Start the high-pressure water and air injector. The high-pressure water and air injector pumps the drilling medium into the closed channel on the outer layer of the flexible drill pipe. The drilling medium drives the downhole motor to work, and the downhole motor drives the drill bit to carry out the drilling operation;

[0041] (5) The drill cuttings generated during the drilling process are discharged from the orifice through the closed channel on the inner layer of the flexible drill pipe;

[0042] (6) When sticking or drill cuttings blockage occurs, the drilling rig drives the flexible drill pipe to rotate to release the sticking or drill cuttings blockage.

[0043] In the method of this application, the flexible drill pipe utilizes two sandwich annulus channels, namely the inner closed channel and the outer closed channel, and through the pneumatic conveying method, realizes the effective separation of the drilling fluid (gas) and the rock (coal) cuttings and the rapid discharge outside the hole, and further realizes the efficient and continuous drilling operation. This technology is mainly applied to the geological exploration and mineral mining industries, especially in the borehole operation and gas drainage in coal mines. Aiming at the complex formation conditions and the requirement of high-efficiency slag discharge, it realizes the integrated operation of drilling, pressure relief, slag discharge and extraction.

[0044] In this application, the fixing rope is selected as a steel wire rope, such as high-carbon steel 82B, 72A, or ropes with similar properties; the thickness of the first sealing layer and the second sealing layer is 3 - 8 mm; the thickness of the outer wire mesh and the inner wire mesh pipe is 3 - 8 mm. After vulcanization bonding and solidification, both the first sealing layer and the second sealing layer are tubular. The inner diameter of the inner layer of the second sealing layer is 60 - 120 mm, and the diameter of the outer wire mesh pipe is 160 - 210 mm. Description of the Drawings

[0045] Figure 1 It is the front view of a flexible drill pipe according to Embodiment 1 of the present invention;

[0046] Figure 2 It is Figure 1 the A-A cross-sectional view of

[0047] Figure 3 It is Figure 2 the three-dimensional view after the connecting ring and the connecting block in

[0048] Figure 4 It is Figure 2 the three-dimensional view of the outer connecting female thread in

[0049] Figure 5 It is Figure 2 the three-dimensional view of the outer connecting female thread in

[0050] Figure 6 It is Figure 2 the three-dimensional view of the support frame in

[0051] Figure 7 It is Figure 2Stereogram of the middle retaining ring;

[0052] Figure 8 is Figure 2 Stereogram of the middle connecting rod

[0053] Figure 9 is Figure 2 Schematic structural diagram after the middle connecting rod assembly is connected to the connecting ring;

[0054] Figure 10 is Figure 2 Enlarged view at B of

[0055] Figure 11 is Figure 2 Enlarged view at C of

[0056] Figure 12 Schematic structural diagram of an inner slag-discharging drilling device according to Embodiment 2 of the present invention;

[0057] Figure 13 Schematic structural diagram of an inner slag-discharging drilling device during use according to Embodiment 2 of the present invention. Specific embodiments

[0058] The following is a further detailed description through specific embodiments:

[0059] The reference numerals in the accompanying drawings of the specification include: outer connecting male buckle 1, connecting rod 2, connecting ring 3, fixing rope 4, first sealing layer 5, outer steel wire mesh tube 6, outer connecting female buckle 7, connecting tube 71, stepped groove 72, outer constriction 73, inner constriction 74, support frame 8, circular ring 81, support block 82, retaining ring 9, groove 91, wedge block 10, friction pad 11, inner connecting female buckle 12, inner steel wire mesh tube 13, second sealing layer 14, spiral blade 15, spiral groove 16, inner connecting male buckle 17, fixing ring 18, connecting block 19, through groove 20, high-pressure water and air device D1, delivery pipe D2, drive motor D3, pinion D4, brake D5, large gear D6, rear gripper D7, front gripper D8, flexible drill pipe D9, directional corrector D10, downhole motor D11, pulse generator D12, drill bit D13, rock stratum E, coal seam F.

[0060] Embodiment 1 is basically as shown in the appendix Figures 1 to 11As shown: A flexible drill pipe, including an outer connecting male thread 1, an outer connecting female thread 7, an inner connecting male thread 17, an inner connecting female thread 12, an outer drill pipe, an inner drill pipe, and two support frames 8; the outer connecting male thread 1 and the outer connecting female thread 7 are arranged oppositely and the main bodies are both connecting cylinders 71 with a through hole in the axial direction. The outer walls of the opposite ends of the outer connecting male thread 1 and the outer connecting female thread 7 are both provided with outer constrictions 73, and eight connecting blocks 19 are integrally formed along the circumference at the ends. Through grooves 20 are provided on the connecting blocks 19. The through grooves 20 on the connecting blocks 19 connected to the outer connecting male thread 1 are arranged on the inner sides thereof, and the through grooves 20 on the connecting blocks 19 connected to the outer connecting female thread 7 are arranged on the outer sides thereof. A fixing ring 18 coaxial with it is integrally formed on the inner wall of the outer connecting male thread 1. The end of the outer connecting male thread 1 away from the outer connecting female thread 7 is a tapered surface with an inward constriction; inside the end of the outer connecting female thread 7 away from the outer connecting male thread 1, there is an inner constriction 74. A retaining ring 9 is provided at the inner constriction 74. Four grooves 91 are evenly distributed on the retaining ring 9. Four stepped grooves 72 for cooperating with the grooves 91 are provided on the outer wall of the connecting cylinder 71 of the outer connecting female thread 7. The stepped grooves 72 penetrate the connecting cylinder 71. The cross-section of the stepped grooves 72 is square. Wedge blocks 10 are provided in the stepped grooves 72 and extend into the corresponding grooves 91.

[0061] The inner connecting male thread 17 and the inner connecting female thread 12 are arranged oppositely. The inner connecting male thread 17 has a through hole in the axial direction. Both ends of the inner connecting male thread 17 are provided with constrictions. There are two constrictions at the end close to the inner connecting female thread 12 and they are in a stepped shape. There are three constrictions at the end away from the inner connecting female thread 12 and they are in a stepped shape. For the convenience of description, the five constrictions on the inner connecting male thread 17 are respectively named the first constriction, the second constriction, the third constriction, the fourth constriction, and the fifth constriction from left to right; the inner connecting female thread 12 has a through hole in the axial direction and the inside is a stepped hole. There are also two constrictions at the end of the inner connecting female thread 12 close to the inner connecting male thread 17 and they are in a stepped shape. There is also a constriction at the end of the inner connecting female thread 12 away from the inner connecting male thread 17. For the convenience of description, the three constrictions on the inner connecting female thread 12 are respectively named the sixth constriction, the seventh constriction, and the eighth constriction from left to right.

[0062] The outer drill pipe includes an outer steel wire mesh tube 6, two first sealing layers 5 covering the inner and outer surfaces of the outer steel wire mesh tube 6, six sets of connecting rod 2 assemblies, and connecting rings 3 located between adjacent connecting rod 2 assemblies. Each set of connecting rod 2 assemblies includes eight connecting rods 2. The eight connecting rods 2 in the same set are distributed along the circumference. Chamfers are provided at both ends of the connecting rod 2, and through holes penetrating its thickness direction are provided at both ends of the connecting rod 2. The opposite ends of the connecting rods 2 of adjacent sets of connecting rod 2 assemblies are respectively movably connected to the corresponding connecting rings 3. Specifically: The through holes at both ends of the eight connecting rods 2 in the same set are respectively strung together by a fixing rope 4. The fixing rope 4 is a steel rope, and the head and tail ends of the fixing rope 4 are fixedly connected; Eight connecting blocks 19 are distributed along the circumference on both side walls of the connecting ring 3. Through grooves 20 are provided on the connecting blocks 19 on both sides of the connecting ring 3. The through groove 20 on one side of the connecting ring 3 is located outside the corresponding connecting block 19, and the through groove 20 on the other side of the connecting ring 3 is located inside the corresponding connecting block 19; The fixing rope 4 is clamped in the through groove 20 of the corresponding connecting block 19. The connecting rod 2 is located between adjacent connecting blocks 19 on the connecting ring 3. The six sets of connecting rod 2 assemblies, the five connecting rings 3, and the corresponding connecting blocks 19 form a movable skeleton through the fixing rope 4. The movable skeleton and the outer steel wire mesh tube 6 are located between the two first sealing layers 5. The first sealing layer 5 is made of wear-resistant rubber; The movable skeleton, the outer steel wire mesh tube 6, and the first sealing layer 5 are fixed by vulcanization bonding. Specifically: The outer steel wire mesh tube 6 is netted on the movable skeleton, and then the wear-resistant rubber material is bonded to the outer wall of the outer steel wire mesh tube 6 and the inner wall of the movable skeleton by vulcanization bonding. The wear-resistant rubber material fills the gap between the outer steel wire mesh tube 6 and the movable skeleton, and a 6-mm-thick first sealing layer is formed on the outer wall of the outer steel wire mesh tube 6 and the inner wall of the movable skeleton; Spiral grooves 16 are provided on the outer wall of the outer first sealing layer 5.

[0063] The length of the inner first sealing layer 5 > the length of the outer first sealing layer 5 > the length of the outer steel wire mesh tube 6 > the length of the movable skeleton; The outer wall of the part of the inner first sealing layer 5 exceeding the movable skeleton is fixedly connected to the inner walls of the outer connecting male buckle 1 and the outer connecting female buckle 7 by vulcanization bonding. The inner first sealing layer 5 extends to the inner constriction 74 of the outer connecting female buckle 7; The inner wall of the part of the outer first sealing layer 5 exceeding the outer steel wire mesh tube 6 is fixedly connected to the outer walls of the outer connecting male buckle 1 and the outer connecting female buckle 7 by vulcanization bonding. The outer first sealing layer 5 extends to the tapered surface where the outer connecting male buckle 1 is constricted inward; The parts of the outer steel wire mesh tube 6 exceeding the movable skeleton are respectively sleeved and fixedly connected to the outer constrictions 73 of the outer connecting male buckle 1 and the outer connecting female buckle 7 by vulcanization bonding of the outer first sealing layer 5; The fixing ropes 4 on the free ends of the connecting rods 2 of the two sets of connecting rod 2 assemblies at both ends of the movable skeleton are respectively clamped in the through grooves 20 of the outer connecting male buckle 1 and the outer connecting female buckle 7; An axially penetrating outer closed channel is formed between the outer connecting male buckle 1, the outer connecting female buckle 7, and the inner first sealing layer 5.

[0064] The inner drill pipe includes an inner steel wire mesh pipe 13 and a second sealing layer 14 coated on the inner and outer walls of the inner steel wire mesh pipe 13. The second sealing layer 14 is made of wear-resistant rubber. The inner steel wire mesh pipe 13 and the second sealing layer 14 are fixed by vulcanization bonding. Specifically: the wear-resistant rubber material is bonded to the inner and outer walls of the inner steel wire mesh pipe 13 by vulcanization bonding process. The wear-resistant rubber material fills the gaps on the inner steel wire mesh pipe 13 and forms a 5-mm-thick second sealing layer on the inner and outer walls of the inner steel wire mesh pipe 13. The inner steel wire mesh pipe 13 and the second sealing layer 14 are coaxial. A spiral blade 15 is provided on the inner wall of the second sealing layer 14 of the inner layer. The length of the second sealing layer 14 of the outer layer > the length of the inner steel wire mesh pipe 13 > the length of the second sealing layer 14 of the inner layer; the inner wall of the part where the second sealing layer 14 of the outer layer extends beyond the inner steel wire mesh pipe 13 is fixed to the outer walls of the inner connecting male joint 17 and the inner connecting female joint 12 by vulcanization bonding, that is, fixed at the fourth necking and the seventh necking. The part where the inner steel wire mesh pipe 13 extends beyond the second sealing layer 14 of the inner layer is fixed to the outer walls of the inner connecting male joint 17 and the inner connecting female joint 12 by vulcanization bonding of the second sealing layer 14 of the outer layer, that is, fixed at the fifth necking and the sixth necking; both ends of the second sealing layer 14 of the inner layer are fixed to the opposite ends of the inner connecting male joint 17 and the inner connecting female joint 12 by vulcanization bonding; an inner closed channel, that is, an inner channel, which is axially through, is formed among the inner connecting female joint 12, the inner connecting male joint 17 and the inner steel wire mesh pipe 13.

[0065] Both of the two support frames 8 include a circular ring 81 and three support blocks 82 integrally formed and evenly distributed on the outer wall of the circular ring 81. The inner diameters of the fixing ring 18 and the retaining ring 9 are both larger than the outer diameter of the circular ring 81, and the inner diameters of the fixing ring 18 and the retaining ring 9 are both smaller than the outer diameter of the circular ring 81 plus the length of the support block 82; the inner diameter of the circular ring 81 is smaller than the maximum outer diameter of the inner connecting male joint 17 and the inner connecting female joint 12; the circular rings 81 of the two support frames 8 are respectively sleeved at the third necking and the eighth necking, and friction pads 11 are provided at the joints of the circular ring 81 and the third necking and the eighth necking; the side of the circular ring 81 connected to the inner connecting male joint 17 away from the inner connecting female joint 12 abuts against the side wall of the fixing ring 18, and the side of the circular ring 81 connected to the inner connecting female joint 12 away from the inner connecting male joint 17 abuts against the side wall of the retaining ring 9; the ends of the support blocks 82 of the two support frames 8 all abut against the inner wall of the inner first sealing layer 5.

[0066] Embodiment 2

[0067] An inner slag-discharging drilling device, basically as shown in the appendix Figure 12As shown in the figure, it includes a drilling rig, a brake D5, and the flexible drill pipe D9 of Embodiment 1. The drilling rig includes a driving motor D3 and a reduction gearbox. In the reduction gearbox, there are a large gear D6 and a small gear D4 that mesh with each other. The small gear D4 is connected to the output shaft of the driving motor D3, and the large gear D6 is connected to the brake D5. One end of the flexible drill pipe D9 provided with an outer connecting female thread 7 is connected to the brake D5. The flexible drill pipe D9 is connected with a front gripper D8 and a rear gripper D7, and the front gripper D8 and the rear gripper D7 are close to the large gear D6. The inner connecting male thread 17 of the flexible drill pipe D9 is connected with an orientation corrector D10, the orientation corrector D10 is connected with a downhole motor D11, the downhole motor D11 is connected with a pulse generator D12, and the pulse generator D12 is connected with a drill bit D13. The inner connecting female thread 12 is connected with a high-pressure air and water separator D1 through a delivery pipe D2.

[0068] In this application, the drilling rig, the brake D5, the front gripper D8, the rear gripper D7, the orientation corrector D10, the downhole motor D11, the pulse generator D12, the drill bit D13, and the high-pressure air and water separator D1 are all equipment in the prior art and will not be elaborated here.

[0069] The method for using the inner-return drilling equipment of Embodiment 2 for drilling and gas drainage. The structural schematic diagram during drainage is as shown in the appendix Figure 13 As shown in the figure, according to the geological conditions of the coal seam F and the rock stratum E and the drilling requirements, select a suitable drill bit D13. Figure 13 In the figure, the range of α is 0.5 - 5°, and the curvature radius R of the flexible drill pipe is 0 - 30°. For the working conditions of deep-hole hard-rock drilling, high-gas mines, steeply inclined coal seams, precise coring, and / or protecting the borehole wall, reverse circulation drilling operations are used throughout the whole layer; or normal circulation drilling operations are used in the upper strata and reverse circulation drilling operations are used in the lower strata. For shallow holes, loose strata, limited budgets, and / or scenarios with low requirements for drilling speed, normal circulation drilling operations are used.

[0070] The reverse circulation drilling operation includes the following steps:

[0071] (4) Start the high-pressure water and air separator D1. The high-pressure water and air separator D1 pumps the drilling medium (high-pressure liquid fireproof foam in gas) into the outer sealed channel of the flexible drill pipe D9, and the drilling medium quickly flows to the drill bit D13. The drilling medium plays a role in cooling and lubricating at the drill bit D13, reducing the temperature of the drill bit D13 during high-speed drilling, reducing the friction between the drill bit D13 and the coal body, and extending the service life of the drill bit D13; at the same time, the drilling medium drives the downhole motor D11 to work, and the downhole motor D11 drives the drill bit D13 to rotate and the flexible drill pipe D9 and advances towards the coal seam F. In the initial stage of drilling, slowly control the advancing speed and closely observe the drilling conditions to ensure that the drilling direction is accurate. During this process, the orientation corrector D10 monitors the drilling trajectory in real time and feeds the data back to the control system of the drilling rig. If it is found that the drilling trajectory deviates from the design requirements, the control system adjusts the advancing direction of the downhole motor according to the feedback data to accurately correct the drilling trajectory.

[0072] (5) The drill cuttings generated by the drill bit D13 driven by the downhole motor D11, under the combined action of the periodic pulse impact force generated by the pulse generator D12 and the high-pressure gas, are mixed with the high-pressure gas to form a gas-cutting mixture. The gas-cutting mixture enters the inner sealed channel of the flexible drill pipe D9 through the slag discharge channel, and the gas is discharged together with the drill cuttings to achieve gas extraction. Due to the action of the spiral blade 15 on the outer wall of the inner drill pipe, the gas-cutting mixture forms an orderly spiral flow in the channel, enhancing the slag discharge capacity and enabling it to be smoothly discharged out of the hole.

[0073] (6) When sticking or drill cuttings blockage occurs, start the drive motor D3. The drive motor D3 outputs high-speed rotational power, which is decelerated and torque-increased by the reduction gearbox and then transmitted to the flexible drill pipe D9 through the brake D5. The brake D5 accurately controls the rotation speed and torque of the flexible drill pipe D9 according to the drilling conditions to release sticking or drill cuttings blockage.

[0074] The difference in the operation between the normal circulation drilling operation and the reverse circulation drilling operation is that the drilling medium is pumped into the inner sealed channel of the flexible drill pipe D9, and the drill cuttings are discharged from the outer sealed channel out of the hole.

[0075] The above are only embodiments of the present invention. Common knowledge such as specific structures and characteristics in the solutions is not described in detail here. It should be noted that for those skilled in the art, without departing from the structure of the present invention, several deformations and improvements can be made, which should also be regarded as the protection scope of the present invention, and these will not affect the implementation effect of the present invention and the practicality of the patent. The protection scope required by this application should be based on the content of its claims, and the specific implementation manners in the specification can be used to explain the content of the claims.

Claims

1. An internal slag removal drilling device, comprising a drilling rig and a flexible drill rod, wherein the output end of the drilling rig is connected to a brake, the brake is connected to the flexible drill rod, the end of the flexible drill rod away from the drilling rig is connected to a directional corrector, the directional corrector is connected to a bottom hole motor, and the bottom hole motor is connected to a drill bit; characterized in that: The flexible drill rod includes an outer drill rod, which includes an outer connecting male buckle, an outer connecting female buckle and a movable skeleton movably connected therebetween, and the movable skeleton is penetrated in the axial direction, and the outer wall and the inner wall of the movable skeleton are coated with a first sealing layer that is wear-resistant, pressure-resistant, corrosion-resistant and tough; the outer connecting male buckle and the outer connecting female buckle are penetrated in the axial direction and are fixedly connected with support frames inside, and gaps are left between the support frames and the outer connecting male buckle and the outer connecting female buckle; the two support frames are respectively fixedly connected with an inner connecting male buckle and an inner connecting female buckle, and the same deformable inner drill rod is fixedly connected between the inner connecting female buckle and the inner connecting male buckle, and an inner closed passage penetrating in the axial direction is formed between the inner connecting female buckle, the inner connecting male buckle and the inner drill rod; an outer closed passage penetrating in the axial direction is formed between the outer connecting male buckle, the outer connecting female buckle and the inner first sealing layer; the inner connecting female buckle is connected with a high-pressure wind water device, and the directional corrector is connected to the inner connecting male buckle.

2. A flexible drill rod according to claim 1, characterized in that: An outer steel wire mesh tube is fixedly sleeved on the outer wall of the movable frame, and the first outer sealing layer is coated on the outer wall of the outer steel wire mesh tube.

3. A flexible drill rod according to claim 2, characterized in that: The inner drill pipe comprises an inner steel wire mesh tube and a second sealing layer which is coated on the inner and outer surfaces of the inner steel wire mesh tube and has the properties of toughness, wear resistance, pressure resistance and corrosion resistance.

4. A flexible drill rod according to claim 3, characterized in that: The first sealing layer and / or the second sealing layer is a rubber layer, a special plastic layer or a thermoplastic elastomer layer.

5. A flexible drill rod according to claim 4, characterized in that: The first sealing layer and the second sealing layer are both rubber layers. The first sealing layer is fixed to the outer steel wire mesh tube and the movable frame by vulcanization bonding; the second sealing layer is fixedly connected to the inner steel wire mesh tube by vulcanization bonding.

6. A flexible drill rod according to claim 5, characterized in that: The inner wall of the second sealing layer of the inner layer is provided with a spiral blade made of rubber material with toughness, wear resistance, pressure resistance and corrosion resistance. The spiral blade is integrally formed on the second sealing layer by vulcanization bonding and fixing.

7. A flexible drill rod according to claim 6, characterized in that: The outer wall of the first sealing layer of the outer layer is provided with a spiral groove.

8. A flexible drill rod according to any one of claims 1 to 7, characterized in that: The movable skeleton includes multiple groups of connecting rod assemblies and connecting rings located between adjacent connecting rod assemblies, each group of connecting rod assemblies includes multiple connecting rods, and the multiple connecting rods in the same group are distributed along the circumference. The connecting rods of two adjacent groups of connecting rod assemblies are movably connected through connecting rings, and the ends of the outermost connecting rods away from the connecting rings are movably connected to the outer layer connecting male buckle and the outer layer connecting female buckle respectively.

9. A flexible drill rod according to claim 8, characterized in that: Both ends of the connecting rod are provided with through holes penetrating the thickness direction thereof, and the through holes at both ends of multiple connecting rods of the same group are respectively connected in series by a fixing rope, and the head and tail ends of the fixing rope are fixedly connected; multiple connecting blocks are circumferentially distributed on both sides of the connecting ring, and the ends of the connecting rods are located between adjacent connecting blocks, and the fixing ropes are connected in series between multiple connecting rods and connecting blocks located in the same circumferential direction.

10. A flexible drill rod according to claim 9, characterized in that: The number of connecting blocks on the same side of the connecting ring is not less than the number of connecting rods in the same group, and the connecting blocks on both sides of the connecting ring are provided with through grooves and / or connecting holes; the fixing rope is connected to the through grooves and / or through holes of the corresponding connecting blocks, and the connecting rods are located between adjacent connecting blocks on the connecting ring.

11. A flexible drill rod according to claim 10, characterized in that: The outer walls of the opposite ends of the outer layer connecting male buckle and the outer layer connecting female buckle are provided with neckings and the ends are also provided with multiple connecting blocks distributed along the circumference. The connecting blocks are not less than the number of connecting rods in the same group, and the connecting blocks are also provided with through grooves and / or connecting holes; the fixing ropes on the connecting rod assemblies at both ends are connected to the through grooves and / or through holes of the corresponding connecting blocks, and the connecting rods are located between adjacent connecting blocks on the connecting ring; the two ends of the outer layer steel wire mesh tube are respectively sleeved on the neckings of the outer layer connecting male buckle and the outer layer connecting female buckle outer wall, and the outer first sealing layer is fixed on the outer wall of the outer layer connecting male buckle and the outer layer connecting female buckle.

12. A flexible drill rod according to claim 11, characterized in that: The openings of the through slots on the connecting blocks on both sides of the connecting ring face the inside and outside of the connecting blocks respectively, or the openings of the through slots on multiple connecting blocks on the same side face the inside and outside of the connecting blocks alternately.

13. A flexible drill rod according to claim 12, characterized in that: The inner part of one end of the outer layer connecting female buckle away from the outer layer connecting male buckle is also provided with a necking, and a retaining ring is provided at the necking, and a plurality of grooves are evenly distributed on the retaining ring. The outer wall of the outer layer connecting female buckle is provided with a plurality of stepped grooves used in conjunction with the grooves, and a wedge block is provided in the stepped groove, and the wedge block extends into the corresponding groove.

14. The internal slag removal drilling equipment according to claim 13, characterized in that: A pulse generator is connected between the bottom hole motor and the drill bit.

15. The internal slag removal drilling equipment according to claim 14, characterized in that: The drilling rig comprises a driving motor and a reduction gear box, the driving motor is connected to an input end gear of the reduction gear box, and the brake is connected to an output end gear of the reduction gear box.

16. The internal slag removal drilling equipment according to claim 15, characterized in that: The flexible hose is connected with a clamp.

17. A method for drilling and extracting gas using the internal slag drilling equipment according to any one of claims 1 to 7 and 9 to 16, which is as follows: For deep hole hard rock drilling, high gas mines, steeply inclined coal seams, precise coring and / or hole wall protection, reverse circulation drilling is used for the entire layer; or positive circulation drilling is used in the upper formation and reverse circulation drilling is used in the lower formation; positive circulation drilling is used for shallow holes, loose formations, limited budgets and / or low drilling speed requirements; The positive cycle drilling operation includes the following steps: (1) Start the high-pressure blower, which pumps the drilling medium into the closed channel of the inner layer of the flexible drill pipe. The drilling medium drives the bottom hole motor to work, and the bottom hole motor drives the drill bit to perform drilling operations; (2) The drilling debris generated during the drilling process is discharged from the hole through the outer closed channel of the flexible drill pipe; (3) When the drill is stuck or the drill is blocked by drilling debris, the drilling rig drives the flexible drill rod to rotate to remove the stuck drill or drilling debris blockage; Reverse circulation drilling operations include the following steps: (4) Starting the high-pressure blower, which pumps the drilling medium into the flexible drill pipe from the closed channel on the outer layer. The drilling medium drives the bottom hole motor to work, and the bottom hole motor drives the drill bit to perform drilling operations; (5) The drilling debris generated during the drilling process is discharged from the orifice through the inner closed channel of the flexible drill pipe; (6) When the drill is stuck or the drill is blocked by drilling debris, the drilling rig drives the flexible drill rod to rotate to remove the stuck drill or drilling debris blockage.

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