A device for controlling the flow of produced liquid in a well

Abstract

The present application relates to tubing flow control technical field, specifically, it is a kind of device for controlling the flow of produced liquid in well.It includes bending tubing, bending tubing includes horizontal pipeline and vertical pipeline, vertical pipeline is provided with pumping element, and the horizontal pipeline is provided with oil extraction opening.The present application drives cylinder to push extruding shaft, drives conical blocking piece to move along axial direction, controls the distance change between conical head and left conical space of two-way funnel channel, adjusts channel sectional area, and the smaller the distance is, the smaller the flow is, in addition, drives conical top displacement by driving push rod, uses conical top to extrude blocking disc to move, adjusts the position of blocking disc in the other side conical space of two-way funnel channel, thereby forms the control to flow in the other side conical channel space of two-way funnel channel, realizes the accurate two-way regulation of the flow of liquid in two-way funnel channel, thereby adapts to the variable downhole working condition and the flow property of different oil layers.

Description

Technical Field

[0001] This invention relates to the field of tubing flow control technology, and more particularly to a device for controlling the flow rate of produced fluids in a well. Background Technology

[0002] In modern oil wells, after drilling to the oil layer, an oil layer casing is run in, and oil well cement is injected into the annular space between the casing and the well wall. Then, according to the requirements of oilfield development, the oil layer is perforated with a perforating gun to form a channel, and an oil tubing is run in. Using appropriate flow induction methods, the oil is raised from the bottom of the well to the wellhead.

[0003] In oil reservoirs, the flow rate of produced fluids is typically controlled by a flow control device when the fluids enter the tubing and are discharged outward through the tubing.

[0004] Because the liquids in different reservoirs of the oil layer have certain compositional differences and contain impurities, some of the impurities that follow the flow control can easily clog the flow control channels. Since the liquid in the oil layer is relatively viscous, the impurities that are blocked may be trapped and stick together, causing continuous blockage.

[0005] Furthermore, since flow rate is controlled by adjusting the size of the flow channel, the channel size can be reduced when the flow rate needs to be increased. Reducing the channel size increases the risk of impurities remaining or viscous liquid clogging.

[0006] To address the aforementioned issues, existing technologies urgently need improvement. Summary of the Invention

[0007] This invention provides a device for controlling the flow rate in a produced fluid well. Through a bidirectional flow control structure that allows for opposing control, it helps to better control the flow rate in the channel area. It also prevents excessive impurities from entering the pipeline and clogging it by using anti-clogging mechanisms installed in the oil production section and the oil pumping section, thereby solving the problems mentioned in the background art.

[0008] To achieve the above objectives, the present invention provides a device for controlling the flow rate of produced liquid in a well, including a bent tubing, which includes a horizontal pipe and a vertical pipe. An oil pumping component is installed inside the vertical pipe. An oil outlet is provided on the horizontal pipe. The device also includes an anti-clogging mechanism and a flow control structure installed at the oil outlet and the bend of the bent tubing. The anti-clogging mechanism includes an agitating anti-clogging component installed inside the oil outlet and a combing assembly installed at the bend of the bent tubing. The agitating anti-clogging component includes a drive motor installed at the end of the bent tubing and an anti-clogging swivel block rotatably installed inside the horizontal pipe. The anti-clogging swivel block is rotatably installed inside the horizontal pipe via a rotating shaft and is connected to the output end of the drive motor.

[0009] The flow control structure includes a bidirectional funnel channel set in a horizontal pipe, a conical control component set on one side of the bidirectional funnel channel, and a controllable shielding component set on the other side.

[0010] The controllable shielding component includes a shielding disc disposed in one channel of the bidirectional funnel channel and an elastic component that drives the shielding disc to move toward the center of the bidirectional funnel channel.

[0011] The conical control component includes a drive component, a conical shielding component, and a regulating push component. The output shaft of the drive component passes through the bend of the curved oil pipe and is coaxial with the horizontal pipe. The conical shielding component is located at the end of the shaft of the drive component and faces the shielding plate. The regulating push component is located at the end of the conical shielding component and acts on the shielding plate, so that the conical shielding component and the shielding plate form a bidirectional flow control effect inside the bidirectional funnel channel.

[0012] The elastic element includes an internal mounting ring, a sliding shaft, and an extrusion spring disposed within a horizontal pipe. The sliding shaft movably passes through the center of the internal mounting ring, with one end connected to a baffle plate and the other end movably inserted into the rotating shaft end of the anti-blocking swivel block. The extrusion spring is disposed within the rotating shaft of the anti-blocking swivel block, and the end of the extrusion spring acts on the sliding shaft, causing the sliding shaft and the baffle plate to maintain a tendency to move towards the center of the bidirectional funnel channel.

[0013] The conical shielding component includes a conical head, an annular support frame, and a stacked channel. The conical head is disposed at the end of the drive shaft, the annular support frame is disposed at the edge of the conical head, and the stacked channel is disposed inside the annular support frame and fits against the inner side of the horizontal pipe.

[0014] The stacked channel includes multiple channels with progressively smaller diameters at the center. This allows the liquid to pass through the conical head and the inside of the horizontal pipe, and then through the stacked channel, where it is accelerated by the intermittent flow of the channels. This enables the slow-moving liquid, which is controlled by the flow rate, to pass through the horizontal pipe at a faster speed and finally enter the vertical pipe to be extracted by the pumping unit. The stacked channel further accelerates the slow-moving fluid after throttling, thus improving the pumping efficiency.

[0015] The conical head is hollow at the end. The regulating pusher includes a drive push rod, a movable shaft, and a conical top. The drive push rod is disposed inside the hollow end of the conical head. The movable shaft is movably inserted into the end of the conical head and connected to the drive push rod. The conical top is disposed in close contact with the end of the conical head and is connected to the movable shaft.

[0016] The conical apex forms a complete conical structure at the end of the conical head, and the apex is directly opposite the center of the baffle plate. This allows the liquid flow rate to be controlled by adjusting the distance and position of the conical head within the conical space on one side of the bidirectional funnel channel when the conical head is moved forward. In addition, the movable shaft and the conical apex can be moved forward by driving the push rod, and the conical apex can be used to squeeze the baffle plate to move. By adjusting the position of the baffle plate within the conical space on the other side of the bidirectional funnel channel, the liquid flow rate can be controlled. This creates flow control within the conical channel space on the other side of the bidirectional funnel channel, thus forming bidirectional flow space control within the bidirectional funnel channel.

[0017] The driving component includes a driving cylinder, an extrusion shaft, and a bending support block. The bending support block is located at the bend of the bending oil pipe. The driving cylinder is located outside the bending support block. The extrusion shaft movably passes through the bending support block and the bend of the bending oil pipe. One end of the extrusion shaft is connected to the output end of the driving cylinder, and the other end is connected to a tapered head. The combing assembly includes a convex combing block and a sealed bearing. The sealed bearing is located at the connection between the extrusion shaft and the bending oil pipe. The convex combing block is located inside the bending oil pipe and below the connection between the extrusion shaft and the bending oil pipe.

[0018] The convex combing block has an arc-shaped end, forming an outwardly convex arc-shaped separation surface below the bend in the oil pipe and the connection point of the extrusion shaft. This helps to comb the liquid flowing through this area to both sides, preventing the liquid from being trapped and accumulating at the bend in the oil pipe and the connection point of the extrusion shaft.

[0019] In this technical solution, the anti-blocking mechanism solves the blockage problem at the oil wellhead and bends through a dual-mode approach of mechanical rotation and fluid combing.

[0020] Compared with the prior art, the present invention provides a device for controlling the flow rate in a produced liquid well, which has the following beneficial effects:

[0021] This invention uses a driving cylinder to push a squeezing shaft, which in turn moves a conical baffle along the axial direction. This controls the change in the distance between the conical head and the conical space on the left side of the bidirectional funnel channel, adjusting the channel cross-sectional area. The smaller the distance, the smaller the flow rate. In addition, a driving push rod drives the conical top to move, using the conical top to squeeze the baffle plate and adjust its position in the conical space on the other side of the bidirectional funnel channel. This creates flow control within the conical channel space on the other side of the bidirectional funnel channel, achieving precise bidirectional adjustment of the liquid flow rate in the bidirectional funnel channel, thus adapting to varying downhole conditions and the flow properties of different oil layers. Attached Figure Description

[0022] Figure 1 This is a schematic diagram of the overall structure of the present invention;

[0023] Figure 2 This is a schematic diagram of the overall structure of the bent oil pipe after partial sectioning in this invention;

[0024] Figure 3 This is a schematic diagram showing the structural distribution of the agitation anti-blocking component and the elastic component in this invention;

[0025] Figure 4 This is a schematic diagram showing the structural distribution of the combing component and the conical shielding component in this invention;

[0026] Figure 5 This is a schematic diagram showing the overall distribution of the regulating and pushing components within the conical head in this invention;

[0027] Figure 6 This is a schematic diagram of the overall structure of the bent oil pipe from another perspective after being partially cut apart in this invention.

[0028] Figure 7 for Figure 6 Enlarged view of the structure at point A in the middle;

[0029] Figure 8 This is a front view of the overall structure of the bent oil pipe after partial sectioning in this invention.

[0030] In the diagram: 1. Bent oil pipe; 11. Horizontal pipe; 12. Vertical pipe; 2. Oil extraction component; 3. Oil outlet; 4. Agitator and anti-clogging component; 41. Drive motor; 42. Anti-clogging swirl block; 5. Combing assembly; 51. Convex combing block; 52. Sealed bearing; 6. Two-way funnel channel; 7. Conical control component; 71. Drive component; 711. Drive cylinder; 712. Extrusion shaft; 713. Bent support block; 72. Conical shielding component; 721. Conical head; 722. Annular support frame; 723. Stacked channel; 73. Adjustment and pushing component; 731. Drive push rod; 732. Movable shaft; 733. Conical top; 8. Controllable shielding component; 81. Shielding disc; 82. Elastic component; 821. Built-in mounting ring; 822. Sliding shaft; 823. Extrusion spring. Detailed Implementation

[0031] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0032] Reference Figures 1 to 8As shown, the present invention provides a device for controlling the flow rate of produced liquid in a well. In order to form bidirectional flow control of the produced liquid and adapt to the changing downhole conditions and the flow properties of different oil layers, the device includes a bent tubing 1. The bent tubing 1 is composed of a horizontal pipe 11 and a vertical pipe 12 forming an L-shaped structure. An oil pumping component 2 is installed inside the vertical pipe 12. An oil production port 3 is opened on the horizontal pipe 11. The device also includes an anti-blocking mechanism and a flow control structure installed at the oil production port 3 and the bend of the bent tubing 1.

[0033] The anti-blocking mechanism is located in the section from the oil outlet 3 to the bend. The anti-blocking mechanism includes an agitating anti-blocking component 4 located inside the oil outlet 3 and a combing component 5 located at the bend of the bend in the oil pipe 1.

[0034] The flow control structure includes a bidirectional funnel channel 6 installed in the horizontal pipe 11, a conical control component 7 installed on one side of the bidirectional funnel channel 6, and a controllable shielding component 8 installed on the other side.

[0035] like Figure 3 and Figure 5 As shown, the bidirectional funnel channel 6 is a bidirectional conical flow channel with large diameters at both ends and a small diameter in the center. The controllable shielding component 8 is located on the side of the bidirectional funnel channel 6 near the oil production port 3, and the conical control component 7 is located on the side of the bidirectional funnel channel 6 near the bend.

[0036] The controllable shielding component 8 includes a shielding disk 81 disposed in a channel on one side of the bidirectional funnel channel 6 and an elastic component 82 that drives the shielding disk 81 to move toward the center of the bidirectional funnel channel 6.

[0037] The conical control component 7 includes a drive component 71, a conical shielding component 72, and a regulating push component 73. The output shaft of the drive component 71 passes through the bend of the bent oil pipe 1 and is coaxial with the horizontal pipe 11. The conical shielding component 72 is located at the end of the shaft of the drive component 71 and faces the shielding plate 81. The regulating push component 73 is located at the end of the conical shielding component 72 and acts on the shielding plate 81, so that the conical shielding component 72 and the shielding plate 81 form a bidirectional flow control effect inside the bidirectional funnel channel 6.

[0038] like Figure 3 As shown, the agitation anti-clogging component 4 includes a drive motor 41 disposed at the end of the bent oil pipe 1 and an anti-clogging swivel block 42 rotatably disposed inside the horizontal pipe 11. The anti-clogging swivel block 42 is rotatably mounted inside the horizontal pipe 11 via a rotating shaft and is connected to the output end of the drive motor 41 via a coupling. When rotating, it breaks up the sediment.

[0039] The elastic element 82 includes an internal mounting ring 821, a sliding shaft 822, and an extrusion spring 823 disposed within the horizontal pipe 11. The sliding shaft 822 movably passes through the center of the internal mounting ring 821, with one end of the sliding shaft 822 connected to the baffle plate 81 and the other end movably inserted into the rotating end of the anti-blocking swivel block 42. The extrusion spring 823 is disposed within the rotating shaft of the anti-blocking swivel block 42, and the end of the extrusion spring 823 acts on the sliding shaft 822, causing the sliding shaft 822 and the baffle plate 81 to maintain a tendency to move towards the center of the bidirectional funnel channel 6.

[0040] like Figure 2 As shown, the conical shielding member 72 includes a conical head 721, an annular support frame 722, and a stacked channel 723. The conical head 721 is located at the end of the shaft of the drive member 71, the annular support frame 722 is located at the edge of the conical head 721, and the stacked channel 723 is located inside the annular support frame 722, and the stacked channel 723 is attached to the inside of the horizontal pipe 11.

[0041] The stacked channel 723 includes multiple channels, and the diameter of the channels decreases sequentially at the center. This allows the liquid to pass through the conical head 721 and the inside of the horizontal pipe 11, and then through the stacked channel 723. The intermittent channels create an acceleration effect, allowing the slow liquid, which is controlled by the flow rate, to pass through the horizontal pipe 11 at a faster speed and finally enter the vertical pipe 12 to be extracted by the pumping unit 2.

[0042] like Figure 5 As shown, the conical head 721 has a hollow end. The regulating pusher 73 includes a drive push rod 731, a movable shaft 732, and a conical top 733. The drive push rod 731 is disposed inside the hollow end of the conical head 721. The movable shaft 732 is movably inserted into the end of the conical head 721 and is connected to the drive push rod 731. The conical top 733 is disposed in close contact with the end of the conical head 721 and is connected to the movable shaft 732.

[0043] The conical top 733 forms a complete conical structure at the end of the conical head 721, and the conical top 733 is directly facing the center of the baffle plate 81. When the conical head 721 is moved forward, the distance and position of the conical head 721 in the conical space on one side of the bidirectional funnel channel 6 can be adjusted to control the liquid flow rate in the conical space on one side of the bidirectional funnel channel 6. In addition, the movable shaft 732 and the conical top 733 can be moved forward by driving the push rod 731. The conical top 733 squeezes the baffle plate 81 to move. By adjusting the position of the baffle plate 81 in the conical space on the other side of the bidirectional funnel channel 6, the liquid flow rate can be controlled. Thus, flow control is formed in the conical channel space on the other side of the bidirectional funnel channel 6, and bidirectional flow space control is formed inside the bidirectional funnel channel 6.

[0044] like Figure 2As shown, the driving component 71 includes a driving cylinder 711, an extrusion shaft 712, and a bending support block 713. The bending support block 713 is located at the bend of the bending oil pipe 1. The driving cylinder 711 is located outside the bending support block 713. The extrusion shaft 712 moves through the bending support block 713 and the bend of the bending oil pipe 1. One end of the extrusion shaft 712 is connected to the output end of the driving cylinder 711, and the other end is connected to the conical head 721. The driving cylinder 711 pushes the extrusion shaft 712, causing the conical blocking component 72 to move axially. The distance between the conical head 721 and the conical space on the left side of the bidirectional funnel channel 6 changes, adjusting the cross-sectional area of ​​the channel. The smaller the distance, the smaller the flow rate.

[0045] It should be clarified that by independently adjusting the position of the conical baffle 72 and the displacement of the conical top 733, a dynamic balance throttling effect is formed on both sides of the bidirectional funnel channel 6. In addition, the low-speed liquid after throttling enters the stacked channel 723, and the flow velocity is increased stepwise through the annular channel with decreasing diameter, and finally flows into the vertical pipe 12 at high speed and is extracted by the oil extraction component 2.

[0046] like Figure 6 As shown, the combing assembly 5 includes a convex combing block 51 and a sealing bearing 52. The sealing bearing 52 is located at the connection between the extrusion shaft 712 and the bent oil pipe 1. The sealing bearing 52 is embedded in the wall of the bent oil pipe 1 and wraps around the extrusion shaft 712 to achieve dynamic sealing. The convex combing block 51 is located inside the bent oil pipe 1 and below the connection between the extrusion shaft 712 and the bent oil pipe 1.

[0047] The end of the convex combing block 51 is arc-shaped, thus forming an outwardly convex arc-shaped separation surface below the bend of the bent oil pipe 1 and the connection of the extrusion shaft 712. This helps the liquid flowing through this area to be combed to both sides, preventing the liquid from being trapped and accumulating at the connection of the bent oil pipe 1 and the extrusion shaft 712.

[0048] It should be clarified that the drive motor 41 drives the anti-clogging swirl block 42 to rotate, breaking up impurities at the three oil outlets. When the liquid flows through the bend, the arc-shaped separation surface of the convex comb block 51 guides the fluid to both sides to avoid stagnation, thus forming an anti-clogging effect on the flowing liquid.

[0049] Working principle: Formation produced fluid enters the device through the oil outlet 3 on the horizontal pipeline 11. The drive motor 41 drives the anti-clogging swirl block 42 to rotate continuously near the oil outlet 3. The rotating anti-clogging swirl block 42 plays a stirring and breaking role, preventing sand, wax, or other impurities from depositing and clogging the channel at the oil outlet 3. The inflowing fluid first flows to the bidirectional funnel channel 6. Under the action of the elastic element 82, the baffle plate 81 always tends to move towards the central constriction of the bidirectional funnel channel 6, closing the bidirectional funnel channel 6. The drive cylinder 711 pushes the conical baffle 72 to move axially along the horizontal pipe 11 via the extrusion shaft 712. The movement of the conical head 721 changes the distance between the conical space near the bend in the bidirectional funnel channel 6. The smaller the distance, the smaller the effective flow cross-sectional area of ​​the channel on that side, and the stronger the throttling effect on the liquid flowing towards the bend. In addition, the drive push rod 731 can independently push the movable shaft 732 and the conical top 733 to extend forward. The extended conical top 733 directly pushes the baffle plate 81, overcoming the elastic element 82. The force forces the shielding plate 81 to move away from the central constriction, which increases the effective flow cross-sectional area of ​​the channel near the oil outlet 3 and reduces the throttling effect on that side. This creates a dynamic and independent throttling effect in the conical spaces on both sides of the bidirectional funnel channel 6, achieving bidirectional and refined flow control of the liquid flowing in from the oil outlet 3 and out from the bend. This enhances the device's adaptability to various downhole conditions, such as oil layers with different permeability. After being throttled by the bidirectional funnel channel 6, the liquid flow rate is relatively slow. The low-speed liquid then flows through the stacked channel 723 to accelerate and finally enters the bend of the bend in the tubing 1. Here, the convex combing block 51 plays a role. Its arc-shaped separation surface is located below the connection between the extrusion shaft 712 and the pipe. It can actively comb and guide the liquid flowing through this point to both sides of the bend, preventing the liquid from stagnating and accumulating at the root of the extrusion shaft 712 or the dead corner of the bend, thus preventing blockage. Finally, the accelerated and combed liquid flows smoothly into the vertical pipe 12 and is pumped upwards out of the wellbore by the pumping unit 2.

[0050] The foregoing has shown and described the basic principles, main features, and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The embodiments and descriptions in the specification are merely preferred examples and are not intended to limit the invention. Various changes and modifications can be made to the invention without departing from its spirit and scope, and all such changes and modifications fall within the scope of the present invention as claimed. The scope of protection of the present invention is defined by the appended claims and their equivalents.

Claims

1. A device for controlling the flow of produced liquid in a well, comprising a bent pipe (1) comprising a horizontal pipe (11) and a vertical pipe (12) in which an oil pumping element (2) is arranged, said horizontal pipe (11) being provided with a production opening (3), characterized in that, Also include: The two-way funnel passage (6) is provided with a conical control member (7) on one side close to the bending part of the oil pipe (1) and a controllable shielding member (8) on the other side close to the oil extraction port (3); The controllable shielding member (8) comprises a shielding disc (81) arranged in the conical passage on one side of the two-way funnel passage (6) and an elastic member (82) for driving the shielding disc (81) to move to the center of the two-way funnel passage (6); The conical control member (7) comprises a driving member (71), the output shaft of the driving member (71) penetrates the bending part of the oil pipe (1) and is coaxial with the horizontal pipeline (11), the shaft end of the driving member (71) is provided with a conical shielding member (72), the end of the conical shielding member (72) is provided with a regulating pushing member (73), the regulating pushing member (73) acts on the shielding disc (81), the conical shielding member (72) adjusts the flow passage width by moving in the conical passage on one side of the two-way funnel passage (6), and the regulating pushing member (73) adjusts the flow gap by pushing the shielding disc (81) to move in the conical passage on the other side of the two-way funnel passage (6), thereby forming two-way flow control in the two-way funnel passage (6).

2. The apparatus of claim 1, wherein, Also include an agitation anti-blocking member (4) arranged inside the oil extraction port (3), the agitation anti-blocking member (4) comprises a driving motor (41) arranged at the end of the oil pipe (1) and an anti-blocking rotating block (42) rotatably arranged inside the horizontal pipeline (11), the anti-blocking rotating block (42) is rotatably installed inside the horizontal pipeline (11) through a rotating shaft and is connected to the output end of the driving motor (41).

3. The apparatus of claim 1, wherein, The elastic member (82) comprises an embedded mounting ring (821), a sliding shaft (822) and an extrusion spring (823) arranged in the horizontal pipeline (11), the sliding shaft (822) movably penetrates the center of the embedded mounting ring (821), one end of the sliding shaft (822) is connected to the shielding disc (81), and the other end movably penetrates the end of the rotating shaft of the anti-blocking rotating block (42), the extrusion spring (823) is arranged in the rotating shaft of the anti-blocking rotating block (42), and the end of the extrusion spring (823) acts on the sliding shaft (822), so that the sliding shaft (822) and the shielding disc (81) have a tendency to move towards the center of the two-way funnel passage (6).

4. The apparatus of claim 1, wherein, The conical shielding member (72) comprises a conical head (721), an annular support frame (722) and a laminated passage (723), the conical head (721) is arranged at the end of the shaft of the driving member (71), the annular support frame (722) is arranged at the edge of the conical head (721), and the laminated passage (723) is arranged inside the annular support frame (722) and is attached to the inside of the horizontal pipeline (11).

5. The apparatus of claim 4, wherein, The laminated passage (723) comprises a plurality of passages, and the diameters of the passages at the centers thereof decrease in turn.

6. The apparatus of claim 4, wherein, The conical head (721) is hollow at the end, the regulating pusher (73) comprises a driving push rod (731), a movable shaft (732) and a conical top (733), the driving push rod (731) is arranged inside the hollow end of the conical head (721), the movable shaft (732) is movably inserted into the end of the conical head (721) and is connected with the driving push rod (731), and the conical top (733) is arranged on the end of the conical head (721) and is connected with the movable shaft (732). The conical top (733) is arranged at the end of the conical head (721) to form a complete conical structure, and the conical top is opposite to the center of the shielding disc (81).

7. The apparatus of claim 6, wherein, The driving member (71) comprises a driving cylinder (711), an extrusion shaft (712) and a bending support block (713), the bending support block (713) is arranged at the bending position of the bending oil pipe (1), the driving cylinder (711) is arranged outside the bending support block (713), the extrusion shaft (712) movably penetrates through the bending support block (713) and the bending position of the bending oil pipe (1), one end of the extrusion shaft (712) is connected with the output end of the driving cylinder (711), and the other end is connected with the conical head (721).

8. The apparatus of claim 7, wherein, The bending oil pipe (1) further comprises a combing assembly (5) arranged at the bending position, the combing assembly (5) comprises a convex combing block (51) and a sealing bearing (52), the sealing bearing (52) is arranged at the connection position of the extrusion shaft (712) and the bending oil pipe (1), and the convex combing block (51) is arranged inside the bending oil pipe (1) and below the connection position of the extrusion shaft (712) and the bending oil pipe (1). The end of the convex combing block (51) is arc-shaped.

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