CN106286440B - A kind of control system of the telescopic downhole tractor based on hydraulic control - Google Patents

Abstract

The invention relates to a control system of a telescopic downhole tractor based on hydraulic control, which belongs to the field of petroleum and natural gas development equipment. The control system of a hydraulically driven downhole tractor includes a fuel tank nipple, a motor, a reducer, a hydraulic pump and a valve assembly , the motor is powered by the ground through a cable, the motor is connected to the reducer, the reducer is connected to the hydraulic pump, and the hydraulic pump is connected to the valve group, wherein the liquid outlet of the hydraulic pump is connected to the hydraulically controlled two-position four-way reversing valve. The advantages of the present invention are: the telescopic crawling of the tractor is realized through the hydraulic control system; the control system of the telescopic downhole tractor has its own hydraulic station, which does not need to supply hydraulic oil on the ground; the hydraulic control valve is used to effectively improve the efficiency of the control system; the traction process is controlled It can ensure the normal operation of the mud circulation system; it can be applied to horizontal well logging and equipment transportation, as well as traction control operations for slim hole wells.

Description

A control system of telescopic downhole tractor based on hydraulic control

technical field

The invention relates to the field of oil and gas development equipment, in particular to a control system of a telescopic downhole tractor based on hydraulic control.

Background technique

The so-called horizontal well refers to a directional well in which the wellbore continues to extend for a certain length after the wellbore trajectory reaches the level. "Reaching the level" means that the inclination angle reaches about 90°, not strictly 90°. "Extending a certain length" generally means extending in the oil layer, and the extension length is greater than six times the thickness of the oil layer. According to research, horizontal wells have economic value only when the length of the reservoir extension is greater than six times the thickness of the reservoir. The main factor limiting the length of the horizontal section is that the borehole friction increases with the extension of the horizontal section, making it difficult to run the tools in the horizontal section.

At present, horizontal wells, directional wells and extended-reach wells are widely used at home and abroad to explore and develop deep, deep-sea and complex oil and gas resources. The two major problems of logging and instrument delivery in the application of horizontal wells have gradually become the technical key to oil and gas field development and oil and gas storage and transportation: 1. Well logging: how to transport logging tools and instruments down the horizontal well to realize the monitoring of the working status of the horizontal well, When the logging tool enters the horizontal well, how to ensure good coaxiality between the logging tool and the horizontal well; 2. Instrument transportation: how to complete various downhole construction operations, the logging tool must overcome the difficulty of lowering caused by borehole bending , including the flexibility of the instrument and the increase in resistance.

Therefore, the oil industry urgently needs a coiled tubing tractor that can carry out tool transportation, downhole monitoring and construction operations in horizontal wells, directional wells and extended-reach wells, and requires the tractor to have a simple structure, a wide range of adaptable calibers, large traction force and automation. high-level features. After investigation, it was found that the existing domestic coiled tubing tractors could hardly meet the above work requirements. Therefore, the development of hydraulically controlled telescopic downhole tractor has important significance.

Contents of the invention

The purpose of the present invention is to overcome the shortcomings of the prior art, to provide a control system based on hydraulic control of the telescopic downhole tractor, to realize the crawling of the downhole tractor through the hydraulic control system; the telescopic downhole tractor control system has its own hydraulic station , no need to supply hydraulic oil on the ground; the use of hydraulic control valves effectively improves the efficiency of the control system; the normal operation of the mud circulation system can be guaranteed during the traction control process, and it can provide large traction force; it is suitable for horizontal well logging and equipment transportation and slim boreholes Well traction control operations.

The purpose of the present invention is achieved through the following technical solutions: a control system based on a hydraulically controlled telescopic downhole tractor, including a fuel tank, a hydraulic pump, a hydraulically controlled two-position four-way reversing valve, a rear support arm and a front support arm, The inlet of the hydraulic pump is connected to the oil tank. When the hydraulic control two-position four-way reversing valve is in the left position, the first inlet of the hydraulic control two-position four-way reversing valve is connected to the outlet of the hydraulic pump, and the hydraulic control two-position four-way reversing valve The first outlet of the valve is respectively connected to the inlet of one-way sequence valve A and the inlet of one-way sequence valve B, the outlet of one-way sequence valve A is connected to the rear support cylinder, and the output end of the rear support cylinder is connected to the rear support arm, and can Control the opening of the hydraulic control check valve C, the hydraulic control check valve C is also connected with the front support cylinder, the outlet of the one-way sequence valve B is respectively connected with the rear chamber of the rear telescopic cylinder and the front chamber of the front telescopic cylinder, and the outlet of the rear telescopic cylinder A coaxial rear central shaft is installed on the piston in the cylinder, and the rear central shaft is load-connected with the rear telescopic cylinder. A coaxial front central shaft is installed on the piston in the front telescopic cylinder, and the front central shaft is connected with the front telescopic cylinder. The front cavity of the telescopic cylinder and the rear cavity of the front telescopic cylinder are respectively connected with the inlet of the one-way overflow valve B, and the outlet of the one-way overflow valve B is connected with the second inlet of the hydraulically controlled two-position four-way reversing valve. The second outlet of the two-position four-way reversing valve communicates with the fuel tank to control the reversing of the hydraulically controlled two-position four-way valve. The outlet of the one-way overflow valve B is also connected with the hydraulically controlled one-way valve D. Control the oil on the right side of the hydraulic control two-position four-way reversing valve to flow back to the oil tank; connected, the third outlet is respectively connected with the inlet of the one-way sequence valve C and the inlet of the one-way sequence valve D, the outlet of the one-way sequence valve D is connected with the front support cylinder, the output end of the front support cylinder is connected with the front support arm, and It can control the opening of the hydraulic control check valve B. The hydraulic control check valve B is also connected to the rear support cylinder. The outlet of the one-way sequence valve C is respectively connected to the front chamber of the rear telescopic cylinder and the rear chamber of the front telescopic cylinder. The rear telescopic cylinder The rear cavity of the front telescopic cylinder and the front cavity of the front telescopic cylinder are respectively connected with the inlet of the one-way overflow valve A, and the outlet of the one-way overflow valve A is connected with the fourth inlet of the hydraulically controlled two-position four-way reversing valve, and the hydraulically controlled two-position The fourth outlet of the four-way reversing valve is connected with the oil tank, and controls the reversing of the hydraulically controlled two-position four-way valve. The outlet of the one-way overflow valve A is also connected with the hydraulically controlled one-way valve A, which controls the liquid The left side of the two-position four-way reversing valve is controlled and the oil flows back to the oil tank.

The inlet of the hydraulic pump is provided with an air filter, and the outlet is provided with a one-way valve.

When the hydraulically controlled two-position four-way reversing valve is in the left position, the first outlet of the hydraulically controlled two-position four-way reversing valve is also connected to the inlet of the throttle valve A, and the outlet of the throttle valve A is connected to the hydraulically controlled one-way valve. C connection.

When the hydraulically controlled two-position four-way reversing valve is in the right position, the third outlet of the hydraulically controlled two-position four-way reversing valve is also connected to the inlet of the throttle valve B, and the outlet of the throttle valve B is connected to the hydraulically controlled one-way valve. B is connected.

The outlet of the hydraulic pump is also connected with the inlet of the overflow valve A, and the outlet of the overflow valve A is connected with the oil tank.

Oil filters are installed on all hydraulic oil lines flowing back to the oil tank.

An overflow valve B is also installed on all the hydraulic oil pipelines flowing back to the oil tank, and the overflow valve B is connected in parallel with the oil filter.

The control system is installed inside the retractable downhole tractor.

The present invention has the following advantages:

1. The crawling of the telescopic downhole tractor is realized through the hydraulic control system. The control system has its own hydraulic source, and only one cable on the ground is needed to supply power to the motor, avoiding the use of a ground hydraulic station.

2. An overflow valve is set between the liquid outlet of the hydraulic pump and the oil tank to prevent the hydraulic oil from being pressed into the oil cavity when the piston is at the maximum stroke, which will cause damage to the hydraulic pump and the motor. When the pressure in the oil cavity is higher than the overflow When the threshold value of the flow valve is set, the hydraulic oil pumped by the hydraulic pump directly flows back to the oil tank through the overflow valve, thereby realizing the protection of the hydraulic pump and the motor.

3. The valve group adopts a hydraulically controlled two-position four-way valve and a hydraulically controlled one-way valve, which reduces the number of valve parts and improves control efficiency. In addition, the hydraulic control system can easily realize stepless speed regulation in a large range, and the speed regulation range is large (because hydraulic cylinders and hydraulic motors can operate at very low speeds and speeds); As the working medium, it has the ability to absorb vibration, so the movement is stable; the relative moving surface of the hydraulic component is self-lubricated by hydraulic oil, so the working life is long.

4. Through the hydraulic control, combined with the two-way locking and grabbing mechanism based on the self-locking slope, it can provide a large traction force, and at the same time, the normal operation of the mud circulation system can be guaranteed during the control traction process.

Description of drawings

Fig. 1 is the hydraulic circuit diagram when the hydraulically controlled two-position four-way reversing valve of the present invention is in the left position;

Fig. 2 is a hydraulic circuit diagram when the hydraulically controlled two-position four-way reversing valve of the present invention is in the right position;

Fig. 3 is a schematic diagram of the forward crawling principle of the present invention;

In the figure: 1-fuel tank, 2-air filter, 3-hydraulic pump, 4-check valve, 5-oil filter, 6-relief valve A, 7-hydraulic control two-position four-way reversing valve, 8-hydraulic Control check valve A, 9-hydraulic control check valve B, 10-one-way sequence valve A, 11-one-way overflow valve A, 12-one-way sequence valve B, 13-one-way sequence valve C, 14- One-way overflow valve B, 15-one-way sequence valve D, 16-hydraulic control one-way valve C, 17-throttle valve A, 18-hydraulic control one-way valve D, 19-rear support cylinder, 20-rear support Arm, 21-Rear Telescopic Cylinder, 22-Rear Telescopic Cylinder Load, 23-Front Telescopic Cylinder, 24-Front Telescopic Cylinder Load, 25-Front Support Arm, 26-Front Support Cylinder, 27-Throttle Valve B, 28-Overflow Flow valve B, 29-rear central shaft, 30-rear friction block, 31-control nipple, 32-front friction block, 33-front central shaft.

detailed description

The present invention will be further described below in conjunction with the accompanying drawings, but the protection scope of the present invention is not limited to the following description.

A control system of a telescopic downhole tractor based on hydraulic control, including a fuel tank 1, a hydraulic pump 3, a hydraulically controlled two-position four-way reversing valve 7, a rear support arm 20 and a front support arm 25, the inlet of the hydraulic pump 3 and the The oil tank 1 is connected, as shown in Figure 1, when the hydraulically controlled two-position four-way reversing valve 7 is in the left position, the first inlet of the hydraulically controlled two-position four-way reversing valve 7 is connected to the outlet of the hydraulic pump 3, and the hydraulically controlled two-position four-way reversing valve 7 is connected to the outlet of the hydraulic pump 3. The first outlet of the four-way reversing valve 7 is respectively connected to the inlet of the one-way sequence valve A10 and the inlet of the one-way sequence valve B12, the outlet of the one-way sequence valve A10 is connected to the rear support cylinder 19, and the output end of the rear support cylinder 19 It is connected with the rear support arm 20 and can control the opening of the hydraulically controlled one-way valve C16. The hydraulically controlled one-way valve C16 is also connected with the front support cylinder 26. The front cavity of telescopic cylinder 23 is connected, and coaxial rear central shaft 29 is installed on the piston in the cylinder of rear telescopic cylinder 21, and rear central shaft 29 is connected with rear telescopic cylinder load 22. The front central shaft 33 of the shaft, the front central shaft 33 is connected with the front telescopic cylinder load 24, the front cavity of the rear telescopic cylinder 21 and the rear cavity of the front telescopic cylinder 23 are respectively connected with the inlet of the one-way overflow valve B14, and the one-way overflow The outlet of the valve B14 is connected with the second inlet of the hydraulically controlled two-position four-way reversing valve 7, and the second outlet of the hydraulically controlled two-position four-way reversing valve 7 is connected with the fuel tank 1, and the hydraulically controlled two-position four-way valve 7 is switched. The outlet of the one-way overflow valve B14 is also connected with the hydraulically controlled one-way valve D18, and the hydraulically controlled one-way valve D18 controls the oil on the right side of the hydraulically controlled two-position four-way reversing valve 7 to flow back to the oil tank 1; as shown in Figure 2 As shown, when the hydraulically controlled two-position four-way reversing valve 7 is in the right position, the third inlet of the hydraulically controlled two-position four-way reversing valve 7 is connected to the outlet of the hydraulic pump 3, and the third outlet is connected to the outlet of the one-way sequence valve C13 respectively. The inlet is connected to the inlet of the one-way sequence valve D15, the outlet of the one-way sequence valve D15 is connected to the front support cylinder 26, the output end of the front support cylinder 26 is connected to the front support arm 25, and can control the opening of the hydraulically controlled one-way valve B9, The hydraulic control check valve B9 is also connected with the rear support cylinder 19, the outlet of the one-way sequence valve C13 is respectively connected with the front chamber of the rear telescopic cylinder 21 and the rear chamber of the front telescopic cylinder 23, and the rear chamber of the rear telescopic cylinder 21 is connected with the front telescopic cylinder. The front cavity of the cylinder 23 communicates with the inlet of the one-way overflow valve A11 respectively, and the outlet of the one-way overflow valve A11 communicates with the fourth inlet of the hydraulically controlled two-position four-way reversing valve 7, and the hydraulically controlled two-position four-way reversing valve The fourth outlet of the valve 7 is connected with the oil tank 1 to control the reversing of the hydraulically controlled two-position four-way valve 7, and the outlet of the one-way overflow valve A11 is also connected with the hydraulically controlled one-way valve A8, which controls the hydraulically controlled The oil on the left side of the two-position four-way reversing valve 7 flows back to the oil tank 1.

The inlet of the hydraulic pump 3 is provided with an air filter 2 , and the outlet is provided with a one-way valve 4 .

When the hydraulically controlled two-position four-way reversing valve 7 is in the left position, the first outlet of the hydraulically controlled two-position four-way reversing valve 7 is also connected to the inlet of the throttle valve A17, and the outlet of the throttle valve A17 is connected to the hydraulic control unit Connect to valve C16.

When the hydraulically controlled two-position four-way reversing valve 7 is in the right position, the third outlet of the hydraulically controlled two-position four-way reversing valve 7 is also connected to the inlet of the throttle valve B27, and the outlet of the throttle valve B27 is connected to the hydraulic control unit Connect to valve B9.

The outlet of the hydraulic pump 3 is also connected to the inlet of the overflow valve A6, and the outlet of the overflow valve A6 is connected to the oil tank 1.

Oil filters 5 are installed on all the hydraulic oil pipelines that flow back to the oil tank 1 .

An overflow valve B28 is installed on all the hydraulic oil pipelines flowing back to the oil tank 1, and the overflow valve B28 is connected in parallel with the oil filter 5.

The control system is installed inside the telescopic downhole tractor, and the crawling of the telescopic downhole tractor is realized through the hydraulic control system. The control system has its own hydraulic source, and only one cable on the ground is needed to supply power to the motor, avoiding the use of a ground hydraulic station.

The working process of the present invention is as follows: as shown in Figure 3,

Motor energization-A state: assume that the tractor is fully extended as the initial state, and both the front friction block 32 and the rear friction block 30 are in a retracted state. At this time, power is supplied to the downhole motor from the ground through the cable, and the motor drives the hydraulic pump 3, which is connected to the hydraulically controlled two-position four-way valve 7 through the one-way valve 4. At this time, the hydraulically controlled two-position four-way valve 7 is in the left position, and the outlet is connected with the one-way sequence valve A10, the one-way sequence valve B12, and the throttle valve A17. The friction block 30 is supported (three friction blocks are evenly distributed on a circle, simplified as one in the schematic diagram), so that the rear friction block 30 is locked with the well wall, and the rear friction block 30 and the push rod piston are locked through the inclined plane mechanism To overcome the problem that the traction force is limited by constant static friction, then the throttle valve A17 hydraulically acts on the hydraulic control check valve C16 to open the hydraulic control check valve C16, and the spring force acts on the piston in the front support cylinder 26 to make the front The friction block 32 remains in a contracted state. As the pressure continues to rise, the one-way sequence valve B12 opens. Since the retractor is in an extended state, at this time, as the pressure increases, the one-way overflow valve A11 connected to the one-way sequence valve B12 opens, and the one-way overflow On the one hand, the outlet of valve A11 is connected to hydraulically controlled two-position four-way valve 7 to control the direction change of hydraulically controlled two-position four-way valve 7 (from left to right); on the other hand, it is connected to hydraulically controlled one-way valve A8 so that the hydraulically controlled two The oil on the left side of the four-way valve 7 flows back to the oil tank 1.

State A-State B: The hydraulically controlled two-position four-way valve 7 is in the right position, and the outlet is connected to the one-way sequence valve C13 and the one-way sequence valve D15, as well as the throttle valve B27. When liquid enters, the one-way sequence valve D15 Open it first, push the front friction block 32 to support (on a circle, three friction blocks are evenly distributed, and the description here is simplified to one), so that the front friction block 32 and the well wall, the front friction block 32 and the push rod piston Locking, through the slope mechanism to overcome the problem that the traction force is limited by constant static friction, then the throttle valve B27 hydraulically acts on the hydraulic control check valve B9 to open the hydraulic control check valve B9, and the spring force acts on the rear support cylinder 19 The inner piston makes the rear friction block 30 contract, unlocking the support function.

B state-C state: continue to follow the pressure rise, the one-way sequence valve C13 is opened, and at this time, the hydraulic oil enters the front telescopic cylinder 23 and the rear telescopic cylinder 21 . Front telescopic cylinder 23 and front support cylinder 26 and front support 32 blocks now have rigid connection relation, keep static, when guaranteeing that front telescopic cylinder 23 enters liquid, the front central shaft 33 in front telescopic cylinder 23 moves forward; Liquid enters the cylinder 21, and there is a solid connection between the rear central shaft 29, the control nipple 31, and the front central shaft 33. The front central shaft 33 and the rear central shaft 29 will move forward under the hydraulic pressure in the front telescopic cylinder 23, and the rear telescopic The cylinder body 21 moves forward relative to the rear central axis 29 under the hydraulic pressure in the rear telescopic cylinder 21 .

C state-D state: As the pressure rises, the one-way overflow valve B14 connected to the one-way sequence valve C13 opens, and the outlet of the one-way overflow valve B14 is connected to the hydraulically controlled two-position four-way valve 7 on the one hand to control the hydraulically controlled The two-position four-way valve 7 changes direction (from right to left), and on the other hand, it is connected to the hydraulic control check valve D18, so that the oil on the right side of the hydraulic control two-position four-way valve 7 flows back to the oil tank 1. At this time, the hydraulically controlled two-position four-way valve 7 is in the left position, and the outlet is connected with the one-way sequence valve A10, the one-way sequence valve B12, and the throttle valve A17. The friction block 30 is supported (three support blocks are evenly distributed on a circle, simplified as one in the schematic diagram), so that the rear friction block 30 is locked with the well wall, and the rear friction block 30 and the push rod piston are locked through the inclined plane mechanism To overcome the problem that the traction force is limited by constant static friction, the throttle valve A17 hydraulically acts on the hydraulically controlled check valve C16 to open the hydraulically controlled check valve C16, causing the front friction block 32 to shrink and unlock the support function.

D state-A state: As the pressure continues to rise, the one-way sequence valve B12 opens, pushing the front central shaft 33 to move forward, and at the same time, the front telescopic cylinder 23 stretches forward under the action of hydraulic pressure. The one-way overflow valve A11 connected to the sequence valve B12 is opened, and the outlet of the one-way overflow valve A11 is connected to the hydraulically controlled two-position four-way valve 7 on the one hand to control the direction change of the hydraulically controlled two-position four-way valve 7 (from left to right On the other hand, connect the hydraulically controlled one-way valve A8, so that the oil on the left side of the hydraulically controlled two-position four-way valve 7 flows back to the oil tank 1.

Let the tractor repeat the process of "A state-B state-C state-D state-A state", so that the tractor can realize underground traction and crawling.

Claims (8)

1. A kind of 1. control system of the telescopic downhole tractor based on hydraulic control, it is characterised in that：Including fuel tank（1）, liquid Press pump（3）, the position and four-way reversing valve of hydraulic control two（7）, rear support arm（20）With front support arm（25）, hydraulic pump（3）Entrance with oil Case（1）Connection, the position and four-way reversing valve of hydraulic control two（7）During in left position, the position and four-way reversing valve of hydraulic control two（7）First entrance and liquid Press pump（3）Outlet connection, the position and four-way reversing valve of hydraulic control two（7）First outlet respectively with one way sequence valve A（10）Entrance and One way sequence valve B（12）Entrance connection, one way sequence valve A（10）Outlet and rear support cylinder（19）Connection, rear support cylinder （19）Output end and rear support arm（20）Connection, and hydraulic control one-way valve C can be controlled（16）Open, hydraulic control one-way valve C（16） Also with front support cylinder（26）Connection, one way sequence valve B（12）Outlet respectively with rear telescoping cylinder（21）Back cavity and front stretching cylinder （23）Ante-chamber connection, rear telescoping cylinder（21）Cylinder inner carrier on coaxial rear center's axle is installed, rear center's axle with it is rear flexible Cylinder loads（22）Connection, front stretching cylinder（23）Coaxial preceding central shaft, preceding central shaft and front stretching cylinder are installed on cylinder inner carrier Load（24）Connection, rear telescoping cylinder（21）Ante-chamber and front stretching cylinder（23）Back cavity respectively with one-way overflow valve B（14）Enter Mouth connection, one-way overflow valve B（14）Outlet and the position and four-way reversing valve of hydraulic control two（7）Second entrance connection, hydraulic control two four Logical reversal valve（7）Second outlet and fuel tank（1）Connection, control the position and four-way reversing valve of hydraulic control two（7）Commutation, one-way overflow valve B （14）Outlet also with hydraulic control one-way valve D（18）Connection, hydraulic control one-way valve D（18）Control the position and four-way reversing valve of hydraulic control two（7）It is right Side is fuel-displaced to flow back to fuel tank（1）；The position and four-way reversing valve of hydraulic control two（7）During in right position, the position and four-way reversing valve of hydraulic control two（7）The 3rd Entrance and hydraulic pump（3）Outlet connection, the 3rd outlet respectively with one way sequence valve C（13）Entrance and one way sequence valve D （15）Entrance connection, one way sequence valve D（15）Outlet and front support cylinder（26）Connection, front support cylinder（26）Output end with Front support arm（25）Connection, and hydraulic control one-way valve B can be controlled（9）Open, hydraulic control one-way valve B（9）Also with rear support cylinder（19）Even Connect, one way sequence valve C（13）Outlet respectively with rear telescoping cylinder（21）Ante-chamber and front stretching cylinder（23）Back cavity connection, after stretch Contracting cylinder（21）Back cavity and front stretching cylinder（23）Ante-chamber respectively with one-way overflow valve A（11）Entrance connection, one-way overflow valve A （11）Outlet and the position and four-way reversing valve of hydraulic control two（7）The 4th entrance connection, the position and four-way reversing valve of hydraulic control two（7）The 4th go out Mouth and fuel tank（1）Connection, control the position and four-way reversing valve of hydraulic control two（7）Commutation, one-way overflow valve A（11）Outlet also with hydraulic control list To valve A（8）Connection, hydraulic control one-way valve A（8）Control the position and four-way reversing valve of hydraulic control two（7）Left side is fuel-displaced to flow back to fuel tank（1）.
2. 2. a kind of control system of the telescopic downhole tractor based on hydraulic control, its feature exist according to claim 1 In：The hydraulic pump（3）Porch be provided with air filter（2）, exit is provided with check valve（4）.
3. 3. a kind of control system of the telescopic downhole tractor based on hydraulic control, its feature exist according to claim 1 In：The position and four-way reversing valve of hydraulic control two（7）During in left position, the position and four-way reversing valve of hydraulic control two（7）First outlet also with throttling Valve A（17）Entrance connection, throttle valve A（17）Outlet and hydraulic control one-way valve C（16）Connection.
4. 4. a kind of control system of the telescopic downhole tractor based on hydraulic control, its feature exist according to claim 1 In：The position and four-way reversing valve of hydraulic control two（7）During in right position, the position and four-way reversing valve of hydraulic control two（7）3rd outlet also with throttling Valve B（27）Entrance connection, choke valve B（27）Outlet and hydraulic control one-way valve B（9）Connection.
5. 5. a kind of control system of the telescopic downhole tractor based on hydraulic control, its feature exist according to claim 1 In：The hydraulic pump（3）Outlet also with overflow valve A（6）Entrance connection, overflow valve A（6）Outlet and fuel tank（1）Connection.
6. A kind of 6. control system of the telescopic downhole tractor based on hydraulic control according to Claims 1 to 5 any one System, it is characterised in that：It is all to flow back to fuel tank（1）Hydraulic oil pipeline on oily filter is installed（5）.
7. 7. a kind of control system of the telescopic downhole tractor based on hydraulic control, its feature exist according to claim 6 In：It is all to flow back to fuel tank（1）Hydraulic oil pipeline on be also equipped with overflow valve B（28）, the overflow valve B（28）With the oily filter （5）It is in parallel.
8. 8. a kind of control system of the telescopic downhole tractor based on hydraulic control, its feature exist according to claim 1 In：The control system is installed on inside telescopic downhole tractor.