WO2023000649A1

WO2023000649A1 - Dual pipe

Info

Publication number: WO2023000649A1
Application number: PCT/CN2022/075206
Authority: WO
Inventors: 徐梓辰
Original assignee: 万晓跃
Priority date: 2021-07-19
Filing date: 2022-01-30
Publication date: 2023-01-26

Abstract

A dual pipe, comprising an inner pipe column (1) and a flexible outer pipe column (4). The lower end of the inner pipe column is connected to a guide device (2). The lower end of the guide device is connected to a drill bit (3). The guide device can drive the drill bit to deflect by a preset angle, and the interior of the inner pipe column is provided with a through flow channel (11) used for circulating a drilling circulation medium. The flexible outer pipe column is sleeved on the exterior of the inner pipe column. An annular space (5) for circulating the drilling circulation medium is formed between the flexible outer pipe column and the inner pipe column, and the upper portion of the guide device or the lower portion of the inner pipe column is hinged to the lower portion of the flexible outer pipe column. Under the condition that the dual pipe rotates, the drill bit can be driven by the guide device to deflect by a preset angle in a preset direction, so as to change the trajectory of a borehole, thereby achieving a short build-up rate.

Description

Double pipe related application This application claims the priority of the Chinese invention patent with the patent application number 202110814021.7, the application date is 2021.07.19, and the invention name is "double pipe"; this application requires the patent application number 202121638377.1, and the application date is 2021.07.19 1. Priority of Chinese utility model patent titled "double pipe" Technical field The present invention relates to the field of drilling technology and oil and gas production technology, especially a kind of double pipe. BACKGROUND OF THE INVENTION Exploration and development of underground material resources and space resources require extensive application of drilling techniques. The existing steering drilling technologies mainly include downhole motor steering drilling technology and rotary steering drilling technology. The maximum slope build-up rate achievable by the above-mentioned technologies generally does not exceed 15°/30 meters. For shallow formations, soft formations and fragile formations, there is currently no effective way to develop horizontal wells, directional wells or lateral wells. Aiming at the problems of shallow formations, soil layers, soft formations and fragile formations that are prone to collapse, the present invention proposes to use double flexible pipes with guiding devices to realize high-curvature controllable trajectory drilling or realize extended well sections through high-curvature well sections drilling. The advantage is that during the drilling process, the hinged flexible outer pipe is used as the protective pipe to protect and support the well wall, and the flexible inner pipe string and the hinged flexible outer pipe string form a circulation channel for drilling fluid circulation, which realizes the drilling fluid circulation. circulation, avoiding the drilling fluid from directly scouring the formation; avoiding the collapsed objects from directly blocking the wellbore; when the formation collapses, the bearing body and the drill bit can be pulled out directly through the inner flexible pipe, and the outer flexible pipe is left in the formation to reach the casing or conduit or pile foundation Effect. SUMMARY OF THE INVENTION The object of the present invention is to provide a dual pipe enabling steerable drilling with a certain borehole extension. The above object of the present invention can be achieved by the following technical solutions: The present invention provides a double pipe, which includes: an inner pipe string, the lower end of which is connected with a guide device, the lower end of the guide device is connected with a drill bit, and the guide device The drill bit can be driven to deflect at a preset angle, and the inside of the inner pipe string is provided with a through flow channel for circulation of drilling circulating medium; a flexible outer pipe string, which is sleeved outside the inner pipe string, and an annular space for the circulation of the drilling circulating medium is formed between the flexible outer pipe string and the inner pipe string, and the guide device The upper part or the lower part of the inner pipe string is hinged to the corresponding position of the lower part of the flexible outer pipe string. The characteristics and advantages of the present invention are: the double pipe of the present invention, by setting the guide device, under the condition of rotation, the drill bit can be driven by the guide device to deflect the preset angle according to the preset direction, so as to change the trajectory of the wellbore, so as to realize short Radius build-up; By setting the flexible outer pipe string, under the condition of rotation, the torque used to drive the drill bit to rotate can be well transmitted to the steering device, so as to realize steerable drilling with a certain wellbore extension length. BRIEF DESCRIPTION OF THE DRAWINGS The following drawings are only intended to illustrate and explain the present invention schematically, and do not limit the scope of the present invention. Wherein: Fig. 1 is a kind of structural representation of double pipe of the present invention; Fig. 2 is another kind of structural representation of double pipe of the present invention; Fig. 3 is another kind of structural representation of double pipe of the present invention; Fig. 4 is this Yet another structural schematic view of the double pipe of the invention; FIG. 5 is a diagram of the installation structure of the double pipe of the present invention; FIG. 6 is a partial enlarged view of A in FIG. 4 . Explanation of reference numbers:

1. Inner pipe string; 11. Through flow channel; 111. Pressure hose; 112. Rigid pipe string;

2. Guide device; 21. Sleeve; 22. Bearing body; 23. Transmission shaft;

24. The first hinged structure; 25. Driving the hydraulic cylinder;

26. Eccentric ring; 27. Electric drive actuator;

28. The second hinged structure; 291. The first centralizing structure; 292. The second centralizing structure;

3. Drill bit; 4. Flexible outer pipe string; 41. Outer connection pup joint; 42. Outer hinged structure;

5. Annular space; 51. Righting bearing; 52. Hydraulic system; 53. Electric energy transmission device;

6. Suspension device; 7. Centralizing device; 71. Centralizing bearing; 72. Roller centralizer;

9. Jumper wires; 99. Power mechanism. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS In order to have a clearer understanding of the technical features, purposes and effects of the present invention, the present invention will now be described with reference to the accompanying drawings specific implementation. In the description of the present invention, unless otherwise specified, "plurality" means two or more. In order to have a clearer understanding of the technical solutions, objectives and effects of the present invention, specific implementations of the present invention will now be described in conjunction with the accompanying drawings. Wherein, the use of adjective or adverbial modifiers "upper" and "lower", "inner" and "outer" is only to facilitate relative reference between groups of terms, and does not describe any specific Orientation constraints. In addition, the terms "first", "second", etc. are only used for descriptive purposes, and cannot be understood as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Features such as "two" can explicitly or implicitly include one or more of these features. In the description of the present invention, unless otherwise specified, the meaning of "multiple" is two or more. Scheme 1 is shown in Fig. 1. As shown in FIG. 2 and FIG. 3, the present invention provides a double pipe, which includes an inner pipe string 1 and a flexible outer pipe string 4, wherein: the lower end of the inner pipe string 1 is connected with a guide device 2, and the guide device 2 The lower end is connected with a drill bit 3, and the guide device 2 can drive the drill bit 3 to deflect a preset angle, that is, the guide device 2 can drive the drill bit 3 to deflect a preset angle in a preset direction, thereby changing the wellbore trajectory to achieve a short build-up rate; The inside of the pipe string 1 is provided with a through flow channel 11 for the circulation of the drilling circulation medium. The drilling circulation medium can flow to the drill bit 3 through the through flow channel 11, so as to carry the rock deviation at the drill bit 3 and return through the annular space between the inner and outer pipe strings. , wherein, the specific structure and working principle of the drill bit 3 are all existing technologies, and will not be repeated here; the flexible outer string 4 is sleeved outside the inner string 1, and the flexible outer string 4 and the inner string 1 An annular space is formed between them for circulation of the drilling circulating medium, and the drilling circulating medium can return to the wellhead from the annular space, and the upper part of the guide device 2 or the lower part of the inner pipe string 1 is hinged to the corresponding position of the lower part of the flexible outer pipe string 4, so that the flexible The outer pipe string 4 can not only transmit the WOB torque to the guide device 2, but also protect the inner pipe string 1. The double pipe of the present invention, by setting the guide device 2, can pass through the guide device 2 under the condition of rotation. The device 2 drives the drill bit 3 to deflect the preset angle according to the preset direction to change the wellbore trajectory, thereby realizing short-radius deflection; by setting the flexible outer string 4, the steering device 2 can be well guided under the condition of rotation The torque used to drive the rotation of the drill bit 3 is transmitted, so as to realize steerable drilling with a certain wellbore extension length. Further, as shown in Figure 1, Figure 2 and Figure 3, the flexible outer string 4 includes a plurality of sequentially hinged from top to bottom The outer connecting short joints 41 of the two adjacent outer connecting joints 41 are connected through the outer hinge structure 42, and the lowermost outer connecting joints 41 are connected with the upper end of the guide device 2, that is, the flexible outer pipe string 4 It is a hinged structure. Due to the large diameter of the flexible outer pipe string 4, in order to meet the requirements of deflection, the flexibility of the flexible outer pipe string 4 can be increased to the greatest extent by using a hinged joint. Among them, the outer hinge structure 42 may be the matching structure of the universal joint and the sleeve 21 in the prior art, or the matching structure of the ball seat and the ball head in the prior art, which will not be repeated here. Certainly, the flexible outer pipe string 4 may also be a slotted pipe, and, in order to ensure the tightness of the annular space, the slots of the slotted pipe are filled with sealing material. Further, the inner pipe string 1 is a pressure-bearing hose 111 or a rigid pipe string 112. During use, the pressure-bearing hose 111 or the rigid pipe string 112 can be selected as the inner pipe string 1 according to the trajectory of the drilled well. Further, as shown in Fig. 1, Fig. 2 and Fig. 3, a plurality of centralizing devices 7 arranged at intervals are arranged between the flexible outer pipe string 4 and the inner pipe string 1, and the centralizing devices 7 can keep the inner pipe string 1 and the flexible outer pipe An annular space is always formed between the strings 4 to ensure that the circulating medium can flow from the inside of the inner string 1 to the drill bit 3, and then return to the wellhead from the annular space between the inner string 1 and the flexible outer string 4. Further, a stabilizing device 7 is provided between each outer connecting sub-section 41 and the inner pipe string 1 to avoid buckling or twisting between each outer connecting sub-section 41, which hinders the transmission of the WOB torque, so that the WOB torque can be Passed smoothly. Further, as shown in FIGS. 1 and 2, the centralizing device 7 is a centralizing bearing 71 or a roller centralizer 72. Specifically, both the centralizing bearing 71 and the roller centralizer 72 can make the inner pipe string 1 relatively flexible to the outer pipe string 4. Rotate to transmit drilling power during the process of inserting into mud or other rheological formations. Preferably, the roller centralizer 72 can also play a supporting role. Further, as shown in FIG. 2, a suspension device 6 is connected between the inner pipe string 1 and the flexible outer pipe string 4, and the suspension device 6 is located on the upper part of the inner pipe string 1. Specifically, when the inner pipe string 1 is a rigid pipe string When 112, the suspension device 6 includes a thrust bearing and a righting bearing 71, or a composite bearing with both righting and thrust functions, so that the axial displacement of the inner pipe string 1 and the flexible outer pipe string 4 does not occur, and the inner pipe string 4 can not be hindered at the same time. The tubular string 1 rotates inside the flexible outer tubular string 4 . Further, as shown in Figure 1, Figure 2 and Figure 3, the steering device 2 is connected to the wellhead control terminal through a jumper line 9, and the control terminal of the wellhead can issue control instructions to the steering device 2. In addition, the control terminal of the wellhead can also guide the steering device. The device 2 transmits electric power to avoid the extra cost and the risk of power failure caused by downhole power generation; in the embodiment shown in Fig. It is transmitted to the hydraulic system 52 to realize steering control. Further, as shown in Fig. 1, Fig. 2 and Fig. 3, the guiding device 2 includes a transmission shaft 23, a bearing body 22 and a sleeve 21 which are sheathed sequentially from the inside to the outside, and the upper end of the sleeve 21 and the flexible outer pipe column 4 The lower end is hinged, the upper end of the bearing body 22 is connected to the lower end of the inner pipe string 1, the lower end of the transmission shaft 23 is connected to the drill bit 3, and an annular movable space is provided between the transmission shaft 23 and the bearing body 22, and a deflection is provided in the annular movable space. mechanism, the deflection mechanism can drive the transmission shaft 23 to move relative to the bearing body 22, so as to drive the drill bit 3 to deflect a preset angle in a preset direction, thereby changing the wellbore trajectory, Thereby realizing short-radius build-up. In one embodiment of the present invention, as shown in FIG. 1 and FIG. 2, the upper part of the sleeve 21 is connected to the transmission shaft 23 or the bearing body 22 through a first hinge structure 24, and the deflection mechanism includes at least three sets of edges The driving hydraulic cylinders 25 arranged at intervals in the lower part of the bearing body 22 in the circumferential direction, preferably, the driving hydraulic cylinders 25 are evenly arranged along the circumference of the bearing body 22, and the driving hydraulic cylinders 25 include pistons arranged in the outer wall of the bearing body 22 The structure accommodation cavity and the driving piston structure arranged in the piston structure accommodation cavity, the driving piston structure can push the transmission shaft 23 and the bearing body 22 to rotate relative to the sleeve, so that the drill bit 3 at the lower end of the bearing body 22 can cut the symmetrical orientation laterally strata. In another embodiment of the present invention, as shown in FIGS. 4, 5 and 6, the lower part of the sleeve 21 is connected to the transmission shaft 23 or the bearing body 22 through a first hinge structure 24, and the driving piston structure can Push the transmission shaft 23 and the bearing body 22 to deflect relative to the sleeve. At this time, the bearing body and the transmission shaft use the first hinge structure 24 as a fulcrum to pry the drill bit to cut the formation in the corresponding orientation. It should be noted that the transmission shaft 23 and the bearing body 22 are two independent blocks connected by a central bearing; or, the bearing body 22 itself plays the role of a transmission shaft, driving the drill bit to rotate to cut the formation, that is, the implementation In this case, the separate transmission shaft 23 can be omitted. In addition, drill bits include hydrojet bits for cutting broken soft formations. In another embodiment of the present invention, as shown in Figure 3, the deflection mechanism includes an eccentric ring 26 and an electric drive actuator 27, the electric drive actuator 27 is arranged on the bearing body 22, and the eccentric ring 26 is arranged on the drive shaft 23 and the Between the bearing bodies 22, the lower part of the transmission shaft 23 and the bearing body 22 are connected through a second hinge structure 28. The electric drive actuator 27 can drive the eccentric ring 26 to rotate, and the rotation of the eccentric ring 26 can drive the transmission shaft 23 and the bearing body. The body 22 moves relative to each other. Specifically, the electrical actuator is a drive motor, which can drive the eccentric ring 26 to rotate, and the rotation of the eccentric ring 26 can drive the transmission shaft 23 to swing around the second hinge structure 28 and/or around the bearing body 22 The axis of rotation; the upper part of the bearing body 22 and the sleeve 21 is provided with a first centralization structure 291, the lower part of the bearing body 22 and the sleeve 21 is provided with a second centralization structure 292, and the second hinged structure 28 is located at the first Between the centralizing structure 291 and the second centralizing structure 292, the first centralizing structure 291 and the second centralizing structure 292 can ensure that the controllable flexible WOB torque transmission string is always coaxial with the borehole. It should be noted that the specific working principle of the above-mentioned deflection mechanism is the prior art, and will not be repeated here. Of course, the deflection mechanism can also adopt any other existing structure that can drive the drill bit to deflect the preset angle according to the preset direction. To sum up, the double pipe of the present invention is provided with a guide device so that under the condition of rotation, the drill bit can be driven by the guide device to deflect a preset angle in a preset direction, so as to change the wellbore trajectory, thereby achieving short-radius deflection ; By setting the flexible outer pipe string, under the condition of rotation, the torque for driving the drill bit to rotate can be well transmitted to the steering device, so as to realize the steerable drilling with a certain wellbore extension length. Scheme 2 As shown in Figures 1-4 and Figure 6, the present invention provides a double pipe, which includes: an inner pipe string 1, a guide device 2 is connected to the lower end of the guide device 2, and a drill bit 3 is connected to the lower end of the guide device 2 , the guiding device 2 can drive the drill bit 3 to deflect at a preset angle, and the interior of the inner pipe string 1 is provided with a through flow channel for the circulation of drilling circulating medium; the flexible outer pipe string 4 is sleeved on the outside of the inner pipe string 1 and is flexible An annular space for circulation of drilling circulating medium is formed between the outer string 4 and the inner string 1 . Under the conditions of the present invention, when drilling in the positive circulation mode, the drilling circulation medium can flow through the through flow channel inside the inner pipe string 1, flow through the bearing body or the transmission shaft, and then flow through the drill bit to remove the rock and soil debris at the bottom of the well. It is taken away from the bottom of the well, then flows through the annular space between the bearing body and the sleeve, and then continues to flow through the annular space formed between the flexible outer string 4 and the inner string 1 to return to the wellhead. Alternatively, under the conditions of the present invention, when the reverse circulation drilling method is used for drilling, the drilling circulation medium can pass through the annular space formed between the flexible outer string 4 and the inner string 1, and flow to the annular space between the sleeve and the bearing body , and then flows through the drill bit to take the rock and soil fragments at the bottom of the well away from the bottom of the well, and the returned drilling circulating medium flows to the inner pipe string through the through passage in the bearing body or the transmission shaft, and returns to the wellhead through the inner pipe string. The circulation modes of the above two drilling circulating media can largely avoid the erosion of the soil by the drilling fluid. As shown in Figures 4 and 6, an annular space 5 is always formed between the inner pipe string 1 and the flexible outer pipe string 4 to ensure that the circulating medium can flow from the inside of the inner pipe string 1 to the drill bit 3, and then from the inner pipe string 1 and the flexible outer pipe string 4. The annular space 5 between the flexible outer string 4 returns to the wellhead, or the circulating medium can flow from the annular space 5 between the inner string 1 and the flexible outer string 4 to the drill bit 3, and then return to the wellhead from inside the inner string 1. The above has described the technical solution of using the steering device 2 to drive the drill bit 3 to deflect at a preset angle in a preset direction, so as to change the wellbore trajectory. Specifically, when the drill bit 3 is deflected, and when the drill bit 3 cuts the side wall of the wellbore laterally, the wellbore trajectory will be deflected to this side, thereby changing the wellbore trajectory. The steering device 2 drives the drill bit 3 to deflect by a preset angle to deflect the wellbore trajectory. Since the flexible outer tubing string 4 is flexible, the flexible outer tubing string 4 will also deflect along with the deflection of the wellbore trajectory. The guide device 2 can be fixedly connected to the lower end of the flexible outer pipe string 4 , and the guide device 2 deflects together with the flexible outer pipe string 4 . In order to facilitate the change of trajectory of the double pipe and make the deflection more flexible, in one embodiment, the guide device 2 and the flexible outer pipe string 4 can be connected in a hinged manner, specifically, the guide device 2 and the flexible outer pipe string 4 The hinges are realized through the outer hinge structure 42. In another embodiment, the guide device 2 is connected to the lower end of the inner pipe string 1, and the guide device 2 is connected to the lower end of the inner pipe string 1. When the wellbore trajectory is deflected, the guide device 2 can deflect relative to the flexible outer pipe string 4. . In one embodiment, the guiding device includes a bearing body and a sleeve, and the upper end of the sleeve is connected with the lower part of the flexible outer string Hinged, the upper end of the bearing body is connected to the lower end of the inner pipe string, and the drill bit is connected to the lower end of the bearing body. The guide device 2 and the flexible outer pipe string 4 are hinged through the casing 21 being hinged to the flexible outer pipe string 4 . Further, the bearing body 22 can deflect relative to the sleeve 21, thereby driving the drill bit 3 to deflect. Further, as shown in Figures 1 and 2, the guiding device 2 also includes a transmission shaft 23, the upper end of the sleeve 21 is hinged to the lower end of the flexible outer pipe string 4, the upper end of the transmission shaft 23 is connected to the lower end of the inner pipe string 1, and the transmission The lower end of the shaft 23 is in contact with the drill bit 3 . The bearing body 22 is rotatably connected to the transmission shaft 23 through a central bearing 51 , and the transmission shaft 23 can rotate around its own axis. In this embodiment, the drill bit 3 is connected with the bearing body 22 through the transmission shaft 23 . As shown in FIG. 3 , the transmission shaft 23 can deflect relative to the sleeve 21, and the drill bit 3 is connected to the lower end of the transmission shaft 23, thereby driving the drill bit 3 to deflect, so that the guide device 2 drives the drill bit 3 to deflect by a preset angle. As shown in FIG. 1 and FIG. 2 , the sleeve 21 and the bearing body 22 are connected through a first hinge structure 24 , and the first hinge structure 24 is arranged on the upper part of the sleeve 21 . The first hinged structure 24 is not limited to be disposed on the upper part of the sleeve 21 , but can also be disposed on the middle or lower part of the sleeve 21 , and the first hinged structure 24 serves as a fulcrum for the bearing body 22 to rotate relative to the sleeve 21 . The structure in which the sleeve 21 and the bearing body 22 are connected through the first hinge structure 24 has been introduced above. The connection between the sleeve 21 and the bearing body 22 is not limited to the first hinge structure 24. The sleeve 21 and the bearing body 22 Other structures capable of realizing the deflectable connection between the bearing body 22 and the sleeve 21 may also be used. The bearing body 22 is connected to the inner pipe string 1. As another embodiment, the rotatable connection structure can also be arranged between the inner pipe string 1 and the sleeve 21, that is, the inner pipe string 1 and the sleeve 21 are rotatable. ground connection, the bearing body 22 drives the inner pipe string 1 to deflect together relative to the sleeve 21; or, as shown in FIG. 4 and FIG. As shown in FIG. 3 , the connection structure between the transmission shaft 23 and the bearing body 22 through the second hinge structure 28 has been introduced above. The connection between the transmission shaft 23 and the bearing body 22 is not limited to the use of the second hinged structure 28, and other rotatably connected structures can also be used between the transmission shaft 23 and the bearing body 22, and the rotatably connected structure serves as the transmission shaft 23 is a fulcrum for rotation relative to the bearing body 22 . As shown in Figure 3, a first centering structure 291 is provided between the upper part of the bearing body 22 and the sleeve 21, and the bearing body

A second supporting structure 292 is provided between the lower part of 22 and the sleeve 21 . The transmission shaft 23 is connected with a deflection mechanism, and the deflection mechanism can drive the transmission shaft 23 to deflect relative to the sleeve 21 . Specifically, the deflection mechanism drives the transmission shaft 23 and the bearing body 22 to deflect relative to the sleeve 21; A deflection movement takes place so that a relative deflection of the transmission shaft 23 relative to the sleeve 21 is achieved. The bearing body is provided with at least one group of driving hydraulic cylinders, and the driving hydraulic cylinders include a piston structure accommodating chamber arranged in the outer wall of the bearing body and a driving piston structure arranged in the piston structure accommodating chamber; the driving piston structure can push the bearing body Relative sleeve deflection movement. Further, as shown in FIG. 1 and FIG. 2, the deflection mechanism includes at least three sets of driving hydraulic cylinders 25 arranged at intervals along the circumferential direction of the bearing body 22. Preferably, each driving hydraulic cylinder 25 is evenly arranged along the circumferential direction of the bearing body 22. In other words, the driving piston structure can push the bearing body 22 to move relative to the sleeve 21, so that the drill bit 3 at the lower end of the bearing body 22 can laterally cut the formation in a symmetrical orientation. Further, the first hinged structure is arranged under the driving hydraulic cylinder, or the driving hydraulic cylinder is arranged under the first hinged structure. A hydraulic system 52 is also provided on the bearing body, and the hydraulic system 52 is used to adjust the hydraulic pressure inside the driving hydraulic cylinder and is used to abut against the sleeve. As shown in Figure 3, the deflection mechanism includes an eccentric ring 26 and an electric drive actuator 27, the electric drive actuator 27 is arranged on the carrying body 22, the eccentric ring 26 is arranged between the transmission shaft 23 and the carrying body 22, and the electric drive actuator 27 can drive the eccentric ring 26 to rotate, and the rotation of the eccentric ring 26 can drive the transmission shaft 23 and the bearing body 22 to move relative to each other. Specifically, the electrical actuator is a drive motor, and the drive motor can drive the eccentric ring 26 to rotate. The driving transmission shaft 23 swings around the second hinge structure 28 and/or rotates around the axis of the bearing body 22 . The connection structure of the deflection mechanism, the transmission shaft 23 and the bearing body 22 has been introduced above, and will not be repeated here. The deflection mechanism can adopt the structure in the prior art. As shown in Fig. 5, the wellhead is provided with a power mechanism 99, and the power mechanism 99 is connected with the inner pipe string 1 and/or the flexible outer pipe string 4, so as to provide the drill bit 3 with a rotating break through the inner pipe string 1 and/or the flexible outer pipe string 4. Rock required torque. The power mechanism is a top drive device, a screw motor, a turntable device or other rotary drive devices with equivalent functions. A plurality of centralizing devices arranged at intervals are arranged between the flexible outer pipe string and the inner pipe string; the centralizing devices are fixedly connected to the outer side of the flexible outer pipe string, and the centralizing devices are provided with holes for circulation of drilling circulating medium. The centralizing device can be a centralizing bearing or a roller centralizer. The flexible outer pipe string includes a plurality of outer connection sub-joints hinged sequentially from top to bottom. Two adjacent outer connection sub-joints are connected by an outer hinge structure, and the outermost connection sub-joint at the bottom is connected with the guide device. Further, a stabilizing device is provided between each outer connection nipple and the inner pipe string. The inner pipe string is a pressure hose, a composite material pipe string or an elastic metal pipe string. The inner tubing string may consist of multiple interconnected pup joints. A suspension device is connected between the inner pipe string and the flexible outer pipe string, and the suspension device is located on the upper part of the inner pipe string. The suspension device is also provided with holes for circulation of drilling circulation medium. Structures such as jumper wires have already been described in Scheme 1, and will not be repeated here. The above descriptions are only illustrative specific implementations of the present invention, and are not intended to limit the scope of the present invention. Any equivalent changes and modifications made by those skilled in the art without departing from the concepts and principles of the present invention shall fall within the protection scope of the present invention.

Claims

claims

1. A double pipe, wherein, the double pipe includes: an inner pipe string, the inner pipe string is provided with a through flow channel for the circulation of the drilling circulating medium; a guide device connected to the lower end of the inner pipe string, the A drill bit is connected to the lower end of the guide device, and the guide device can drive the drill bit to deflect by a preset angle; a flexible outer pipe string is sleeved outside the inner pipe string, and the flexible outer pipe string is connected to the An annular space for circulation of the drilling circulation medium is formed between the inner pipe strings.

2. The double pipe according to claim 1, wherein the upper part of the guide device is hinged to the corresponding position between the lower part of the flexible outer pipe string.

3. The double pipe according to claim 1, wherein, the flexible outer pipe string includes a plurality of outer connection sub-joints hinged sequentially from top to bottom, and two adjacent outer connection sub-joints are connected through outer hinges The structures are connected, and the lowermost outer connecting short joint is connected with the guide device.

4. The double pipe according to claim 3, wherein, a plurality of centralizing devices arranged at intervals are provided between the flexible outer pipe string and the inner pipe string; the centralizing devices are fixedly connected to the flexible outer pipe The outside of the column, and the centralizing device is provided with a hole through which the drilling circulating medium can circulate.

5. The double pipe according to claim 1, wherein the inner pipe string is a pressure-bearing hose, a composite material pipe string or an elastic metal pipe string.

6. The double pipe according to claim 1, wherein a suspension device is connected between the inner pipe string and the flexible outer pipe string, and the suspension device is located on the upper part of the inner pipe string.

7. The double pipe according to any one of claims 1-6, wherein the guide device comprises a bearing body and a sleeve, the upper end of the sleeve is hinged to the lower part of the flexible outer pipe string, the The upper end of the bearing body is connected to the lower end of the inner pipe string, and the drill bit is connected to the lower end of the bearing body.

8. The double pipe according to claim 7, wherein, the guide device further comprises a transmission shaft, the transmission shaft is rotatably connected to the bearing body, and the transmission shaft can rotate on its own axis as the axis movement, the drill bit is connected to the lower end of the transmission shaft; the transmission shaft can be relatively deflected relative to the sleeve.

9. The double pipe according to claim 7 or 8, wherein, the load-bearing body and the sleeve are deflectably connected, and/or, the transmission shaft and the sleeve are deflectably connected connect.

10. The double pipe according to claim 8, wherein, the transmission shaft and the bearing body are rotatably connected through centralizing bearings.

11. The double tube according to claim 7, 8 or 9, wherein, the sleeve and the bearing body are communicated connected through the first hinge structure.

12. The dual pipe according to claim 8 or 9, wherein the first hinge structure connects the transmission shaft and the sleeve respectively.

13. The double pipe according to claim 7, wherein, at least one set of driving hydraulic cylinders is provided on the bearing body, and the driving hydraulic cylinders include a piston structure accommodation chamber and a piston structure disposed in the outer wall of the bearing body A driving piston structure disposed in the piston structure accommodating cavity; the driving piston structure can push the bearing body to deflect and move relative to the sleeve.

14. The double pipe according to claim 11 or 12, wherein, at least one set of driving hydraulic cylinders is provided on the bearing body, and the driving hydraulic cylinders include a piston structure accommodated in the outer wall of the bearing body a cavity and a driving piston structure disposed in the piston structure accommodating cavity; the driving piston structure can push the bearing body to deflect and move relative to the sleeve; the first hinge structure is disposed below the driving hydraulic cylinder, or , the driving hydraulic cylinder is arranged below the first hinged structure.

15. The double pipe according to claim 13 or 14, wherein a hydraulic system is further provided on the bearing body, and the hydraulic system is used to adjust the hydraulic pressure inside the driving hydraulic cylinder for abutting against the sleeve.

16. A double pipe, wherein the double pipe comprises: an inner pipe string, a guide device is connected to the lower end of the guide device, a drill bit is connected to the lower end of the guide device, and the guide device can drive the drill bit to deflect by a preset angle, The inside of the inner pipe string is provided with a through flow channel for the circulation of drilling circulating medium; the flexible outer pipe string is sleeved outside the inner pipe string, and the flexible outer pipe string and the inner pipe string An annular space for circulation of the drilling circulating medium is formed between them, and the upper part of the guide device or the lower part of the inner pipe string is hinged to the corresponding position of the lower part of the flexible outer pipe string.

17. The double pipe according to claim 16, wherein, the flexible outer pipe string includes a plurality of outer connection sub-joints hinged sequentially from top to bottom, and two adjacent outer connection sub-joints are connected through outer hinges The structures are connected, and the lowermost outer connecting short joint is connected with the guide device.

18. The double pipe according to claim 17, wherein a plurality of spaced apart centralizing devices are provided between the flexible outer pipe string and the inner pipe string.

19. The double pipe according to claim 18, wherein the centralizing device is a centralizing bearing or a roller centralizer.

20. The double pipe according to claim 18, wherein, between each of the outer connecting nipples and the inner pipe string