Flexible drill rod

Abstract

The utility model discloses a flexible drill rod in the technical field of drill rods. An outer-layer drill rod is composed of an outer-layer connecting male buckle, a female buckle, a plurality of sets of connecting rod assemblies distributed circumferentially and a connecting ring. Each connecting rod assembly comprises a plurality of connecting rods distributed along the circumference, the adjacent assemblies are movably connected through connecting rings, and the connecting rod at the outermost end is fixed to the male buckle and the female buckle. First sealing layers cover the inner and outer walls of the connecting rod assembly and the connecting ring. Supporting frames are fixed in the male buckle and the female buckle, gaps are reserved, the supporting frames are connected with the inner-layer male buckle and the inner-layer female buckle respectively, and the supporting frames and the inner-layer male buckle and the inner-layer female buckle are connected through a deformable inner-layer drill rod to form an inner-layer closed channel with a through axis; the outer-layer closed channel is defined by a male buckle, a female buckle and an inner-layer elastic body, and a double-layer closed structure is achieved. According to the flexible drill rod, the drilling efficiency and safety can be effectively improved.

Description

TECHNICAL FIELD

[0001] The utility model belongs to the technical field of drill pipe, especially relates to a flexible drill pipe. BACKGROUND

[0002] The flexible drill pipe is a kind of special drill pipe for drilling operation, especially in the field of gas exploitation such as coal seam drilling.The flexible drill pipe is made of high-strength alloy steel or composite material, and has the characteristics of bendable deformation and original state recovery.The flexible drill pipe generally includes two drill pipe joints and a plurality of drill pipe short sections connected in head and tail, and the free ends of the two drill pipe short sections located at the outermost end are respectively fixedly connected to the two drill pipe joints.Compared with the conventional rigid drill pipe, the flexible drill pipe can better adapt to complex geological conditions and drilling trajectory requirements during drilling, and can realize directional drilling through smaller bending radius, reduce the occurrence of accidents such as sticking and breaking, and improve the success rate and efficiency of drilling.

[0003] However, the existing flexible drill pipe has the following problems:1. After the flexible drill pipe completes drilling, it needs to be taken out, and the hole is sealed before gas extraction;Therefore, the gas cannot be extracted during drilling and flexible drill pipe extraction, which wastes a lot of time.2. During the drilling process of the flexible drill pipe, the soft coal seam, ground stress and coal structure are easy to break the coal body around the drill hole, and the disturbance of the flexible drill pipe during drilling will destroy the original stress balance of the hole wall, reduce the stability of the hole wall, cause the inner wall of the slag discharge channel (i.e.the hole wall) to collapse, and further block the slag discharge channel, affecting the slag discharge effect.3. The contact state between the flexible drill pipe and the hole wall changes constantly due to the influence of coal seam stress, bending of the flexible drill pipe and other factors, resulting in different gap sizes between them;The smaller the gap, the more difficult it is to discharge the slag powder, and the larger the gap, the slower the slag discharge speed, and the more likely it is to cause the slag powder to accumulate in the hole.4. The commonly used wind or water power slag discharge method has irregular annular space between the drill pipe and the hole wall when discharging slag on the surface of the flexible drill pipe, and the fluid flowing in the space has large resistance, so it is difficult to form a stable and efficient slag discharge flow field;Moreover, as the drilling depth increases, the fluid pressure loss is also large, and the pressure and flow rate when reaching the hole bottom may not be enough to effectively discharge the slag powder.5. Since the particle size of the slag powder cannot be completely uniform, and may contain a lot of sticky substances, it is easy to form local blockage in the spiral groove, notched groove and other parts of the drill pipe;Once local blockage is formed, the effective cross-sectional area of the slag discharge channel will be reduced, thereby affecting the overall slag discharge efficiency, and even possibly causing the pressure in the drill hole to rise, leading to safety accidents.

[0004] Therefore, it is of positive significance to design a flexible drill pipe with fixed slag discharge channel for improving the efficiency of gas exploitation. INVENTION CONTENTS

[0005] The utility model intends to provide a flexible drill pipe to solve the problems of the flexible drill pipe in the above background technology.

[0006] The flexible drill pipe in the scheme comprises an outer drill pipe, the outer drill pipe comprising an outer connecting male buckle, an outer connecting female buckle and a movable skeleton movably connected between the two, the axis direction of the movable skeleton being through, and the outer wall and the inner wall of the movable skeleton being both coated with a first sealing layer which is wear-resistant, pressure-resistant, corrosion-resistant and tough; the axis direction of the outer connecting male buckle and the outer connecting female buckle is through, and a support frame is fixedly connected inside each of the outer connecting male buckle and the outer connecting female buckle, and a gap is left between the support frame and the outer connecting male buckle and the outer connecting female buckle; an inner connecting male buckle and an inner connecting female buckle are fixedly connected on the two support frames respectively, and a deformable inner drill pipe is fixedly connected between the inner connecting female buckle and the inner connecting male buckle, and an inner layer closed channel with the axis direction being through is formed between the inner connecting female buckle, the inner connecting male buckle and the inner drill pipe; an outer layer closed channel with the axis direction being through is formed between the outer connecting male buckle, the outer connecting female buckle and the inner first sealing layer.

[0007] The working principle of the scheme is as follows: during drilling, a suitable drill bit is selected according to the geological conditions of the coal rock stratum and the drilling requirements, and the drill bit and a hole bottom motor are installed at the front end of the flexible drill pipe, i.e. at the end of the connecting male buckle; a drilling machine is connected to the flexible drill pipe close to the end of the connecting female buckle, and the end of the connecting female buckle is connected to a high-pressure air and water device. At the same time, the hole bottom motor is ensured to be firmly connected to the flexible drill pipe and to transmit smoothly. During drilling operation, the flexible drill pipe can perform positive circulation and reverse circulation drilling operation through the high-pressure air and water device.

[0008] During positive circulation operation, the high-pressure air and water device pumps drilling medium (such as high-pressure water, mud, high-pressure liquid fireproof foam or high-pressure gas) from the inner layer closed channel of the flexible drill pipe, the drilling medium drives the hole bottom motor to work, and the drilling medium enters the hole bottom through the drill bit, carries the drill cuttings and then returns to the hole opening from the outer layer closed channel, forming a positive circulation of "inward and outward".

[0009] During reverse circulation operation, the high-pressure air and water device pumps drilling medium (such as high-pressure water, mud, high-pressure liquid fireproof foam or high-pressure gas) from the outer layer closed channel of the flexible drill pipe, the drilling medium drives the hole bottom motor to work, and the drilling medium enters the hole bottom through the drill bit, carries the drill cuttings and then returns to the hole opening through the inner layer closed channel of the flexible drill pipe, forming a reverse circulation of "outward and inward".

[0010] The beneficial effects of the scheme are as follows:

[0011] 1. During positive circulation, the outer layer closed channel (i.e. the interlayer annulus between the outer drill pipe and the inner drill pipe) is relatively regular, reducing the resistance of fluid flow. Compared with the traditional flexible drill pipe, it is easier to form a stable and efficient slag discharge flow field. Even if the drilling depth increases, due to the improvement of the stability of the flow field, the fluid pressure loss is controlled to a certain extent, which can ensure that it still has enough pressure and flow rate when reaching the hole bottom, and the slag powder can be effectively discharged.

[0012] 2. When the reverse circulation is used, the outer layer of the closed channel is used to deliver the high-pressure liquid fireproof foam and gas to cool and lubricate the drill bit, while the inner layer of the closed channel is used to discharge the residue, and the discharged gas contains gas. This means that during the drilling process, gas can be extracted from the drilling hole without waiting for the drilling to be completed and the flexible drill pipe to be removed for gas extraction, greatly saving time and improving the overall efficiency of gas extraction.

[0013] 3. When the reverse circulation is used, the residue discharge channel of the flexible drill pipe is formed by the inner layer of the closed channel. Its relatively regular shape and stable structure can maintain the overall residue discharge efficiency stable even if the residue particle size is uneven or contains sticky substances, effectively avoiding safety accidents caused by the increase of the pressure in the drilling hole.

[0014] 4. The combination design of the movable skeleton and the deformable inner layer drill pipe gives the flexible drill pipe excellent toughness. During the drilling process, the flexible drill pipe can flexibly adjust the drilling angle and drilling direction according to the complex geological conditions and drilling trajectory. Even if it encounters narrow space and complex geological structure, the drill pipe can realize directional drilling through a small bending radius, reduce the probability of accidents such as sticking and breaking, and greatly improve the success rate of drilling. At the same time, it effectively avoids the poor discharge of residue caused by the change of the contact state between the drill pipe and the hole wall, ensuring the smooth discharge of residue.

[0015] Further, the outer wall of the movable skeleton is sleeved with an outer layer of steel wire mesh pipe, and the first sealing layer of the outer layer is wrapped on the outer wall of the outer layer of steel wire mesh pipe. The outer layer of steel wire mesh pipe enhances the overall structural strength of the outer layer of the drill pipe, so that it is not easy to deform or be damaged under the action of external force under complex geological conditions. The first sealing layer is wrapped on the outer wall of the outer layer of steel wire mesh pipe, which can protect the outer layer of steel wire mesh pipe from wear and tear, and on the other hand, it can better adapt to deformation when the flexible drill pipe is bent, maintaining the stability of the residue discharge channel. At the same time, the outer layer of steel wire mesh pipe forms a whole constraint on the movable skeleton, preventing the structure from collapsing when a local overload breaks.

[0016] Further, the inner layer of the drill pipe includes an inner layer of steel wire mesh pipe and a second sealing layer wrapped on the inner and outer surfaces of the inner layer of steel wire mesh pipe and having the properties of toughness, wear resistance, pressure resistance and corrosion resistance. The inner layer of steel wire mesh pipe provides a certain structural strength, so that the inner layer of the drill pipe can maintain its shape when subjected to external force and is not easy to be flattened or excessively deformed, ensuring the normal use of the inner layer of the closed channel. The second sealing layer not only enhances the wear resistance of the inner layer of the drill pipe, reducing the wear of the inner wall of the inner layer of the drill pipe during the delivery of high-pressure liquid fireproof foam and gas, but also can adapt to the bending deformation of the flexible drill pipe during the drilling process due to its toughness, avoiding damage caused by stress concentration due to rigid structure, and prolonging the service life of the inner layer of the drill pipe.

[0017] Further, 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, the special plastic layer or the thermoplastic elastomer layer all have good toughness, wear resistance, pressure resistance and corrosion resistance.

[0018] Further, the first sealing layer and the second sealing layer are both rubber layers, and the first sealing layer is fixedly connected to the outer steel wire mesh pipe and the movable skeleton by vulcanization bonding. The second sealing layer is fixedly connected to the inner steel wire mesh pipe by vulcanization bonding. By the vulcanization bonding, the gaps between the outer steel wire mesh pipe and the movable skeleton are filled and solidified by the liquid rubber, so that the sealing performance, the connection strength, the structural stability, the wear resistance and the corrosion resistance of the outer drill pipe are greatly improved. 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. At the same time, the vulcanization bonding ensures that the components will not slide or separate during the deformation process, so that the structure can work normally under complex working conditions. The vulcanization process enables the steel wire mesh to be combined with the rubber molecules at the molecular level, eliminates the weak interface of traditional glue bonding, and forms a "reinforced concrete" structure by embedding the inner steel wire mesh in the rubber layer. When the flexible drill pipe is bent, the interface stress is uniformly dispersed to avoid delamination and cracking, and it is particularly suitable for frequent bending working conditions.

[0019] Further, 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, and the spiral blade is integrally formed on the second sealing layer by vulcanization bonding. The spiral blade generates a rotational flow effect when conveying drill cuttings, so that the fluid is pushed along the axial direction of the flexible drill pipe instead of being simply driven by pressure. This active conveying method can reduce fluid pressure loss, and is particularly suitable for long-distance drilling. At the same time, the rotational flow can prevent the deposition of slag powder on the inner wall of the flexible drill pipe and avoid the blockage of the inner channel. When the reverse circulation slag discharge is blocked or the drill pipe is stuck, the drill rig drives the flexible drill pipe to rotate, so that the slag discharge is unblocked and the drill pipe is prevented from being stuck.

[0020] Further, the outer wall of the first sealing layer of the outer layer is provided with a spiral groove. The spiral groove can change the fluid flow state between the outer drill pipe and the hole wall, so that the gas carrying drill cuttings during the slag discharge forms a more orderly spiral flow under the guidance of the spiral groove, thereby enhancing the slag discharge capacity. At the same time, the spiral groove can also increase the friction between the outer drill pipe and the hole wall to a certain extent, so that the flexible drill pipe is not easy to slide relatively during the drilling process due to the action of the coal seam stress, thereby improving the stability of the flexible drill pipe in the hole. When the slag discharge is blocked or the drill pipe is stuck, the drill rig drives the flexible drill pipe to rotate, so that the slag discharge is unblocked and the drill pipe is prevented from being stuck.

[0021] Further, the movable framework comprises a plurality of connecting rod assemblies and connecting rings between adjacent connecting rod assemblies, each connecting rod assembly comprises a plurality of connecting rods, the connecting rods in the same connecting rod assembly are distributed along a circumference, the connecting rods of adjacent connecting rod assemblies are movably connected through the connecting rings, and the outermost ends of the connecting rods are movably connected to the outer connecting male buckle and the outer connecting female buckle, respectively. The movable framework is composed of a plurality of connecting rod assemblies and a plurality of connecting rings. During drilling, when a connecting rod is broken by impact, the wire mesh can temporarily bear the load to maintain the shape of the slag discharge channel until the current drilling cycle is completed, thereby significantly improving the fault tolerance rate of the flexible drill rod.

[0022] Further, the connecting rod is provided with a through hole penetrating through the thickness direction of the connecting rod at both ends, the through holes at both ends of the connecting rods in the same connecting rod assembly are connected by a fixed rope, and the fixed rope is fixedly connected at both ends. The connecting ring is provided with a plurality of connecting blocks distributed along a circumference at both sides, the end of the connecting rod is located between adjacent connecting blocks, and the connecting rods and the connecting blocks located on the same circumference are connected by the fixed rope. The connecting rods are connected by the fixed rope, which allows a deflection angle of 0°-30° between adjacent connecting rings and maintains the rigidity in the circumferential direction through the tension of the rope. Compared with a pure hinged structure, the design can provide necessary torsional rigidity when drilling vertically and prevent the flexible drill rod from spinning out of control in the hole.

[0023] Further, the number of connecting blocks on one side of the connecting ring is not less than the number of connecting rods in the same connecting rod assembly, and the connecting blocks on both sides of the connecting ring are provided with through grooves and / or connecting holes. The fixed rope is connected in the through groove and / or the connecting hole of the connecting block corresponding to the fixed rope, and the connecting rod is located between the adjacent connecting blocks on the connecting ring. Through the arrangement of the through groove and / or the connecting hole, the connecting rod and the connecting ring are connected by the fixed rope, which is simple to operate.

[0024] Further, the opposite end outer walls of the outer layer connecting male buckle and the outer layer connecting female buckle are each provided with a necking portion, and the end portions thereof are also circumferentially distributed with a plurality of connecting blocks, the number of the connecting blocks is not less than the number of the connecting rods in the same group, and the connecting blocks are also provided with through grooves and / or connecting holes; the fixed ropes on the connecting rod assemblies at the two ends are connected in the through grooves and / or connecting holes of the corresponding connecting blocks, and the connecting rods are located between the adjacent connecting blocks on the connecting ring; the outer layer wire mesh pipe is respectively sleeved at the necking portions of the outer walls of the outer layer connecting male buckle and the outer layer connecting female buckle, and the first sealing layer of the outer layer is fixed to the outer walls of the outer layer connecting male buckle and the outer layer connecting female buckle. The necking portions on the outer layer connecting male buckle and the outer layer connecting female buckle facilitate the installation and fixation of the outer layer wire mesh pipe, make the outer layer wire mesh pipe tightly cooperate with the outer layer connecting male buckle and the outer layer connecting female buckle, and enhance the stability of the overall structure. The connecting blocks and the through grooves and connecting holes cooperate with the fixed ropes on the connecting rod assemblies, realize the flexible connection between the outer layer drill rod and the outer layer connecting male buckle and the outer layer connecting female buckle, and make the flexible drill rod flexibly adapt to different drilling trajectories in the drilling process. Meanwhile, the first sealing layer is fixed to the outer walls of the outer layer connecting male buckle and the outer layer connecting female buckle, further protects the connecting parts, and improves the wear resistance and sealing performance of the connecting parts.

[0025] Further, the groove openings of the through grooves on the connecting blocks on the two sides of the connecting ring are respectively directed towards the inner side and the outer side of the connecting blocks, or the groove openings of the through grooves on the multiple connecting blocks on the same side are alternately directed towards the inner side and the outer side of the connecting blocks. The distribution of the through grooves makes the connection positions of the fixed ropes on the connecting blocks more flexible and various. When the flexible drill rod is bent and deformed, the fixed ropes at different positions can better cooperate and adapt to the deformation requirements of the flexible drill rod, and avoid damage to the connecting parts due to uneven force on the fixed ropes. Meanwhile, this design increases the redundancy of the connecting structure and improves the reliability and stability of the outer layer drill rod under complex working conditions.

[0026] Further, the inner portion of the end of the outer layer connecting female buckle away from the outer layer connecting male buckle is also provided with a necking portion, the necking portion is provided with a check ring, the check ring is uniformly distributed with a plurality of grooves, the outer wall of the outer layer connecting female buckle is provided with a plurality of stepped grooves matched with the grooves, the stepped grooves are provided with wedge blocks, and the wedge blocks extend into the corresponding grooves. The check ring at the necking portion cooperates with the wedge blocks to play a locking and sealing role.

[0027] Further, the inner layer connecting male buckle and the inner layer connecting female buckle are each sleeved with a friction pad, and the friction pad is located at the connecting position of the inner layer connecting male buckle and the inner layer connecting female buckle and the support frame. The friction pad can increase the friction force between the inner layer connecting male buckle, the inner layer connecting female buckle and the support frame, and prevent the inner layer drill rod from relatively moving due to vibration or force during work. Meanwhile, the friction pad can also play a buffering role, reduce the impact force transmitted by the inner layer drill rod to the support frame, protect the connecting parts of the support frame and the inner layer drill rod, prolong the service life of the connecting parts, and ensure the stability and reliability of the inner layer sealed channel.

[0028] In the application, the fixed rope is selected from steel wire rope, such as high-carbon steel 82B, 72A, or a rope with similar performance; the thickness of the first sealing layer and the second sealing layer is 3-8 mm; the thickness of the outer layer steel wire mesh and the inner layer steel wire mesh tube is 3-8 mm. The first sealing layer and the second sealing layer are tubular after vulcanization bonding and solidification, the inner diameter of the inner layer of the second sealing layer is 60-120 mm, and the diameter of the outer layer steel wire mesh tube is 160-210 mm. BRIEF DESCRIPTION OF DRAWINGS

[0029] Figure 1 It is a front view of a flexible drill pipe according to Embodiment 1 of the present application;

[0030] Figure 2 It is an A-A sectional view of the flexible drill pipe according to Embodiment 1 of the present application; Figure 1

[0031] Figure 3 It is a perspective view of the connection ring and the connection block after connection in the flexible drill pipe according to Embodiment 1 of the present application; Figure 2

[0032] Figure 4 It is a perspective view of the outer layer connection female buckle in the flexible drill pipe according to Embodiment 1 of the present application; Figure 2

[0033] Figure 5 It is another perspective view of the outer layer connection female buckle in the flexible drill pipe according to Embodiment 1 of the present application; Figure 2

[0034] Figure 6 It is a perspective view of the support frame in the flexible drill pipe according to Embodiment 1 of the present application; Figure 2

[0035] Figure 7 It is a perspective view of the stop ring in the flexible drill pipe according to Embodiment 1 of the present application; Figure 2

[0036] Figure 8 It is a perspective view of the connection rod in the flexible drill pipe according to Embodiment 1 of the present application Figure 2

[0037] Figure 9 It is a structural schematic view of the connection rod assembly and the connection ring after connection in the flexible drill pipe according to Embodiment 1 of the present application; Figure 2

[0038] Figure 10 It is an enlarged view of B in the flexible drill pipe according to Embodiment 1 of the present application; Figure 2

[0039] Figure 11 It is an enlarged view of C in the flexible drill pipe according to Embodiment 1 of the present application. Figure 2 DETAILED DESCRIPTION The following will be further described in detail through specific embodiments:

[0040]

[0041] ​​​​​​​​​​The reference numerals in the accompanying drawings include: outer male connector 1, connecting rod 2, connecting ring 3, fixing rope 4, first sealing layer 5, outer wire mesh tube 6, outer female connector 7, connecting cylinder 71, stepped groove 72, outer constriction 73, inner constriction 74, support frame 8, ring 81, support block 82, retaining ring 9, groove 91, wedge block 10, friction pad 11, inner female connector 12, inner wire mesh tube 13, second sealing layer 14, spiral blade 15, spiral groove 16, inner male connector 17, fixing ring 18, connecting block 19, and through groove 20.

[0042] Example 1 is basically as shown in the appendix. Figures 1-11 As shown: A flexible drill pipe includes an outer male connecting thread 1, an outer female connecting thread 7, an inner male connecting thread 17, an inner female connecting thread 12, an outer drill pipe, an inner drill pipe, and two support frames 8; the outer male connecting thread 1 and the outer female connecting thread 7 are arranged opposite each other and are both through-axis in the main body of the connecting cylinder 71; the outer walls of the opposite ends of the outer male connecting thread 1 and the outer female connecting thread 7 are provided with outward constriction 73 and the ends are integrally formed with eight connecting blocks 19 along the circumference; each connecting block 19 is provided with a through groove 20; the through groove 20 on the connecting block 19 connected to the outer male connecting thread 1 is located on its inner side; the through groove on the connecting block 19 connected to the outer female connecting thread 7 is located on its inner side. 20 is set on its outer side. The inner wall of the outer male buckle 1 is integrally formed with a fixing ring 18 coaxial with it. The end of the outer male buckle 1 away from the outer female buckle 7 is an inwardly tapered surface. The inner end of the outer female buckle 7 away from the outer male buckle 1 is provided with an inwardly tapered opening 74. A retaining ring 9 is provided at the inwardly tapered opening 74. Four grooves 91 are evenly distributed on the retaining ring 9. The outer wall of the connecting cylinder 71 of the outer female buckle 7 is provided with four stepped grooves 72 that cooperate with the grooves 91. The stepped grooves 72 penetrate the connecting cylinder 71. The cross section of the stepped grooves 72 is square. A wedge 10 is provided in the stepped grooves 72. The wedge 10 extends into the corresponding groove 91.

[0043] The inner male connector 17 and the inner female connector 12 are arranged opposite to each other. The axis of the inner male connector 17 is continuous. Both ends of the inner male connector 17 are provided with constricted openings. The end closer to the inner female connector 12 has two constricted openings in a stepped shape, and the end farther away from the inner female connector 12 has three constricted openings in a stepped shape. For ease of description, the five constricted openings on the inner male connector 17 are named from left to right as the first constricted opening, the second constricted opening, the third constricted opening, the fourth constricted opening, and the fifth constricted opening. The axis of the inner female connector 12 is continuous and the interior is a stepped hole. The end of the inner female connector 12 closer to the inner male connector 17 is also provided with two constricted openings in a stepped shape, and the end of the inner female connector 12 farther away from the inner male connector 17 is also provided with a constricted opening. For ease of description, the three constricted openings on the inner female connector 12 are named from left to right as the sixth constricted opening, the seventh constricted opening, and the eighth constricted opening.

[0044] The outer layer drill pipe comprises an outer layer steel wire mesh pipe 6, two first sealing layers 5 wrapped on the outer surface of the outer layer steel wire mesh pipe 6, six groups of connecting rod 2 assemblies and connecting rings 3 located between adjacent connecting rod 2 assemblies, each group of connecting rod 2 assemblies comprises eight connecting rods 2, the eight connecting rods 2 in the same group are distributed along the circumference, the two ends of the connecting rod 2 are provided with chamfers, the two ends of the connecting rod 2 are provided with through holes penetrating the thickness direction of the connecting rod 2, the opposite ends of the connecting rods 2 of the adjacent two groups of connecting rod 2 assemblies are movably connected to the corresponding connecting rings 3, specifically: the through holes at the two ends of the eight connecting rods 2 in the same group are connected by a fixed rope 4 respectively, the fixed rope 4 is a steel rope, and the two ends of the fixed rope 4 are fixedly connected; eight connecting blocks 19 are distributed on the two side walls of the connecting ring 3 along the circumference, the connecting blocks 19 on the two sides of the connecting ring 3 are provided with through grooves 20, the through grooves 20 on one side of the connecting ring 3 are located on the outer side of the corresponding connecting blocks 19, and the through grooves 20 on the other side of the connecting ring 3 are located on the inner side of the corresponding connecting blocks 19; the fixed rope 4 is clamped in the through groove 20 of the corresponding connecting block 19, the connecting rod 2 is located between the adjacent connecting blocks 19 on the connecting ring 3, the six groups of connecting rod 2 assemblies, the five connecting rings 3 and the corresponding connecting blocks 19 form a movable framework through the fixed rope 4, the movable framework and the outer layer steel wire mesh pipe 6 are located between the two first sealing layers 5, and the first sealing layer 5 is made of wear-resistant rubber material; the movable framework, the outer layer steel wire mesh pipe 6 and the first sealing layer 5 are fixed by vulcanization bonding, specifically: the outer layer steel wire mesh pipe 6 is connected to the movable framework, then the wear-resistant rubber material is bonded to the outer wall of the outer layer steel wire mesh pipe 6 and the inner wall of the movable framework by using the vulcanization bonding process, the wear-resistant rubber material fills the gap on the outer layer steel wire mesh pipe 6 and the movable framework, and forms a first sealing layer with a thickness of 3-8 mm on the outer wall of the outer layer steel wire mesh pipe 6 and the inner wall of the movable framework; the outer wall of the first sealing layer 5 of the outer layer is provided with a spiral groove 16.

[0045] The length of the inner first sealing layer 5 is greater than the length of the outer first sealing layer 5, the length of the outer wire mesh pipe 6, and the length of the movable skeleton; the outer wall of the part of the inner first sealing layer 5 that exceeds the movable skeleton is fixed to the inner wall of the outer connecting male buckle 1 and the inner wall of the outer connecting female buckle 7 by vulcanization bonding, and the inner first sealing layer 5 extends to the inner tapered surface of the outer connecting male buckle 1; the inner wall of the part of the outer first sealing layer 5 that exceeds the outer wire mesh pipe 6 is fixed to the outer wall of the outer connecting male buckle 1 and the outer connecting female buckle 7 by vulcanization bonding, and the outer first sealing layer 5 extends to the inner tapered surface of the outer connecting male buckle 1; the part of the outer wire mesh pipe 6 that exceeds the movable skeleton is respectively sleeved and fixed to the outer connecting male buckle 1 and the outer connecting female buckle 7 at the outer tapered surface 73 by the vulcanization bonding of the outer first sealing layer 5; the fixed ropes 4 on the free ends of the connecting rods 2 of the two groups 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; the outer connecting male buckle 1, the outer connecting female buckle 7, and the inner first sealing layer 5 form an outer closed channel that penetrates in the axial direction.

[0046] The inner drill pipe comprises an inner wire mesh pipe 13 and a second sealing layer 14 wrapped on the inner and outer walls of the inner wire mesh pipe 13. The second sealing layer 14 is made of wear-resistant rubber material, and the inner 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 wire mesh pipe 13 by vulcanization bonding process, fills the gaps on the inner wire mesh pipe 13, and forms a second sealing layer with a thickness of 3-8 mm on the inner and outer walls of the inner wire mesh pipe 13. The inner wire mesh pipe 13 and the second sealing layer 14 are coaxial. The inner wall of the second sealing layer 14 of the inner layer is provided with a spiral blade 15. The length of the outer second sealing layer 14 is greater than the length of the inner wire mesh pipe 13 and the length of the inner second sealing layer 14. The inner wall of the part of the outer second sealing layer 14 that exceeds the inner wire mesh pipe 13 is fixed to the outer wall of the inner connecting male buckle 17 and the inner connecting female buckle 12 by vulcanization bonding, i.e., fixed at the fourth tapered surface and the seventh tapered surface. The part of the inner wire mesh pipe 13 that exceeds the inner second sealing layer 14 is fixed to the outer wall of the inner connecting male buckle 17 and the inner connecting female buckle 12 by vulcanization bonding of the outer second sealing layer 14, i.e., fixed at the fifth tapered surface and the sixth tapered surface. The two ends of the inner second sealing layer 14 are fixed to the opposite ends of the inner connecting male buckle 17 and the inner connecting female buckle 12 by vulcanization bonding. The inner connecting female buckle 12, the inner connecting male buckle 17, and the inner wire mesh pipe 13 form an inner closed channel that penetrates in the axial direction, i.e., an inner channel.

[0047] Both support frames 8 comprise a circular ring 81 and three support blocks 82 evenly distributed on the outer wall of the circular ring 81, the inner diameter of the fixing ring 18 and the retainer ring 9 is larger than the outer diameter of the circular ring 81, and the inner diameter of the fixing ring 18 and the retainer ring 9 is 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 layer connecting male buckle 17 and the inner layer connecting female buckle 12; the circular rings 81 of the two support frames 8 are respectively sleeved at the third and eighth notches, and the connection parts of the circular rings 81 and the third and eighth notches are all provided with friction pads 11; the side of the circular ring 81 connected with the inner layer connecting male buckle 17 away from the inner layer connecting female buckle 12 abuts against the side wall of the fixing ring 18, and the side of the circular ring 81 connected with the inner layer connecting female buckle 12 away from the inner layer connecting male buckle 17 abuts against the side wall of the retainer ring 9; the end portions of the support blocks 82 of the two support frames 8 all abut against the inner wall of the inner layer first sealing layer 5.

[0048] The difference between example 2 and example 1 is only that the through grooves 20 are alternately arranged on the inner and outer sides of the connecting blocks 19 on the same side.

[0049] The difference between example 3 and example 1 is only that the through grooves 20 and the connecting holes are alternately arranged on the eight connecting blocks 19 on the same side.

[0050] Taking example 1 as an example, the specific implementation process is as follows:

[0051] According to the geological conditions of the coal and rock stratum and the drilling requirements, a suitable drill bit is selected, and the drill bit and the hole bottom motor are installed at the front end of the flexible drill rod, that is, the end connected with the outer layer connecting male buckle 1, and the drilling machine is connected to the flexible drill rod near the connecting female buckle, and the connecting female buckle end is connected with the high-pressure air and water device. At the same time, it is ensured that the hole bottom motor is firmly connected with the flexible drill rod and the transmission is smooth.

[0052] During drilling operation, the flexible drill rod can perform positive circulation and reverse circulation drilling operation through the high-pressure air and water device. During positive circulation operation, the high-pressure liquid fireproof foam and gas are transported to the drill bit through the inner layer sealed channel. The high-pressure liquid fireproof foam and gas are formed into a rotational flow under the action of the helical blade 15 on the inner wall of the inner layer second sealing layer 14, which can more efficiently transport to the drill bit. The rotational flow not only can accelerate the transportation speed, but also can reduce the pressure loss of the fluid in the transportation process, so as to ensure that it still has sufficient cooling and lubricating capacity when it reaches the drill bit.

[0053] The drill bit generates drill cuttings during drilling, and the high-pressure gas carries the drill cuttings through the discharge channel into the annular gap of the outer sealed channel to return to the ground. Since the outer wall of the first sealing layer 5 of the outer drill rod is provided with a spiral groove 16, an orderly spiral flow is formed under the guidance of the spiral groove 16 when the drill is stuck, which prevents the drill rod from being stuck by the hole wall. The spiral groove 16 also increases the friction between the outer drill rod and the hole wall, so that the flexible drill rod is not easy to slide relatively due to the action of the stress of the coal seam and the like during the drilling process, thereby improving the stability of the flexible drill rod in the borehole. Even if the contact state between the outer drill rod and the hole wall changes due to the influence of the stress of the coal seam and the like during the drilling process, the first sealing layer 5 can be self-adaptively adjusted through the elastic deformation of itself.

[0054] During the reverse circulation operation, the high-pressure air and water device pumps the high-pressure liquid drilling medium and high-pressure gas from the outer sealed channel of the flexible drill rod, the drilling medium drives the hole bottom motor to work, and enters the hole bottom through the drill bit, carries the drill cuttings, and then returns to the ground through the inner sealed channel of the flexible drill rod, forming a reverse circulation of "in-out". The following advantages are obtained by adopting the outer circulation: 1. High discharge efficiency: the inner sealed channel has a high flow rate, which can effectively carry large particle drill cuttings, reduce repeated crushing at the hole bottom, and improve the drilling efficiency; suitable for deep holes or complex strata (such as broken zones and fractured strata), the discharge path is short and the resistance is small. 2. Good hole wall stability: the flushing medium enters the hole from the outer sealed channel, which has a small scouring effect on the hole wall, thereby reducing the risk of hole collapse. 3. High safety: the closed discharge system can reduce the escape of gas and dust, and is suitable for high-gas mines or explosive environments. 4. Excellent drilling quality: the drill cuttings are directly discharged from the inner sealed channel, reducing the pollution of the rock sample and making the sampling more accurate.

[0055] The specific use of the forward circulation and the reverse circulation is comprehensively considered according to the drilling depth, the stratum condition, the gas content and the like.

[0056] The above-mentioned is only an embodiment of the present application, and the well-known specific structure and characteristics and the like in the scheme are not described in detail. It should be pointed out that, for those skilled in the art, without departing from the structure of the present application, a number of modifications and improvements can be made, which should also be regarded as the protection scope of the present application, and these will not affect the effect and practicality of the present application. The protection scope claimed in the present application should be subject to the content of its claims, and the specific implementation mode and the like in the specification can be used to explain the content of the claims.

Claims

1. A flexible drill pipe comprising an outer pipe comprising an outer male coupling, an outer female coupling and a movable skeleton movably coupled therebetween, characterized in that: The axis direction of the movable framework is penetrated, and the outer wall and the inner wall of the movable framework are covered with a first sealing layer which is wear-resistant, pressure-resistant, corrosion-resistant and tough; the axis direction of the outer layer connecting male buckle and the outer layer connecting female buckle is penetrated, and the inner part of each is fixedly connected with a support frame; a gap is left between the support frame and the outer layer connecting male buckle and the outer layer connecting female buckle; the inner layer connecting male buckle and the inner layer connecting female buckle are fixedly connected on the two support frames respectively, and the inner layer connecting female buckle and the inner layer connecting male buckle are fixedly connected with a same inner layer drill rod, and the inner layer connecting female buckle, the inner layer connecting male buckle and the inner layer drill rod form an inner layer closed channel which is penetrated in the axis direction; the outer layer connecting male buckle, the outer layer connecting female buckle and the inner layer first sealing layer form an outer layer closed channel which is penetrated in the axis direction.

2. A flexible drill pipe as defined in claim 1, characterized by: The outer wall of the movable framework is fixedly sleeved with an outer layer steel wire mesh pipe, and the first sealing layer of the outer layer is covered on the outer wall of the outer layer steel wire mesh pipe.

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

4. A flexible drill pipe as defined in claim 3, wherein: 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 pipe as defined in claim 4, characterized by: The first sealing layer and the second sealing layer are both rubber layers, and the first sealing layer is fixedly connected with the outer layer steel wire mesh pipe and the movable framework by vulcanization adhesion; the second sealing layer is fixedly connected with the inner layer steel wire mesh pipe by vulcanization adhesion.

6. A flexible drill pipe as defined in claim 5, characterized by: The inner wall of the second sealing layer of the inner layer is provided with spiral blades made of rubber material which has the properties of toughness, wear resistance, pressure resistance and corrosion resistance, and the spiral blades are integrally formed on the second sealing layer by vulcanization adhesion.

7. A flexible drill pipe as defined in claim 6, characterized by: The outer wall of the first sealing layer of the outer layer is provided with spiral grooves.

8. A flexible drill pipe according to any one of claims 1 to 7, characterised in that: The movable framework comprises a plurality of connecting rod assemblies and connecting rings between adjacent connecting rod assemblies, each connecting rod assembly comprises a plurality of connecting rods, the connecting rods in the same group are distributed along the circumference, the connecting rods of adjacent two connecting rod assemblies are movably connected through the 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 pipe as defined in claim 8, characterized by: The two ends of the connecting rod are provided with through holes penetrating the thickness direction, the through holes at the two ends of the connecting rods in the same group are respectively connected by a fixed rope, and the two ends of the fixed rope are fixedly connected; a plurality of connecting blocks are circumferentially distributed on the two sides of the connecting ring, the ends of the connecting rods are located between adjacent connecting blocks, and the connecting rods and the connecting blocks in the same circumferential direction are connected by the fixed rope.

10. A flexible drill pipe as defined in claim 9, characterized by: The number of the connecting blocks on the same side of the connecting ring is not less than the number of the connecting rods in the same group, and the connecting blocks on the two sides of the connecting ring are provided with through grooves and / or connecting holes; the fixed rope is connected in the through groove and / or the connecting hole of the connecting block corresponding to the fixed rope, and the connecting rod is located between the adjacent connecting blocks on the connecting ring.

11. A flexible drill pipe as defined in claim 10, wherein: The opposite end outer walls of the outer layer connecting male buckle and the outer layer connecting female buckle are provided with neckings, and the end portions thereof are also circumferentially distributed with a plurality of connecting blocks, the number of the connecting blocks is not less than the number of the connecting rods in the same group, and the connecting blocks are also provided with through grooves and / or connecting holes; the fixed ropes on the connecting rod assemblies at the two ends are connected in the through grooves and / or the through holes of the corresponding connecting blocks, and the connecting rods are located between the adjacent connecting blocks on the connecting ring; the outer layer steel wire mesh pipe is respectively sleeved at the neckings of the outer walls of the outer layer connecting male buckle and the outer layer connecting female buckle, and the first sealing layer of the outer layer is fixed to the outer walls of the outer layer connecting male buckle and the outer layer connecting female buckle.

12. A flexible drill pipe as defined in claim 11, wherein: The groove opening directions of the through grooves on the connecting blocks on the two sides of the connecting ring are respectively towards the inner side and the outer side of the connecting blocks, or the groove opening directions of the through grooves on the multiple connecting blocks on the same side are alternately towards the inner side and the outer side of the connecting blocks.

13. A flexible drill pipe as defined in claim 12, wherein: The inner portion of the end of the outer layer connecting female buckle away from the outer layer connecting male buckle is also provided with a necking, the necking is provided with a stop ring, the stop ring is uniformly distributed with a plurality of grooves, the outer wall of the outer layer connecting female buckle is provided with a plurality of stepped grooves matched with the grooves, the stepped grooves are provided with wedge blocks, and the wedge blocks extend into the corresponding grooves.

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