A downhole oil well retractable tool

Abstract

The utility model discloses a kind of petroleum downhole telescopic action tools, it is related to oil and gas well exploitation equipment manufacturing technical field, including power unit, transmission unit and telescopic lead screw unit connected in turn, the power unit includes control panel shell and motor shell, the control panel shell one end and motor shell end portion are threadedly connected;The control panel shell inside is with chamber, control panel is fixed in chamber, the motor is built-in in the motor shell;The other end of control panel shell is equipped with the adapter for and the connection of external tool, to pass through external tool for control panel transmission signal and power supply;The plug-in connection of sealed plug and sealed socket between the control panel and motor, to for the motor transmission signal and power supply.Using this scheme, built-in control panel is changed into external control panel, to facilitate the heat dissipation of high-power motor in harsh environment, and can be realized convenient maintenance by quick disassembly.

Description

Technical Field

[0001] This utility model relates to the field of oil and gas well extraction equipment manufacturing technology, specifically to a downhole telescopic tool for oil wells. Background Technology

[0002] In oil exploration and development, it is necessary to isolate oil, gas and water layers in the casing well. Through layered oil testing, gas testing and fracturing, test data and fluid properties of each layer are obtained to more accurately evaluate or fracture and transform oil and gas reservoirs.

[0003] Bridge plugs are indispensable downhole sealing tools in oil and gas development. There are several setting methods, with hydraulically driven bridge plug setting tools and explosively driven bridge plug setting tools being the most commonly used. The former is suitable for tubing and coiled tubing delivery, while the latter is mainly suitable for cable-driven or coiled tubing delivery. Hydraulic setting requires tubing, resulting in high efficiency and cost. Explosively driven setting, using cable delivery, is limited by the need for pyrotechnic components, and its transportation, storage, and operation are subject to strict legal regulations, making it less flexible.

[0004] To address the aforementioned issues, an invention patent with publication number CN120719950A, entitled "A Motor-Driven Bridge Plug Setting Tool," is disclosed in existing literature. This tool uses a motor to rotate, which drives a reducer to rotate. The reducer outputs rotational power to rotate a transmission screw, which in turn pulls the transmission pipe thread upward. The transmission pipe then pulls the bridge plug center rod upward to complete the setting and release of the bridge plug.

[0005] However, in the above-mentioned scheme, since oilfield wells are often in harsh environments such as high temperature, dust, humidity or corrosion, if the motor control board is placed inside the motor, it will not only increase the size of the motor, but also hinder heat dissipation under high temperature conditions when the motor is at high power, and it will also be inconvenient to disassemble and maintain. Utility Model Content

[0006] To address the shortcomings of existing technologies, this utility model aims to provide a telescopic movement tool for oil wells. By adopting this solution, the control board is changed from being built-in to being external, which facilitates heat dissipation of the high-power motor in harsh environments and enables convenient maintenance through quick disassembly.

[0007] This utility model is achieved through the following technical solution:

[0008] A downhole telescopic tool for oil wells includes a power unit, a transmission unit, and a telescopic screw unit connected in sequence. The power unit includes a control plate housing and a motor housing, with one end of the control plate housing and the end of the motor housing threadedly connected.

[0009] The control board housing has an internal cavity in which the control board is fixed. The motor housing contains a motor. The other end of the control board housing is provided with an adapter for connecting to external tools, so that the external tools can transmit signals and supply power to the control board.

[0010] The control board and the motor are connected by a plug-in connection of sealed pins and sealed sockets to transmit signals and supply power to the motor.

[0011] Compared to existing technologies where placing the motor control board inside the motor in harsh environments increases the motor's size and hinders heat dissipation under high-temperature conditions, especially with high-power motors, and also makes disassembly and maintenance difficult, this invention provides a telescopic motion tool for oil wells. This solution replaces the internal control board with an external one, improving heat dissipation for high-power motors in harsh environments and enabling convenient maintenance through quick disassembly. Specifically, the telescopic motion tool includes a power unit, a gearbox unit, and a telescopic screw unit connected sequentially from top to bottom. The power unit, serving as the power output, includes a control board housing and a motor housing connected sequentially from top to bottom, protecting the control board and motor respectively. This separate placement of the control board and motor facilitates heat dissipation within their respective chambers, and the control board and motor can be inspected and maintained separately by disassembling them using threads. An adapter is connected to the upper end of the control board housing. The adapter is used to connect with external tools, such as cable heads, to transmit signals and provide power to the control board. The control board is connected to the sealed pins on the motor through a sealed socket to achieve signal transmission and power supply through a plug-in connection. The adapter and plug-in connection method are existing technologies and will not be described in detail here.

[0012] To achieve a detachable connection for the adapter, the other end of the control board housing has a threaded groove, and the adapter and the threaded groove are connected by threads; the adapter axis has a spring contact assembly, and the two ends of the spring contact assembly have axially telescopic contacts, which are interconnected.

[0013] The contacts at the end of the adapter furthest from the control panel housing are used to connect to external tools, and the contacts of the adapter located in the threaded groove are used to contact the conductive plate at the bottom of the threaded groove to transmit signals and power.

[0014] To further optimize the system and protect the control board by sealing it inside, a support bracket protective shell is also coaxially provided inside the cavity. The control board is located inside the support bracket protective shell and is connected to the support bracket and the inner side of the support bracket protective shell.

[0015] The support bracket protective shell has an upper end cover and a lower end cover at both ends respectively. The upper end cover has a mating groove on the side facing the adapter, and the conductive sheet is fixed in the mating groove. The bottom of the threaded groove is open and is used for the contact to pass through and extend into the conductive sheet in the mating groove.

[0016] To further optimize the design and prevent the conductive sheet from retracting, a conductive sheet retaining ring is provided circumferentially inside the docking groove. The conductive sheet retaining ring is used to hold the conductive sheet at its periphery.

[0017] To achieve further optimization and grounding, a grounding conductive ring is coaxially arranged around the end of the support frame protective shell facing the motor. The grounding conductive ring is connected to the support frame protective shell through a grounding screw. The ground wire in the control board is connected to and tightened with the grounding screw.

[0018] Further optimizations include providing vibration damping for the control board. The support frame protective shell has a lower connector at the end facing the motor, and the sealing socket is embedded at the end of the lower connector facing the motor. The motor end has an upper connector, and the upper connector end has a sealing pin embedded in it. The lower connector end and the space between the lower connector and the upper connector are filled with vibration damping pads.

[0019] For further optimization, to facilitate assembly with the reducer unit, the motor housing has an axial through hole at the end away from the control board housing, and the rotating shaft of the motor extends into the through hole;

[0020] A motor coupling is fitted onto the rotating shaft of the motor, and a support spring is also provided in the through hole. The support spring is used to provide thrust to the motor coupling so that the end of the motor coupling away from the motor extends out of the motor housing.

[0021] Further optimization is made to achieve a reduction ratio of over 2000 to generate a pulling force of over 30 tons, thereby driving the bridge piston to set, or providing a large-tonnage thrust or pull force to a jammed tool string to disengage it from the jamming point and achieve unblocking. The transmission unit includes an internal gear ring and an intermediate joint. One end of the internal gear ring is threaded to the end of the motor housing, and the other end of the internal gear ring is threaded to the end of the intermediate joint.

[0022] The internal gear ring has a built-in reduction assembly, which includes a multi-stage planetary gear pair connected in series.

[0023] The rotating shaft of the motor is connected to the input shaft of the reduction gear assembly via a motor coupling.

[0024] To further optimize the rotational motion into a telescopic motion, the telescopic screw unit includes a guide housing and a push cylinder. One end of the guide housing is threadedly connected to the intermediate joint of the transmission unit, and the other end of the guide housing is threadedly connected to the end of the push cylinder.

[0025] A lead screw is rotatably connected coaxially inside the guide housing, and one end of the lead screw is connected to the output shaft of the transmission unit through a lead screw coupling;

[0026] The guide housing is also coaxially provided with a push rod, which is slidably connected to the inner side of the guide housing and can slide along the axial direction of the guide housing;

[0027] One end of the push rod is coaxially equipped with a deep threaded groove, and the other end of the push rod extends out of the push cylinder away from the guide housing; the other end of the lead screw extends into the deep threaded groove and is threadedly connected.

[0028] To further optimize the sealing process and remove oil stains from the surface of the push rod during retraction, the upper end of the push cylinder has a reduced diameter section. The reduced diameter section and the push rod are slidably connected. At least one set of sliding sealing rings and scraper sealing rings are provided between the inner wall of the reduced diameter section and the outer wall of the push rod. The scraper sealing ring is located at the end of the reduced diameter section away from the lead screw.

[0029] Compared with the prior art, this utility model has the following advantages and beneficial effects:

[0030] 1. This utility model provides a telescopic movement tool for oil wells. By adopting this solution, the control board is changed from being built-in to being external, which facilitates heat dissipation of the high-power motor in harsh environments and enables convenient maintenance through quick disassembly.

[0031] 2. This utility model provides a telescopic action tool for oil wells. Through the coordinated action of surface power supply and downhole motor, multi-stage planetary gearbox and lead screw, it can generate a pushing and pulling force of more than 30 tons downhole. It can be used for actions such as pipe string retrieval and packer setting downhole. This invention is simple to operate, has low cost per operation, and is intelligent and controllable.

[0032] 3. This utility model provides a downhole telescopic tool for oil wells, equipped with two sets of sliding sealing rings and one set of scraper sealing rings. The sliding sealing rings bear the downhole fluid pressure, and the scraper sealing rings remove oil stains from the surface of the push rod when it retracts, protecting the sliding sealing rings from being scratched and rendered ineffective by mud and sand in the well fluid. Attached Figure Description

[0033] The accompanying drawings, which are included to provide a further understanding of the embodiments of the present invention and form part of this application, do not constitute a limitation thereof. In the drawings:

[0034] Figure 1 A schematic diagram of the structure of the oil well downhole telescopic tool provided by this utility model;

[0035] Figure 2 A schematic diagram of the power unit provided by this utility model;

[0036] Figure 3 A schematic diagram of the structure of the transmission unit provided by this utility model;

[0037] Figure 4 This is a schematic diagram of the telescopic lead screw unit provided by this utility model.

[0038] The attached diagram shows the markings and corresponding component names:

[0039] 1-Power unit; 101-Control board housing; 102-Motor housing; 103-Adapter; 104-Adapter sealing ring; 105-Control board housing sealing ring; 106-Spring contact assembly; 107-Conductive sheet retaining ring; 108-Conductive sheet; 109-Upper end cover; 110-End cover fastening screw; 111-Support bracket protective shell; 112-Control board; 113-Control board fastening screw; 114-Support bracket fastening screw. 115-Support bracket, 116-Lower end cover, 117-Lower end cover fastening screw, 118-Grounding conductive ring, 119-Grounding screw, 120-Shock damping pad, 121-Sealed socket, 122-Socket / pin locking ring, 123-Upper connector, 124-Sealed pin, 125-Motor shock damping pad, 126-Housing sealing ring, 127-Motor, 128-Motor locking screw, 129-Support spring, 130-Motor coupling;

[0040] 2-Transmission unit, 201-Internal gear ring, 202-Intermediate joint, 203-Input shaft, 204-Reduction assembly, 205-Output shaft;

[0041] 3-Telescopic screw unit, 301-Guide housing, 302-Push cylinder, 303-Screw coupling, 304-Locking ring, 305-Screw rod, 306-Pressure ring, 307-Thrust bearing, 308-Push rod, 309-Sliding seal ring, 310-Scraper rod seal ring. Detailed Implementation

[0042] To make the objectives, technical solutions, and advantages of this utility model clearer, the present utility model will be further described in detail below with reference to the embodiments and accompanying drawings. The illustrative embodiments and descriptions of this utility model are only used to explain this utility model and are not intended to limit this utility model.

[0043] Example 1: This Example 1 provides a downhole telescopic tool for oil wells, such as... Figures 1-2As shown, it mainly includes a power unit 1, a transmission unit 2, and a telescopic lead screw unit 3. The specific structure of the power unit 1 is as follows:

[0044] The power unit 1 includes a control board housing 101, a motor housing 102, an adapter 103, an adapter sealing ring 104, a control board housing sealing ring 105, a spring contact assembly 106, a conductive sheet retaining ring 107, a conductive sheet 108, an upper end cover 109, an end cover fastening screw 110, a support bracket protective shell 111, a control board 112, a control board fastening screw 113, a support bracket fastening screw 114, a support bracket 115, a lower end cover 116, a lower end cover fastening screw 117, a grounding conductive ring 118, a grounding screw 119, a shock-absorbing pad 120, a sealing socket 121, a socket / pin locking ring 122, an upper connector 123, a sealing pin 124, a motor shock-absorbing ring 125, a housing sealing ring 126, a motor 127, a motor locking screw 128, a support spring 129, and a motor coupling 130.

[0045] The control panel housing 101 is threadedly connected to the motor housing 102, and together with the housing sealing ring 126, it withstands the downhole fluid pressure and protects the internal components of the power unit 1.

[0046] The adapter 103 is threadedly connected to the control board housing 101, and the internal structure is sealed by the control board housing sealing ring 105 and the spring contact assembly 106.

[0047] The contacts at both ends of the spring contact assembly 106 can be freely compressed and retracted. The left contact is connected to the upper tool (such as a cable head), and the right contact is connected to the conductive sheet 108. The two contacts are connected, and signals and power can be transmitted left and right.

[0048] The conductive sheet retaining ring 107 is located on the upper end cover 109 to limit the conductive sheet 108 and prevent it from coming out; the upper end cover 109 and the support bracket protective shell 111 are connected by the end cover fastening screw 110; the control board 112 and the support bracket 115 are connected by the control board fastening screw 113; the support bracket 115 and the support bracket protective shell 111 are connected by the support bracket fastening screw 114; the lower end cover 116 and the support bracket protective shell 111 are connected by the lower end cover fastening screw 117.

[0049] The grounding conductive ring 118 is connected to the support bracket protective shell 111 by a grounding screw 119. The ground wire in the control board 112 is connected to the grounding screw 119 and pressed tightly to achieve grounding.

[0050] The shock-absorbing pad 120 is nested with the support frame protective shell 111 and is made of soft material to provide shock absorption for the control board; the sealing socket 121 is nested with the support frame protective shell 111 and is secured by the socket / pin locking ring 122; the sealing pin 124 is nested with the motor upper connector 123 and is secured by the socket / pin locking ring 122; the sealing socket 121 and the sealing pin 124 are matched and inserted to realize the conduction of multi-core signal power lines inside, connecting the power supply and signal lines of the control board 112 and the motor 127.

[0051] The motor 127 is located inside the motor housing 102 and is fastened by the motor locking screw 127. The left and right ends are provided with motor shock absorber rings 125 to provide shock absorption protection. The motor 127 is a high-temperature brushless motor.

[0052] The motor coupling 130 is fitted with the rotating shaft of the motor 127, and a support spring 129 is provided in the middle. The outer side of the motor coupling 130 has a limit ring. One end of the support spring 129 is connected to the limit ring, and the other end is connected to the housing of the motor 127. When the support spring 129 is in the free state, the motor coupling 130 is pushed out of the motor housing 102 by the support spring 129, which facilitates the alignment and assembly with the gearbox unit 2. After assembly, the spring is compressed, and the motor coupling 130 and the output shaft of the motor 127 have increased mating surfaces, so as to achieve stable torque transmission.

[0053] In the above structure, the left end of the power unit 1 is connected to the cable (cable motor), while the other end of the cable is connected to the controller and power supply of this solution. The cable core is connected to the copper contact on the left end of the spring contact assembly 106, enabling signal and power supply conduction between the cable and this solution. The copper contact has a built-in spring, which is compressed after assembly to ensure reliable contact between the contacts. The adapter sealing ring 104 cooperates with the cable motor to isolate the downhole fluid pressure. The right end of the spring contact assembly 106 is in contact with the conductive plate 108, which is connected to the control board 112 by a wire. The signals and power supply from the well are transmitted to the control board 112 through the cable, the spring contact assembly 106, and the conductive plate 108.

[0054] The sealed socket 121 is connected to the control board 112 by a wire, and the sealed pin 124 is connected to the motor 127 by a wire. The sealed socket 121 and the sealed pin 124 are multi-core sockets / pins that cooperate with each other, making them easy to assemble and disassemble. The upper cover 109, the shock-absorbing pad 120, and the motor shock-absorbing ring 125 are all made of flexible materials to provide shock absorption protection for the control board 112 and the motor 127.

[0055] The speed of motor 127 can be freely controlled by control board 112, and the output torque exceeds 1 N·m.

[0056] In summary, the left end of the power unit 1 is connected to the upper device (such as the cable motor head), while the right end is connected to the gearbox unit 2, so as to receive signals and power supply from the well, control the motor 127 to rotate as needed, and provide a shock-absorbing and pressure-bearing environment for the control board 112 and the motor 127.

[0057] Example 2: This Example 2 is a further optimization based on Example 1, providing a specific structure for the transmission unit 2, such as... Figure 3 As shown.

[0058] The transmission unit 2 includes an internal gear ring 201, an intermediate joint 202, an input shaft 203, a reduction assembly 204, and an output shaft 205.

[0059] The internal gear ring 201 is threadedly connected to the intermediate joint 202 and works together with the housing sealing ring 126 to withstand the downhole fluid pressure and protect the internal components of the gearbox unit 2.

[0060] The reduction assembly 204 includes a planetary gear pair with multiple reduction stages connected in series to achieve speed reduction through successively decreasing gear reduction ratios. This is the existing reducer structure and will not be described in detail here. The reduction ratio of the transmission unit 2 exceeds 2000. Considering the efficiency loss of the multi-stage planetary gear set, the transmission unit 2 can amplify the 1 N.m torque output by the motor 127 to more than 1000 N.m.

[0061] In summary, the left end of the transmission unit 2 is threaded to the power unit 1, and the right end is threaded to the lead screw unit 3, which transforms the high-speed, low-torque output of the power unit 1 into a low-speed, high-torque output. The internal gear ring 201 serves as both a pressure-bearing housing and the internal gear of the planetary gear pair, maximizing the use of internal space and ensuring structural strength.

[0062] Example 3: This Example 3 is a further optimization based on Example 2, providing a specific structure for a telescopic lead screw unit, such as... Figure 4 As shown.

[0063] The telescopic lead screw unit 3 includes a guide housing 301, a push cylinder 302, a lead screw coupling 303, a locking ring 304, a lead screw 305, a pressure ring 306, a thrust bearing 307, a push rod 308, a sliding seal ring 309, and a scraper seal ring 310.

[0064] The guide housing 301 is threadedly connected to the push cylinder 302 and works together with the housing sealing ring 126 to withstand the downhole fluid pressure and protect the internal components of the lead screw unit 3.

[0065] The left end of the lead screw coupling 303 is connected to the output shaft 205, and the right end is connected to the lead screw 305, so as to transmit the torque output by the output shaft 205 to the lead screw 305.

[0066] The left end of the lead screw 305 is sequentially fitted with a pressure ring 306, a thrust bearing 307, and another pressure ring 306, and secured with a locking ring 304 before being installed into the guide housing 301. The right end of the lead screw 305 is threadedly engaged with the push rod 308.

[0067] The outer surface of the push rod 308 has two sets of symmetrical protruding flat keys, which cooperate with the keyway in the guide housing 301. After the lead screw 305 rotates, the push rod 308 will move left and right along the axis due to the limit of the flat keys.

[0068] The pusher cylinder 302 is equipped with three sets of sealing grooves, two sets of sliding sealing rings 309, and one set of scraper sealing ring 310. The sliding sealing ring 309 bears the downhole fluid pressure, while the scraper sealing ring 310 removes oil stains from the surface of the pusher rod 308 when it retracts, and protects the sliding seal 309 from being scratched and failing by mud and sand in the well fluid.

[0069] In the above scheme, the telescopic screw unit 3 adjusts the rotational motion into linear motion through the screw 305 and push rod 308. The thread helix angle of the screw 305 and push rod 308 is <6°, ensuring that when the push rod 308 is subjected to axial external force (such as well fluid pressure), the screw 305 will not be rotated under force (i.e., the screw structure is self-locking), thereby protecting the upper transmission unit 2 and the motor 127.

[0070] Two sets of pressure-bearing rings 306 and thrust bearings 307 provide reverse support force for the lead screw 305 and push rod 308, ensuring that while outputting a push-pull force of over 30 tons, this design does not generate significant internal frictional resistance. The thread length of the lead screw 305 and push rod 308 exceeds 200mm, ensuring that the pressure on the thread working surface is less than 200MPa when outputting a push-pull force of over 30 tons, thus improving the service life of the telescopic lead screw unit 3.

[0071] The left end of the lead screw unit 3 is connected to the transmission unit 2, which converts the rotational motion output by the transmission unit 2 into linear motion, thereby realizing the downhole telescopic action.

[0072] In summary, the power unit 1, transmission unit 2, and telescopic screw unit 3 in this solution are connected in sequence to form a downhole telescopic motion tool for oil wells. The cable hoists the tool down to the designated position, and the power supply above ground drives the tool motor to rotate. By collecting the current, voltage, and speed of the downhole motor, the displacement and operation status of the tool are determined. After the operation is completed, the tool is retrieved, the motor is reversed, and the tool is returned to its original position. The operation process is simple, and the tool can be lowered into the well for operation without maintenance.

[0073] The specific embodiments described above further illustrate the purpose, technical solution, and beneficial effects of this utility model. It should be understood that the above description is only a specific embodiment of this utility model and is not intended to limit the scope of protection of this utility model. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this utility model should be included within the scope of protection of this utility model.

Claims

1. A telescopic actuation tool for oil wells, comprising a power unit (1), a transmission unit (2), and a telescopic screw unit (3) connected in sequence, characterized in that: The power unit (1) includes a control board housing (101) and a motor housing (102), with one end of the control board housing (101) and the end of the motor housing (102) being threadedly connected. The control board housing (101) has a cavity inside, and a control board (112) is fixed inside the cavity. The motor housing (102) has a motor (127) inside. The other end of the control board housing (101) is provided with an adapter (103) for connecting with external tools, so as to transmit signals and supply power to the control board (112) through external tools. The control board (112) and the motor (127) are connected by a plug-in connection of a sealed pin (124) and a sealed socket (121) to transmit signals and supply power to the motor (127).

2. The oil well downhole telescopic tool according to claim 1, characterized in that, The control panel housing (101) has a threaded groove at the other end, and the adapter (103) is connected to the threaded groove by a thread; the adapter (103) has a spring contact assembly (106) on its axis, and the two ends of the spring contact assembly (106) have axially telescopic contacts, and the two contacts are interconnected. The contacts of the adapter (103) at the end away from the control panel housing (101) are used to connect with external tools. The contacts of the adapter (103) located in the threaded groove are used to contact the conductive sheet (108) at the bottom of the threaded groove to transmit signals and power.

3. The oil well downhole telescopic tool according to claim 2, characterized in that, The cavity is also coaxially provided with a support frame protective shell (111), and the control board (112) is located inside the support frame protective shell (111) and is connected to the inner side of the support frame protective shell (111) through the support frame (115); The support bracket protective shell (111) has an upper end cover (109) and a lower end cover (116) respectively closed at both ends. The upper end cover (109) has a mating groove on the side facing the adapter (103). The conductive sheet (108) is fixed in the mating groove. The bottom of the threaded groove is open and is used for the contact to pass through and extend into the conductive sheet (108) in the mating groove.

4. The oil well downhole telescopic tool according to claim 3, characterized in that, The inner circumferential groove of the docking groove is equipped with a conductive sheet retaining ring (107), which is used to abut against the periphery of the conductive sheet (108).

5. The oil well downhole telescopic tool according to claim 3, characterized in that, The support frame protective shell (111) has a grounding conductive ring (118) coaxially arranged at one end facing the motor (127). The grounding conductive ring (118) is connected to the support frame protective shell (111) through a grounding screw (119). The ground wire in the control board (112) is connected to the grounding screw (119) and pressed tightly.

6. The oil well downhole telescopic tool according to claim 3, characterized in that, The support frame protective shell (111) has a lower connector at the end facing the motor (127), and the sealing socket (121) is embedded at the end of the lower connector facing the motor (127); the motor (127) has an upper connector (123) at the end, and the upper connector (123) has a sealing pin (124) embedded at the end; the lower connector end and the space between the lower connector and the upper connector (123) are filled with shock-absorbing pads (120).

7. A downhole telescopic tool for oil wells according to any one of claims 1 to 6, characterized in that, The motor housing (102) has an axial through hole at one end away from the control board housing (101), and the rotating shaft of the motor (127) extends into the through hole; A motor coupling (130) is fitted on the rotating shaft of the motor (127), and a support spring (129) is also provided in the through hole. The support spring (129) is used to provide thrust to the motor coupling (130) so that the end of the motor coupling (130) away from the motor (127) extends out of the motor housing (102).

8. A downhole telescopic tool for oil wells according to any one of claims 1 to 6, characterized in that, The transmission unit (2) includes an internal gear ring (201) and an intermediate joint (202). One end of the internal gear ring (201) is threaded to the end of the motor housing (102), and the other end of the internal gear ring (201) is threaded to the end of the intermediate joint (202). The internal gear ring (201) has a built-in reduction assembly (204), which includes a multi-stage planetary gear pair connected in series. The rotating shaft of the motor (127) is connected to the input shaft (203) of the reduction assembly (204) via a motor coupling (130).

9. A downhole telescopic tool for oil wells according to any one of claims 1 to 6, characterized in that, The telescopic lead screw unit (3) includes a guide housing (301) and a push cylinder (302). One end of the guide housing (301) is threadedly connected to the intermediate joint (202) of the transmission unit (2), and the other end of the guide housing (301) is threadedly connected to the end of the push cylinder (302). The guide housing (301) is coaxially rotatably connected to a lead screw (305), and one end of the lead screw (305) is connected to the output shaft (205) of the transmission unit (2) through a lead screw coupling (303); The guide housing (301) is also coaxially provided with a push rod (308), which is slidably connected to the inner side of the guide housing (301) and can slide along the axial direction of the guide housing (301); One end of the push rod (308) is coaxially equipped with a deep threaded groove, and the other end of the push rod (308) extends out of the push cylinder (302) away from the guide housing (301); the other end of the lead screw (305) extends into the deep threaded groove and is threadedly connected.

10. A downhole telescopic tool for oil wells according to claim 9, characterized in that, The upper end of the push cylinder (302) has a reduced diameter section, which is slidably connected to the push rod (308). At least one set of sliding sealing rings (309) and scraper sealing rings (310) are provided between the inner wall of the reduced diameter section and the outer wall of the push rod (308). The scraper sealing ring (310) is located at the end of the reduced diameter section away from the lead screw (305).

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