Two-stage relay plunger lifting device and method for horizontal wells and movable ball core plunger

Abstract

The present invention provides a two-stage relay plunger lifting device for a horizontal well, a method thereof, and a movable ball core plunger. The two-stage relay plunger lifting device for a horizontal well includes, from bottom to top, a first pressure-controlled check valve, a first plunger buffer, a movable ball core plunger, a second plunger buffer, a second pressure-controlled check valve, a third pressure-controlled check valve, a third plunger buffer, a common plunger, and a common plunger lifting wellhead device. The two-stage relay plunger lifting production method for a horizontal well can be a production cycle in which a well is shut down and a well is opened once. The present invention can utilize the natural energy of the formation or other energy to achieve pressure changes in various parts of the well, and realize the reciprocating motion of the movable ball core plunger at both ends of the horizontal section oil pipe, thereby driving the accumulated liquid near the target point B of the horizontal section to the vertical well section, and finally using a common plunger or other lifting methods to completely discharge the liquid from the wellhead.

Description

Technical Field

[0001] The present invention belongs to the technical field of oil and gas well drainage and production, and specifically relates to a two-stage relay plunger lifting device for a horizontal well, a two-stage relay plunger lifting production method for a horizontal well, and a movable ball core plunger that can be used in the aforementioned device and production method. Background Art

[0002] With the increasing application of horizontal wells, the development of horizontal well drainage technology has attracted more and more attention from oil and gas fields at home and abroad. At present, the drainage technologies for horizontal wells mainly include foam drainage, optimized string drainage, gas lift drainage, plunger gas lift drainage, etc. The application of these existing drainage technologies in horizontal wells has certain effects, but there are also certain defects.

[0003] Foam drainage technology is applicable to water-producing gas wells. This technology is to inject a certain surfactant or high-molecular polymer into the bottom of the well. With the help of the stirring of the wellbore fluid, it fully contacts with the accumulated liquid at the bottom of the well to produce a large amount of low-density water-containing foam, reduce the slip loss in the wellbore, and improve the wellbore's liquid lifting capacity. At the same time, the foaming agent used in foam drainage technology is usually put into or injected from the wellhead, and can often only act near the wellbore area of ​​the A target point (equivalent to the starting position of the horizontal section oil pipe) of the horizontal well, and the accumulated liquid in the longer horizontal section cannot be discharged. Especially for downward-dipping horizontal wells, the effect of foam drainage is more limited. At the same time, the foam drainage process has the disadvantages of short maintenance time of the drainage effect of a single operation, low drainage efficiency, and limitation by the properties of the wellbore liquid.

[0004] The optimal pipe string drainage technology is to optimize the size of the production pipe string when the gas well energy is low and cannot carry liquid production normally, thereby reducing the critical liquid carrying flow rate and improving the liquid carrying production capacity of the gas well, thereby achieving the purpose of drainage. At the same time, the optimal pipe string drainage process requires the insertion of production pipe strings of different sizes at different production stages, requiring well repair operations, which is costly, and as the diameter of the pipe string decreases, it may cause the tools to be partially or completely unable to be inserted.

[0005] Gas lift drainage technology uses high-pressure gas energy or booster equipment to inject high-pressure gas (natural gas or nitrogen) into the wellbore, and uses the high-pressure gas energy to return the bottom hole liquid from the oil pipe (or casing annulus) to the ground. Gas lift drainage technology is restricted by the reflux of the lifting liquid, and the system lifting efficiency is poor.

[0006] The plunger gas lift drainage technology is to place a plunger in the tubing as a gas-liquid mechanical separation interface, fully utilizing the gas well's own energy to push the plunger to bring the liquid out of the wellbore, achieving periodic liquid lifting, effectively preventing gas from rising and liquid from slipping, and improving lifting efficiency. However, for the plunger gas lift drainage process, the operation of the plunger system is severely restricted by the well inclination. The currently known maximum well inclination angle of the retainer is about 70°, that is, the accumulated liquid below the retainer cannot be discharged, and it is difficult to fundamentally solve the problem of liquid accumulation in the horizontal section.

[0007] In addition to the above-mentioned drainage technologies, horizontal wells usually also use a variety of composite technologies for drainage, such as pressurization + gas lift composite drainage technology, plunger + foam composite drainage technology, etc. The main purpose is to make full use of the advantages of each drainage process and maximize the drainage efficiency of horizontal wells.

[0008] As for the plunger suitable for horizontal wells, some research has been done by predecessors:

[0009] A Chinese invention patent application with publication date of September 8, 2017 and publication number CN107143316A discloses a new type of plunger suitable for plunger lifting in directional wells and horizontal wells. The plunger is a pad-type spherical plunger, but the plunger body lacks a buffer structure, is easily damaged, and can only fall to the vicinity of target point A, and cannot discharge the accumulated fluid in the horizontal section.

[0010] A Chinese invention patent application with a publication date of December 12, 2012 and publication number CN102817594A discloses a method and device for draining water and producing gas from a horizontal well. The method divides the wellbore into three sections, uses the wellbore's own energy to carry the accumulated liquid in the horizontal section to the vertical well section, and finally discharges it using traditional technology. The invention patent application does not fundamentally solve the problem of difficulty in draining liquid from the horizontal section, especially for low-pressure wells or downward-inclined horizontal wells, where it is difficult for the accumulated liquid in the horizontal section to reach the vertical well section by relying on the formation's own energy.

[0011] To sum up, after analysis and research, the inventors stated that the currently known horizontal well production technology is basically only effective for liquid accumulation near the wellbore target point A and its upper part, but it is difficult to "reach" the liquid accumulation in the horizontal section. The biggest problem restricting the production capacity of horizontal wells is often the liquid accumulation in the horizontal section. Therefore, solving the liquid accumulation in the horizontal section has become an urgent problem to be solved to improve the recovery rate of horizontal wells. Summary of the invention

[0012] The purpose of the present invention is to solve at least one of the above-mentioned deficiencies in the prior art. For example, one of the purposes of the present invention is to solve the problem of difficulty in draining the accumulated liquid in the horizontal section caused by the inability of conventional lifting process devices to reach the vicinity of the end of the oil pipe.

[0013] In order to achieve the above-mentioned purpose, one aspect of the present invention provides a two-stage relay plunger lifting device for a horizontal well, comprising a first pressure-controlled check valve, a first plunger buffer, a movable ball core plunger, a second plunger buffer, a second pressure-controlled check valve, a third pressure-controlled check valve, a third plunger buffer, a common plunger and a common plunger lifting wellhead device which are sequentially arranged in the oil pipe from the end of the oil pipe to the wellhead, wherein the first pressure-controlled check valve is located in the horizontal section of the oil pipe and is arranged near the target point B, and can be closed when the pressure in the horizontal section of the oil pipe is greater than the first pressure value, and opened when the pressure in the horizontal section of the oil pipe is less than the first pressure value, so that the horizontal section of the oil pipe is connected to the bottom of the well. The fluids are isolated and connected accordingly; the movable ball core plunger is arranged in the horizontal section of the oil pipe in the form of a right buffer platform closer to the end of the oil pipe; the second pressure-controlled check valve is located in the oil pipe and is arranged near the target point A, and can be closed when the pressure in the horizontal section of the oil pipe is greater than the second pressure value, and opened when the pressure in the horizontal section of the oil pipe is less than the second pressure value, thereby isolating and connecting the horizontal section of the oil pipe and the casing accordingly; the third pressure-controlled check valve is arranged at the bottom of the vertical well section of the oil pipe, and can be closed when the pressure in the vertical well section of the oil pipe is greater than the third pressure value, and opened when the pressure in the vertical well section of the oil pipe is less than the third pressure value, thereby isolating and connecting the vertical well section of the oil pipe and the horizontal section of the oil pipe accordingly.

[0014] In an exemplary embodiment of the two-stage relay plunger lifting device for a horizontal well of the present invention, the first plunger buffer can be arranged close to the first pressure-controlled check valve, the second plunger buffer can be arranged close to the second pressure-controlled check valve to buffer the movable ball core plunger approaching during the movement, and the third plunger buffer can be arranged close to the third pressure-controlled check valve to buffer the ordinary plunger approaching during the movement.

[0015] In an exemplary embodiment of the horizontal well two-stage relay plunger lifting device of the present invention, one or more of the first pressure-controlled check valve, the second pressure-controlled check valve and the third pressure-controlled check valve may have the following check valve structure, and the check valve structure may include: a columnar valve body having an outer diameter equal to the inner diameter of the oil pipe; a fluid channel penetrating the length direction of the columnar valve body; a pressure chamber arranged in the columnar valve body; a pressure-sensitive airbag accommodated in a part of the pressure chamber and having one end fixed to the pressure chamber and the other end; a pressure-conducting channel arranged in the A pressure-sensitive airbag is provided in a cylindrical valve body and can connect the pressure to be measured with another part of the pressure chamber, so that the pressure-sensitive airbag expands or contracts accordingly when the pressure to be measured decreases or increases; a limiting mechanism is provided in the cylindrical valve body; a valve slot is provided in the cylindrical valve body and connects the other part of the pressure chamber with the limiting mechanism; a valve stem is provided in the valve slot and has a stem body provided with a valve hole, one end fixedly connected to the other end of the pressure-sensitive airbag, and the other end located in the limiting mechanism, the valve hole can disconnect or conduct the fluid channel accordingly when the valve stem is driven by the expansion or contraction of the pressure-sensitive airbag. Wherein, the fluid channel can be S-shaped, and the pressure-conducting channel can be J-shaped. In addition, the limiting mechanism can further include a limiting platform and a limiting slot, the limiting slot can accommodate the other end of the moving valve stem, and the limiting platform can prevent the other end of the valve stem from escaping from the limiting slot.

[0016] In an exemplary embodiment of the horizontal well two-stage relay plunger lifting device of the present invention, the movable ball core plunger includes a movable ball core, a left buffer platform and a right buffer platform, and an outer cylinder and an inner cylinder that are fitted on each other, wherein an annular flow channel surrounding the central axis of the inner cylinder is formed between the outer cylinder and the inner cylinder, a central flow channel along the central axis is formed in the inner cylinder, and one or more connecting holes connecting the annular flow channel and the central flow channel are arranged on the cylinder wall of the inner cylinder; the right end of the left buffer platform is fixedly connected to the left end of the outer cylinder and the left end of the inner cylinder, and a central flow channel through hole that can connect the central flow channel with the outside world is formed at the axial position of the left buffer platform; the left end of the right buffer platform is fixedly connected to the right end of the inner cylinder, and is fixedly connected to the right end of the outer cylinder through an end plate provided with an annular flow channel through hole, and the annular flow channel through hole can connect the annular flow channel with the outside world; the movable ball core is arranged in the central flow channel and can move freely in the central flow channel.

[0017] In addition, the movable ball core plunger may further include a spiral guide groove arranged on the outer wall of the outer tube. In addition, the movable ball core plunger may further include a left ball core clamping groove arranged at the connection between the central flow channel and the central flow channel through hole, and a right ball core clamping groove arranged at the connection between the left end of the right buffer platform and the right end of the inner tube.

[0018] Another aspect of the present invention provides a horizontal well two-stage relay plunger lifting production method, which is implemented by using the above-mentioned horizontal well two-stage relay plunger lifting device.

[0019] In an exemplary embodiment of the horizontal well two-stage relay plunger lifting production method of the present invention, the production method may include one or more production cycles, the production cycle consists of one well shut-in and one well opening, and the production cycle may include the following steps:

[0020] S1. After the well is shut in, the pressure in the vertical well section tubing increases, causing the third pressure-controlled check valve to close, so that the fluid in the vertical well section tubing cannot enter the horizontal well section tubing, and the ordinary plunger is separated from the ordinary plunger lifting wellhead device, and falls along the vertical well section tubing under the action of gravity, and finally sits on the third plunger buffer; during this period, because the fluid in the horizontal section tubing was discharged into the vertical well section tubing during the well opening stage of the previous production cycle, the pressure in the horizontal section tubing decreases, causing the second pressure-controlled check valve to open, so that the fluid in the annulus of the casing can flow out through the second pressure-controlled check valve. The fluid flowing into the horizontal section of the oil pipe flows into the central flow channel of the movable ball core plunger through the central flow channel through-hole, and pushes the movable ball core to move to the right, and finally stops at the right end of the central flow channel, so that the movable ball core plunger is forced to move toward the end of the oil pipe; with the inflow of the fluid and the movement of the movable ball core plunger to the end of the oil pipe, the pressure in the horizontal section of the oil pipe increases, causing the first pressure-controlled check valve to close, and the movable ball core plunger finally stops in front of the first plunger buffer; when the pressure in the horizontal section of the oil pipe increases to a certain set critical value, the second pressure-controlled check valve is closed;

[0021] S2. After the well is opened, the wellhead pressure decreases, and the ordinary plunger pushes the liquid on its upper part to move upward along the vertical well section tubing. The pressure on the upper part of the third pressure-controlled check valve decreases, causing the third pressure-controlled check valve to open. The fluid in the horizontal section tubing flows into the vertical well section under the action of the bottom hole pressure, further pushing the ordinary plunger to move upward to the wellhead. At this point, the liquid that flowed from the horizontal section tubing into the vertical section tubing in the opening stage of the previous production cycle is discharged from the wellhead; during this period, the movable ball core plunger pushes the liquid in the horizontal section tubing to move to the starting position of the horizontal section tubing, and the pressure in the tubing near the first pressure-controlled check valve decreases, causing the first pressure-controlled check valve to open, and the fluid at the bottom of the well enters the horizontal section tubing, further pushing the movable ball core plunger to move to the starting position of the horizontal section tubing; when the movable ball core plunger hits the second plunger buffer, the process of discharging liquid from the horizontal section tubing to the vertical section tubing ends; after the well is closed, the next production cycle begins, and this cycle is repeated to achieve the drainage of accumulated liquid in the horizontal section.

[0022] In another exemplary embodiment of the horizontal well two-stage relay plunger lifting production method of the present invention, in the step S1, during the movement of the movable ball core plunger, the fluid in the horizontal section of the oil pipe on its right side can flow into the annular flow channel through the annular flow channel through hole, and flow into the central flow channel through the connecting hole, and merge with the fluid that pushes the movable ball core, thereby reducing the resistance of the movable ball core plunger to move toward the end of the oil pipe. In addition, in the step S2, during the movement of the movable ball core plunger to the starting position of the horizontal section of the oil pipe, the fluid at the end of the oil pipe can enter the annular flow channel of the movable ball core plunger through the annular flow channel through hole under the action of pressure, and enter the central flow channel through the inner and outer flow channel connecting hole, pushing the movable ball core to move to the left, and finally stopping at the left end of the central flow channel, so that the movable ball core plunger is completely sealed, thereby improving the discharge efficiency of the liquid in the horizontal section of the oil pipe.

[0023] Compared with the prior art, the beneficial effects of the present invention include at least one of the following: 1) making full use of wellbore energy to improve drainage efficiency; 2) solving the problem of difficulty in draining horizontal section liquid accumulation caused by the inability of conventional lifting process equipment to reach the vicinity of target point B, and effectively improving the recovery rate of liquid in the horizontal section. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] The above and / or other objects and features of the present invention will become more apparent through the following description in conjunction with the accompanying drawings, in which:

[0025] Figure 1 A schematic diagram showing an exemplary embodiment of a two-stage relay plunger lifting device for a horizontal well of the present invention;

[0026] Figure 2 Shows Figure 1 A schematic diagram of the external structure of a pressure-controlled check valve;

[0027] Figure 3 Shows Figure 2 A cross-sectional view of a pressure-controlled check valve in an open state;

[0028] Figure 4 Shows Figure 2 A cross-sectional view of a pressure-controlled check valve in a closed state;

[0029] Figure 5 Shows Figure 1 A schematic diagram of the external structure of the movable ball core plunger;

[0030] Figure 6 Shows Figure 5 A front cross-sectional view of a movable ball core plunger;

[0031] Figure 7 Shows Figure 5 Right side cross-sectional view of the movable ball core plunger.

[0032] Description of reference numerals:

[0033] 1-first pressure-controlled check valve, 101-fluid channel, 102-pressure-conducting channel, 103-pressure chamber, 104-pressure-sensing airbag, 105-valve stem, 106-limiting groove, 107-limiting platform, 108-valve hole, 109-valve slot;

[0034] 2-movable ball core plunger, 21-left buffer platform, 22-right buffer platform, 23-outer cylinder, 24-spiral guide groove, 25-annular flow channel through hole, 26-annular flow channel, 27-inner cylinder, 28-connecting hole, 29-central flow channel, 210-movable ball core, 211-central flow channel through hole, 212-right ball core slot, 213-left ball core slot;

[0035] 3-second pressure-controlled check valve, 4-third pressure-controlled check valve, 5-ordinary plunger lifting wellhead device, 6-casing, 7-oil pipe, 8-ordinary plunger, 9-third plunger buffer, 10-second plunger buffer, 11-first plunger buffer. DETAILED DESCRIPTION

[0036] Hereinafter, a horizontal well two-stage relay plunger lifting device and method thereof and a movable ball core plunger of the present invention will be described in detail in conjunction with exemplary embodiments.

[0037] It should be noted that “upper”, “lower”, “left”, “right”, “inside” and “outside” are merely for the convenience of description and to constitute relative orientation or position relationships, and do not indicate or imply that the referred to component must have this specific orientation or position.

[0038] Figure 1 A schematic diagram showing an exemplary embodiment of a two-stage relay plunger lifting device for a horizontal well of the present invention.

[0039] like Figure 1 As shown, in an exemplary embodiment of the present invention, the horizontal well two-stage relay plunger lifting device includes a first pressure-controlled check valve 1, a first plunger buffer 11, a movable ball core plunger 2, a second plunger buffer 10, a second pressure-controlled check valve 3, a third pressure-controlled check valve 4, a third plunger buffer 9, a common plunger 8 and a common plunger lifting wellhead device 5, which are sequentially arranged in the oil pipe 7 from the end of the oil pipe to the wellhead. Here, the end of the oil pipe is equivalent to the target point B, which can roughly correspond to Figure 1 The first pressure-controlled check valve 1 is located in the position. The common plunger lifting wellhead device can also be a common plunger gas lift wellhead device.

[0040] like Figure 1As shown, the first pressure-controlled check valve 1 is located in the horizontal section of the oil pipe and is arranged at the end of the oil pipe. It can be closed when the pressure in the horizontal section of the oil pipe is greater than the first pressure value, thereby isolating the horizontal section of the oil pipe from the bottom hole fluid; it can also be opened when the pressure in the horizontal section of the oil pipe is less than the first pressure value, thereby connecting the horizontal section of the oil pipe with the bottom hole fluid. Here, it should be noted that in the present invention, the horizontal section of the oil pipe may not be completely horizontal, for example, it may be slightly inclined, and even in a longer scale, its inclination direction may fluctuate.

[0041] The second pressure-controlled check valve 3 is located in the oil pipe 7 and is arranged near the starting position of the horizontal section of the oil pipe. It can be closed when the pressure in the horizontal section of the oil pipe is greater than the second pressure value, thereby isolating the horizontal section of the oil pipe from the casing 6; it can also be opened when the pressure in the horizontal section of the oil pipe is less than the second pressure value, thereby connecting the horizontal section of the oil pipe to the casing 6. Here, the starting position of the horizontal section of the oil pipe is equivalent to the target point A, which can roughly correspond to Figure 1 The location where the horizontal section of tubing begins.

[0042] The third pressure-controlled check valve 4 is arranged at the bottom of the vertical well section oil pipe, and can be closed when the pressure in the vertical well section oil pipe is greater than the third pressure value, thereby isolating the vertical well section oil pipe from the horizontal section oil pipe; it can also be opened when the pressure in the vertical well section oil pipe is less than the third pressure value, thereby connecting the vertical well section oil pipe with the horizontal section oil pipe.

[0043] Figure 2 Shows Figure 1 A schematic diagram of the external structure of a pressure-controlled check valve; Figure 3 Shows Figure 2 A cross-sectional view of a pressure-controlled check valve in an open state; Figure 4 Shows Figure 2 Cross-sectional view of a pressure-controlled check valve in the closed state.

[0044] One or more of the first pressure-controlled check valve 1, the second pressure-controlled check valve 3, and the third pressure-controlled check valve 4 may have a Figures 2 to 4 The one-flow valve structure shown.

[0045] like Figures 2 to 4 As shown, the single-flow valve structure may include: a columnar valve body as the main body, a fluid channel 101, a pressure-conducting channel 102, a pressure chamber 103, a pressure-sensing airbag 104, a valve stem 105, a limiting mechanism composed of a limiting groove 106 and a limiting platform 107, a valve hole 108, and a valve slot 109.

[0046] Specifically, the columnar valve body has an outer diameter equal to the inner diameter of the oil pipe 7 .

[0047] The fluid channel 101 is arranged through the length direction of the columnar valve body (equivalent to Figure 3 In the conduction state, the fluid at the upper end of the columnar valve body can flow to the lower end of the columnar valve body, thereby realizing a one-way conduction function. For example, the fluid channel 101 can be in an S-shaped shape to better match the valve hole 108 of the valve stem 105. However, the present invention is not limited thereto, and for example, the fluid channel can also be in a spiral form or other forms.

[0048] The pressure chamber 103 is arranged in the cylindrical valve body, for example, it can be in the form of Figure 3 The cylindrical cavity shown. The pressure-sensing airbag 104 is accommodated in a part (e.g., the upper part) of the pressure chamber 103, and has one end (e.g., the upper end or the top end) fixed to the pressure chamber 103, and the other end (e.g., the lower end or the bottom end). The pressure-sensing airbag 104 is filled with a predetermined pressure. The pressure-conducting channel 102 is arranged in the columnar valve body, and can connect the pressure to be measured of the fluid at the upper end of the columnar valve body with another part (e.g., the lower part) of the pressure chamber 103, so that the pressure-sensing airbag 104 expands accordingly when the pressure to be measured decreases; and the pressure-sensing airbag 104 contracts accordingly when the pressure to be measured increases. For example, the pressure-conducting channel 102 may be J-shaped so as to better communicate with the pressure chamber 103. However, the present invention is not limited to this. For example, the pressure-conducting channel may also be in a spiral form or other forms.

[0049] The limiting groove 106 and the limiting platform 107 of the limiting mechanism are arranged in the columnar valve body. The limiting groove 106 can accommodate the lower end of the moving valve stem 105. The limiting platform 107 can prevent the lower end of the valve stem 105 from slipping out of the limiting groove 106. However, it should be noted that the structure of the limiting mechanism used in the present invention is not limited thereto. For those skilled in the art, other structures that can accommodate the movement of the lower end of the valve stem and prevent it from slipping out can also be used.

[0050] The valve slot 109 is disposed in the columnar valve body and connects the lower part of the pressure chamber 103 with the limit mechanism. The valve stem 105 is disposed in the valve slot 109 and has a stem body provided with a valve hole 108, one end (e.g., the upper end) fixedly connected to the lower end of the pressure-sensing airbag 104, and the other end (e.g., the lower end) located in the limit mechanism.

[0051] like Figure 4 As shown, the valve hole 108 can disconnect the fluid channel 101 when the valve stem 105 is driven by the expansion of the pressure-sensitive airbag 104; it can also open the fluid channel 101 when the valve stem 105 is driven by the contraction of the pressure-sensitive airbag 104, as shown in FIG. Figure 3 shown.

[0052] However, it should be noted that the structure of the pressure-controlled one-flow valve used in the present invention is not limited thereto. For ordinary technicians in this field, other one-way valves that can achieve pressure-controlled one-way conduction can also be used as the first pressure-controlled one-flow valve 1, the second pressure-controlled one-flow valve 3 and / or the third pressure-controlled one-flow valve 4 of this exemplary embodiment.

[0053] The movable ball core plunger 2 is provided with a right buffer platform (for example, Figure 1 , 5 , the right end in 6) is arranged in the horizontal section of the oil pipe in a form closer to the end of the oil pipe.

[0054] Figure 5 Shows Figure 1 A schematic diagram of the external structure of the movable ball core plunger; Figure 6 Shows Figure 5 A front cross-sectional view of a movable ball core plunger; Figure 7 Shows Figure 5 Right side cross-sectional view of the movable ball core plunger.

[0055] like Figures 5 to 7 As shown, the movable ball core plunger includes a movable ball core 210, a left buffer platform 21 and a right buffer platform 22, an outer cylinder 23, an inner cylinder 27 sleeved in the outer cylinder 23, and a spiral guide groove 24, a left ball core slot 213, and a right ball core slot 212.

[0056] The outer cylinder 23 and the inner cylinder 27 form a central axis (such as Figure 6 The inner cylinder 27 is provided with an annular flow channel 26 extending in the left and right directions. A central flow channel 29 along the central axis is formed in the inner cylinder 27. One or more connecting holes 28 are provided on the cylinder wall of the inner cylinder 27 to connect the annular flow channel 26 with the central flow channel 29.

[0057] The right end of the left buffer table 21 is fixedly connected to the left end of the outer cylinder 23 and the left end of the inner cylinder 27. A central flow channel through hole 211 is formed at the axial position of the left buffer table 21 to connect the central flow channel 29 with the outside. In addition, the outer cylinder can be integrally formed with the left buffer table.

[0058] The left end of the right buffer table 22 is fixedly connected to the right end of the inner cylinder 27, and is fixedly connected to the right end of the outer cylinder 23 through an end plate provided with an annular flow channel through hole 25, and the annular flow channel through hole 25 can connect the annular flow channel 26 with the outside. In addition, the inner cylinder can be integrally formed with the right buffer table.

[0059] The movable core 210 is disposed in the central flow channel 29 and can move freely in the central flow channel 29 .

[0060] The spiral guide groove 24 is arranged on the outer wall of the outer cylinder, so as to facilitate the movable ball core plunger to move along the horizontal section of the oil pipe. Figure 1 and Figure 6 However, the movable ball core plunger of the present invention is not limited thereto, and it may not contain the spiral guide groove, but may be replaced by other solutions such as the outer wall of the outer cylinder with a lower friction coefficient, or by adjusting the lubrication conditions in the oil pipe.

[0061] The left ball core clamping groove 213 can be provided at the connection between the central flow channel 29 and the central flow channel through hole 211, so as to be more conducive to the accommodation and left-side limit of the movable ball core 210. The right ball core clamping groove 212 can be provided at the connection between the left end of the right buffer platform 22 and the right end of the inner tube 27, so as to be more conducive to the accommodation and right-side limit of the movable ball core 210. However, the movable ball core plunger of the present invention is not limited thereto, and it does not contain the left ball core clamping groove and the right ball core clamping groove, but directly limits the movable ball core by reducing the diameter of the connection between the left and right sides of the central flow channel.

[0062] like Figure 1 As shown, the first plunger buffer 11 is arranged near the left side of the first pressure-controlled check valve 1, and the second plunger buffer 10 is arranged near the right side of the second pressure-controlled check valve 3, so as to play a buffering role for the movable ball core plunger 2 approaching during the movement, so as to protect the first pressure-controlled check valve 1 and the second pressure-controlled check valve 3 accordingly. The third plunger buffer 9 is arranged near the upper side of the third pressure-controlled check valve 4, so as to play a buffering role for the ordinary plunger 8 approaching during the movement, so as to protect the third pressure-controlled check valve 4.

[0063] In addition, although the above exemplary embodiment shows the use of a third plunger buffer and a common plunger in cooperation with a common plunger lifting wellhead device to achieve fluid lifting in a vertical well section; however, the horizontal well two-stage relay plunger lifting device of the present invention may not be limited to this. For example, the third plunger buffer and the common plunger may not be provided, and the common plunger lifting wellhead device may be replaced with a lifting wellhead device, so that natural drainage, foam drainage, gas lift drainage and other lifting methods can be directly used to replace the common plunger lifting fluid.

[0064] In addition, without changing the principle of the above exemplary embodiment, some structures of the movable ball core plunger may be changed, for example, the shape, arrangement, spacing, aperture and other parameters of the connecting holes connecting the inner and outer flow channels may be changed.

[0065] In another exemplary embodiment of the present invention, a horizontal well two-stage relay plunger lifting production method is implemented using the horizontal well two-stage relay plunger lifting device as described above.

[0066] When the present invention is applied, it is required that the inner diameter of the oil pipe 7 in the same plunger running section must be consistent, and all devices including various pressure-controlled check valves and the movable ball core plunger 2 can be pre-set in the oil pipe 7 and lowered into the wellbore together with the oil pipe 7. If salvage is required, the movable ball core plunger 2 can be moved to the second plunger buffer 10 by using the well opening and closing system, and then salvaged by conventional salvage tools.

[0067] like Figure 1 As shown, with one well shut-in and one well opening as one production cycle, a specific implementation method of an exemplary embodiment of the horizontal well two-stage relay plunger lifting production method of the present invention may include the following steps:

[0068] S1. After the well is shut in, the pressure in the vertical well section oil pipe 7 increases, causing the third pressure-controlled check valve 4 to close, isolating the upper and lower fluids of the third pressure-controlled check valve 4. At the same time, the ordinary plunger 8 detaches from the ordinary plunger lifting wellhead device 5, and falls along the vertical well section oil pipe 7 under the action of gravity, and finally sits on the third plunger buffer 9.

[0069] Further, such as Figure 3 As shown, the third pressure-controlled check valve 4 is installed in the oil pipe 7, and the fluid channel 101 is the only channel for the fluid to pass through the third pressure-controlled check valve. When the pressure in the vertical well section oil pipe drops, the pressure is transmitted to the pressure chamber 103 through the pressure-conducting channel 102, causing the internal pressure of the pressure-sensitive airbag 104 to be greater than the external pressure. The pressure-sensitive airbag 104 expands, driving the valve stem 105 to move downward. When the valve hole 108 is connected to the fluid channel 101, the pressure-controlled check valve opens. The limit platform 107 moves in the limit groove 106 to prevent the valve stem 105 from moving too much and causing the pressure-controlled check valve to close again. Similarly, if Figure 4 As shown, when the external pressure increases, the pressure-sensing airbag 104 will contract, driving the valve stem 105 to move upward, causing the valve hole 108 to be disconnected from the fluid channel 101, and the pressure-controlled one-flow valve to close. At this time, the limit platform 107 will prevent the valve stem 105 from moving too much upward and causing it to disengage from the valve slot 109.

[0070] During this period, since the fluid in the horizontal section of the oil pipe 7 was discharged into the vertical well section during the well opening stage of the previous production cycle, the pressure in the horizontal section of the oil pipe 7 is reduced, that is, the pressure in the horizontal well section casing 6 is greater than the pressure in the corresponding horizontal well section of the oil pipe 7, causing the second pressure-controlled check valve 3 to open into the oil pipe. At this time, the horizontal section casing 6 is connected to the oil pipe 7, and the fluid in the oil casing annulus flows into the horizontal section of the oil pipe 7 through the second pressure-controlled check valve 3.

[0071] Further, such as Figure 6As shown, the fluid flowing into the horizontal section oil pipe 7 flows into the central flow channel 29 of the movable ball core plunger 2 through the central flow channel through hole 211, and pushes the movable ball core to move to the right, and finally stops in the right ball core slot 212. The movable ball core plunger 2 is therefore forced to move toward the target point B.

[0072] Furthermore, during the movement of the movable ball core plunger 2, the fluid on the end side of the oil pipe 7 flows into the annular flow channel 26 through the annular flow channel through hole 25, and flows into the central flow channel 29 through the connecting hole 28, and merges with the fluid that pushes the movable ball core, thereby reducing the resistance of the movable ball core plunger 2 to move toward the target point B.

[0073] Furthermore, the outer surface of the outer cylinder 23 of the movable ball core plunger 2 is engraved with a spiral guide groove 24 . During the movement of the movable ball core plunger 2 , the fluid can pass through the spiral guide groove 24 to cause the movable ball core plunger 2 to rotate, thereby reducing the friction between the movable ball core plunger 2 and the oil pipe 7 .

[0074] Furthermore, with the inflow of fluid and the movement of the movable ball core plunger 2 toward the target point B, the pressure in the horizontal section oil pipe 7 increases, that is, the pressure in the horizontal section oil pipe 7 is greater than the pressure in the outer sleeve 6 at the end of the horizontal section oil pipe, resulting in the closure of the first pressure-controlled one-flow valve 1, that is, the oil pipe 7 and the sleeve 6 are disconnected at the first pressure-controlled one-flow valve. At this time, the movable ball core plunger 2 finally stops in front of the first plunger buffer 11.

[0075] When the pressure in the horizontal section oil pipe 7 increases to a certain set critical value, that is, the pressure in the horizontal well section casing 6 is greater than the pressure in the corresponding horizontal well section oil pipe 7, the second pressure-controlled one-flow valve 3 is closed. At this time, at the second pressure-controlled one-flow valve, the horizontal section casing 6 is disconnected from the oil pipe 7.

[0076] S2. After the well is opened, the wellhead pressure decreases, that is, the pressure in the well is greater than the wellhead pressure, causing the common plunger 8 to push the upper liquid to move upward along the vertical well section tubing 7, and at the same time causing the pressure on the upper part of the third pressure-controlled check valve 4 to decrease, that is, the lower pressure of the third pressure-controlled check valve 4 is greater than the upper pressure, and then the third pressure-controlled check valve 4 opens in the direction of the diameter section tubing 7, and the diameter section tubing 7 is connected with the horizontal section tubing 7. The fluid in the horizontal section tubing 7 flows into the vertical well section under the action of the bottom hole pressure, further pushing the common plunger 8 upward to the wellhead, and the liquid that flows from the horizontal section tubing into the vertical section tubing in the opening stage of the previous production cycle is discharged from the wellhead.

[0077] At the same time, the flow of fluid in the oil pipe 7 drives the movable ball core plunger 2 to move toward the target point A, and the pressure in the oil pipe 7 near the first pressure-controlled one-flow valve 1 drops, that is, the pressure in the oil pipe 7 at the first pressure-controlled one-flow valve 1 is less than the pressure in the casing 6, causing the first pressure-controlled one-flow valve 1 to open in the direction of the diameter section oil pipe 7, that is, the corresponding oil pipe 7 at the first pressure-controlled one-flow valve 1 is connected with the casing 6, causing the fluid in the casing 6 to flow into the horizontal section oil pipe 7 through the first pressure-controlled one-flow valve 1, further pushing the movable ball core plunger 2 to move toward the target point A.

[0078] Further, such as Figure 6 As shown, during the movement of the movable ball core plunger 2 toward the target point A, the fluid at the end of the oil pipe enters the annular flow channel 26 of the movable ball core plunger 2 through the annular flow channel through hole 25 under the action of pressure, and flows into the central flow channel 29 through the connecting hole inside and outside, pushing the movable ball core to move to the left, and finally sitting in the left ball core slot 213, so that the movable ball core plunger 2 is completely sealed, thereby improving the discharge efficiency of the liquid in the horizontal section of the oil pipe 7.

[0079] Furthermore, when the movable ball core plunger 2 hits the second plunger buffer 10, the drainage process from the horizontal section oil pipe 7 to the vertical well section oil pipe 7 is completed, and the next production cycle begins after the well is shut down. This cycle is repeated, thereby solving the problem of difficulty in draining the accumulated liquid in the horizontal section.

[0080] Although the present invention has been described above in conjunction with the exemplary embodiments and the accompanying drawings, it should be apparent to those skilled in the art that various modifications may be made to the above-described embodiments without departing from the spirit and scope of the claims.

Claims

1. A two-stage relay plunger lifting device for a horizontal well, characterized in that: The horizontal well two-stage relay plunger lifting device comprises a first pressure-controlled check valve, a first plunger buffer, a movable ball core plunger, a second plunger buffer, a second pressure-controlled check valve, a third pressure-controlled check valve, and a lifting wellhead device, which are sequentially arranged in the oil pipe from the end of the oil pipe to the wellhead, wherein: The first pressure-controlled check valve is located in the horizontal section of the oil pipe and is arranged at the end of the oil pipe, and can be closed when the pressure in the horizontal section of the oil pipe is greater than a first pressure value, and opened when the pressure in the horizontal section of the oil pipe is less than the first pressure value, so that the horizontal section of the oil pipe is isolated from or connected to the bottom hole fluid; The movable ball core plunger is arranged in the horizontal section oil pipe in a form that the right buffer platform is closer to the end of the oil pipe; The movable ball core plunger comprises a movable ball core, a left buffer table and a right buffer table, and an outer tube and an inner tube which are fitted into each other; wherein an annular flow channel surrounding the central axis of the inner tube is formed between the outer tube and the inner tube, a central flow channel along the central axis is formed in the inner tube, and one or more connecting holes connecting the annular flow channel and the central flow channel are arranged on the tube wall of the inner tube; the right end of the left buffer table is fixedly connected to the left end of the outer tube and the left end of the inner tube, and a central flow channel through hole which can connect the central flow channel with the outside is formed at the axial position of the left buffer table; the left end of the right buffer table is fixedly connected to the right end of the inner tube, and is fixedly connected to the right end of the outer tube through an end plate provided with an annular flow channel through hole, and the annular flow channel through hole can connect the annular flow channel with the outside; the movable ball core is arranged in the central flow channel and can move freely in the central flow channel; The second pressure-controlled check valve is located in the oil pipe and is arranged near the starting position of the horizontal section of the oil pipe, and can be closed when the pressure in the horizontal section of the oil pipe is greater than the second pressure value, and opened when the pressure in the horizontal section of the oil pipe is less than the second pressure value, so that the horizontal section of the oil pipe and the casing are isolated and connected respectively; The third pressure-controlled check valve is arranged at the bottom of the vertical well section oil pipe, and can be closed when the pressure in the vertical well section oil pipe is greater than the third pressure value, and opened when the pressure in the vertical well section oil pipe is less than the third pressure value, thereby isolating and connecting the vertical well section oil pipe and the horizontal section oil pipe respectively.

2. The horizontal well two-stage relay plunger lifting device according to claim 1 is characterized in that: The movable ball core plunger also includes a spiral guide groove arranged on the outer wall of the outer cylinder.

3. The horizontal well two-stage relay plunger lifting device according to claim 1, characterized in that: The movable ball core plunger also includes a left ball core clamping groove provided at the connection between the central flow channel and the central flow channel through hole, and a right ball core clamping groove provided at the connection between the left end of the right buffer platform and the right end of the inner tube.

4. The horizontal well two-stage relay plunger lifting device according to claim 1, characterized in that: The first plunger buffer is arranged close to the first pressure-controlled check valve, and the second plunger buffer is arranged close to the second pressure-controlled check valve, so as to play a buffering role for the movable ball core plunger approaching during the movement.

5. The horizontal well two-stage relay plunger lifting device according to claim 1, characterized in that: The two-stage relay plunger lifting device for horizontal wells also includes a third plunger buffer and a common plunger which are sequentially arranged between the third pressure-controlled check valve and the lifting wellhead device along the direction from the end of the oil pipe to the wellhead.

6. The horizontal well two-stage relay plunger lifting device according to claim 5, characterized in that: The third plunger buffer is arranged close to the third pressure-controlled check valve to play a buffering role for the common plunger approaching during the movement process.

7. The horizontal well two-stage relay plunger lifting device according to claim 1, characterized in that: One or more of the first pressure-controlled check valve, the second pressure-controlled check valve, and the third pressure-controlled check valve has the following check valve structure, and the check valve structure includes: A cylindrical valve body having an outer diameter equal to the inner diameter of the oil pipe; A fluid channel is arranged throughout the length direction of the columnar valve body; A pressure chamber, disposed in the cylindrical valve body; A pressure-sensitive airbag is accommodated in a portion of the pressure chamber and has one end fixed to the pressure chamber and the other end; A pressure-conducting channel is provided in the columnar valve body and is capable of connecting the pressure to be measured with another part of the pressure chamber, so that the pressure-sensing airbag expands or contracts accordingly when the pressure to be measured decreases or increases; A limiting mechanism, arranged in the columnar valve body; a valve slot, disposed in the cylindrical valve body and connecting the other part of the pressure chamber with the limiting mechanism; The valve stem is arranged in the valve groove and has a stem body provided with a valve hole, one end fixedly connected to the other end of the pressure-sensitive airbag, and the other end located in the limiting mechanism. The valve hole can disconnect or conduct the fluid channel accordingly when the valve stem is driven by the expansion or contraction of the pressure-sensitive airbag.

8. The horizontal well two-stage relay plunger lifting device according to claim 7, characterized in that: The fluid channel is S-shaped, and the pressure-conducting channel is J-shaped.

9. The horizontal well two-stage relay plunger lifting device according to claim 7, characterized in that: The limiting mechanism comprises a limiting platform and a limiting groove, wherein the limiting groove can accommodate the other end of the moving valve stem, and the limiting platform can prevent the other end of the valve stem from escaping from the limiting groove.

10. A two-stage relay plunger lifting production method for a horizontal well, characterized in that: The production method is implemented by using the device as described in any one of claims 1 to 9.

11. The horizontal well two-stage relay plunger lifting production method according to claim 10, characterized in that: The production method includes one or more production cycles, wherein the production cycle consists of one well shut-in and one well opening, and the production cycle includes the following steps: S1. After the well is shut in, the pressure in the vertical well section tubing increases, causing the third pressure-controlled check valve to close, so that the fluid in the vertical well section tubing cannot enter the horizontal section tubing. The ordinary plunger is separated from the ordinary plunger lifting wellhead device and falls along the vertical well section tubing under the action of gravity, and finally sits on the third plunger buffer; During this period, because the fluid in the horizontal section tubing was discharged into the vertical section tubing during the well opening stage of the previous production cycle, the pressure in the horizontal section tubing decreased, causing the second pressure-controlled check valve to open, allowing the fluid in the annulus of the casing to flow into the horizontal section tubing through the second pressure-controlled check valve; The fluid flowing into the horizontal section oil pipe flows into the central flow channel of the movable ball core plunger through the central flow channel through hole, and pushes the movable ball core to move rightward, and finally stops at the right end of the central flow channel. As a result, the movable ball core plunger is forced to move toward the end of the oil pipe; As the fluid flows in and the movable ball core plunger moves toward the end of the oil pipe, the pressure in the horizontal section of the oil pipe increases, causing the first pressure-controlled check valve to close, and the movable ball core plunger finally stops in front of the first plunger buffer; When the pressure in the horizontal section of the oil pipe increases to a certain set critical value, the second pressure-controlled check valve is closed; S2. After the well is opened, the wellhead pressure decreases, and the ordinary plunger pushes the liquid above it to move upward along the vertical well section tubing. The pressure above the third pressure-controlled check valve decreases, causing the third pressure-controlled check valve to open. The fluid in the horizontal section tubing flows into the vertical well section under the action of the bottom hole pressure, further pushing the ordinary plunger to move upward to the wellhead. At this point, the liquid that flowed from the horizontal section tubing into the vertical section tubing during the opening stage of the previous production cycle is discharged from the wellhead. During this period, the movable ball core plunger pushes the liquid in the horizontal section tubing to move toward the starting position of the horizontal section tubing, and the pressure in the tubing near the first pressure-controlled check valve drops, causing the first pressure-controlled check valve to open, so that the fluid at the bottom of the well enters the horizontal section tubing, further pushing the movable ball core plunger to move toward the starting position of the horizontal section tubing; When the movable ball core plunger hits the second plunger buffer, the process of discharging liquid from the horizontal section tubing to the vertical well section tubing ends; After the well is shut down, the next production cycle begins, and this cycle is repeated to achieve drainage of accumulated liquid in the horizontal section.

12. The horizontal well two-stage relay plunger lifting production method according to claim 11, characterized in that: In step S1, when the movable ball core plunger moves, the fluid in the right horizontal section of the oil pipe flows into the annular flow channel through the annular flow channel through the annular flow channel through-hole, and flows into the central flow channel through the connecting hole, and merges with the fluid that pushes the movable ball core, thereby reducing the resistance of the movable ball core plunger to move toward the end of the oil pipe.

13. The horizontal well two-stage relay plunger lifting production method according to claim 11, characterized in that: In the step S2, during the movement of the movable ball core plunger toward the starting position of the horizontal section oil pipe, the fluid at the end of the oil pipe enters the annular flow channel of the movable ball core plunger through the annular flow channel through-hole under the action of pressure, and flows into the central flow channel through the connecting hole inside and outside, pushing the movable ball core to move to the left, and finally stops at the left end of the central flow channel, so that the movable ball core plunger is completely sealed, thereby improving the discharge efficiency of the liquid in the horizontal section oil pipe.

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