Self-floating oil pipe inner drifting device and drifting method

Abstract

The invention belongs to the technical field of oil and gas well conventional oil pipe drifting, and particularly provides a self-floating oil pipe inner drifting device and drifting method.The lower end of an oil pipe is connected with a throttling nozzle, the oil pipe is connected with one end of a first channel and one end of a third channel, and a sleeve is connected with one end of a second channel and one end of a fourth channel; the other end of the channel I and the other end of the channel III are connected with a circulating flushing device; during drifting, the oil pipe is arranged in the hollow drift size gauge tool; when the hollow drift size gauge tool encounters resistance in an oil pipe, the self-floating type oil pipe inner fisher is connected with the hollow drift size gauge tool in a matched mode, and the problems that an existing conventional drift size mode needs a large number of devices, cost is high, labor intensity is large, underground engineering accidents are prone to occurring, and potential safety hazards are large are solved. Non-transmission drifting is achieved, the drifting efficiency in the oil pipe is improved, the construction cost and the technical field application difficulty are reduced, and safety and reliability are achieved.

Description

Technical Field

[0001] The invention belongs to the technical field of conventional oil pipe well cleaning in oil and gas wells, and in particular relates to a self-floating oil pipe internal well cleaning device and a well cleaning method. Background Art

[0002] The main purpose of well cleaning is to remove debris or burrs on the inner wall of the casing or tubing, so that the casing or tubing is unobstructed, and to verify the depth of the well cleaning. Well cleaning in the tubing is to use special tools and equipment to clean the tubing. It is generally divided into two methods: well cleaning in the tubing on the ground and well cleaning in the tubing in the well. Well cleaning in the tubing on the ground is to use a special diameter gauge to clean each tubing one by one, while well cleaning in the tubing in the well currently uses steel (wire) cable soft well cleaning technology and continuous tubing well cleaning technology. These two well cleaning methods have been used in the field for many years and the technology is mature. However, conventional well cleaning methods require a lot of equipment, incur high costs, are labor-intensive, are prone to underground engineering accidents, and have great safety hazards.

[0003] The Chinese patent document with the publication number CN201521273U discloses a well-clearing device for acoustic logging when encountering obstacles. The upper and lower parts of the oil pipe coupling are respectively connected to a plurality of weighted rods and a slurry storage barrel connected to a punch. There are mud discharge channels around the slurry storage barrel body, and there are through holes in the center of the slurry storage barrel and the punch that are connected to the mud discharge channels. The weighted rods are connected to the connecting rod and the connecting head through the oil pipe joint. The inner cavities of the upper joint and the lower connecting head of the oil pipe are both groove-shaped and match the two ends of the connecting rod. The connecting rod can be axially strung in the groove-shaped inner cavity of the oil pipe joint and the connecting head. The upper joint and the lower connecting head of the oil pipe are both external threads, which are connected to the internal threads of the lower joint of the oil pipe and the upper connecting head with a hole on the top. This document mainly solves the problem that the acoustic quality is affected by the collision and impact of the drilling tool on the inner wall of the casing and the change of the medium in the casing when the drill pipe or oil pipe is used for well clearing operations. The device is provided with a weighted rod, and after the well is cleared, it still needs to be lifted up to take out the device, and the structure is complex and the equipment is large; it does not solve the problems that the existing conventional well clearing methods require a lot of equipment, incur high costs, are labor-intensive, are prone to underground engineering accidents, and have great safety hazards. Summary of the invention

[0004] The invention provides a self-floating well cleaning device and a well cleaning method in an oil pipe, aiming to overcome the problems in the prior art that conventional well cleaning methods require a lot of equipment, incur high costs, have high labor intensity, are prone to underground engineering accidents, and have great safety hazards.

[0005] To this end, the present invention provides a self-floating oil pipe internal well-clearing device, in which the oil pipe is sleeved in the casing, and the self-floating oil pipe internal well-clearing device comprises a circulating flushing unit, a self-floating oil pipe internal salvage device, a hollow well-clearing gauge and a throttle nozzle, the circulating flushing unit comprises channel one, channel two, channel three, channel four and the circulating flushing device, the lower end of the oil pipe is connected to the throttle nozzle, the oil pipe is respectively connected to one end of channel one and one end of channel three, the casing is respectively connected to one end of channel two and one end of channel four, and the other end of channel one and the other end of channel three are both connected to the circulating flushing device; when clearing the well, the oil pipe is placed in the hollow well-clearing gauge; when the hollow well-clearing gauge encounters resistance in the oil pipe, the self-floating oil pipe internal salvage device and the hollow well-clearing gauge are matched and connected.

[0006] Preferably, channel one is provided with switch gate one, channel two is provided with switch gate two, channel three is provided with switch gate three, channel four is provided with switch gate four, and the oil pipe is provided with switch gate five and switch gate six in sequence from top to bottom.

[0007] Preferably, the diameter of the throttle nozzle is smaller than the inner diameter of the oil pipe.

[0008] Preferably, the self-floating tubing salvage device comprises a guide device 1, a floating chamber and a salvage tube, the number of the floating chambers is multiple, and the guide device 1, the multiple floating chambers and the salvage tube are connected in sequence from top to bottom.

[0009] Preferably, the interiors of the guide 1, the floating chamber and the overshot tube are all hollow.

[0010] Preferably, the guide, a plurality of floating chambers and a salvage tube are sequentially connected by threads from top to bottom.

[0011] Preferably, the top of the guide 1 is V-shaped with the sharp corner of the V facing upward.

[0012] Preferably, the hollow well gauge comprises a fishing head and a second guide, the fishing head and the second guide are connected in sequence from top to bottom, and the fishing head and the fishing tube are matched and connected.

[0013] Preferably, a plurality of water passage grooves are provided on the outer side of the guide device 2, the plurality of water passage grooves are circumferentially evenly spaced, and each water passage groove is provided along the axial direction.

[0014] A well cleaning method for a self-floating oil pipe inner well cleaning device comprises the following steps:

[0015] S1. Open the switch gates 5 and 6, put the hollow well gauge into the oil pipe, and close the switch gate 5;

[0016] S2, open channel 1 and channel 4, close channel 2 and channel 3, start the circulating flushing device to pump liquid into the oil pipe, and observe the change of pump pressure;

[0017] S3. When the pump pressure suddenly increases, the hollow well gauge has reached the bottom of the tubing, and the inner wall of the tubing has no shrinkage or deformation; stop the pump, open channels 2 and 3, close channels 1 and 4, and reversely circulate to flush out the hollow well gauge in the tubing;

[0018] S4. When the pump pressure does not increase and the amount of liquid pumped in exceeds 1.5 times the volume of the tubing, the hollow well gauge encounters obstruction at any position in the middle of the tubing and the pump stops;

[0019] S5, open channel 1, channel 4 and switch gate 5, close channel 2 and channel 3, put the self-floating tubing salvage device into the tubing, start the circulating flushing device to pump liquid into the tubing, pump the self-floating tubing salvage device downward in the tubing, and observe the change of pump pressure; when the amount of liquid pumped in exceeds 1.5 times the volume of the tubing, stop the pump;

[0020] S6. Start timing after closing channel 1 and channel 4, and stop timing when the salvage device in the floating tubing returns to the ground. Obtain the obstruction depth of the hollow well gauge based on the time and the rising speed.

[0021] Beneficial effects of the present invention:

[0022] 1. The self-floating tubing well-clearing device and well-clearing method provided by the present invention include a circulating flushing unit, a self-floating tubing salvage device, a hollow well-clearing gauge and a throttle nozzle. Through the combination of the circulating flushing unit, the hollow well-clearing gauge and the throttle nozzle, well-clearing, scraping and pressure testing in conventional tubing of oil and water wells are realized; through the combination of the circulating flushing unit, the self-floating tubing salvage device, the hollow well-clearing gauge and the throttle nozzle, the obstruction depth is calculated, and both the hollow well-clearing gauge and the self-floating tubing salvage device float up by buoyancy, and no manual transmission is required; transmission-free well-clearing is achieved, the efficiency of tubing well-clearing is improved, the construction cost and the difficulty of technical field application are reduced, and because there is no transmission wire cable and no manual operation is required, the probability of drilling stuck in the well is zero, which is safe and reliable.

[0023] 2. The self-floating well-clearing device and well-clearing method provided by the present invention can be used for well-clearing, scraping, pressure testing, calculation of obstruction depth, verification of well-clearing depth and other operational needs in oil pipes, and is highly practical. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] The present invention will be further described in detail below with reference to the accompanying drawings.

[0025] Figure 1 It is a structural schematic diagram of a self-floating oil pipe inner well-passing device;

[0026] Figure 2 It is a schematic diagram of the structure of a self-floating tubing salvage device;

[0027] Figure 3 It is a structural schematic diagram of a hollow well gauge.

[0028] Description of reference numerals: 1. Circulation flushing unit; 2. Self-floating tubing inner fishing device; 3. Hollow well gauge; 4. Choke nozzle; 5. Casing; 6. Tubing;

[0029] 11. Channel 1; 12. Channel 2; 13. Channel 3; 14. Channel 4; 15. Circulating flushing device; 111. Switch gate 1; 121. Switch gate 2; 131. Switch gate 3; 141. Switch gate 4; 51. Switch gate 5; 52. Switch gate 6; 201. Guide 1; 202. Floating chamber; 203. Overshot; 301. Overshot head; 302. Water trough; 303. Guide 2. DETAILED DESCRIPTION

[0030] The principles and features of the present invention are described below in conjunction with the accompanying drawings.

[0031] Embodiment 1:

[0032] like Figure 1 As shown, a self-floating tubing well-clearing device is provided, wherein a tubing 6 is sleeved in a casing 5, and the self-floating tubing well-clearing device comprises a circulating flushing unit 1, a self-floating tubing salvage device 2, a hollow well-clearing gauge 3 and a throttle 4. The circulating flushing unit 1 comprises a channel 11, a channel 2 12, a channel 3 13, a channel 4 14 and a circulating flushing device 15. The lower end of the tubing 6 is connected to the throttle 4, the tubing 6 is respectively connected to one end of the channel 1 11 and one end of the channel 3 13, the casing 5 is respectively connected to one end of the channel 2 12 and one end of the channel 4 14, and the other end of the channel 1 11 and the other end of the channel 3 13 are both connected to the circulating flushing device 15; when clearing the well, the tubing 6 is placed inside the hollow well-clearing gauge 3; when the hollow well-clearing gauge 3 encounters resistance in the tubing 6, the self-floating tubing salvage device 2 and the hollow well-clearing gauge 3 are matched and connected.

[0033] Compared with the prior art, the self-floating oil pipe well-clearing device of the present invention has the following advantages:

[0034] Existing technology: During the testing and pumping of oil and gas wells, the phenomenon of test instruments or pumping tools encountering obstructions and jams is increasing, which seriously affects the development of layered testing and pumping. In recent years, the main method is to use the oil pipe to clear the well in the early stage. After technical research and innovation, two technologies have been formed: the conventional diameter gauge clearing pipe on the ground and the wire and cable clearing well in the well. The advantages and disadvantages in the production of oil fields are analyzed as follows:

[0035] The conventional diameter gauge on the ground is used to check the diameter of the oil pipes one by one with a rope or rod on the ground. The advantages are that it has no mature content, low cost, safety and reliability, but the labor intensity of the operators is particularly high, time-consuming and laborious. When the oil pipes are connected and lowered into the well, the torque of the hydraulic clamp on the oil pipe and other reasons may cause the pipe string to deform and shrink in diameter, which cannot be discovered and affects the construction.

[0036] Well clearing with wire rope and cable utilizes wire rope and cable to transport well clearing tools. Its advantages are mature technology and fast well clearing speed, but it requires the installation of a well clearing vehicle, which is costly. In the process of well clearing with wire rope and cable, if the cable gets stuck in the well during the lifting process, it is easy to pull out and break the cable, causing great trouble to the salvage work and easily causing drill jam accidents in the well.

[0037] The present invention realizes well cleaning, scraping and pressure testing in conventional oil pipes of oil and water wells through the combination of a circulating flushing unit 1, a hollow well cleaning gauge 3 and a throttle nozzle 4; the obstruction depth is calculated through the combination of the circulating flushing unit 1, a self-floating oil pipe inner salvage device 2, a hollow well cleaning gauge 3 and a throttle nozzle 4, and both the hollow well cleaning gauge 3 and the self-floating oil pipe inner salvage device 2 float up by buoyancy, without the need for manual transmission; the transmission-free well cleaning is realized, the well cleaning efficiency in the oil pipe is improved, the construction cost and the difficulty of technical field application are reduced, and because there is no transmission wire cable and no manual operation is required, the probability of drilling stuck in the well is zero, and the device is safe and reliable.

[0038] Preferably, the channel 1 11 is provided with a switch gate 1 111, the channel 2 12 is provided with a switch gate 2 121, the channel 3 13 is provided with a switch gate 3 131, the channel 4 14 is provided with a switch gate 4 141, and the oil pipe 5 is provided with a switch gate 5 51 and a switch gate 6 52 in sequence from top to bottom.

[0039] The opening and closing of the channel is controlled by switching gate one 111, switching gate two 121, switching gate three 131, switching gate four 141, switching gate five 51 and switching gate six 52. The structure is simple and the operation is convenient. Specifically, the number of switching gate one 111, switching gate two 121, switching gate three 131, switching gate four 141, switching gate five 51 and switching gate six 52 is selected according to actual needs to meet the use requirements.

[0040] Preferably, the diameter of the throttle nozzle 4 is smaller than the inner diameter of the oil pipe to achieve its throttling effect.

[0041] Embodiment 2:

[0042] On the basis of Example 1, Figure 2 As shown, the self-floating tubing salvage device 2 includes a guide 201, a floating chamber 202 and a salvage tube 203. There are multiple floating chambers 202. The guide 201, multiple floating chambers 202 and salvage tubes 203 are connected in sequence from top to bottom.

[0043] The guide 201 plays a guiding role, and the overshot tube 203 is convenient for connecting to the overshot head 301. The number of floating chambers 202 can be increased to 5 to 10 according to the density of the liquid in the well to meet the use requirements.

[0044] Preferably, the interiors of the guide 201, the floating chamber 202 and the overshot tube 203 are all hollow.

[0045] The hollow structure reduces its own weight, making it easier to float and increasing the floating speed.

[0046] Preferably, the guide 201, the plurality of floating chambers 202 and the overshot tube 203 are sequentially connected by threads from top to bottom.

[0047] The connection and disassembly are convenient, and the number of floating chambers 202 can be increased or decreased as needed, which is convenient to operate.

[0048] Preferably, the top of the guide 201 is V-shaped with the sharp corner of the V facing upward.

[0049] This structure minimizes resistance when floating.

[0050] Preferably, the bottom of the overshot tube 203 is recessed upward, and the recessed portion is connected to the overshot head 301. The structure is simple and the connection is convenient.

[0051] Preferably, the material of the self-floating tubing salvage device 2 is an alloy. Specifically, the lower the density of the alloy, the better. In actual operation, it can be selected according to the needs and meet the use requirements. The specific composition and density are not limited here.

[0052] Embodiment 3:

[0053] On the basis of Example 2, Figure 3 As shown, the hollow well gauge 3 includes a fishing head 301 and a second guide 303, the fishing head 301 and the second guide 303 are connected in sequence from top to bottom, and the fishing head 301 and the overshot tube 203 are matched and connected.

[0054] The fishing head 301 is convenient for connecting to the overshot tube 203, and the guide 2 303 plays a role of stable guidance.

[0055] Preferably, a plurality of water grooves 302 are provided on the outer side of the second guide 303, the plurality of water grooves 302 are circumferentially evenly spaced, and each water groove 302 is provided along the axial direction.

[0056] When moving, water flows through the water channel 302 of the structure, which plays a role in stabilizing the direction.

[0057] Preferably, the lower end of the overshot tube 203 is semi-spherical, so as to reduce the downward resistance.

[0058] Preferably, the middle part of the overshot tube 203 is hollow, which reduces its own weight and facilitates floating and salvaging.

[0059] Preferably, the fishing head 301 is T-shaped for easy clamping.

[0060] Embodiment 4:

[0061] On the basis of Example 3, a well cleaning method of a self-floating oil pipe well cleaning device comprises the following steps:

[0062] S1, open the switch gate 51 and the switch gate 6 52, put the hollow well gauge 3 into the oil pipe 6, and close the switch gate 51;

[0063] S2, open channel 1 11 and channel 4 14, close channel 2 12 and channel 3 13, start the circulating flushing device 15 to pump liquid into the oil pipe, and observe the change of pump pressure;

[0064] Specifically, open the switch gate 111 on the channel 11 and the switch gate 4 141 on the channel 4 14, close the switch gate 2 121 on the channel 2 12 and the switch gate 3 131 on the channel 3 13, and establish a circulation channel from the oil pipe 6 to the casing 5; start the circulation flushing device 15, slowly pump liquid from the oil pipe 6, and observe the change of pump pressure to prevent the pump from getting stuck. During the pumping process, there are two situations in the pump pressure: the pump pressure does not change or the pump pressure suddenly increases.

[0065] S3, when the pump pressure suddenly increases, the hollow well gauge 3 has reached the bottom of the oil pipe 6, and the inner wall of the oil pipe has no shrinkage or deformation; stop the pump, open channel 2 12 and channel 3 13, close channel 1 11 and channel 4 14, and reverse circulation flushes out the hollow well gauge 3 in the oil pipe 6;

[0066] Specifically, a sudden increase in pump pressure indicates that the hollow well gauge 3 encounters an obstruction at the bottom end of the oil pipe 6, and the hollow well gauge 3 has reached the bottom end of the oil pipe 6, without any shrinkage or deformation of the inner wall of the oil pipe 6; stop the pump, open the switch gate 2 121 on the channel 2 12 and the switch gate 3 131 on the channel 3 13, close the switch gate 1 111 on the channel 1 11 and the switch gate 4 141 on the channel 4 14, and reverse circulation is used to flush out the hollow well gauge 3 in the well.

[0067] S4, when the pump pressure does not increase and the amount of liquid pumped in exceeds 1.5 times the internal volume of the oil pipe 6, the hollow well gauge 3 encounters resistance at any position in the middle of the oil pipe 6, and the pump is stopped;

[0068] Specifically, if the pump pressure does not increase, that is, the amount of liquid pumped exceeds 1.5 times the volume of the tubing, it means that the hollow well gauge 3 encounters resistance at any position in the middle of the tubing, indicating that the inner wall of the tubing has a reduced diameter or deformed, and the pump is stopped.

[0069] S5, open channel 11, channel 4 14 and switch gate 5 51, close channel 2 12 and channel 3 13, put the self-floating tubing salvage device 2 into the tubing 6, start the circulating flushing device 15 to pump liquid into the tubing 6, pump the self-floating tubing salvage device 2 downward in the tubing 6, and observe the change of pump pressure; when the amount of liquid pumped in exceeds 1.5 times the inner volume of the tubing 6, stop the pump;

[0070] Specifically, the switch gate 1 111 on the channel 1 1 and the switch gate 4 141 on the channel 4 14 are opened, the switch gate 2 121 on the channel 2 12 and the switch gate 3 131 on the channel 3 13 are closed, a circulation channel from the oil pipe 6 to the casing 5 is established, the switch gate 5 51 is opened, the self-floating oil pipe salvage device 2 is put into the oil pipe, the circulation flushing device 15 is started, the liquid is slowly pumped from the oil pipe 6, the self-floating oil pipe salvage device 2 is pumped downward in the oil pipe 6, and the change in pump pressure is observed. When the amount of liquid pumped in exceeds 1.5 times the inner volume of the oil pipe, the pump is stopped.

[0071] S6. Start timing after closing channel 11 and channel 4 14, and stop timing when the self-floating tubing inner salvage device 2 returns to the ground. Obtain the obstruction depth of the hollow well gauge 3 based on the time and the rising speed.

[0072] After closing the switch gate 111 on the channel 11 and the switch gate 4 141 on the channel 4 14, start timing and stop timing when the salvage device 2 in the floating oil pipe returns to the ground. Calculate the floating length based on the time and the floating speed. This length is the obstruction depth of the tool. It is recommended to use this method for wells with an obstruction depth error within ±20 meters.

[0073] Embodiment 5:

[0074] For a well where circulation cannot be established, that is, the oil pipe 6 and the casing 5 cannot circulate, at this time, the self-floating tubing salvage device 2 should be connected to the hollow well gauge 3 on the ground, the switch gate 5 51 and the switch gate 6 52 should be opened, the circulation flushing device 15 should be turned on, and liquid should be slowly pumped from the oil pipe 6 to pump the self-floating tubing salvage device 2 down in the oil pipe 6, and the pump pressure change should be observed. If the pump pressure suddenly increases, it means that the hollow well gauge 3 encounters resistance at the bottom end of the oil pipe 6, the hollow well gauge 3 has reached the bottom end of the oil pipe 6, and the inner wall of the oil pipe 6 has no shrinkage or deformation. Stop the pump and wait for the self-floating tubing salvage device 2 and the hollow well gauge 3 to return to the ground. The amount of liquid pumped in exceeds 1.2 times the volume of the oil pipe, and the pump pressure does not change. The pump should be stopped, timing should be started, and the depth of resistance should be calculated when the salvage device returns to the ground.

[0075] Embodiment 6:

[0076] For the well passing in the above oil pipe 6, the hollow well passing gauge 3 can pass to the well that encounters resistance at the bottom of the oil pipe 6, and can slowly pressurize to test the seal inside the oil pipe. The pressure test method adopts the conventional pressure test method.

[0077] In May 2023, this achievement was successfully tested for the first time in Ansai Oilfield. The circulation equipment after the fracturing operation was used to circulate the well to a depth of 3068 meters in the oil pipeline. The oil pipeline was also pressure tested, reducing the construction process and providing an early verification for the smooth progress of the next pumping operation.

[0078] When this achievement was tested in a well in Ansai Oilfield, 6 self-floating tubing salvors 2 were installed to pump and salvage the hollow well gauge in the well. The rising speed was 300 meters per minute and the process lasted 450 seconds. The theoretical well depth was 2250 meters. After drilling to verify, the actual obstruction depth was 2238 meters, which was within the allowable error range.

[0079] In the description of the present invention, it needs to be understood that if there are terms such as "upper", "lower", "right", etc., the orientation or position relationship indicated is based on the orientation or position relationship shown in the drawings, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation. Therefore, the terms describing the position relationship in the drawings are only used for illustrative purposes and cannot be understood as a limitation on the present invention.

[0080] The above examples are merely illustrative of the present invention and do not constitute a limitation on the protection scope of the present invention. All designs that are the same or similar to the present invention fall within the protection scope of the present invention.

Claims

1. A self-floating oil pipe well-passing device, wherein the casing (5) is sleeved with an oil pipe (6), Features: The self-floating tubing well-clearing device comprises a circulating flushing unit (1), a self-floating tubing salvage device (2), a hollow well-clearing gauge (3) and a throttle (4). The circulating flushing unit (1) comprises a channel one (11), a channel two (12), a channel three (13), a channel four (14) and a circulating flushing device (15). The lower end of the tubing (6) is connected to the throttle (4). The tubing (6) is respectively connected to one end of the channel one (11) and one end of the channel three (13). The casing (5) is respectively connected to one end of the channel two (12) and one end of the channel four (14). The other end of the channel one (11) and the other end of the channel three (13) are both connected to the circulating flushing device (15). When clearing the well, the tubing (6) is placed inside the hollow well-clearing gauge (3). When the hollow well-clearing gauge (3) encounters resistance in the tubing (6), the self-floating tubing salvage device (2) and the hollow well-clearing gauge (3) are matched and connected.

2. The self-floating oil pipe well-clearing device according to claim 1, Features: The channel one (11) is provided with a switch gate one (111), the channel two (12) is provided with a switch gate two (121), the channel three (13) is provided with a switch gate three (131), the channel four (14) is provided with a switch gate four (141), and the oil pipe (5) is provided with a switch gate five (51) and a switch gate six (52) in turn from top to bottom.

3. The self-floating oil pipe well-passing device according to claim 1, Features: The diameter of the throttle nozzle (4) is smaller than the inner diameter of the oil pipe.

4. The self-floating oil pipe well-clearing device according to claim 1, Features: The self-floating tubing salvage device (2) comprises a guide device (201), a floating chamber (202) and a salvage tube (203). There are multiple floating chambers (202). The guide device (201), multiple floating chambers (202) and salvage tubes (203) are connected in sequence from top to bottom.

5. The self-floating oil pipe well-clearing device according to claim 4, Features: The interiors of the guide 1 (201), the floating chamber (202) and the overshot tube (203) are all hollow.

6. The self-floating oil pipe well-clearing device according to claim 5, Features: The guide device 1 (201), the plurality of floating chambers (202) and the overshot tube (203) are connected in sequence from top to bottom through threads.

7. The self-floating oil pipe well-clearing device according to claim 6, Features: The top of the guide 1 (201) is V-shaped with the sharp corner of the V facing upward.

8. The self-floating oil pipe well-passing device according to claim 5, Features: The hollow well gauge (3) comprises a fishing head (301) and a second guide (303), the fishing head (301) and the second guide (303) are connected in sequence from top to bottom, and the fishing head (301) and the fishing tube (203) are matched and connected.

9. The self-floating oil pipe well-clearing device according to claim 8, Features: A plurality of water passage grooves (302) are provided on the outer side of the second guide (303), the plurality of water passage grooves (302) are distributed at equal intervals in the circumferential direction, and each water passage groove (302) is provided along the axial direction.

10. A well cleaning method for a self-floating well cleaning device in an oil pipe, Features: The steps include: S1, open the switch gate five (51) and the switch gate six (52), put the hollow well gauge (3) into the oil pipe (6), and close the switch gate five (51); S2, open channel 1 (11) and channel 4 (14), close channel 2 (12) and channel 3 (13), start the circulating flushing device (15) to pump liquid into the oil pipe, and observe the change of pump pressure; S3, when the pump pressure suddenly increases, the hollow well gauge (3) has reached the bottom of the oil pipe (6), and the inner wall of the oil pipe has no shrinkage or deformation; stop the pump, open channel two (12) and channel three (13), close channel one (11) and channel four (14), and reversely circulate to flush out the hollow well gauge (3) in the oil pipe (6); S4. When the pump pressure does not increase and the amount of liquid pumped in exceeds 1.5 times the internal volume of the oil pipe (6), the hollow well gauge (3) encounters obstruction at any position in the middle of the oil pipe (6) and the pump is stopped; S5, opening channel 1 (11), channel 4 (14) and switch gate 5 (51), closing channel 2 (12) and channel 3 (13), dropping the self-floating tubing salvage device (2) into the tubing (6), starting the circulating flushing device (15) to pump liquid into the tubing (6), pumping the self-floating tubing salvage device (2) downward in the tubing (6), and observing the change in pump pressure; when the amount of liquid pumped in exceeds 1.5 times the internal volume of the tubing (6), stopping the pump; S6. After closing the channel 1 (11) and the channel 4 (14), start timing, and stop timing when the floating tubing inner salvage device (2) returns to the surface. According to the time and the rising speed, obtain the obstruction depth of the hollow well gauge (3).

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