Downhole circulation structure and method for preventing well control

Abstract

The invention provides a downhole circulation structure and method for preventing well control. The underground circulation structure for preventing well control comprises an output part and a circulation part, the output part is used for outputting liquid; a circulating channel capable of establishing liquid circulation for the wellhead is arranged on the circulating part; the input end of the circulating channel is arranged outside the wellhead and is connected with the output end of the output part; the output end of the circulating channel firstly extends towards the interior of the well mouth in the axial direction of the well mouth and then extends towards the exterior of the well mouth in the axial direction of the well mouth, so that the output end of the circulating channel is also arranged outside the well mouth; the output part can convey liquid into the circulation channel, and the conveyed liquid can reach the interior of the well mouth along the circulation channel and then reach the exterior of the well mouth along the circulation channel, so that liquid circulation is established at the well mouth. Through liquid circulation, pressure in a well can be balanced, well control risks are reduced, safety accidents are avoided, safety is improved, drilling efficiency is improved, and smooth implementation of an exploration target is guaranteed.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of oil exploration and development drilling, and particularly relates to a downhole circulation structure and method for preventing well control. BACKGROUND

[0002] With the gradual standardization of oil and gas exploration and development, along with the continuous development of resources, the depth of development is gradually improved, and the difficulty of development is also correspondingly improved. Among them, in the drilling operation of deep wells or ultra-deep wells of oil and gas wells, whether the oil and gas wells can be safely controlled has attracted more and more attention.

[0003] In the development and drilling process of deep wells or ultra-deep wells of oil and gas wells, there are development problems such as complex geological conditions, numerous pressure systems and difficult prediction. The original casing capable of preventing well control accidents is difficult to meet the actual drilling requirements due to the sudden complex formation pressure system encountered in the drilling process as the development depth gradually increases. Meanwhile, the case of high and low pressure in the same layer in the actual drilling process also appears more and more frequently, and the well leakage problem is increasingly prominent, which leads to the gradual reduction of the application effect of the original casing, thereby easily leading to well control risks, causing safety accidents, and affecting the safety of drilling. Accordingly, when safety problems occur, drilling cannot continue, which will affect the drilling efficiency of the drilling process.

[0004] Furthermore, the overall drilling process may also be affected by difficult-to-reverse effects, resulting in the final failure to achieve the exploration target.

[0005] Therefore, in the existing oil and gas exploration and development process, well control accidents are prone to occur, and as the development depth gradually increases, the effect of preventing well control gradually decreases, while the difficulty of preventing well control gradually increases. SUMMARY

[0006] In view of the above problems, the present application provides a downhole circulation structure and method for preventing well control, wherein a downhole circulation structure for preventing well control comprises:

[0007] an output part, the output end of the output part being capable of outputting liquid;

[0008] a circulation part, the circulation part being capable of being fixed to a wellhead, and a circulation channel capable of establishing liquid circulation for the wellhead being arranged on the circulation part;

[0009] the input end of the circulation channel is arranged outside the wellhead and is capable of being connected with the output end of the output part;

[0010] The output end of the circulation channel first extends into the wellhead along the axial direction of the wellhead, and then extends outward along the axial direction of the wellhead, so that the output end of the circulation channel is also located outside the wellhead.

[0011] The output section can deliver liquid into the circulation channel. The delivered liquid can first reach the inside of the wellhead along the circulation channel, and then reach the outside of the wellhead along the circulation channel, so as to establish a liquid circulation at the wellhead.

[0012] In some specific embodiments, the circulation channel includes:

[0013] A first channel, one end of which is located outside the wellhead and is used to connect to the output end of the output unit, and the other end of which is located inside the wellhead, so that liquid can be delivered into the wellhead through the first channel;

[0014] The second channel has one end located inside the wellhead and the other end located outside the wellhead, so that the liquid delivered to the inside of the wellhead can be discharged through the second channel.

[0015] In some specific embodiments, the loop section includes:

[0016] A housing that can be inserted into the wellhead and is axially arranged around the wellhead so that it can cover the inner wall of the wellhead;

[0017] The pipe body is inserted into the interior of the shell along the axial direction of the wellhead, so that the inner wall of the pipe body forms the first channel, and the outer wall of the pipe body and the inner wall of the shell form the second channel.

[0018] One end of the tube is connected to the output section.

[0019] In some specific embodiments, the output section includes:

[0020] A nozzle for supplying the liquid to be delivered;

[0021] The nozzle's output end is detachably connected to the circulation section via the connector, so that the nozzle communicates with the first channel.

[0022] In some specific embodiments, a connecting seat is movably sleeved on the outer wall of the connector, so that the connecting seat can rotate about the axial direction of the connector;

[0023] The connecting seat and the circulation part are threaded together.

[0024] In some specific embodiments, the connector can also slide along the axial direction of the joint within a preset range to reduce the impact force when conveying liquid.

[0025] In some specific embodiments, a sealing ring is embedded on the outer wall of the connector for sealing.

[0026] In some specific embodiments, a straightening section is provided at the end of the connector away from the nozzle;

[0027] When the connector is connected to the circulation section, the straightening section can be inserted into the first channel. The straightening section is used to guide and straighten the connection between the connector and the circulation section.

[0028] In some specific embodiments, the end of the connector away from the nozzle is provided with a drill rod to facilitate the delivery of liquid into the first channel.

[0029] A downhole circulation method for preventing well control, based on the same concept, employing a downhole circulation structure for preventing well control as described in any of the above specific embodiments, is characterized by comprising the following steps:

[0030] The input end of the circulation unit is fixed to the outside of the wellhead, and the main body of the circulation unit is inserted into the inside of the wellhead so that the input end of the circulation unit can communicate with the inside of the wellhead. At the same time, the output end of the circulation unit is also fixed to the outside of the wellhead so that the inside of the wellhead can communicate with the output end of the circulation unit.

[0031] Connect the output terminal of the output section to the input terminal of the loop section;

[0032] Start the output section so that the liquid output from the output section can first reach the inside of the wellhead along the circulation section;

[0033] Maintaining the output section allows the liquid inside the wellhead to travel along the circulation section to the outside of the wellhead, thus achieving liquid circulation at the wellhead.

[0034] The downhole circulation structure for preventing well control defects of this invention, through a circulation unit fixedly connected to the wellhead, establishes a liquid circulation channel at the wellhead. One end of this circulation channel is located outside the wellhead, and the other end is also located outside the wellhead. The main body of the circulation channel connects the interior of the wellhead to both ends of the circulation channel. Simultaneously, under the action of the output unit, liquid is delivered to one end of the circulation channel, allowing the delivered liquid to first reach the interior of the wellhead along the circulation channel, and then reach the other end of the circulation channel, thus forming a liquid circulation channel at the wellhead. This liquid circulation balances the pressure within the well, reducing the probability of well control defects and preventing safety accidents, thereby improving the safety of the drilling process. Correspondingly, it also increases drilling efficiency, ensuring the successful achievement of the final exploration objectives.

[0035] The downhole circulation method for preventing well control of the present invention employs the downhole circulation structure for preventing well control described above. Therefore, the downhole circulation method for preventing well control has the same beneficial effects as the downhole circulation structure for preventing well control described above, and will not be described again here.

[0036] Other features and advantages of the invention will be set forth in the description which follows, and will be apparent in part from the description, or may be learned by practicing the invention. The objects and other advantages of the invention may be realized and obtained by means of the structures pointed out in the description, claims and drawings. Attached Figure Description

[0037] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0038] Figure 1 A schematic diagram of a downhole circulation structure for preventing well control is shown in an embodiment of the present invention;

[0039] Figure 2 A schematic diagram of the downhole circulation structure for preventing well control, as shown in an embodiment of the present invention, is presented before installation.

[0040] Figure 3 Another schematic diagram of the downhole circulation structure for preventing well control, as shown in an embodiment of the present invention, is presented before installation.

[0041] Figure 4 A schematic diagram of the output section in an embodiment of the present invention is shown.

[0042] In the diagram, 100 is the circulation section; 110 is the pipe body; 120 is the shell; 200 is the output section; 210 is the nozzle; 221 is the connecting seat; 220 is the connector; 230 is the straightening section; 240 is the drill rod; 300 is the circulation channel; 310 is the first channel; and 320 is the second channel. Detailed Implementation

[0043] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0044] Reference Figure 1 This invention provides a downhole circulation structure for preventing well control failure, comprising: an output section 200 and a circulation section 100. The output end of the output section 200 is capable of outputting liquid. The circulation section 100 can be fixed to the wellhead, and a circulation channel 300 is provided on the circulation section 100, which can establish liquid circulation for the wellhead. The input end of the circulation channel 300 is located outside the wellhead and can be connected to the output end of the output section 200, allowing the liquid output by the output section 200 to reach the circulation channel 300. The output end of the circulation channel 300 first extends axially into the wellhead and then extends axially outward from the wellhead, allowing the output end of the circulation channel 300 to also be located outside the wellhead. This allows the output unit 200 to deliver liquid into the circulation channel 300. The liquid delivered into the circulation channel 300 can first reach the inside of the wellhead along the circulation channel 300, and then reach the outside of the wellhead along the circulation channel 300, thereby establishing a liquid circulation at the wellhead through the circulation channel 300.

[0045] Specifically, one end of the circulation channel 300 is located outside the wellhead and can be connected to the output end of the output unit 200. The other end of the circulation channel 300 is also located outside the wellhead and communicates with the external environment of the wellhead. The main body of the circulation channel 300 extends axially into the wellhead and then axially outwards, allowing the interior of the wellhead to communicate with both ends of the circulation channel 300 via its main body. This ensures that the output end of the output unit 200 is connected to the interior of the wellhead via the main body of the circulation channel 300, and that the external environment of the wellhead is also connected to the interior of the wellhead via the main body of the circulation channel 300. When the output unit 200 outputs liquid, the output liquid reaches one end of the circulation channel 300 and flows along the main body of the circulation channel 300 to the inside of the wellhead. As the output unit 200 continuously outputs liquid, the liquid inside the wellhead continuously accumulates. The liquid that reaches the inside of the wellhead and accumulates can continue to flow along the main body of the circulation channel 300 to the other end of the circulation channel 300. Through the connection between the circulation channel 300 and the outside, the liquid can be continuously discharged to the outside. Thus, the liquid flow within the circulation channel 300 establishes a liquid circulation at the wellhead. Under the action of liquid circulation, the pressure inside the wellhead can be balanced, thereby reducing the probability of well control risks and preventing safety accidents. This improves the safety of the entire drilling process. Correspondingly, the improved drilling safety also saves time spent on equipment maintenance or accident handling, thereby improving drilling efficiency and ensuring the successful achievement of the final exploration objectives.

[0046] It should be noted that there are no strict requirements for the configuration of the circulation channel 300 of the circulation unit 100. The purpose of the circulation channel 300 is to establish liquid circulation. Therefore, the configuration of the circulation channel 300 only needs to allow the output end of the output unit 200 to connect with the inside of the wellhead, so that the output unit 200 can deliver liquid into the inside of the wellhead, and allow the inside of the wellhead to connect with the outside of the wellhead, so that the liquid delivered to the inside of the wellhead can reach the external environment of the wellhead.

[0047] In some specific embodiments of the present invention, reference is made to... Figure 2The circulation channel 300 includes a first channel 310 and a second channel 320. One end of the first channel 310 is located outside the wellhead, allowing the output end of the output unit 200 to connect to this end. The other end of the first channel 310 is located inside the wellhead, enabling the output end of the output unit 200 to communicate with the interior of the wellhead via the first channel 310, thus allowing liquid to be delivered into the wellhead. One end of the second channel 320 is also located inside the wellhead, while the other end is located outside, allowing the interior of the wellhead to communicate with the external environment (the outside world) via the second channel 320. This allows liquid delivered to the interior of the wellhead to be discharged back to the outside via the second channel 320, thereby establishing the circulation channel 300.

[0048] Specifically, one end of the first channel 310 is fixedly disposed outside the wellhead, and the other end of the first channel 310 extends into the wellhead along the axial direction of the wellhead and is disposed inside the wellhead, so that the inside and outside of the wellhead can be connected through the first channel 310. The end of the first channel 310 disposed outside the wellhead can be connected to the output end of the output unit 200, so that the output end of the output unit 200 is connected to the inside of the wellhead through the first channel 310, and the output unit 200 can deliver liquid into the inside of the wellhead through the first channel 310. One end of the second channel 320 is located inside the wellhead, and the other end of the second channel 320 extends outward along the axial direction of the wellhead and is located outside the wellhead, so that the inside and outside of the wellhead can be connected through the second channel 320. As the output unit 200 continuously delivers liquid into the wellhead through the first channel 310, the liquid inside the wellhead will gradually accumulate, thereby raising the liquid level inside the wellhead and continuously discharging it to the outside through the second channel 320, achieving liquid circulation in the wellhead.

[0049] Furthermore, both the first channel 310 and the output section 200 are sealed to prevent the liquid delivered from the output end of the output section 200 into the first channel 310 from overflowing from the end of the first channel 310 located outside the wellhead due to inadequate sealing between the first channel 310 and the output section 200. This forces the liquid to be discharged to the outside only through the second channel 320, thus ensuring the pressure balance effect of the liquid circulation on the wellhead and the stability of the liquid circulation.

[0050] Furthermore, there can be multiple second channels 320, with one end of each second channel 320 located inside the wellhead and the other end of each second channel 320 located outside the wellhead, thereby facilitating the discharge of liquid.

[0051] Furthermore, the multiple second channels 320 are symmetrically arranged to ensure that the liquid discharge effect of each second channel 320 is similar, thereby guaranteeing the pressure balance and stability of the liquid circulation at the wellhead.

[0052] Furthermore, multiple second channels 320 are evenly arranged around the first channel 310 along its axis, thereby further ensuring the pressure balance and stability of the liquid circulation at the wellhead.

[0053] In some specific embodiments of the present invention, reference is made to... Figure 2 The circulation unit 100 includes a pipe body 110. One end of the pipe body 110 is disposed outside the wellhead, and the other end of the pipe body 110 is inserted into the wellhead along the axial direction of the wellhead, so that the inner wall of the pipe body 110 can form a first channel 310. There is a certain gap between the outer wall of the pipe body 110 and the inner wall of the wellhead, so that the outer wall of the pipe body 110 and the inner wall of the wellhead can form a second channel 320, and the second channel 320 is arranged axially around the first channel 310. The end of the pipe body 110 disposed outside the wellhead is connected to the output end of the output unit 200, so that liquid can be transported into the wellhead through the first channel 310 inside the pipe body 110. The liquid transported into the wellhead can be discharged to the outside through the second channel 320 formed by the gap between the outer wall of the pipe body 110 and the inner wall of the wellhead. The structure is relatively simple and flexible, and it is easy to implement liquid circulation.

[0054] Furthermore, the circulation unit 100 also includes a housing 120. The housing 120 is cylindrical, with one end located outside the wellhead and the other end inserted into the wellhead along its axial direction. The sidewalls of the housing 120 surround the wellhead along its axial direction, and the size of the housing 120 allows for sufficient contact between its outer wall and the inner wall of the wellhead, thus covering the inner wall of the wellhead. The pipe 110 is correspondingly inserted into the housing 120 along the axial direction of the wellhead, such that its inner wall still forms the first channel 310. Simultaneously, a certain gap exists between the outer wall of the pipe 110 and the inner wall of the housing 120, allowing them to form a second channel 320. The housing 120 ensures smooth liquid discharge, thereby guaranteeing the stability of liquid circulation. Furthermore, the structure remains relatively simple and flexible, facilitating the implementation of liquid circulation.

[0055] First, it should be noted that the length and width of the shell 120 and the pipe 110 are related to the depth and width of the wellhead.

[0056] Secondly, it should be noted that the tube body 110 can be an expansion tube, which facilitates the transport of liquids.

[0057] In some specific embodiments of the present invention, reference is made to... Figure 4 The output section 200 includes a nozzle 210. The nozzle 210 can be connected to a liquid source, thereby providing the liquid to be transported. The output end of the nozzle 210 is detachably connected to one end of the pipe body 110 located outside the wellhead, thereby allowing the nozzle 210 to communicate with the first channel 310 and to transport liquid into the wellhead through the first channel 310.

[0058] Furthermore, the output section 200 also includes a connector 220. The connector 220 is tubular and detachably disposed at one end of the pipe body 110 located outside the wellhead, so that the output end of the nozzle 210 can be connected to the first channel 310 through the connector 220, which facilitates the installation and removal of the nozzle 210 and thereby improves the efficiency of liquid circulation.

[0059] Furthermore, the inner end of the connector 220 away from the wellhead is provided with a threaded connection, which allows the connector 220 to be threadedly connected to the nozzle 210, facilitating installation and disassembly.

[0060] Furthermore, the outer wall of the connector 220 is provided with external threads, and the inner wall of the end of the pipe body 110 located outside the wellhead is provided with internal threads. The external threads of the connector 220 and the internal threads of the pipe body 110 are mutually compatible, allowing the connector 220 to be rotatably inserted into the end of the pipe body 110 located outside the wellhead, thereby establishing a threaded connection between the connector 220 and the pipe body 110. This not only facilitates installation and disassembly but also ensures a tight seal between the connector 220 and the pipe body 110 through the rotational misalignment between the external and internal threads. This prevents liquid delivered to the first channel 310 from overflowing from the end of the pipe body 110 located outside the wellhead, ensuring the stability of the liquid circulation.

[0061] In some specific embodiments of the present invention, reference is made to... Figure 3A connecting seat 221 is movably sleeved on the outer wall of the connector 220, and the connecting seat 221 can rotate around the axial direction of the connector 220. Furthermore, the outer wall of the connecting seat 221 is provided with an external thread that matches the internal thread of the pipe body 110, so that the connector 220 can be threadedly connected to the pipe body 110 through the connecting seat 221. When it is necessary to connect the connector 220 and the pipe body 110, simply align the connector 220 with the end of the pipe body 110 located outside the wellhead and keep the position of the connector 220 unchanged. Then, by continuously rotating the connecting seat 221 around the axis of the connector 220, the connecting seat 221 can be gradually screwed into the interior of the end of the pipe body 110 located outside the wellhead. The connection between the connector 220 and the pipe body 110 can be achieved without rotating the connector 220. Furthermore, the connector 220 can be connected to the nozzle 210 before connecting the connector 220 to the pipe body 110, which facilitates the installation and disassembly of the connector 220 and the nozzle 210.

[0062] Furthermore, a one-way valve is installed inside the connector 220, which prevents the liquid delivered to the wellhead from flowing back through the connector 220, and forces the liquid inside the wellhead to be discharged only through the second channel 320, thus ensuring the stability of the liquid circulation.

[0063] In some specific embodiments of the present invention, reference is made to... Figure 1 , Figure 2 and Figure 3 The connecting seat 221 can also slide along the axial direction of the connector 220 within a preset range. That is, after the connecting seat 221 is connected to the pipe body 110, the connector 220 can move up and down in the connecting seat 221 along the axial direction of the connector 220. Thus, the movement of the connector 220 can reduce the impact force when the nozzle 210 outputs liquid through the connector 220, ensure the stability of liquid output, and avoid wear between components caused by an overly rigid connection.

[0064] Furthermore, a limiting groove is formed on the outer wall of the connector 220. The limiting groove is arranged around the axial direction of the connector 220, and both ends of the limiting groove extend along the axial direction of the connector 220. The connecting seat 221 is sleeved in the limiting groove, and the connecting seat 221 can move up and down along the axial direction of the connector 220 within the limiting groove. That is, the range of movement of the connector 220 along the axial direction of the connector 220 within the connecting seat 221 is limited by the limiting groove, thereby preventing the connection between the connector 220 and the pipe body 110 from becoming too loose due to the movement of the connecting seat 221. At the same time, the recessed structure of the limiting groove also makes the gap between the connector 220 and the connecting seat 221 present a tortuous structure. Under the limiting effect of both ends of the limiting groove, the gap between the connector 220 and the connecting seat 221 can play a certain sealing role, thereby further ensuring the sealing performance between the connector 220 and the connecting seat 221, preventing liquid leakage, and ensuring the stability of liquid circulation.

[0065] Furthermore, a sealing ring is embedded on the outer wall of the connecting seat 221. The sealing ring is sleeved around the axial direction of the joint 220 on the outer wall of the connecting seat 221, so that the outer wall of the connecting seat 221 can abut against the inner wall of the pipe body 110 through the sealing ring, thereby sealing the gap between the connecting seat 221 and the pipe body 110 through the sealing ring.

[0066] Furthermore, the sealing ring is made of rubber, which can further increase the friction of the sealing ring, thereby strengthening the connection between the connecting seat 221 and the pipe body 110 and making the connection between the connecting seat 221 and the pipe body 110 more stable.

[0067] Furthermore, there are multiple sealing rings, which are evenly distributed along the axial direction of the joint 220 and are all embedded on the outer wall of the connecting seat 221, further improving the sealing effect between the connecting seat 221 and the pipe body 110.

[0068] Furthermore, there are two sealing rings, which are sequentially embedded in the outer wall of the inner end of the connecting seat 221 near the wellhead. Generally, two sealing rings are sufficient to meet the sealing requirements. If there are fewer than two sealing rings, liquid leakage may occur, while if there are more than two sealing rings, it will result in wasted costs.

[0069] In some specific embodiments of the present invention, reference is made to... Figure 3A straightening section 230 is provided at the end of the connector 220 away from the nozzle 210. The straightening section 230 is also tubular, and the inner end of the connector 220 near the wellhead is provided with a straight thread, allowing the connector 220 to be threadedly connected to the straightening section 230. When the connector 220 is connected to the outer end of the pipe body 110 located at the wellhead, the straightening section 230 can be inserted into the first channel 310 of the pipe body 110 first. The straightening section 230 helps the operator to align the connector 220 and the pipe body 110 coaxially, thus guiding and straightening the connection between the connector 220 and the pipe body 110, facilitating installation and connection.

[0070] Furthermore, the width of the straightening section 230 is greater than the width of the limiting groove of the connector 220. When the straightening section 230 is connected to the connector 220, the connecting seat 221 can slide further into the outer periphery of the straightening section 230 along the axial direction of the connector 220. The larger width of the straightening section 230 allows it to hold the connecting seat 221 in place, thus fixing the relative position between the connecting seat 221 and the connector 220. This prevents violent shaking caused by the connecting seat 221 moving freely on the connector 220 during liquid transport, and also avoids wear between components due to an overly rigid connection. When the liquid impact force is too large, the connecting seat 221 will disengage from the straightening section 230, thus providing cushioning.

[0071] Furthermore, two sealing rings are also sequentially embedded on the outer wall of the upper end of the straightening section 230, which may ensure the sealing effect between the connecting seat 221 and the straightening section 230. In addition, after the connecting seat 221 and the straightening section 230 are engaged, the friction of the sealing rings can improve the firmness of the engagement between the connecting seat 221 and the straightening section 230.

[0072] In some specific embodiments of the present invention, reference is made to... Figure 1 and Figure 3 The end of the connector 220 away from the nozzle 210 is provided with a drill rod 240 to facilitate the delivery of liquid into the first channel 310. Specifically, the end of the straightening section 230 away from the connector 220 is provided with a threaded connection, so that the straightening section 230 and the drill rod 240 can be threadedly connected.

[0073] The present invention also provides a downhole circulation method for preventing well control, employing a downhole circulation structure for preventing well control as described in any of the above specific embodiments, comprising the following steps:

[0074] The input end of the circulation unit 100 is fixed to the outside of the wellhead, and the main body of the circulation unit 100 is inserted into the inside of the wellhead so that the input end of the circulation unit 100 can communicate with the inside of the wellhead. At the same time, the output end of the circulation unit 100 is also fixed to the outside of the wellhead so that the inside of the wellhead can communicate with the output end of the circulation unit 100.

[0075] Connect the output terminal of the output unit 200 to the input terminal of the circulation unit 100.

[0076] Start the output unit 200 so that the liquid output by the output unit 200 can first reach the inside of the wellhead along the circulation unit 100.

[0077] Maintaining the start of the output section 200 allows the liquid inside the wellhead to travel along the circulation section 100 to the outside of the wellhead, thus achieving liquid circulation at the wellhead.

[0078] Specifically, the pipe body 110 and the shell are fixed at the wellhead. The outer wall of the shell fits against the inner wall of the wellhead, with one end of the shell inserted into the wellhead and the other end fixed to the outside of the wellhead. One end of the pipe body 110 is inserted into the wellhead, and the other end is fixed to the outside of the wellhead, thus completing the installation of the pipe body 110 and the shell. This allows the inner wall of the pipe body 110 to form a first channel 310, while the outer wall of the pipe body 110 and the inner wall of the shell can form a second channel 320. The first channel 310, the interior of the wellhead, and the second channel 320 are sequentially connected, thus initially completing the construction of the circulation channel 300.

[0079] The output end of the nozzle 210 is threaded to the upper end of the connector 220, the upper end of the stabilizer section 230 is threaded to the lower end of the connector 220, and the upper end of the drill pipe 240 is threaded to the lower end of the stabilizer section 230. Next, the drill pipe 240 and the stabilizer section 230 are sequentially inserted into the first channel 310 of the pipe body 110 from the end located outside the wellhead. During insertion, the stabilizer section 230 guides and stabilizes the connector 220 and the pipe body 110, ensuring coaxial alignment between them. The connector 220 is aligned with the end of the pipe body 110 located outside the wellhead, positioned directly above this end. Simultaneously, the drill pipe 240, located at the lower end of the stabilizer section 230, is gradually inserted to a position close to the end of the pipe body located inside the wellhead, facilitating the delivery of fluid into the wellhead.

[0080] The connecting seat 221 is rotated around the axial direction of the connector 220, so that the external thread on the outer wall of the connecting seat 221 can cooperate with the internal thread on the inner wall of the end of the pipe body 110 located outside the wellhead, thereby threading the connecting seat 221 to the end of the pipe body 110 located outside the wellhead, and driving the connector 220 during the threading process, realizing the connection between the connector 220 and the pipe body 110, thereby connecting the output end of the nozzle 210 to the first channel 310.

[0081] Pull the connector 220 upwards to move the connecting seat 221 downwards relative to the connector 220, so that the lower end of the connecting seat 221 can be engaged with the upper end of the straightening section 230, thereby fixing the relative position between the connecting seat 221 and the connector 220.

[0082] The nozzle 210 is controlled to output liquid, allowing the output liquid to pass sequentially through the connector 220, the centralizing section 230, and the drill pipe 240 to reach the first channel, and then along the first channel 310 to reach the inside of the wellhead. The state of liquid output from the nozzle 210 is maintained, thereby continuously delivering liquid into the inside of the wellhead, allowing the liquid to accumulate inside the wellhead.

[0083] As liquid accumulates inside the wellhead, the liquid level inside the wellhead will continue to rise. Because the end of the first channel located outside the wellhead is sealed, the liquid inside the wellhead can only be discharged to the outside of the wellhead through the second channel 320, thereby realizing the circulation of liquid at the wellhead.

[0084] Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A downhole circulation structure for preventing well control, characterized in that, include: The output section, the output end of which is capable of outputting liquid; The circulation unit can be fixed to the wellhead, and the circulation unit is provided with a circulation channel that can establish liquid circulation for the wellhead; The input end of the circulation channel is located outside the wellhead and can be connected to the output end of the output section; The output end of the circulation channel first extends into the wellhead along the axial direction of the wellhead, and then extends outward along the axial direction of the wellhead, so that the output end of the circulation channel is also located outside the wellhead. The output section can deliver liquid into the circulation channel. The delivered liquid can first reach the inside of the wellhead along the circulation channel, and then reach the outside of the wellhead along the circulation channel, so as to establish a liquid circulation at the wellhead.

2. The downhole circulation structure for preventing well control according to claim 1, characterized in that, The circulation channel includes: A first channel, one end of which is located outside the wellhead and is used to connect to the output end of the output unit, and the other end of which is located inside the wellhead, so that liquid can be delivered into the wellhead through the first channel; The second channel has one end located inside the wellhead and the other end located outside the wellhead, so that the liquid delivered to the inside of the wellhead can be discharged through the second channel.

3. The downhole circulation structure for preventing well control according to claim 2, characterized in that, The circulation section includes: A housing that can be inserted into the wellhead and is axially arranged around the wellhead so that it can cover the inner wall of the wellhead; The pipe body is inserted into the interior of the shell along the axial direction of the wellhead, so that the inner wall of the pipe body forms the first channel, and the outer wall of the pipe body and the inner wall of the shell form the second channel. One end of the tube is connected to the output section.

4. The downhole circulation structure for preventing well control according to claim 2, characterized in that, The output section includes: A nozzle for supplying the liquid to be delivered; The nozzle's output end is detachably connected to the circulation section via the connector, so that the nozzle communicates with the first channel.

5. The downhole circulation structure for preventing well control according to claim 4, characterized in that, A connecting seat is movably sleeved on the outer wall of the connector so that the connecting seat can rotate about the axial direction of the connector; The connecting seat and the circulation part are threaded together.

6. The downhole circulation structure for preventing well control according to claim 5, characterized in that, The connector can also slide along the axial direction of the joint within a preset range to reduce the impact force when conveying liquid.

7. The downhole circulation structure for preventing well control according to claim 5, characterized in that, A sealing ring is embedded on the outer wall of the connector for sealing.

8. The downhole circulation structure for preventing well control according to any one of claims 4 to 7, characterized in that, A straightening section is provided at the end of the connector away from the nozzle; When the connector is connected to the circulation section, the straightening section can be inserted into the first channel. The straightening section is used to guide and straighten the connection between the connector and the circulation section.

9. The downhole circulation structure for preventing well control according to any one of claims 4 to 7, characterized in that, A drill rod is provided at the end of the connector away from the nozzle to facilitate the delivery of liquid into the first channel.

10. A downhole circulation method for preventing well control, employing the downhole circulation structure for preventing well control as described in any one of claims 1 to 9, characterized in that, Includes the following steps: The input end of the circulation unit is fixed to the outside of the wellhead, and the main body of the circulation unit is inserted into the inside of the wellhead so that the input end of the circulation unit can communicate with the inside of the wellhead. At the same time, the output end of the circulation unit is also fixed to the outside of the wellhead so that the inside of the wellhead can communicate with the output end of the circulation unit. Connect the output terminal of the output section to the input terminal of the loop section; Start the output section so that the liquid output from the output section can first reach the inside of the wellhead along the circulation section; Maintaining the output section allows the liquid inside the wellhead to travel along the circulation section to the outside of the wellhead, thus achieving liquid circulation at the wellhead.

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