Flexible pup joints and downhole operation tools

Abstract

The embodiments of the present application relate to the technical field of oil and gas drilling, and specifically to a flexible short joint and downhole operation tool. By arranging a connector in the first hollow cylindrical structure of the flexible drill collar, arranging a fixing portion at intervals on the inner wall of the connector, and extending the fixing portion toward the outer wall of the end of the connecting pipe, the connecting pipe is arranged in the flexible drill collar, and the second hollow cylindrical structure formed on the inner wall of the connecting pipe forms a channel for wiring. The power supply and signal lines of the downhole equipment pass through the second hollow structure, and there is no need to drill holes on the inner wall of the flexible drill collar to arrange the wiring channel, thereby improving the structural strength of the flexible drill collar and enabling the flexible drill collar to exert better bending performance. An annular flow channel is formed between the outer wall of the connecting pipe and the inner wall of the flexible drill collar, and mud flows through the annular flow channel. Due to the protection of the connecting pipe, the downhole line is not easily damaged by mud erosion.

Description

Technical Field

[0001] The embodiments of the present invention relate to the technical field of oil and natural gas drilling, and in particular to a flexible pup joint and a downhole operating tool. Background Art

[0002] Currently, over 40% of directional wells drilled in oil exploration and development utilize rotary steerable systems. The advantage of rotary steerable systems is their ability to control downhole drilling direction in real time, adjusting the drilling direction by changing the drill bit. During this process, the tubing string bends with the steerable system's drilling direction. The primary bending point in the tubing string is the flexible sub, which can bend in any direction, providing a fulcrum for the steerable system and altering the instrument's stress state, thereby increasing or decreasing the wellbore's inclination and controlling the wellbore trajectory.

[0003] The inventors of the present application have found in their research that the existing flexible pup joints generally have complex structures, and their bending and sealing properties cannot well meet the requirements of the flexible pup joints, which affects the applicability and stability of the flexible pup joints. Summary of the Invention

[0004] In view of the above problems, embodiments of the present invention provide a flexible pup joint and a downhole operating tool to solve the above problems in the prior art.

[0005] According to one aspect of an embodiment of the present invention, a flexible sub is provided, comprising: a flexible drill collar, a connecting pipe, and a connector. The inner wall of the flexible drill collar forms a first hollow cylindrical structure, the connector is disposed within the first hollow cylindrical structure, and fixing portions are disposed at intervals on the inner wall of the connector. The fixing portions extend toward the outer wall of the end of the connecting pipe and are used to position the connecting pipe within the flexible drill collar.

[0006] The inner wall of the connecting pipe forms a second hollow cylindrical structure, an annular flow channel is formed between the outer wall of the connecting pipe and the inner wall of the flexible drill collar, and the second hollow cylindrical structure is used to form a wiring channel.

[0007] The technical solution provided by the embodiment of the present application is to arrange a connector in the first hollow cylindrical structure of the flexible drill collar, arrange a fixing portion at intervals on the inner wall of the connector, extend the fixing portion toward the outer wall of the end of the connecting pipe, arrange the connecting pipe in the flexible drill collar, and form a second hollow cylindrical structure formed on the inner wall of the connecting pipe to form a channel for wiring. The power supply and signal lines of the downhole equipment pass through the second hollow structure, and there is no need to drill holes on the inner wall of the flexible drill collar to arrange the wiring channel, thereby improving the structural strength of the flexible drill collar and enabling the flexible drill collar to exert better bending performance. An annular flow channel is formed between the outer wall of the connecting pipe and the inner wall of the flexible drill collar, and mud flows through the annular flow channel. Due to the protection of the connecting pipe, the downhole line is not easily damaged by mud erosion. According to the actual operation situation, an external centralizer can be installed at one end of the flexible drill collar to provide support when the flexible short section bends and abuts against the well wall. When the external centralizer needs to be disassembled, since the power supply and signal lines in the flexible short section are arranged in the connecting pipe, the disassembly between the flexible drill collar and the external centralizer will not affect the line connection. The external centralizer can be quickly and conveniently disassembled from one end of the flexible drill collar. It has a wide applicability and ensures the stability and efficiency of downhole operations.

[0008] In one optional embodiment, the present application provides a flexible sub, comprising a flexible drill collar, a connecting pipe, and a connector. The inner wall of the flexible drill collar forms a first hollow cylindrical structure, within which a connector is disposed. The inner wall of the connector is provided with a fixing portion spaced apart, extending toward the outer wall of the connecting pipe end, for securing the connecting pipe within the flexible drill collar. The inner wall of the connecting pipe forms a second hollow cylindrical structure, with a first annular flow channel formed between the outer wall of the connecting pipe and the inner wall of the flexible drill collar. The second hollow cylindrical structure is used to form a routing channel. By disposing a connecting pipe having a second hollow cylindrical structure within the first hollow cylindrical structure of the flexible drill collar and securing the connecting pipe within the flexible drill collar via the connector, the second hollow cylindrical structure serves as a channel for downhole routing. Because the connecting pipe protects the line, the risk of damage to the line caused by mud scour is reduced. An annular flow channel is formed within the first hollow cylindrical structure through the outer wall of the connecting pipe and the inner wall of the flexible drill collar, serving as a mud channel and ensuring smooth mud flow through the flexible sub. Since the downhole line is arranged in the second hollow cylindrical structure of the connecting pipe, there is no channel for arranging the downhole line on the flexible drill collar, and there is no need to drill holes in the flexible drill collar, which ensures the structural strength of the flexible drill collar, improves the bending performance of the flexible drill collar, and reduces the difficulty of production and assembly.

[0009] In an optional manner, an internal stabilizer is sleeved on the outer wall of the connecting pipe, and protrusions are spaced apart on the outer wall of the internal stabilizer, which abut against the inner wall of the flexible drill collar, so as to make the central axis of the connecting pipe coincide with the central axis of the flexible drill collar. By sleeved on the outer wall of the connecting pipe with the internal stabilizer, the protrusions spaced apart on the internal stabilizer abut against the outer wall of the flexible drill collar, so that the connecting pipe can be better maintained in the flexible drill collar. While the connector fixes the connecting pipe, the internal stabilizer is used to abut and fix the connecting pipe against the inner wall of the flexible drill collar, thereby reducing the risk of wear of the outer wall of the connecting pipe and the inner wall of the flexible drill collar caused by the tilt of the connecting pipe during downhole operations. At the same time, it also ensures the stability of the annular flow channel formed between the outer wall of the connecting pipe and the inner wall of the flexible drill collar, and the circulation of mud is not easily affected.

[0010] In one optional embodiment, the convex portion is made of rubber. When the internal centralizer supports the connecting pipe, the convex portion on the internal centralizer, made of rubber, has excellent cushioning capacity. When the flexible sub is used in downhole operations and the pipe string vibrates, the convex portion of the rubber material effectively cushions the vibration, achieving the purpose of shock absorption, reducing the impact of vibration on the wiring within the connecting pipe, reducing the probability of failure, and improving equipment stability.

[0011] In one optional method, an external stabilizer is detachably connected to one end of the flexible drill collar, and the inner wall of the external stabilizer forms a third hollow cylindrical structure. A connecting pipe extends into the third hollow cylindrical structure, forming a second annular flow channel between the flexible drill collar and the inner wall of the external stabilizer. Because the flexible drill collar does not have a channel for wiring, the wiring on the flexible drill collar is not affected when connecting or removing the external stabilizer. Therefore, the external stabilizer can be easily and conveniently connected to the flexible drill collar. The detachable connection method can also adapt to various downhole operating conditions. The specifications and use of the external stabilizer can also be adjusted according to actual conditions, improving the applicability and controllability of the equipment and simplifying the operating process.

[0012] In one optional embodiment, the outer diameter of the external centralizer is larger than the outer diameter of the flexible drill collar. When the flexible drill collar bends, the outer wall of the external centralizer abuts the wellbore wall, providing support for the flexible drill collar. By making the outer diameter of the external centralizer larger than the outer diameter of the flexible drill collar, during downhole operations, the external centralizer is more likely to come into frictional contact with the wellbore wall than the flexible drill collar. When the external centralizer contacts the wellbore wall, it can provide support for the bending of the flexible drill collar. The flexible drill collar does not need to contact the wellbore wall to provide support while bending. Instead, the external centralizer provides support instead. This protects the stability of the flexible drill collar, makes the flexible drill collar less susceptible to damage, and makes the operation of the flexible sub more stable.

[0013] In one optional embodiment, the end of the flexible drill collar away from the external centralizer is connected to the upper tubular string. The inner wall of the upper tubular string forms a fourth hollow cylindrical structure. A first routing pipeline is disposed within the upper tubular string wall. A first diverter is disposed within the fourth hollow cylindrical structure. A first diverter tube extends from the first diverter toward the connecting pipe. The first diverter tube is hollow, one end of the first diverter tube is connected to the connecting pipe, and the other end of the first diverter tube is connected to the first routing pipeline within the upper tubular string wall. The connecting pipe, the first diverter tube, and the first routing pipeline within the upper tubular string wall form a routing channel. By setting a first diverter in the fourth hollow cylindrical structure of the upper tubular string, the line in the flexible drill collar connecting pipe is connected to the line in the first routing pipeline in the upper tubular string wall, so that the mud channel is restored to the central flow channel, saving space for the fourth hollow cylindrical structure of the upper tubular string. When other downhole tools need to be installed in the upper tubular string, they will not be unable to be installed due to the space occupied by the connecting pipe in the middle of the pipeline, thereby improving the applicability and controllability of the equipment. The first diverter also plays the role of mud diversion. When mud flows from the upper tubular string into the annular flow channel in the flexible drill collar, or from the annular flow channel in the flexible drill collar into the upper tubular string, the first diverter uses the first diverter pipe as a barrier to separate the mud flow channel, reducing the intensity of mud scouring during flow channel conversion and reducing the risk of component damage caused by mud scouring.

[0014] In one optional embodiment, one end of the external centralizer is connected to a rotary steering structure, in which a second wiring pipeline is provided; a second diverter is provided at one end of the connecting pipe near the rotary steering structure, the second diverter including a second diverter tube, the second diverter tube being hollow, one end of the second diverter tube being connected to the connecting pipe, and the other end of the second diverter tube being connected to the second wiring pipeline, and the connecting pipe, the second diverter tube and the second wiring pipeline forming a wiring channel. By providing the second diverter in the rotary steering structure, the circuit in the flexible drill collar connecting pipe is connected to the circuit in the second wiring pipeline in the rotary steering structure, so that the mud channel is restored to a central flow channel, and the rotary steering structure can better accommodate the necessary structures for implementing rotary steering drilling, such as the deflection shaft and the drill bit shaft. The wiring channel can be connected to the motors of these devices to supply them with power, so that the rotary steering structure can operate normally. The second diverter also plays the role of mud diversion. When the mud passes through, the second diverter uses the second diversion pipe as a barrier to separate the mud flow channel, reducing the scouring intensity of the mud during the flow channel conversion and reducing the risk of component damage caused by mud scouring.

[0015] In an optional manner, the fixing portions are distributed at 120-degree intervals along the circumference of the connector, and the outer surface of the fixing portions is streamlined. By setting three fixing portions at 120 degrees to each other on the connector to connect the connecting pipe and the flexible short section, the connecting pipe has three fixing points on the inner wall of the flexible drill collar, and the fixing points are evenly distributed at 120-degree angles to each other, forming three approximate triangular structures with the connector, which have good stability and make the connection between the fixing portion and the connector or the connecting pipe more stable and less likely to break. The fixing portions arranged at 120-degree intervals have a larger interval, which has less impact on the normal circulation of mud and is less likely to cause mud blockage and failure. Due to the streamlined design of the fixing portion, the resistance encountered by the fixing portion in the liquid is reduced, the scouring intensity of the fixing portion during mud circulation is low, and the fixing portion is not easily damaged by mud scouring, thereby improving durability and reducing failure rate.

[0016] In an optional manner, the flexible drill collar is made of an elastic material. By using the elastic material to make the flexible drill collar, the bending capacity of the flexible drill collar is improved, and the applicability of the flexible sub is enhanced.

[0017] In an optional manner, the present application also provides a downhole operation tool, including a flexible pup joint as described in the above embodiment. When the rotary guide structure performs a guided drilling operation, the flexible pup joint can provide a support point for it. Since the flexible pup joint provided in the present application adopts a method of setting a connecting pipe and a connector in the first hollow cylindrical structure of the flexible drill collar, there is no need to drill holes in the side wall of the flexible drill collar to provide a wiring channel, which greatly improves the bending performance of the flexible drill collar of the flexible pup joint, and can provide better bending performance for the rotary guide structure connected to the flexible pup joint, and the downhole operation tool is more stable during downhole operation. The wiring channel is set in the flexible pup joint by means of a connecting pipe and a connector, which greatly enhances the safety of the downhole line and makes it less likely to be damaged by mud scouring. At the same time, the setting of the connector can reduce the scouring intensity of the mud to a certain extent, further reducing the risk of mud scouring damaging the line and improving the durability of the downhole operation tool.

[0018] The above description is only an overview of the technical solution of the present invention. In order to more clearly understand the technical means of the present invention, it can be implemented in accordance with the contents of the specification. In order to make the above and other purposes, features and advantages of the present invention more obvious and easy to understand, the specific implementation methods of the present invention are specifically listed below. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Various other advantages and benefits will become apparent to those skilled in the art upon reading the detailed description of the preferred embodiment below. The accompanying drawings are for illustration purposes only and are not to be considered as limiting the present invention. The same reference symbols are used throughout the drawings to represent the same components. In the drawings:

[0020] Figure 1 shows a side cross-sectional view of the overall structure provided by an embodiment of the present invention;

[0021] Figure 2 A side cross-sectional view of a connector provided by an embodiment of the present invention is shown;

[0022] Figure 3 A bottom cross-sectional view of an inner centralizer provided in an embodiment of the present invention is shown;

[0023] Figure 4 A side cross-sectional view of an upper pipe string provided by an embodiment of the present invention is shown;

[0024] Figure 5 shows a side cross-sectional view of a first diverter provided by an embodiment of the present invention;

[0025] Figure 6 A bottom cross-sectional view of a diverter provided by an embodiment of the present invention is shown.

[0026] Figure 7 A side cross-sectional view of a rotary guide structure provided by an embodiment of the present invention is shown;

[0027] Figure 8 shows a side cross-sectional view of a second diverter provided by an embodiment of the present invention;

[0028] Figure 9 shows a cross-sectional view of the bottom of a connector provided by an embodiment of the present invention;

[0029] The accompanying drawings in the specific implementation manner are as follows:

[0030] 100, flexible short section;

[0031] 110. Flexible drill collar;

[0032] 111. First hollow cylindrical structure, 112. Bend, 113. Upper pipe string;

[0033] 1131. Fourth hollow cylindrical structure, 1132. First wiring pipeline, 1133. First diverter, 1134. First diverter pipe;

[0034] 120, connecting pipe;

[0035] 121. second hollow cylindrical structure, 122. first annular flow channel, 123. second annular flow channel;

[0036] 130. Connector;

[0037] 131, fixed part;

[0038] 1311, screws;

[0039] 140, internal centralizer;

[0040] 141. Convex part;

[0041] 150, external centralizer;

[0042] 151. a third hollow cylindrical structure, 152. a rotary guide structure;

[0043] 1521. Second wiring pipeline, 1522. Second diverter, 1523. Second diverter pipe. DETAILED DESCRIPTION

[0044] The following embodiments of the technical solution of the present application will be described in detail with reference to the accompanying drawings. The following embodiments are only used to more clearly illustrate the technical solution of the present application and are therefore only examples and are not intended to limit the scope of protection of the present application.

[0045] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by those skilled in the art to which this application belongs; the terms used herein are only for the purpose of describing specific embodiments and are not intended to limit this application; the terms "including" and "having" and any variations thereof in the specification and claims of this application and the above-mentioned figure descriptions are intended to cover non-exclusive inclusions.

[0046] In the description of the embodiments of this application, the technical terms "first" and "second" are used only to distinguish different objects and should not be understood to indicate or imply relative importance or implicitly specify the quantity, specific order, or primary and secondary relationship of the indicated technical features. In the description of the embodiments of this application, the meaning of "plurality" is more than two, unless otherwise clearly and specifically defined.

[0047] References herein to "embodiments" mean that a particular feature, structure, or characteristic described in connection with the embodiments may be included in at least one embodiment of the present application. The appearance of this phrase in various places in the specification does not necessarily refer to the same embodiment, nor does it constitute an independent or alternative embodiment that is mutually exclusive of other embodiments. It is understood, both explicitly and implicitly, by those skilled in the art that the embodiments described herein may be combined with other embodiments.

[0048] In the description of the embodiments of this application, the term "and / or" is simply a description of the association relationship between associated objects, indicating that three relationships can exist. For example, A and / or B can represent the following three situations: A exists, A and B exist at the same time, and B exists. In addition, the character " / " in this document generally indicates that the associated objects are in an "or" relationship.

[0049] In the description of the embodiments of the present application, the term "multiple" refers to more than two (including two). Similarly, "multiple groups" refers to more than two groups (including two groups), and "multiple pieces" refers to more than two pieces (including two pieces).

[0050] In the description of the embodiments of the present application, the technical terms "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "clockwise", "counterclockwise", "axial", "radial", "circumferential", etc., indicating the orientation or position relationship, are based on the orientation or position relationship shown in the accompanying drawings, and are only for the convenience of describing the embodiments of the present application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the embodiments of the present application.

[0051] In the description of the embodiments of the present application, unless otherwise expressly specified or limited, technical terms such as "installed," "connected," "connected," and "fixed" should be understood in a broad sense. For example, they can refer to fixed connections, detachable connections, or integration; mechanical connections or electrical connections; direct connections or indirect connections through an intermediate medium; internal connections between two components or interactions between two components. Those skilled in the art can understand the specific meanings of the above terms in the embodiments of the present application based on specific circumstances.

[0052] During drilling operations, rotary steerable systems are often used to achieve precise drilling direction. A rotary steerable system is a directional drilling system that provides real-time steering while the drill string rotates. It has been a major revolution in directional drilling technology since the 1990s. Drilling with rotary steerable systems offers advantages such as low friction and torsional resistance, high penetration rates, low costs, short well construction cycles, smooth wellbore trajectories, ease of control, and the ability to extend horizontal sections. It is considered the future direction of modern steerable drilling technology. The rotary steerable system requires the bending of the tubing to achieve downhole direction changes and transmit pressure to the drill bit, necessitating the use of a flexible sub. The flexible sub also serves as a power and signal connection for the rotary steerable system. To ensure optimal coordination between the flexible sub and the rotary steerable system and to enable the rotary steerable system to effectively increase and decrease inclination to control the wellbore trajectory, it is crucial to improve the flexible sub's bending performance and reduce its failure rate.

[0053] The inventors of the present application discovered in their research that when the flexible pup joint cooperates with the rotary guide structure for operation, the bending effect of the flexible pup joint is mainly achieved by the drill collar part of the flexible pup joint. The existing flexible pup joint adopts a design in which the mud channel is centered and a wiring hole is opened in the drill collar as a line channel. The structure is complex, and the opening of the drill collar of the flexible pup joint will reduce the bending and sealing performance of the flexible pup joint, affecting the applicability and stability of the flexible pup joint. At the same time, the flexible pup joint in the prior art cannot effectively reduce the loss of the internal line of the flexible pup joint caused by mud scouring. The drill collar, which is the main bending part, has a complex structure and limited structural strength, which affects the bending performance, is not conducive to the smooth progress of downhole operations, and the equipment is difficult to manufacture and assemble. In addition, in the prior art, the external stabilizer used for support and the drill collar are often set as a whole. The two cannot be disassembled, and the applicability of the equipment is poor. Therefore, there is an urgent need to develop a flexible pup joint with good bending performance, high durability, simple structure and wide applicability.

[0054] In order to solve the above problems, the inventors have designed a flexible pup joint after research. A connecting pipe is arranged in the flexible pup joint, and the connecting pipe is fixed in the drill collar through a connector. An annular flow channel is formed between the outer wall of the connecting pipe and the inner wall of the drill collar, so that the power supply and signal lines pass through the connecting pipe, and the mud passes through the annular flow channel. This improves the bending performance of the flexible pup joint, reduces the risk of line damage, reduces the difficulty of equipment production and assembly, and improves the applicability of the equipment.

[0055] In an embodiment of the present application, a connector is provided in the first hollow cylindrical structure of the flexible drill collar, a fixing portion is provided at intervals on the inner wall of the connector, the fixing portion extends toward the outer wall of the end of the connecting pipe, the connecting pipe is provided in the flexible drill collar, and the second hollow cylindrical structure formed on the inner wall of the connecting pipe forms a channel for wiring. The power supply and signal lines of the downhole equipment pass through the second hollow structure, and there is no need to drill holes on the inner wall of the flexible drill collar to arrange the wiring channel, thereby improving the structural strength of the flexible drill collar and enabling the flexible drill collar to exert better bending performance. An annular flow channel is formed between the outer wall of the connecting pipe and the inner wall of the flexible drill collar, and mud flows through the annular flow channel. Due to the protection of the connecting pipe, the downhole line is not easily damaged by mud erosion. According to the actual operation situation, an external centralizer can be installed at one end of the flexible drill collar to provide support when the flexible short section bends and abuts against the well wall. When the external centralizer needs to be disassembled, since the power supply and signal lines in the flexible short section are arranged in the connecting pipe, the disassembly between the flexible drill collar and the external centralizer will not affect the line connection. The external centralizer can be quickly and conveniently disassembled from one end of the flexible drill collar. It has a wide applicability and ensures the stability and efficiency of downhole operations.

[0056] The flexible nipple disclosed in the embodiments of the present application can be used for, but is not limited to, drilling, cementing, testing, completion, water injection, downhole operations, and other operations. It can also be applied to any other scenario requiring a curved structure. In the embodiments of the present application, only downhole operations are used as an example for illustration.

[0057] According to some embodiments of the present application, referring to Figure 1 , Figure 1 The figure shows a side cross-sectional view of the overall structure provided by an embodiment of the present invention. The present application provides a flexible sub 100, comprising a flexible drill collar 110, a connecting pipe 120, and a connector 130. A first hollow cylindrical structure 111 is formed on the inner wall of the flexible drill collar 110. A connector 130 is disposed within the first hollow cylindrical structure 111. Fixing portions 131 are provided at intervals on the inner wall of the connector 130. The fixing portions 131 extend toward the outer wall of the end of the connecting pipe 120 and are used to set the connecting pipe 120 within the flexible drill collar 110. A second hollow cylindrical structure 121 is formed on the inner wall of the connecting pipe 120. A first annular flow channel 122 is formed between the outer wall of the connecting pipe 120 and the inner wall of the flexible drill collar 110. The second hollow cylindrical structure 121 is used to form a wiring channel.

[0058] The flexible drill collar 110 is a hollow cylindrical structure, wherein a first hollow cylindrical structure 111 is formed in the hollow interior. The first hollow cylindrical structure 111 can be used as a channel for the circulation of downhole fluid or for placing downhole tools. In this embodiment, it is only described as a mud channel. The flexible drill collar 110 is the main bending part 112 in the flexible short section 100. When subjected to radial force, the flexible drill collar 110 bends. In order to better enable the flexible drill collar 110 to exert its bending performance, a bending part 112 can be provided on the flexible drill collar 110. The outer diameter of the bending part 112 is smaller than the outer diameter of the main body of the flexible drill collar 110, so that the flexible drill collar 110 has a relatively slender part. When subjected to radial force, the bending part 112 can better achieve the bending effect of the flexible drill collar 110 and increase the elasticity of the flexible drill collar 110.

[0059] A connecting pipe 120 is provided in the first hollow cylindrical structure 111 of the flexible drill collar 110. The connecting pipe 120 is a hollow cylindrical structure. The inner wall of the connecting pipe 120 forms a second hollow cylindrical structure 121. The second hollow cylindrical structure 121 is used to form a wiring channel. The wiring channel is a line channel that provides power and signals to downhole tools during downhole operations. It can also be used as a channel for the layout of other downhole tools. In this embodiment, only the channel for downhole line layout is used as an example for explanation.

[0060] A first annular flow channel 122 is formed between the outer wall of the connecting pipe 120 and the inner wall of the flexible drill collar 110, so that mud can flow along the annular flow channel in the first hollow cylindrical structure 111. The first annular flow channel 122 can also be used as a channel for downhole fluid circulation or for placing a downhole tool string. In this embodiment, it is only described as a mud channel as an example.

[0061] A connector 130 is provided in the first hollow cylindrical structure 111 of the flexible drill collar 110. The connector 130 is fixed to the inner wall of the first hollow cylindrical structure 111. Figure 2 , Figure 2 A side cross-sectional view of the connector 130 provided in an embodiment of the present invention is shown. In the embodiment of the present application, the connector 130 is fixed to the inner wall of the first hollow cylindrical structure 111 by screws 1311. Other methods can also be used to connect and fix the connector 130 to the inner wall of the first hollow cylindrical structure 111, as long as a stable connection between the two can be easily achieved. In order to facilitate disassembly and replacement, a detachable connection method is preferably adopted. The inner wall of the connector 130 is provided with fixing portions 131 at intervals. The fixing portions 131 extend toward the outer wall of the end of the connecting tube 120 and are fixed to the outer wall of the end of the connecting tube 120, fixing the connecting tube 120 in the first hollow cylindrical structure 111 of the flexible drill collar 110. In the embodiment of the present application, two fixing portions 131 are provided at intervals on the inner wall of the connector 130. Different numbers of fixing portions 131 can also be provided according to actual conditions. In addition, in addition to using screws 1311 for connection, other methods can also be used to fix the connecting pipe 120 in the first hollow cylindrical structure 111 of the flexible drill collar 110. Because the outer wall of the connecting pipe 120 and the inner wall of the flexible drill collar 110 need to serve as an annular flow channel for mud circulation, the setting method and number of the fixing parts 131 should not affect the smooth flow of the annular flow channel.

[0062] Reference Figure 1 The connecting pipe 120 is fixed in the first hollow cylindrical structure 111 of the flexible drill collar 110 through the connector 130. When mud passes through the flexible drill collar 110, the mud passes along the annular flow channel formed between the inner wall of the flexible drill collar 110 and the outer wall of the connecting pipe 120. When the mud reaches the connector 130, it flows through the gap between the fixed parts 131 on the connector 130. The second hollow cylindrical structure 121 in the connecting pipe 120 serves as a wiring channel, and the power and signal lines of the downhole equipment are laid along the second hollow cylindrical structure 121.

[0063] In the embodiment of the present application, a connecting pipe 120 having a second hollow cylindrical structure 121 is arranged in the first hollow cylindrical structure 111 of the flexible drill collar 110. The connecting pipe 120 is fixed in the flexible drill collar 110 through a connector 130, and the second hollow cylindrical structure 121 is used as a channel for arranging downhole lines. Since the connecting pipe 120 serves as protection for the line, the risk of damage to the line caused by mud scouring is reduced. An annular flow channel is formed in the first hollow cylindrical structure 111 through the outer wall of the connecting pipe 120 and the inner wall of the flexible drill collar 110, which serves as a mud channel to ensure smooth circulation of mud in the flexible short joint 100. Since the downhole line is arranged in the second hollow cylindrical structure 121 of the connecting pipe 120, there is no channel for arranging the downhole line on the flexible drill collar 110, and there is no need to drill holes in the flexible drill collar 110. This ensures the structural strength of the flexible drill collar 110, improves the bending performance of the flexible drill collar 110, and reduces the difficulty of production and assembly.

[0064] According to some embodiments of the present application, referring to Figure 1 and Figure 3 , Figure 3 A bottom cross-sectional view of the internal centralizer 140 provided in an embodiment of the present invention is shown. The internal centralizer 140 is sleeved on the outer wall of the connecting tube 120. Protrusions 141 are spaced apart on the outer wall of the internal centralizer 140. The protrusions 141 abut against the inner wall of the flexible drill collar 110 to make the central axis of the connecting tube 120 coincide with the central axis of the flexible drill collar 110.

[0065] An inner centralizer 140 is sleeved on the outer wall of the connecting pipe 120. The outer wall of the inner centralizer 140 is provided with protrusions 141 at intervals, which are used to abut the outer wall of the flexible drill collar 110 and maintain the stability of the connecting pipe 120 in the first hollow cylindrical structure 111 of the flexible drill collar 110. The protrusions 141 of the inner centralizer 140 are arranged at intervals so that mud can flow between the protrusions 141. In the embodiment of the present application, Figure 4 As shown, the internal centralizer 140 has four spaced-apart protrusions 141 . The number of the protrusions 141 can be set according to actual conditions, as long as there is sufficient gap between the protrusions 141 to allow the mud to flow normally. This embodiment of the present application does not impose any special restrictions on this.

[0066] By sleevedly mounting an internal centralizer 140 on the outer wall of the connecting pipe 120, the spaced-apart protrusions 141 on the internal centralizer 140 abut against the outer wall of the flexible drill collar 110, thereby enabling the connecting pipe 120 to be more stably positioned within the flexible drill collar 110. While the connector 130 secures the connecting pipe 120, the internal centralizer 140 abuts and secures the connecting pipe 120 against the inner wall of the flexible drill collar 110. This reduces the risk of wear between the outer wall of the connecting pipe 120 and the inner wall of the flexible drill collar 110 caused by tilting of the connecting pipe 120 during downhole operations. Furthermore, the annular flow channel formed between the outer wall of the connecting pipe 120 and the inner wall of the flexible drill collar 110 is stabilized, thereby less likely to affect the flow of mud.

[0067] According to some embodiments of the present application, the protrusion 141 is made of rubber material.

[0068] The protrusions 141 spaced apart on the inner centralizer 140 are made of a rubber material. When the protrusions 141 contact the inner wall of the flexible drill collar 110 and receive force, they undergo a certain degree of elastic deformation. Furthermore, depending on practical circumstances, the protrusions 141 may also be made of other materials, as long as they provide shock absorption and stability. This embodiment of the present application imposes no particular limitation on this.

[0069] When the inner centralizer 140 supports the connecting pipe 120, the protrusion 141 on the inner centralizer 140 is made of rubber material and has excellent buffering ability. When the flexible pup joint 100 is involved in downhole operations and the pipe string vibrates, the protrusion 141 made of rubber material can effectively buffer the vibration, achieving the purpose of shock absorption, reducing the impact of the vibration on the line in the connecting pipe 120, reducing the probability of failure, and improving the stability of the equipment.

[0070] According to some embodiments of the present application, referring to Figure 1 One end of the flexible drill collar 110 is detachably connected to an external centralizer 150, the inner wall of which forms a third hollow cylindrical structure 151. The connecting pipe 120 extends into the third hollow cylindrical structure 151, forming a second annular flow channel 123 between the connecting pipe 120 and the inner wall of the external centralizer 150.

[0071] One end of the flexible drill collar 110 is detachably connected to an external stabilizer 150. External stabilizer 150 is a hollow cylindrical structure whose inner wall forms a third hollow cylindrical structure 151. When external stabilizer 150 is connected to the outer wall of one end of the flexible drill collar 110, connecting pipe 120 extends into the third hollow cylindrical structure 151 of the external centralizer 150. A second annular flow channel 123 is formed between the outer wall of connecting pipe 120 and the inner wall of the external centralizer 150, serving as a channel for mud circulation. The connection between the flexible drill collar 110 and the external stabilizer 150 can be threaded or snap-fit, as long as the connection between the external centralizer 150 and the flexible drill collar 110 is stable and removable. This embodiment does not impose any specific restrictions on this.

[0072] Since there is no channel for line layout on the flexible drill collar 110, the connection or removal of the external stabilizer 150 on the flexible drill collar 110 will not be affected by the existence of the line on the flexible drill collar 110, so the external stabilizer 150 can be easily and conveniently connected to the flexible drill collar 110. The detachable connection method can also adapt to various downhole operation conditions. The specifications and uses of the external stabilizer 150 can also be adjusted according to actual conditions, which improves the applicability and controllability of the equipment and simplifies the operation process.

[0073] According to some embodiments of the present application, the outer diameter of the external centralizer 150 is larger than the outer diameter of the flexible drill collar 110 . When the flexible drill collar 110 bends, the outer wall of the external centralizer 150 abuts against the well wall to provide support for the flexible drill collar 110 .

[0074] The outer diameter of the external centralizer 150, connected to one end of the flexible drill collar 110, is larger than that of the flexible drill collar 110, providing support and protection for the flexible drill collar 110. The outer diameter parameters of the external centralizer 150 and the flexible drill collar 110 can be adjusted according to actual conditions. It is sufficient to ensure that the outer diameter of the external centralizer 150 is larger than that of the flexible drill collar 110, and that the difference in outer diameter between the external centralizer 150 and the flexible drill collar 110 is sufficient for the external centralizer 150 to provide sufficient support for the flexible drill collar 110. Furthermore, since the external centralizer 150 often directly rubs against the wellbore wall, to improve its durability, it should be made of a wear-resistant material.

[0075] By making the outer diameter of the external centralizer 150 larger than the outer diameter of the flexible drill collar 110, during downhole operations, since the outer diameter of the external centralizer 150 is larger than the outer diameter of the flexible drill collar 110, it is easier for the flexible drill collar 110 to rub against the well wall. When the external centralizer 150 contacts the well wall, it can provide support for the bending of the flexible drill collar 110. The flexible drill collar 110 does not need to contact the well wall to provide support while bending, but is supported by the external centralizer 150 instead, thereby protecting the stability of the flexible drill collar 110, making the flexible drill collar 110 less likely to be damaged, and making the operation of the flexible pup joint 100 more stable.

[0076] According to some embodiments of the present application, referring to Figure 4 and Figure 5 , and further reference Figure 6 , Figure 4 FIG. 1 shows a side cross-sectional view of an upper pipe string 113 provided in an embodiment of the present invention. Figure 5 FIG. 1 shows a side cross-sectional view of a first diverter 1133 provided in an embodiment of the present invention. Figure 6 A cross-sectional view of the bottom of a flow diverter provided by an embodiment of the present invention is shown. The end of the flexible drill collar 110 away from the external centralizer 150 is connected to an upper tubular string 113. A fourth hollow cylindrical structure 1131 is formed on the inner wall of the upper tubular string 113. A first wiring pipeline 1132 is disposed within the wall of the upper tubular string 113. A first flow diverter 1133 is disposed within the fourth hollow cylindrical structure 1131. A first flow diverter 1134 extends from the first flow diverter 1133 toward the connecting pipe 120. The first flow diverter 1134 is hollow inside. One end of the first flow diverter 1134 communicates with the connecting pipe 120, and the other end of the first flow diverter 1134 communicates with the first wiring pipeline 1132 within the wall of the upper tubular string 113. The connecting pipe 120, the first flow diverter 1134, and the first wiring pipeline 1132 within the wall of the upper tubular string 113 form a wiring channel.

[0077] An upper tubular column 113 is connected to one end of the flexible drill collar 110 away from the external centralizer 150. The upper tubular column 113 is a hollow cylindrical structure. A fourth hollow cylindrical structure 1131 is formed on the inner wall of the upper tubular column 113. A first wiring pipeline 1132 is provided in the wall of the upper tubular column 113 for arranging the lines in the upper tubular column 113. A first diverter 1133 is provided in the fourth hollow cylindrical structure 1131. The first diverter 1133 extends toward the connecting pipe 120 with a first diverter pipe 1134 having an inner hollow structure, one end of which is connected to the second diverter pipe 1134 in the connecting pipe 120. The hollow cylindrical structure 121 is connected, and the other end is connected to the first wiring pipeline 1132 in the wall of the upper tubular column 113. By arranging lines in the second hollow cylindrical structure 121 in the connecting pipe 120, the first diversion pipe 1134 and the first wiring pipeline 1132 in the wall of the upper tubular column 113, the line connection between the upper tubular column 113 and the flexible short section 100 is achieved, and the line in the first hollow cylindrical structure 111 located in the flexible drill collar 110 in the flexible short section 100 is connected to the inner wall of the upper tubular column 113, and the annular flow channel is restored to the central flow channel.

[0078] By setting a first diverter 1133 in the fourth hollow cylindrical structure 1131 of the upper tubular string 113, the line in the flexible drill collar 110 connecting pipe 120 is connected to the line in the first wiring pipeline 1132 in the wall of the upper tubular string 113, so that the mud channel is restored to the central flow channel, saving space for the fourth hollow cylindrical structure 1131 of the upper tubular string 113. When other downhole tools need to be installed in the upper tubular string 113, they will not be unable to be installed because the connecting pipe 120 is placed in the middle of the pipeline and occupies space, thereby improving the applicability and controllability of the equipment. The first diverter 1133 also serves to divert mud. When mud flows from the upper tubing string 113 into the inner annular flow channel of the flexible drill collar 110, or flows from the inner annular flow channel of the flexible drill collar 110 into the upper tubing string 113, the first diverter 1133 uses the first diverter pipe 1134 as a barrier to separate the mud flow channel, thereby reducing the scouring intensity of the mud during the flow channel conversion and reducing the risk of component damage caused by mud scouring.

[0079] According to some embodiments of the present application, referring to Figure 7 and Figure 8 , Figure 7 FIG. 1 shows a side cross-sectional view of a rotary guide structure 152 provided in an embodiment of the present invention. Figure 8 A side sectional view of the second diverter 1522 provided in an embodiment of the present invention is shown, wherein one end of the external stabilizer 150 is connected to a rotary guide structure 152, and a second wiring pipeline 1521 is arranged in the rotary guide structure 152; a second diverter 1522 is arranged at one end of the connecting pipe 120 close to the rotary guide structure 152, and the second diverter 1522 includes a second diverter pipe 1523, which is hollow inside, and one end of the second diverter pipe 1523 is connected to the connecting pipe 120, and the other end of the second diverter pipe 1523 is connected to the second wiring pipeline 1521, and the connecting pipe 120, the second diverter pipe 1523 and the second wiring pipeline 1521 form a wiring channel.

[0080] A rotary guide structure 152 is connected to one end of the external centralizer 150. In the embodiment of the present application, the connection between the external centralizer 150 and the rotary guide structure 152 is a threaded connection. Depending on the actual situation, it can also be connected by a snap-on connection or other connection methods. The embodiment of the present application does not specifically limit this. A second wiring pipeline 1521 is provided in the rotary guide structure 152. In order to meet the needs of downhole operations, the second wiring pipeline 1521 should be provided near the side wall of the rotary guide structure 152. A second diverter 1522 is provided at one end of the connecting pipe 120 near the rotary guide structure 152. The bottom cross-sectional view of the second diverter 1522 is the same as that of the second diverter 1522. Figure 6Similarly, the second diverter 1522 includes a second diverter pipe 1523 , which is hollow inside and connected to the connecting pipe 120 at one end. The second diverter 1522 is used to connect the wiring pipeline in the connecting pipe 120 with the second wiring pipeline 1521 in the rotating guide structure 152 .

[0081] By providing a second diverter 1522 within the rotary steering structure 152, the circuit within the flexible drill collar 110 connecting tube 120 is connected to the circuit within the second wiring conduit 1521 within the rotary steering structure 152, restoring the mud channel to a central flow channel. This allows the rotary steering structure 152 to better accommodate the necessary structures for implementing rotary steering drilling, such as the deflection shaft and drill bit shaft. The wiring channel can be connected to the motors of these devices to supply them with energy, allowing the rotary steering structure 152 to operate normally. The second diverter 1522 also serves to divert mud. When mud passes through, the second diverter 1522 uses the second diverter pipe 1523 as a barrier to separate the mud flow path, reducing the intensity of mud scouring during flow path conversion and reducing the risk of component damage caused by mud scouring.

[0082] According to some embodiments of the present application, referring to Figure 9 , Figure 9 1 shows a bottom cross-sectional view of a connector 130 provided in an embodiment of the present invention. The fixing portions 131 are distributed at intervals of 120 degrees along the circumference of the connector 130 , and the outer surface of the fixing portions 131 is streamlined.

[0083] In the embodiment of the present application, the fixing portions 131 on the connector 130 are distributed at intervals of 120 degrees along the circumference of the connector 130, that is, there are three fixing portions 131 distributed circumferentially on the connector 130, and the three fixing portions 131 are at an angle of 120 degrees to each other, and the connector 130 is used to fix the connecting pipe 120 in the first hollow cylindrical structure 111 of the flexible drill collar 110. Different numbers of fixing portions 131 or different angles can also be set on the connector 130. As long as the connection between the fixing portion 131 and the connector 130 and the connecting pipe 120 does not block the flow of mud, the embodiment of the present application does not impose any special restrictions on this. The outer surface of the fixing portion 131 adopts a streamlined design, the purpose of which is to reduce the resistance encountered by the fixing portion 131 during mud circulation and reduce the direct flushing area. Other designs can also be adopted, such as a thin sheet type parallel to the mud flushing direction, and the embodiment of the present application does not impose any special restrictions on this.

[0084] By setting three fixing parts 131 at 120 degrees to each other on the connector 130 to connect the connecting pipe 120 and the flexible short section 100, the connecting pipe 120 has three fixing points on the inner wall of the flexible drill collar 110, and the fixing points are evenly distributed at 120 degrees to each other, forming three approximately triangular structures with the connector 130, which has good stability, making the connection between the fixing parts 131 and the connector 130 or the connecting pipe 120 more stable and less likely to break. The fixing parts 131 set at 120-degree intervals have a larger spacing, which has less impact on the normal circulation of mud and is less likely to cause mud blockage and failure. Due to the streamlined design of the fixing part 131, the resistance encountered by the fixing part 131 in the liquid is reduced, and the scouring intensity of the fixing part 131 during mud circulation is low. The fixing part 131 is not easily damaged by mud scouring, which improves durability and reduces the failure rate.

[0085] According to some embodiments of the present application, the flexible drill collar 110 is made of elastic material.

[0086] Since the flexible drill collar 110 needs to exhibit certain bending properties to realize the main function of the flexible short section 100, the flexible drill collar 110 is made of elastic material so that the flexible drill collar 110 can bend within the allowable range of material strength. According to actual operating conditions, the flexible drill collar 110 can be made of materials with different elastic moduli.

[0087] By using elastic material to make the flexible drill collar 110 , the bending ability of the flexible drill collar 110 is improved, and the applicability of the flexible sub 100 is enhanced.

[0088] According to some embodiments of the present application, the present application further provides a downhole operation tool, comprising the flexible sub 100 as described in the above embodiment.

[0089] Reference Figure 1, connect the upper tubing string 113, the flexible pup joint 100 and the rotary steering structure 152 to form a downhole operation tool. When the rotary steering structure 152 performs directional drilling operations, the flexible pup joint 100 can provide a support point for it. Since the flexible pup joint 100 provided in the present application adopts the method of arranging the connecting pipe 120 and the connector 130 in the first hollow cylindrical structure 111 of the flexible drill collar 110, there is no need to drill holes in the side wall of the flexible drill collar 110 to provide a wiring channel, so that the bending performance of the flexible drill collar 110 of the flexible pup joint 100 is greatly improved, and better bending performance can be provided for the rotary steering structure 152 connected to the flexible pup joint 100, and the downhole operation tool is more stable during downhole operations. The flexible nipple 100 uses a connecting pipe 120 and a connector 130 to set up a wiring channel, which greatly enhances the safety of the downhole line and makes it less likely to be damaged by mud scouring. At the same time, the provision of the connector 130 can reduce the intensity of mud scouring to a certain extent, further reducing the risk of mud scouring damaging the line and improving the durability of the downhole operation tool.

[0090] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present application, rather than to limit them. Although the present application has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some or all of the technical features therein. These modifications or replacements do not deviate the essence of the corresponding technical solutions from the scope of the technical solutions of the embodiments of the present application, and they should all be included in the scope of the claims and specification of the present application. In particular, as long as there is no structural conflict, the various technical features mentioned in the various embodiments can be combined in any way. The present application is not limited to the specific embodiments disclosed herein, but includes all technical solutions that fall within the scope of the claims.

Claims

1. A flexible short section, characterized in that: Including flexible drill collar, connecting pipe and connector; The inner wall of the flexible drill collar forms a first hollow cylindrical structure, a connector is provided in the first hollow cylindrical structure, and fixing portions are provided at intervals on the inner wall of the connector. The fixing portions extend toward the outer wall of the end of the connecting pipe and are used to set the connecting pipe in the flexible drill collar; The inner wall of the connecting pipe forms a second hollow cylindrical structure, a first annular flow channel is formed between the outer wall of the connecting pipe and the inner wall of the flexible drill collar, and the second hollow cylindrical structure is used to form a wiring channel; An inner centralizer is sleeved on the outer wall of the connecting pipe, and convex portions are spaced apart on the outer wall of the inner centralizer. The convex portions abut against the inner wall of the flexible drill collar to make the central axis of the connecting pipe coincide with the central axis of the flexible drill collar; The convex portion is made of rubber material; One end of the flexible drill collar is detachably connected to an external centralizer, and the inner wall of the external centralizer forms a third hollow cylindrical structure; The connecting pipe extends into the third hollow cylindrical structure, and forms a second annular flow channel between the connecting pipe and the inner wall of the outer centralizer.

2. The flexible sub according to claim 1, characterized in that: The outer diameter of the external centralizer is larger than the outer diameter of the flexible drill collar. When the flexible drill collar bends, the outer wall of the external centralizer abuts against the well wall to provide support for the flexible drill collar.

3. The flexible sub according to claim 1, characterized in that: An upper pipe string is connected to one end of the flexible drill collar away from the external centralizer, the inner wall of the upper pipe string forms a fourth hollow cylindrical structure, a first wiring pipeline is provided in the wall of the upper pipe string, a first flow diverter is provided in the fourth hollow cylindrical structure, and a first flow diverter is provided in the first flow diverter extending toward the connecting pipe; The first diverter tube is hollow inside, one end of the first diverter tube is connected to the connecting tube, and the other end of the first diverter tube is connected to the first routing pipeline in the wall of the upper tubular column. The connecting tube, the first diverter tube and the first routing pipeline in the wall of the upper tubular column form a routing channel.

4. The flexible sub according to claim 1, characterized in that: One end of the external stabilizer is connected to a rotary guide structure, and a second wiring pipeline is arranged in the rotary guide structure; a second diverter is provided at one end of the connecting pipe close to the rotary guide structure, and the second diverter includes a second diverter pipe, the interior of the second diverter pipe is hollow, one end of the second diverter pipe is connected to the connecting pipe, and the other end of the second diverter pipe is connected to the second wiring pipeline, and the connecting pipe, the second diverter pipe and the second wiring pipeline form a wiring channel.

5. The flexible sub according to any one of claims 1 to 4, characterized in that: The fixing portions are distributed at intervals of 120 degrees along the circumference of the connector, and the outer surfaces of the fixing portions are streamlined.

6. The flexible sub according to any one of claims 1 to 4, characterized in that: The flexible drill collar is made of elastic material.

7. A downhole operation tool, characterized in that: include: The flexible sub as claimed in any one of claims 1 to 6.

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