Descaling device for inner wall of underground oil pipe

Abstract

The invention discloses an underground oil pipe inner wall descaling device which comprises a crank, two bearings are arranged on the outer wall of the end, away from the handheld end, of the crank in a sleeving mode, the outer rings of the two bearings are fixedly connected with corresponding supporting rods respectively, a sediment pipe is jointly and fixedly connected between the two supporting rods, and threads are arranged on the inner wall of the end, away from the supporting rods, of the sediment pipe; a roller sleeves the outer wall of the crank between the two bearings, a hook is arranged on the outer wall of the roller, a steel wire rope is fixedly connected to the hook and is wound on the roller, and the other end of the steel wire rope penetrates through the sediment pipe and is fixedly connected with a descaling unit. According to the descaling device, descaling treatment can be conducted on the inner wall of the oil pipe in time on a well repairing site, the replacement rate and the rejection rate of the oil pipe are reduced, hoisting and transporting expenses generated during oil pipe replacement are reduced, and the safety risk of a construction site is reduced.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of oil drilling equipment, and particularly relates to a downhole oil pipe inner wall scale removal device. BACKGROUND

[0002] The production of oil extraction wells is a main channel for completing the oil extraction process by means of a tubular oil pump or a rod oil pump to lift crude oil from the downhole to the ground through the oil pipe. The crude oil is concentrated in the downhole oil pipe and continuously lifted, and the crude oil components have salt-containing substances. The molecules crystallize during the residence process, and long-term aggregation causes scale formation. After detection, most of the scale components are barium sulfate strontium crystals. According to on-site tracking verification, the inner wall of the oil pipe is scaled by 3 mm after 300 days of crude oil production, and the oil pipe diameter changes from 62 mm to 58 mm, causing the oil pipe diameter to become smaller and the resistance of the oil rod to increase during the movement process. In daily production, the load increases, the energy consumption increases, the cost of crude oil production is high, and the economic benefit is affected. After the oil pipe of the water injection well is scaled, the oil pipe becomes small. According to on-site detection, the inner wall of the water injection well is scaled by 12 mm after 1200 days of continuous production of the water injection well, and the inner diameter of the oil pipe changes to 40 mm, which seriously affects the water injection production. The injection pressure is increased to 14 Mpa, and the injection pipe pressure is increased to 16.5 Mpa or more to meet the injection production. The increase of the injection pressure causes greater damage to the injection pump, and the pump inspection cycle is significantly shortened from 90 days to 23 days. The situation of safe production is more difficult, and the pressure bearing requirement of the injection pipe network is increased. The inspection cycle of the water injection well is significantly shortened, the scale on the inner wall of the oil pipe of the water injection well cannot be removed, and the scrap rate is significantly increased, resulting in an increase in production cost, and the oil pipe of the water injection well cannot be reused. SUMMARY

[0003] The purpose of the present application is to provide a downhole oil pipe inner wall scale removal device, which solves the problem of the inability to remove the scale on the inner wall of the downhole oil pipe.

[0004] The technical scheme adopted by the present application is that the downhole oil pipe inner wall scale removal device comprises a crank handle, the outer wall of the end of the crank handle away from the hand is sleeved with two bearings, the outer rings of the two bearings are respectively fixedly connected with corresponding support rods, the support rods are fixedly connected with a sediment pipe, and the inner wall of the end of the sediment pipe away from the support rods is provided with threads.

[0005] The present application has the following characteristics:

[0006] The cleaning unit comprises a screw rod, a screw thread hook fixed to one end of the screw rod, the screw thread hook being fixed to a steel wire rope, a first centralizer being sleeved on the outer wall of the screw rod near the screw thread hook, a second centralizer being sleeved on the outer wall of the other end of the screw rod, and a plurality of scraper combination units being arranged on the screw rod between the first centralizer and the second centralizer.

[0007] The first centralizer comprises two centralizing blocks, and the two centralizing blocks are sleeved on the outer wall of the screw rod.

[0008] The centralizing block comprises a centralizing ring, the centralizing ring being sleeved on the outer wall of the screw rod, and the outer wall of the centralizing ring being provided with corresponding centralizing strips in the diameter direction.

[0009] The scraper combination unit comprises a first scraper unit, a second scraper unit, a third scraper unit and a fourth scraper unit, the first scraper unit, the second scraper unit, the third scraper unit and the fourth scraper unit being sequentially sleeved on the outer wall of the screw rod in the direction away from the screw thread hook.

[0010] The first scraper unit comprises n first scrapers, the sector angle of the first scraper being 360° / n, the n first scrapers being sleeved on the outer wall of the screw rod in the circumferential direction, and the n first scrapers being provided with bolts on both sides of the outer wall of the screw rod, n being not less than 1.

[0011] The second scraper unit comprises n second scrapers, the sector angle of the second scraper being 360° / n, the n second scrapers being sleeved on the outer wall of the screw rod in the circumferential direction, the n second scrapers being provided with bolts on both sides of the outer wall of the screw rod, n being not less than 1.

[0012] The third scraper unit comprises n third scrapers, the sector angle of the third scraper being 360° / n, the n third scrapers being sleeved on the outer wall of the screw rod in the circumferential direction, the n third scrapers being provided with bolts on both sides of the outer wall of the screw rod, n being not less than 1.

[0013] The fourth scraper unit comprises n fourth scrapers, the sector angle of the fourth scraper being 360° / n, the n fourth scrapers being sleeved on the outer wall of the screw rod in the circumferential direction, the n fourth scrapers being provided with bolts on both sides of the outer wall of the screw rod, n being not less than 1.

[0014] The first scraper, the second scraper, the third scraper and the fourth scraper are all composed of a sector segment and a base circle segment, the base circle segment is in the shape of a hollow cylinder, the sector segment is arranged on the outer wall of the base circle segment, the first scraper, the second scraper, the third scraper and the fourth scraper are all adapted to the inner diameter of the oil pipe, and the radius of the sector segment of the first scraper, the second scraper, the third scraper and the fourth scraper increases in turn.

[0015] The beneficial effects of the present application are as follows:

[0016] The well down oil pipe inner wall scale removal device provided by the application can timely clean the inner wall of the oil pipe on the well site, reduces the replacement rate and scrap rate of the oil pipe, reduces the hoisting, transportation and other costs of the oil pipe replacement, and reduces the safety risk of the construction site. BRIEF DESCRIPTION OF DRAWINGS

[0017] Figure 1 is a structural schematic view of the well down oil pipe inner wall scale removal device of the application;

[0018] Figure 2 is a structural schematic view of the first centralizer of the well down oil pipe inner wall scale removal device of the application;

[0019] Figure 3 is a structural schematic view of the centralizer block of the well down oil pipe inner wall scale removal device of the application;

[0020] Figure 4 is a structural schematic view of the first scraper of the well down oil pipe inner wall scale removal device of the application.

[0021] In the figure, 1. crank, 2. bearing, 3. roller, 4. hook, 5. steel wire rope, 6. support rod, 7. sediment pipe, 8. screw hook, 9. lead screw, 10. first centralizer, 11. second centralizer, 12. first scraper, 13. second scraper, 14. third scraper, 15. fourth scraper, 16. centralizer block, 17. centralizer ring, 18. centralizer strip. 19. fan-shaped segment, 20. base circle segment. DETAILED DESCRIPTION

[0022] The application will be described in detail below in combination with the drawings and specific embodiments.

[0023] The application provides a well down oil pipe inner wall scale removal device, which can timely clean the inner wall of the oil pipe on the well site, reduces the replacement rate and scrap rate of the oil pipe, reduces the hoisting, transportation and other costs of the oil pipe replacement, and reduces the safety risk of the construction site. Figure 1 As shown in the figure, the device comprises a crank 1, the outer wall of the end of the crank 1 away from the hand is sleeved with two bearings 2, the outer rings of the two bearings 2 are respectively fixedly connected with corresponding support rods 6, the two support rods 6 are jointly fixedly connected with a sediment pipe 7, the inner wall of the end of the sediment pipe 7 away from the support rod 6 is provided with a screw thread, and the sediment pipe 7 is connected with one end of the oil pipe through the screw thread during the cleaning of the scale; the outer wall of the roller 3 sleeved with the two bearings 2 between the crank 1 is provided with a hook 4, the hook 4 is fixedly connected with a steel wire rope 5, the steel wire rope 5 is wound on the roller 3, and the other end of the steel wire rope 5 is fixedly connected with a scale removal unit through the sediment pipe 7; the scale removal unit comprises a lead screw 9, one end of the lead screw 9 is fixedly connected with a screw hook 8, the screw hook 8 is fixedly connected with the steel wire rope 5, the crank 1 is rotated to move the lead screw 9, the outer wall of the end of the lead screw 9 close to the screw hook 8 is sleeved with a first centralizer 10, the lead screw 9 is centrally moved in the oil pipe through the first centralizer 10, the other end of the lead screw 9 is sleeved with a second centralizer 11, the lead screw 9 is centrally moved in the oil pipe through the second centralizer 11, and a plurality of scraper combination units are arranged on the lead screw 9 between the first centralizer 10 and the second centralizer 11.Figure 2 As shown, the first centralizer 10 includes two centralizer blocks 16, which are stacked on the outer wall of the lead screw 9. As shown Figure 3 As shown, the centralizer block 16 includes a centralizer ring 17, which is sleeved on the outer wall of the lead screw 9, and the outer wall of the centralizer ring 17 is provided with corresponding centralizer strips 18 in the diameter direction; the scraper combination unit includes a first scraper unit, a second scraper unit, a third scraper unit, and a fourth scraper unit, which are sequentially sleeved on the outer wall of the lead screw 9 in the direction away from the thread hook 8; the first scraper unit includes n first scrapers 12, the sector angle of the first scraper 12 is 360° / n, and the n first scrapers 12 are sleeved on the outer wall of the lead screw 9 in the circumferential direction, and the outer wall of the lead screw 9 is provided with bolts on both sides of the n first scrapers 12, which facilitates the fixation of the first scraper 12, n is not less than 1, and the first scraper 12 removes the dirt on the inner wall of the oil pipe without dead angle; the second scraper unit includes n second scrapers 13, the sector angle of the second scraper 13 is 360° / n, and the n second scrapers 13 are sleeved on the outer wall of the lead screw 9 in the circumferential direction, and the outer wall of the lead screw 9 is provided with bolts on both sides of the n second scrapers 13, which facilitates the fixation of the second scraper 13, n is not less than 1, and the second scraper 13 removes the dirt on the inner wall of the oil pipe without dead angle; the third scraper unit includes n third scrapers 14, the sector angle of the third scraper 14 is 360° / n, and the n third scrapers 14 are sleeved on the outer wall of the lead screw 9 in the circumferential direction, and the outer wall of the lead screw 9 is provided with bolts on both sides of the n third scrapers 14, which facilitates the fixation of the third scraper 14, n is not less than 1, and the third scraper 14 removes the dirt on the inner wall of the oil pipe without dead angle; the fourth scraper unit includes n fourth scrapers 15, the sector angle of the fourth scraper 15 is 360° / n, and the n fourth scrapers 15 are sleeved on the outer wall of the lead screw 9 in the circumferential direction, and the outer wall of the lead screw 9 is provided with bolts on both sides of the n fourth scrapers 15, which facilitates the fixation of the fourth scraper 15, n is not less than 1, and the fourth scraper 15 removes the dirt on the inner wall of the oil pipe without dead angle. As shown Figure 4 As shown, the first scraper 12, the second scraper 13, the third scraper 14, and the fourth scraper 15 are composed of a sector segment 19 and a base circle segment 20, the base circle segment 20 is in the form of a hollow cylinder, the sector segment 19 is provided on the outer wall of the base circle segment 20, the first scraper 12, the second scraper 13, the third scraper 14, and the fourth scraper 15 are adapted to the inner diameter of the oil pipe, the radius of the sector segment of the first scraper 12, the second scraper 13, the third scraper 14, and the fourth scraper 15 increases in turn, thereby ensuring the removal of the dirt on the inner wall of the oil pipe without dead angle.

[0024] The working principle of the downhole oil pipe inner wall scale removal device provided by the application is as follows: the sediment pipe 7 is threadedly connected to one end of the oil pipe, the scale removal unit is inserted from the other end of the oil pipe, the steel wire rope 5 fixed to the screw hook 8 is fixed to the hook 4 through the oil pipe, the handle 1 is rotated to move the scale removal unit in the oil pipe, and the scale on the inner wall of the oil pipe is removed by the first scraper unit, the second scraper unit, the third scraper unit and the fourth scraper unit.

[0025] Embodiment 1

[0026] The downhole oil pipe inner wall scale removal device provided by the embodiment comprises a handle 1, two bearings 2 are sleeved on the outer wall of the end of the handle 1 away from the hand, the outer rings of the two bearings 2 are respectively fixedly connected to corresponding support rods 6, the support rods 6 are fixedly connected to each other, and the end of the sediment pipe 7 away from the support rods 6 is provided with a thread in the inner wall. Figure 1 The outer wall of the handle 1 is sleeved with a roller 3 between the two bearings 2, the outer wall of the roller 3 is provided with a hook 4, the hook 4 is fixedly connected to a steel wire rope 5, the steel wire rope 5 is wound on the roller 3, and the other end of the steel wire rope 5 is fixedly connected to a scale removal unit through the sediment pipe 7.

[0027] Embodiment 2

[0028] The downhole oil pipe inner wall scale removal device provided by the embodiment comprises a handle 1, two bearings 2 are sleeved on the outer wall of the end of the handle 1 away from the hand, the outer rings of the two bearings 2 are respectively fixedly connected to corresponding support rods 6, the support rods 6 are fixedly connected to each other, and the end of the sediment pipe 7 away from the support rods 6 is provided with a thread in the inner wall. Figure 1 The outer wall of the handle 1 is sleeved with a roller 3 between the two bearings 2, the outer wall of the roller 3 is provided with a hook 4, the hook 4 is fixedly connected to a steel wire rope 5, the steel wire rope 5 is wound on the roller 3, and the other end of the steel wire rope 5 is fixedly connected to a scale removal unit through the sediment pipe 7. Figure 2 The scale removal unit comprises a lead screw 9, one end of the lead screw 9 is fixedly connected to a screw hook 8, the screw hook 8 is fixedly connected to the steel wire rope 5, the outer wall of the end of the lead screw 9 close to the screw hook 8 is sleeved with a first centralizer 10, the outer wall of the other end of the lead screw 9 is sleeved with a second centralizer 11, and a plurality of scraper combination units are arranged on the lead screw 9 between the first centralizer 10 and the second centralizer 11. Figure 3As shown, the straightening block 16 includes a straightening ring 17, which is sleeved on the outer wall of the lead screw 9. The outer wall of the straightening ring 17 is provided with corresponding straightening strips 18 along the diameter direction.

[0029] Example 3

[0030] The downhole tubing descaling device proposed in this embodiment, such as... Figure 1 As shown, the device includes a crank handle 1. Two bearings 2 are fitted onto the outer wall of the end of the crank handle 1 furthest from the hand. Corresponding support rods 6 are fixed to the outer rings of the two bearings 2. A sedimentation tube 7 is fixed between the two support rods 6. The inner wall of the sedimentation tube 7 furthest from the support rods 6 is threaded. A roller 3 is fitted onto the outer wall of the crank handle 1 between the two bearings 2. A hook 4 is provided on the outer wall of the roller 3. A steel wire rope 5 is fixed to the hook 4 and wound around the roller 3. The other end of the steel wire rope 5 passes through the sedimentation tube 7 and is fixed to a descaling unit. The descaling unit includes a screw 9. A threaded hook 8 is fixed to one end of the screw 9 and is fixed to the steel wire rope 5. A first stabilizer 10 is fitted onto the outer wall of the end of the screw 9 closest to the threaded hook 8, and a second stabilizer 11 is fitted onto the outer wall of the other end of the screw 9. Several scraper assembly units are provided on the screw 9 between the first stabilizer 10 and the second stabilizer 11. (The text abruptly ends here.) Figure 2 As shown, the first straightener 10 includes two straightening blocks 16, which are stacked and sleeved on the outer wall of the lead screw 9. Figure 3 As shown, the straightening block 16 includes a straightening ring 17, which is sleeved on the outer wall of the lead screw 9. The outer wall of the straightening ring 17 has corresponding straightening strips 18 along its diameter. The scraper assembly unit includes a first scraper unit, a second scraper unit, a third scraper unit, and a fourth scraper unit. These units are sequentially sleeved on the outer wall of the lead screw 9 along the direction away from the thread hook 8. The first scraper unit includes n first scrapers 12, each with a fan angle of 360° / n. The n first scrapers 12 are sleeved on the outer wall of the lead screw 9 along the circumferential direction, and bolts are provided on both sides of each of the n first scrapers 12 on the outer wall of the lead screw 9. n is not less than 1. The second scraper unit includes n second scrapers 13. The second scraper 13 has a sector angle of 360° / n, and n second scrapers 13 are sleeved on the outer wall of the lead screw 9 along the circumferential direction. Bolts are provided on both sides of the n second scrapers 13 on the outer wall of the lead screw 9, and n is not less than 1. The third scraper unit includes n third scrapers 14, each with a sector angle of 360° / n. The n third scrapers 14 are sleeved on the outer wall of the lead screw 9 along the circumferential direction, and bolts are provided on both sides of the n third scrapers 14 on the outer wall of the lead screw 9, and n is not less than 1. The fourth scraper unit includes n fourth scrapers 15, each with a sector angle of 360° / n. The n fourth scrapers 15 are sleeved on the outer wall of the lead screw 9 along the circumferential direction, and bolts are provided on both sides of the n fourth scrapers 15 on the outer wall of the lead screw 9, and n is not less than 1. Figure 4As shown, the first scraper 12, the second scraper 13, the third scraper 14, and the fourth scraper 15 are all composed of a fan-shaped segment 19 and a base circle segment 20. The base circle segment 20 is a hollow cylinder, and the fan-shaped segment 19 is located on the outer wall of the base circle segment 20. The first scraper 12, the second scraper 13, the third scraper 14, and the fourth scraper 15 are all adapted to the inner diameter of the oil pipe, and the radius of the fan-shaped segment of the first scraper 12, the second scraper 13, the third scraper 14, and the fourth scraper 15 increases sequentially.

[0031] Example 4

[0032] The downhole tubing descaling device proposed in this embodiment, such as... Figure 1 As shown, the device includes a crank handle 1. Two bearings 2 are fitted onto the outer wall of the end of the crank handle 1 furthest from the hand. Corresponding support rods 6 are fixed to the outer rings of the two bearings 2. A sedimentation pipe 7 is fixed between the two support rods 6. The inner wall of the sedimentation pipe 7 furthest from the support rods 6 is threaded, and it is threaded to one end of an oil pipe with an inner diameter of 62mm. A roller 3 is fitted onto the outer wall of the crank handle 1 between the two bearings 2. A hook 4 is provided on the outer wall of the roller 3, and a steel wire rope 5 is fixed to the hook 4. The steel wire rope 5 is wound around the roller 3. The other end of the wire rope 5 passes through the sediment pipe 7 and is fixed to a descaling unit; the descaling unit includes a screw 9 of model M27 with a length of not less than 1000mm. One end of the screw 9 is fixed to a threaded hook 8, which is fixed to the wire rope 5. A first stabilizer 10 is fitted on the outer wall of the end of the screw 9 near the threaded hook 8, and a second stabilizer 11 with an outer diameter of 61mm is fitted on the outer wall of the other end of the screw 9. Several scraper assembly units are provided on the screw 9 between the first stabilizer 10 and the second stabilizer 11. Figure 2 As shown, the first straightener 10 includes two straightening blocks 16, which are stacked and sleeved on the outer wall of the lead screw 9. Figure 3As shown, the straightening block 16 includes a straightening ring 17 with an outer diameter of 40mm. The straightening ring 17 is sleeved on the outer wall of the lead screw 9. The outer wall of the straightening ring 17 has corresponding straightening strips 18 with a length and width of 10mm along the diameter direction. The scraper assembly unit includes a first scraper unit, a second scraper unit, a third scraper unit, and a fourth scraper unit. The first scraper unit, the second scraper unit, the third scraper unit, and the fourth scraper unit are sequentially sleeved on the outer wall of the lead screw 9 in the direction away from the thread hook 8. The distance between the first scraper unit, the second scraper unit, the third scraper unit, and the fourth scraper unit is 150mm, leaving sufficient space for sediment to prevent sediment from causing resistance to the advancement of the descaling unit. The first scraper unit includes three first scrapers 12. The fan angle of the first scraper 12 is 120°. The three first scrapers 12 are arranged along the circumference. The first scraper unit consists of three first scrapers 12, each with bolts on both sides of the outer wall of the lead screw 9. The second scraper unit comprises three second scrapers 13, each with a fan angle of 120°, circumferentially mounted on the outer wall of the lead screw 9. The third scraper unit comprises three third scrapers 14, each with a fan angle of 120°, circumferentially mounted on the outer wall of the lead screw 9. The fourth scraper unit comprises three fourth scrapers 15, each with a fan angle of 120°, circumferentially mounted on the outer wall of the lead screw 9. Bolts are also provided on both sides of the third scraper 14. Figure 4 As shown, the first scraper 12, the second scraper 13, the third scraper 14, and the fourth scraper 15 are all composed of a fan-shaped segment 19 and a base circle segment 20 with an outer diameter of 40 mm. The base circle segment 20 is a hollow cylinder. The fan-shaped segment 19 is located on the outer wall of the base circle segment 20. The first scraper 12, the second scraper 13, the third scraper 14, and the fourth scraper 15 are all adapted to the inner diameter of the oil pipe. The radius of the fan-shaped segment of the first scraper 12 is 29 mm, the radius of the fan-shaped segment of the second scraper 13 is 29.5 mm, the radius of the fan-shaped segment of the third scraper 14 is 30 mm, and the radius of the fan-shaped segment of the fourth scraper 15 is 30.5 mm. The radii of the fan-shaped segments increase sequentially.

Claims

1. A descaling device for the inner wall of downhole tubing, characterized in that, The device includes a crank handle (1), on which two bearings (2) are fitted on the outer wall of the end away from the hand. The outer rings of the two bearings (2) are respectively fixed with corresponding support rods (6). A sedimentation tube (7) is fixed between the two support rods (6). The inner wall of the sedimentation tube (7) away from the support rods (6) is threaded. A roller (3) is fitted on the outer wall of the crank handle (1) between the two bearings (2). A hook (4) is provided on the outer wall of the roller (3). A wire rope (5) is fixed on the hook (4). The wire rope (5) is wound around the roller (3). The other end of the wire rope (5) passes through the sedimentation tube (7) and is fixed with a descaling unit.

2. The descaling device for the inner wall of downhole tubing according to claim 1, characterized in that, The descaling unit includes a lead screw (9), one end of which is fixedly connected to a threaded hook (8), which is fixedly connected to a wire rope (5). A first stabilizer (10) is sleeved on the outer wall of one end of the lead screw (9) near the threaded hook (8), and a second stabilizer (11) is sleeved on the outer wall of the other end of the lead screw (9). Several scraper combination units are provided on the lead screw (9) between the first stabilizer (10) and the second stabilizer (11).

3. The descaling device for the inner wall of downhole tubing according to claim 2, characterized in that, The first straightener (10) includes two straightener blocks (16), which are stacked and sleeved on the outer wall of the lead screw (9).

4. The descaling device for the inner wall of downhole tubing according to claim 3, characterized in that, The straightening block (16) includes a straightening ring (17), which is sleeved on the outer wall of the lead screw (9), and the outer wall of the straightening ring (17) is provided with corresponding straightening strips (18) along the diameter direction.

5. The descaling device for the inner wall of downhole tubing according to claim 4, characterized in that, The scraper assembly unit includes a first scraper unit, a second scraper unit, a third scraper unit, and a fourth scraper unit, which are sequentially sleeved on the outer wall of the lead screw (9) in a direction away from the thread hook (8).

6. The descaling device for the inner wall of downhole tubing according to claim 5, characterized in that, The first scraper unit includes n first scrapers (12), the sector angle of the first scraper (12) is 360° / n, the n first scrapers (12) are sleeved on the outer wall of the lead screw (9) along the circumferential direction, and bolts are provided on both sides of the n first scrapers (12) on the outer wall of the lead screw (9), wherein n is not less than 1.

7. The descaling device for the inner wall of downhole tubing according to claim 6, characterized in that, The second scraper unit includes n second scrapers (13), the sector angle of the second scraper (13) is 360° / n, the n second scrapers (13) are sleeved on the outer wall of the lead screw (9) along the circumferential direction, and bolts are provided on both sides of the n second scrapers (13) on the outer wall of the lead screw (9), and n is not less than 1.

8. The descaling device for the inner wall of downhole tubing according to claim 7, characterized in that, The third scraper unit includes n third scrapers (14), the sector angle of the third scraper (14) is 360° / n, the n third scrapers (14) are sleeved on the outer wall of the lead screw (9) along the circumferential direction, and bolts are provided on both sides of the n third scrapers (14) on the outer wall of the lead screw (9), and n is not less than 1.

9. The descaling device for the inner wall of downhole tubing according to claim 8, characterized in that, The fourth scraper unit includes n fourth scrapers (15), the sector angle of the fourth scraper (15) is 360° / n, the n fourth scrapers (15) are sleeved on the outer wall of the lead screw (9) along the circumferential direction, and bolts are provided on both sides of the n fourth scrapers (15) on the outer wall of the lead screw (9), and n is not less than 1.

10. The descaling device for the inner wall of downhole tubing according to claim 9, characterized in that, The first scraper (12), the second scraper (13), the third scraper (14) and the fourth scraper (15) are all composed of a fan-shaped segment (19) and a base circle segment (20). The base circle segment (20) is a hollow cylinder. The fan-shaped segment (19) is located on the outer wall of the base circle segment (20). The first scraper (12), the second scraper (13), the third scraper (14) and the fourth scraper (15) are all adapted to the inner diameter of the oil pipe. The radius of the fan-shaped segment of the first scraper (12), the second scraper (13), the third scraper (14) and the fourth scraper (15) increases sequentially.

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