Liquid drainage tool and liquid drainage method suitable for horizontal well coiled tubing plunger

Abstract

The invention discloses a fluid drainage tool and method suitable for a coiled tubing plunger of a horizontal well, the fluid drainage tool comprises a downhole limiter, the downhole limiter comprises a limiter body of a barrel structure, a baffle ring is coaxially arranged in the limiter body, a cylindrical helical compression spring is arranged below the baffle ring, and the cylindrical helical compression spring is arranged below the baffle ring. A magnet ring is arranged between the check block and the cylindrical spiral compression spring, a tail blanking plug is arranged at the lower end in the limiting stopper body, the lower end of the limiting stopper body is further connected with a screen pipe, and the lower end of the screen pipe is connected with a lower connector. The downhole limiter device can limit the plunger, determine the maximum falling depth of the plunger, is mounted at the bottom of the coiled tubing, and is lowered along with pressurized well completion of the coiled tubing, the liquid lifting depth of the plunger can be increased, and the lifting depth of the plunger can be increased.

Description

Technical Field

[0001] The present invention relates to the technical field of fluid drainage in oil and gas development, and in particular to a fluid drainage tool and a fluid drainage method suitable for a coiled tubing plunger in a horizontal well. Background Art

[0002] With its advantages of rapid construction and pressure-carrying operation, the continuous tubing operation technology has been well applied in shale gas fields, tight gas fields, and conventional operation in the construction of my country's petroleum engineering field. Combined with the application of technology in recent years, with the continuous improvement of the technical level of continuous tubing operation in my country, this technology has gradually developed from the initial basic sand flushing and well washing to large-scale operation, and has achieved good application results in the exploitation of conventional and unconventional gas fields. At present, more and more gas wells in major oil and gas fields are completed with continuous tubing. This process can improve the efficiency of return flow, reduce environmental pollution, and quickly put into production. It also has the following four advantages: first, the construction time is short; second, there is no need for well killing operation to protect the reservoir; third, there is no need for large-scale operation machines, the continuous tubing is fast in the running speed, and the construction cost is relatively low; fourth, the liquid carrying capacity is strong, which is conducive to the drainage in the initial production stage. However, after the production enters the middle and late stages, due to the reduction of pressure and liquid carrying capacity, the accumulation of liquid in the gas well will lead to unstable production or even flooding, so it is often necessary to intervene in the drainage gas production process. For horizontal wells, the liquid accumulates at the well inclination of 45 to 55 degrees, and the problem of liquid accumulation in the long horizontal section needs to be solved. The biggest difference between the continuous tubing as a production string and the conventional tubing lies in the welds, curvature, ellipticity, etc. of the continuous tubing, which restricts the choice of drainage and gas production technology. Therefore, the current horizontal well continuous tubing lacks a supporting low-cost drainage and production technology to continue gas well production.

[0003] As an economical, environmentally friendly, simple and convenient operation and maintenance drainage gas production process, the plunger gas lift process is implemented in low-permeability water-containing gas wells. The plunger gas lift process can effectively remove the bottom of the well liquid with the help of the plunger, extend the lifting depth, and maintain stable production of the gas well. At the same time, the plunger gas lift process also has technical advantages in stabilizing production and improving the production capacity of a single well. At the same time, it can be connected to the intelligent gas well management and control platform, effectively liberating on-site management manpower and realizing intelligent management of gas wells. Therefore, it has a very good application prospect.

[0004] The current plunger gas lift process is suitable for 2 3 / 8 ″ and 2 7 / 8 If the conventional tubing is replaced with the conventional tubing in the coiled tubing well, the cost is high, the construction period is long, and the safety risk is great. Therefore, how to combine the plunger gas lift process technology on the coiled tubing, continue the effectiveness of the drainage and production process, tap the potential of continuous oil production, and extend the life cycle of the gas well is an urgent problem to be solved.

[0005] In view of this, this application is hereby filed. Summary of the invention

[0006] The problem with the prior art is that the current plunger gas lift process lacks corresponding supporting tools to adapt to the horizontal well coiled tubing. The purpose of the present invention is to provide a plunger drainage tool and drainage method suitable for horizontal well coiled tubing, which can solve the operation limit problem of the plunger in the coiled tubing, thereby integrating the advantages of coiled tubing drainage and gas production and plunger gas lift drainage and gas production, effectively lifting the liquid accumulated in the inclination section of the horizontal well, improving the drainage and gas production capacity of the gas well, and achieving the purpose of reducing costs and increasing efficiency.

[0007] The present invention is achieved through the following technical solutions:

[0008] A tool suitable for horizontal well continuous oil tubing plunger drainage, including a downhole limiter, the downhole limiter includes a limiter body in a cylindrical structure, a stop ring is coaxially arranged in the limiter body, a cylindrical helical compression spring is arranged below the stop ring, a magnet ring is arranged between the stop block and the cylindrical helical compression spring, a tail plugger is arranged at the lower end of the limiter body, the lower end of the limiter body is also connected to a screen tube, and the lower end of the screen tube is connected to a lower joint.

[0009] Furthermore, a retaining ring is arranged between the outer wall of the retaining ring and the inner wall of the limiter body.

[0010] Furthermore, an O-shaped rubber ring is provided between the tail plugger and the inner wall of the limiter body.

[0011] Furthermore, the stopper is an annular structure, and the magnet ring is arranged in the annular cavity of the stopper.

[0012] Furthermore, the stopper is in a hollow bottleneck structure, the stopper neck structure faces upwards and the bottle structure faces downwards, and the magnet ring is arranged in the cavity of the bottle structure.

[0013] Furthermore, it also includes a plunger, which includes a plunger body with a cylindrical structure. A magnetic steel and a coil are arranged in the plunger body for sensing the magnet ring in the downhole limiter.

[0014] Furthermore, the upper end of the plunger body has a fishing neck, and the lower end is connected to a lower joint.

[0015] Furthermore, a battery and a circuit board are also arranged in the plunger body.

[0016] The present invention provides a downhole stopper device that can be matched with a continuous oil pipe. The device is connected to the tail end of the continuous oil pipe and is lowered together with the continuous oil pipe when the well is completed under pressure. The plunger can be extended to lift liquid and improve the plunger lifting depth. The downhole stopper of the present invention plays a limiting role on the plunger and determines the maximum depth to which the plunger can fall. The downhole stopper is installed at the bottom position of the continuous oil pipe and is connected to a conversion joint on the bottom end of the oil pipe through a top thread. When the oil pipe is lowered during well completion, the stopper is lowered together with the oil pipe at the same time. The lowering depth can reach the position of the oil pipe shoe and the depth can reach 70 degrees of well inclination. Compared with the conventional oil pipe that can be cast and fished and can only be lowered to 60 degrees of well inclination due to the influence of the wire operation capacity, the maximum depth to which the plunger of the present invention can descend can reach the deepest position of the wellbore liquid accumulation, has a deeper liquid lifting depth, and has a higher liquid lifting efficiency. When the gas well needs to intervene in the plunger process, the plunger can be immediately put into operation without the need to lower the downhole stopper through the wire operation, thereby reducing the operation risk and extending the effective period of the process.

[0017] The downhole limiter device of the present invention mainly includes four major components: a buffer structure, a magnet ring, a plug and a screen tube. The buffer structure is a block and a cylindrical helical compression spring. Its main function is to prevent the plunger from hard impacting the retainer located in the oil pipe when it falls, and at the same time absorb the impact force of the plunger falling to the top of the spring, preventing the plunger from hard impact and causing wear on the plunger body and the limiter.

[0018] The main liquid accumulation section of horizontal wells is at the well inclination of 45-55 degrees. To maximize the improvement of wellbore liquid accumulation, the position of the plunger each time it is lifted must be above the downhole limiter. The farther the plunger is from the limiter, the worse the effect of improving liquid accumulation will be. Therefore, in order to improve the wellbore liquid accumulation, it is particularly important to judge the plunger's drop depth, especially whether the plunger has dropped to the limiter.

[0019] Therefore, the present invention embeds a magnet ring inside the limiter body to determine the position and direction of the magnet inside the plunger, so as to ensure that the interaction between the magnetic field and the plunger sensor is maximized. It has strong magnetism and can sense whether it has reached the downhole limiter position when the plunger approaches. The plunger can be judged through the operation process of the plunger in the wellbore to determine the plunger's falling depth in the horizontal well and whether the plunger has fallen to the position of the limiter, thereby clarifying the lifting efficiency of the plunger in the horizontal fluid accumulation section. The magnetic positioning inside the plunger is composed of magnetic steel and a coil. When the plunger is put into the well and the magnetic positioning coil inside the plunger reaches the downhole limiter, the magnet ring inside the limiter causes the change of the coil's magnetic lines of force, and the two ends of the coil will output an induced electromotive force signal. This signal is sent to the single-chip microcomputer for collection and storage after low-pass filtering and amplification processing. After the plunger is taken out at a later stage, the data can be read through the ground software to determine the plunger's falling depth, falling time, speed, etc., and clarify the plunger's operating efficiency.

[0020] The present invention arranges a plug at the bottom end of the downhole limiter, the purpose of which is to withstand the formation pressure during the lowering of the completion pipe string to ensure the safe construction. After the placement is successful, the plug is opened by holding the pressure to start well production.

[0021] The present invention additionally connects a screen pipe to the bottom end of the downhole limiter, which is mainly used for sand prevention and control. Horizontal wells usually adopt sand fracturing to establish a seepage channel. When the well is opened for production, the bottom hole pressure airflow will drive the deposited sand body to flow. Therefore, part of the sand particles can be blocked from entering the wellbore through the screen pipe to prevent the oil pipe from being blocked.

[0022] A method for draining a coiled tubing plunger in a horizontal well, comprising the following steps:

[0023] (1) The downhole stopper is installed at the tail end of the coiled tubing, and after the coiled tubing is completed under pressure, the coiled tubing with the downhole stopper installed is lowered into the well;

[0024] (2) When the amount of liquid accumulated in the coiled tubing of the horizontal well increases, the plunger is inserted from the wellhead.

[0025] The drainage method of the present invention can combine the continuous oil pipe with the plunger process. By installing the downhole limiter at the tail end of the continuous oil pipe and connecting the oil pipe to be lowered into the well together when the oil pipe is installed, compared with the traditional salvageable limiter used for conventional oil pipes, in which the limiter is hoisted into the well by a steel wire when the plunger process is required, the downhole limiter of the present invention has a deeper lowering depth, thereby ensuring that the plunger can reach the inclination section of the horizontal wellbore, thereby effectively lifting the accumulated liquid in the inclination section of the horizontal well, ensuring the effectiveness of the process, and improving the drainage and gas production capacity of the gas well; in addition, when the plunger process is required, the present invention can directly throw in the plunger without temporarily using a steel wire operation to lower the downhole limiter, thereby reducing the operation risk and extending the effective period of the process.

[0026] The liquid drainage method of the present invention is suitable for the situation that the formation pressure of the continuous oil pipe gas well decreases in the middle and late stages, the liquid accumulation affects the gas output and a plunger process is required. The plunger tool is put into the wellhead, and when the well is closed, the plunger tool falls and stops at the upper end of the downhole limiter. When the well is opened, the energy of the gas well is used to lift the liquid on the upper part of the plunger to the ground, thereby forming a shut-in re-pressure, and the up and down reciprocating motion of the liquid lifting when the well is opened provides an efficient plunger drainage and gas production process method for the effective development of the continuous oil pipe completion gas well and the extension of the continuous oil production time.

[0027] Compared with the prior art, the present invention has the following advantages and beneficial effects:

[0028] 1. The present invention provides a tool and method for draining a plunger of a coiled tubing in a horizontal well. The downhole stopper device can limit the plunger and determine the maximum depth to which the plunger can fall. The device is installed at the bottom of the coiled tubing and is lowered together with the coiled tubing when the well is completed under pressure. The device can extend the plunger's liquid lifting depth and increase the plunger's lifting depth.

[0029] 2. The embodiment of the present invention provides a tool and method for draining a coiled tubing plunger in a horizontal well. The operation process of the plunger in the wellbore can be sensed by a magnet ring disposed inside the stopper body and a magnet and a coil disposed on the plunger, thereby determining the plunger's drop depth in the horizontal well and whether the plunger has dropped to the position of the stopper, thereby clarifying the lifting efficiency of the plunger in the horizontal liquid accumulation section.

[0030] 3. The embodiment of the present invention provides a tool and method for horizontal well coiled tubing plunger drainage, which is suitable for the situation that the formation pressure of coiled tubing gas wells decreases in the middle and late stages, and the accumulation of liquid affects the gas production and requires a plunger process. The plunger tool is put into the wellhead, and when the well is shut in, the plunger tool falls and stops at the upper end of the downhole stopper. When the well is opened, the energy of the gas well is used to lift the liquid on the top of the plunger to the ground, thereby forming a shut-in re-pressure, and the up and down reciprocating motion of the well opening and lifting liquid provides an efficient plunger drainage gas production process method for the effective development of coiled tubing completion gas wells and the extension of the continuous oil production time;

[0031] 3. The embodiment of the present invention provides a tool and method for draining the continuous tubing plunger in horizontal wells. The plunger process can be implemented in the continuous tubing string without changing the production string, thereby saving the well repair cost of replacing conventional tubing, reducing the operational risk of placing a limiter, shortening the process construction period, and being able to quickly put the plunger into operation when needed to extend the liquid lifting depth, thereby ensuring the production timeliness of the gas well and improving the gas production efficiency of a single well. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] In order to more clearly illustrate the technical solutions of the exemplary embodiments of the present invention, the drawings required for use in the embodiments will be briefly introduced below. It should be understood that the following drawings only show certain embodiments of the present invention and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other related drawings can be obtained based on these drawings without paying creative work.

[0033] Figure 1 A schematic diagram of the structure of a downhole stopper provided in an embodiment of the present invention;

[0034] Figure 2 A schematic diagram of the upper end structure of a downhole stopper provided in an embodiment of the present invention;

[0035] Figure 3 A schematic diagram of a plunger structure provided in an embodiment of the present invention.

[0036] Reference numerals and corresponding parts names:

[0037] 1-limiter device body, 2-retaining ring, 3-cylindrical helical compression spring, 4-tail plugger, 5-O-shaped rubber ring, 6-retaining ring, 7-magnet ring, 8-screen tube, 9-lower joint, 10-plunger body, 11-magnetic steel, 12-coil, 13-fishing neck, 14-lower joint, 15-battery, 16-circuit board. DETAILED DESCRIPTION

[0038] In order to make the objectives, technical solutions and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with embodiments and drawings. The exemplary embodiments of the present invention and their description are only used to explain the present invention and are not intended to limit the present invention.

[0039] In the following description, a large number of specific details are set forth in order to provide a thorough understanding of the present invention. However, it is apparent to one of ordinary skill in the art that these specific details are not necessarily employed to practice the present invention. In other embodiments, in order to avoid obscuring the present invention, well-known structures, circuits, or methods are not specifically described.

[0040] Throughout the specification, references to "one embodiment," "an embodiment," "an example," or "an example" mean that a particular feature, structure, or characteristic described in conjunction with the embodiment or example is included in at least one embodiment of the present invention. Therefore, the phrases "one embodiment," "an embodiment," "an example," or "an example" appearing in various places throughout the specification do not necessarily all refer to the same embodiment or example. In addition, particular features, structures, or characteristics may be combined in one or more embodiments or examples in any suitable combination and / or sub-combination. In addition, it will be appreciated by those of ordinary skill in the art that the figures provided herein are for illustrative purposes and that the figures are not necessarily drawn to scale. The term "and / or" as used herein includes any and all combinations of one or more of the associated listed items.

[0041] In the description of the present invention, the directions or positional relationships indicated by terms such as “front”, “rear”, “left”, “right”, “up”, “down”, “vertical”, “horizontal”, “high”, “low”, “inside” and “outside” are based on the directions or positional relationships shown in the accompanying drawings and are only for the convenience of describing the present invention and simplifying the description. They do not indicate or imply that the device or element referred to must have a specific direction, be constructed and operated in a specific direction. Therefore, they should not be understood as limiting the scope of protection of the present invention.

[0042] Example 1

[0043] like Figure 1-Figure 3As shown, an embodiment of the present invention provides a continuous tubing plunger drainage tool suitable for horizontal wells, including a downhole limiter, the downhole limiter includes a limiter body 1 in a cylindrical structure, a stop ring 2 is coaxially arranged in the limiter body 1, a cylindrical helical compression spring 3 is arranged below the stop ring 2, a magnet ring 7 is arranged between the stop block 2 and the cylindrical helical compression spring 3, a tail plugger 4 is arranged at the lower end of the limiter body 1, and a screen tube 8 is also connected to the lower end of the limiter body 1, and a lower joint 9 is connected to the lower end of the screen tube 8.

[0044] Furthermore, a retaining ring 6 is provided between the outer wall of the retaining ring 2 and the inner wall of the limiter body 1 .

[0045] Furthermore, an O-shaped rubber ring 5 is provided between the tail plug 4 and the inner wall of the stopper body 1 .

[0046] Furthermore, the stopper 2 is an annular structure, and the magnet ring 7 is arranged in the annular cavity of the stopper 2 .

[0047] Furthermore, the stopper 2 is of a hollow bottleneck structure, with the neck structure of the stopper 2 facing upward and the bottle structure facing downward, and the magnet ring 7 is disposed in the cavity of the bottle structure.

[0048] Furthermore, it also includes a plunger, which includes a plunger body 10 with a cylindrical structure. A magnetic steel 11 and a coil 12 are arranged in the plunger body 10 for sensing the magnet ring 7 in the downhole limiter.

[0049] Furthermore, the upper end of the plunger body 10 has a fishing neck 13 , and the lower end is connected to a lower joint 14 .

[0050] Furthermore, a battery 15 and a circuit board 16 are also disposed in the plunger body 10 .

[0051] The present invention provides a downhole stopper device that can be matched with a continuous oil pipe. The device is connected to the tail end of the continuous oil pipe and is lowered together with the continuous oil pipe when the well is completed under pressure. The plunger can be extended to lift liquid and improve the plunger lifting depth. The downhole stopper of the present invention plays a limiting role on the plunger and determines the maximum depth to which the plunger can fall. The downhole stopper is installed at the bottom position of the continuous oil pipe and is connected to a conversion joint on the bottom end of the oil pipe through a top thread. When the oil pipe is lowered during well completion, the stopper is lowered together with the oil pipe at the same time. The lowering depth can reach the position of the oil pipe shoe and the depth can reach 70 degrees of well inclination. Compared with the conventional oil pipe that can be cast and fished and can only be lowered to 60 degrees of well inclination due to the influence of the wire operation capacity, the maximum depth to which the plunger of the present invention can descend can reach the deepest position of the wellbore liquid accumulation, has a deeper liquid lifting depth, and has a higher liquid lifting efficiency. When the gas well needs to intervene in the plunger process, the plunger can be immediately put into operation without the need to lower the downhole stopper through the wire operation, thereby reducing the operation risk and extending the effective period of the process.

[0052] The downhole limiter device of the present invention mainly includes four major components: a buffer structure, a magnet ring, a plug and a screen tube. The buffer structure is a block and a cylindrical helical compression spring. Its main function is to prevent the plunger from hard impacting the retainer located in the oil pipe when it falls, and at the same time absorb the impact force of the plunger falling to the top of the spring, preventing the plunger from hard impact and causing wear on the plunger body and the limiter.

[0053] The main liquid accumulation section of horizontal wells is at the well inclination of 45-55 degrees. To maximize the improvement of wellbore liquid accumulation, the position of the plunger each time it is lifted must be above the downhole limiter. The farther the plunger is from the limiter, the worse the effect of improving liquid accumulation will be. Therefore, in order to improve the wellbore liquid accumulation, it is particularly important to judge the plunger's drop depth, especially whether the plunger has dropped to the limiter.

[0054] Therefore, the present invention embeds a magnet ring inside the limiter body to determine the position and direction of the magnet inside the plunger, so as to ensure that the interaction between the magnetic field and the plunger sensor is maximized. It has strong magnetism and can sense whether it has reached the downhole limiter position when the plunger approaches. The plunger can be judged through the operation process of the plunger in the wellbore to determine the plunger's falling depth in the horizontal well and whether the plunger has fallen to the position of the limiter, thereby clarifying the lifting efficiency of the plunger in the horizontal fluid accumulation section. The magnetic positioning inside the plunger is composed of magnetic steel and a coil. When the plunger is put into the well and the magnetic positioning coil inside the plunger reaches the downhole limiter, the magnet ring inside the limiter causes the change of the coil's magnetic lines of force, and the two ends of the coil will output an induced electromotive force signal. This signal is sent to the single-chip microcomputer for collection and storage after low-pass filtering and amplification processing. After the plunger is taken out at a later stage, the data can be read through the ground software to determine the plunger's falling depth, falling time, speed, etc., and clarify the plunger's operating efficiency.

[0055] The present invention arranges a plug at the bottom end of the downhole limiter, the purpose of which is to withstand the formation pressure during the lowering of the completion pipe string to ensure the safe construction. After the placement is successful, the plug is opened by holding the pressure to start well production.

[0056] The present invention additionally connects a screen pipe to the bottom end of the downhole limiter, which is mainly used for sand prevention and control. Horizontal wells usually adopt sand fracturing to establish a seepage channel. When the well is opened for production, the bottom hole pressure airflow will drive the deposited sand body to flow. Therefore, part of the sand particles can be blocked from entering the wellbore through the screen pipe to prevent the oil pipe from being blocked.

[0057] Example 2

[0058] like Figure 1-Figure 3 As shown, an embodiment of the present invention provides a method for draining a coiled tubing plunger in a horizontal well, comprising the following steps:

[0059] (1) The downhole stopper is installed at the tail end of the coiled tubing, and after the coiled tubing is completed under pressure, the coiled tubing with the downhole stopper installed is lowered into the well;

[0060] (2) When the amount of liquid accumulated in the coiled tubing of the horizontal well increases, the plunger is inserted from the wellhead.

[0061] The drainage method of the present invention can combine the continuous oil pipe with the plunger process. By installing the downhole limiter at the tail end of the continuous oil pipe and connecting the oil pipe to be lowered into the well together when the oil pipe is installed, compared with the traditional salvageable limiter used for conventional oil pipes, in which the limiter is hoisted into the well by a steel wire when the plunger process is required, the downhole limiter of the present invention has a deeper lowering depth and an increased plunger running depth, thereby ensuring that the plunger can reach the inclination section of the horizontal wellbore, thereby effectively lifting the accumulated liquid in the inclination section of the horizontal well, ensuring the effectiveness of the process, and significantly improving the drainage and gas production effect of the plunger gas lift; in addition, when the plunger process is required, the present invention can directly throw in the plunger without temporarily using a steel wire operation to lower the downhole limiter, thereby reducing the operation risk and extending the effective period of the process.

[0062] The liquid drainage method of the present invention is suitable for the situation that the formation pressure of the continuous oil pipe gas well decreases in the middle and late stages, the liquid accumulation affects the gas output and a plunger process is required. The plunger tool is put into the wellhead, and when the well is closed, the plunger tool falls and stops at the upper end of the downhole limiter. When the well is opened, the energy of the gas well is used to lift the liquid on the upper part of the plunger to the ground, thereby forming a shut-in re-pressure, and the up and down reciprocating motion of the liquid lifting when the well is opened provides an efficient plunger drainage and gas production process method for the effective development of the continuous oil pipe completion gas well and the extension of the continuous oil production time.

[0063] The specific implementation methods described above further illustrate the objectives, technical solutions and beneficial effects of the present invention in detail. It should be understood that the above description is only a specific implementation method of the present invention and is not intended to limit the scope of protection of the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A tool for draining coiled tubing plungers in horizontal wells, characterized in that: The invention comprises a downhole limiter, wherein the downhole limiter comprises a limiter body (1) in a cylindrical structure, a stop ring (2) is coaxially arranged inside the limiter body (1), a cylindrical helical compression spring (3) is arranged below the stop ring (2), a magnet ring (7) is arranged between the stop block (2) and the cylindrical helical compression spring (3), a tail plug (4) is arranged at the lower end of the limiter body (1), a screen tube (8) is connected to the lower end of the screen tube (8), and a lower joint (9) is connected to the lower end of the screen tube (8).

2. A tool for horizontal well coiled tubing plunger drainage according to claim 1, characterized in that: A retaining ring (6) is provided between the outer wall of the retaining ring (2) and the inner wall of the stopper body (1).

3. The tool for draining coiled tubing plungers in horizontal wells according to claim 1, characterized in that: An O-shaped rubber ring (5) is provided between the tail plug (4) and the inner wall of the stopper body (1).

4. The tool for draining coiled tubing plungers in horizontal wells according to claim 1, characterized in that: The stopper (2) is an annular structure, and the magnet ring (7) is arranged in the annular cavity of the stopper (2).

5. The tool for draining coiled tubing plungers in horizontal wells according to claim 1, characterized in that: The stopper (2) is in the form of a hollow bottleneck structure, with the neck structure of the stopper (2) facing upwards and the bottle structure facing downwards, and the magnet ring (7) is arranged in the cavity of the bottle structure.

6. The tool for draining coiled tubing plungers in horizontal wells according to claim 1, characterized in that: It also includes a plunger, which includes a plunger body (10) with a cylindrical structure. A magnetic steel (11) and a coil (12) are arranged in the plunger body (10) for sensing a magnet ring (7) in a downhole limiter.

7. The tool for draining coiled tubing plungers in horizontal wells according to claim 6, characterized in that: The upper end of the plunger body (10) is provided with a fishing neck (13), and the lower end is connected with a lower joint (14).

8. The tool for draining coiled tubing plungers in horizontal wells according to claim 6, characterized in that: A battery (15) and a circuit board (16) are also provided in the plunger body (10).

9. A method for draining fluid using the horizontal well coiled tubing plunger draining tool according to claim 1, characterized in that: The steps include: (1) The downhole stopper is installed at the tail end of the coiled tubing, and after the coiled tubing is completed under pressure, the coiled tubing with the downhole stopper installed is lowered into the well; (2) When the amount of liquid accumulated in the coiled tubing of the horizontal well increases, the plunger is inserted from the wellhead.

10. A method for draining liquid from a coiled tubing plunger in a horizontal well according to claim 9, characterized in that: The top end of the downhole stopper is connected to the conversion joint on the bottom end of the connecting oil pipe through a threaded structure.

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