Hydraulic Downhole Brake Device for Cable Logging Tractor

Abstract

The present invention discloses a hydraulic downhole brake device for a cable logging tractor, which solves the problems of the existing device such as complex structure, inconvenient control, occupying space, and easy occurrence of brake locking. The technical solution includes a hydraulic push rod assembly and a support arm connected to the oil circuit of the tractor. The support arms are symmetrically arranged on both sides of the push rod of the hydraulic push rod assembly. The rear end of the support arm is hinged to the support seat at the front end of the hydraulic push rod assembly, and a damping roller is provided at the front end. A guiding groove is axially formed on the support arm. A slider is provided at the front end of the push rod, and guiding blocks are symmetrically provided on both sides of the slider, and the guiding blocks are located in the corresponding guiding grooves on one side. The invention has the advantages of simple structure, small volume, can share the oil circuit of the tractor, can avoid the rapid sliding of downhole tools and prevent the problem of brake locking, pure mechanical control, high safety and reliability, low manufacturing cost and layout difficulty, and is easy to maintain and repair.

Description

Technical Field

[0001] The present invention relates to a downhole tractor, specifically a hydraulic downhole brake device for a cable logging tractor used in a tractor. Background Art

[0002] Nowadays, there are more and more horizontal well logging operations. The wellbore trajectory has an upturned section, and in some cases, the upturned slope even reaches 110°. When the logging downhole tool passes through the upturned section under the action of external force and completes the operation, it is necessary to lift the downhole tool out through the cable. However, when the downhole tool reaches the upturned section, the downhole tool will slide forward under the action of gravity. There is a cable in front of the downhole tool. When the sliding speed of the downhole tool is greater than the lifting speed of the cable, the cable will be wound into the instrument string, causing an operation accident.

[0003] Therefore, it is desired to design a hydraulic brake device for a tractor to avoid the problem of rapid sliding of the downhole tool when passing through the upturned section and when the driving wheel of the tractor loses its acting force.

[0004] Publication No. 215565900U discloses a hydraulic downhole brake device for a cable logging tractor, which includes a brake body, an oil tank assembly, a fixed joint, a support arm joint, a brake arm, a support arm, a piston rod, a sealing plug seat, a compression spring and a control valve block. The first end of the brake arm is hinged to the fixed joint through a first hinge shaft, the second end of the brake arm is hinged to the first end of the support arm through a second hinge shaft, and the second end of the support arm is hinged to the support arm joint through a third hinge shaft; the support arm joint is fixedly connected to the piston rod, and the piston rod movably passes through the sealing plug seat; the compression spring is sleeved on the piston rod; the control valve block is hermetically installed in the brake body. Although this technical solution can also prevent the logging tool from sliding down after reaching the upturned well section. However, there are still the following problems: (1) This solution uses the principle of driving the support arm and the brake arm to open when pressurizing and closing when depressurizing, which can meet the basic requirements of braking. However, since the braking device cannot open and close synchronously with the traction wheel, this structure makes it impossible to directly share the oil circuit of the tractor, and it is necessary to separately set up an oil tank assembly or arrange an oil circuit control device, resulting in problems such as complex design and layout of the entire equipment, occupying the limited space of the tractor, difficult maintenance, and poor reliability. The separate oil circuit requires high-temperature and small-volume hydraulic components, downhole high-temperature control circuits, etc., and the cost is expensive (currently, high-temperature and high-pressure small-volume hydraulic devices at home and abroad, such as solenoid valves and safety valves, are extremely expensive, and high-temperature components of circuit control boards are expensive and have poor reliability); (2) In this solution, the second end of the brake arm is hinged to the first end of the support arm through a second hinge shaft, and the second end of the support arm is hinged to the support arm joint through a third hinge shaft. The axial movement of the piston rod drives the support arm and the brake arm to rotate together to open, so that the brake arm can press on the inner wall of the downhole casing to obtain a relatively large frictional force and supporting force. It is necessary to adjust the oil pressure output by the oil tank assembly 1 to control the pressure of the brake arm 3 on the inner wall of the downhole casing, which further increases the difficulty of control. Once the output pressure is too large, the problem of downhole brake locking will occur. (3) When this brake device works downhole, it is pressurized by a plunger pump through a separate oil circuit. After the work is completed, it is necessary to release the internal oil pressure and retract the support arm. Usually, the solenoid valve is used to release the pressure. In such a small volume, the main oil circuit of the solenoid valve is very small, with a diameter of even less than 1 mm. If the oil fluid cannot be filtered cleanly, there is a risk of blockage. Once blocked, it will cause serious logging accidents (there are countless collars downhole, all with steps. Once stuck inside the steps, it will inevitably cause accidents). Summary of the Invention

[0005] The purpose of the present invention is to solve the above technical problems, and provide a hydraulic downhole brake device for a cable logging tractor for a tractor, which has a simple structure, small volume, can share the oil circuit of the tractor, can avoid the rapid sliding of downhole tools and prevent the problem of brake locking, is purely mechanically controlled, has high safety and reliability, low manufacturing cost and layout difficulty, and is easy to maintain and repair.

[0006] The technical solution of the present invention includes a hydraulic push rod assembly and a support arm connected to the oil circuit of the tractor. The support arms are symmetrically arranged on both sides of the push rod of the hydraulic push rod assembly. The rear end of the support arm is hinged to the support of the front end of the hydraulic push rod assembly, and a damping roller is provided at the front end. A guiding groove is axially formed on the support arm. A slider is provided at the front end of the push rod, and guiding blocks are symmetrically provided on both sides of the slider. The guiding blocks are located in the corresponding guiding grooves on one side.

[0007] The guiding groove has an inclined upward slant segment.

[0008] The rear section of the guiding groove is an inclined upward slant segment, and the front section is a straight segment parallel to the axis.

[0009] It further includes a safety lock assembly for locking the support arm in the pressure relief state.

[0010] The safety lock assembly includes a safety rod and a tension spring installed on the front support of the hydraulic push rod assembly. The middle section of the safety rod is hinged to the support, and one end of the safety rod is connected to the tension spring, and the end face of the other end is a flat surface. A safety groove corresponding to the safety rod is formed on the push rod. The bottom surface of the safety groove is provided with adjacent first and second flat surfaces from front to back. The shortest distance from the first flat surface to the hinge point of the safety rod is equal to the distance from the hinge point of the safety rod to the end face of the other end of the safety rod. The shortest distance from the second flat surface to the hinge point of the safety rod is greater than the maximum radius from the hinge point of the safety rod to the other end.

[0011] The hydraulic push rod assembly includes a housing connected to the oil circuit of the tractor, a push rod installed in the housing at the rear section, a return spring sleeved on the rear section of the push rod, a sealing seat located at the bottom of the return spring, and a support provided at the front end of the housing.

[0012] The support is sleeved on the front section of the push rod. A positioning groove is axially formed on the support, and a positioning screw is correspondingly provided on the push rod. The head of the positioning screw is located in the positioning groove.

[0013] The damping roller is a hexagonal roller, and damping is provided at the hinge of the hexagonal roller and the support arm.

[0014] In view of the problems existing in the background technology, the inventor has made the following improvements:

[0015] (1) By using the cooperation of the inclined upward guiding groove formed on the support arm and the guiding blocks on the slider at the end of the push rod, when pressurized, the push rod moves forward to drive the support arm to close, and when depressurized, the push rod moves backward to drive the support arm to open. This just meets the requirement that when the traction wheel opens, the support arm is in the closed state, and when the traction wheel closes, the support arm opens. Thus, there is no need to separately set up a complex oil circuit control system, and directly share the oil circuit of the tractor, which extremely effectively reduces the equipment layout difficulty and production cost;

[0016] (2) The purpose of the brake device in the present invention is to increase the friction resistance and prevent the instrument from sliding down. It is not necessary to lock the instrument in a certain position. Once the locking failure occurs, it will cause huge losses. Therefore, the purpose of braking is not achieved by applying pressure to the support arm to obtain a relatively large friction and support force on the inner wall of the downhole casing. Instead, a damping roller is set at the front end of the support arm to achieve the purpose of deceleration and braking, and avoid the problem of emergency stop and locking. Therefore, the stroke of the push rod is only limited by the guide groove, and there is no need to control the pressure. It is only necessary to pre-adjust the damping size of the damping roller, which further simplifies the structure and improves safety and reliability.

[0017] (3) Based on the state that the support arm is open when the pressure is applied and the support arm is retracted when the pressure is released, when the tractor is carrying the downhole instrument string and preparing to go down the well for operation, the instrument string is not powered, that is, it is in a non-pressurized state. At this time, the support arm of the brake device will be in an open state, and it will not be able to go down the well smoothly. In order to solve the above technical problems, the inventor designed a safety lock assembly. Before the operation, the support arm is first locked with the safety lock assembly. At this time, the support arms of the tractor and the brake device are both in a retracted state when the pressure is not applied. The safety lock assembly adopts a structure in which the safety rod and the tension spring on the support cooperate with the safety groove on the push rod. In the locked state, the plane end of the other end of the safety rod just contacts the first plane of the safety groove. Limited by the first plane, the safety rod can effectively prevent the displacement of the push rod. The guide block of the slider is located at the rear end of the straight section of the guide groove on the corresponding side. The support arm is kept in the retracted locked state, and under the action of the reset spring 28, it will be more and more tight, and there will be no problem of disengagement. After reaching the well, it only needs to pressurize the inside to the set value, and the push rod can overcome the limit and move forward, so that the second plane of the safety groove moves to below the plane of the other end of the safety rod. Since the second plane is lower than the first plane, the space requirement for the rotation of the safety rod is met, so the safety rod is no longer limited. Under the action of the tension spring, the safety rod leaves the limiting area of ​​the push rod after rotation, and no longer limits the push rod, so as to achieve the purpose of releasing the safety lock and enter the working state of the normal brake device being pressed and retracted, and the pressure relief is stretched. At this time, the guide block of the slider is located at the front end of the straight section of the guide groove on the corresponding side.

[0018] (4) The hydraulic push rod assembly is provided with a reset spring. When the pressure is released, the push rod will quickly move back and reset under the action of the reset spring. When the pressure is applied, the push rod will move forward to overcome the spring pressure, thereby finally driving the guide block on the slider to move in the guide groove to achieve the folding and opening of the support arm. Furthermore, through the cooperation of the positioning groove and the positioning screw, the push rod is prevented from rotating, and the reliability of the axial movement of the push rod is ensured. The present invention can directly replace the original oil seal short section at the rear end of the tractor, thereby further reducing the overall length of the instrument.

[0019] (5) The present invention has a simple structure, small volume, can share the oil circuit of the tractor, can avoid the rapid sliding of downhole tools and prevent the problem of brake locking, is purely mechanically controlled, has high safety and reliability, low manufacturing cost and low layout difficulty, and is easy to maintain and repair. Description of the Drawings

[0020] Figure 1 It is a schematic structural diagram of the present invention and the state diagram when it is opened.

[0021] Figure 2 It is the front view of the support arm.

[0022] Figure 3 It is the state diagram when the safety lock assembly of the present invention is locked.

[0023] Figure 4 It is the state diagram when the safety lock assembly of the present invention is unlocked and retracted.

[0024] Figure 5 It is the schematic top view structure of the present invention.

[0025] Among them, 1 - safety lock assembly, 2 - seal seat, 3 - support, 4 - push rod, 5 - safety rod, 6 - support arm, 7 - damping roller, 8 - return spring, 9 - housing, 10 - slider, 11 - guide block, 12 - guide groove, 13 - straight section, 14 - inclined section, 15 - tension spring, 16 - safety groove, 17 - first plane, 18 - second plane, 19 - positioning groove, 20 - positioning screw, 21 - cylinder wall. Detailed Embodiment

[0026] The present invention will be further explained below with reference to the drawings:

[0027] See Figure 1 and Figure 5 , the device of the present invention includes a hydraulic push rod assembly connected to the oil circuit of the tractor and support arms 6 symmetrically arranged on both sides of the push rod 4 of the hydraulic push rod assembly. The two support arms 6 are synchronously driven by a group of push rod assemblies to move synchronously, realizing synchronous opening or retraction.

[0028] Among them, the hydraulic push rod assembly includes a housing 9 communicating with the oil circuit of the tractor (which can be connected to the oil circuit of the tractor through an oil injection hole to introduce the hydraulic oil of the tractor into the cavity formed by the housing 9), a push rod 4 installed in the rear section of the housing 9, a return spring 8 sleeved on the rear section of the push rod 4, a seal seat 2 located at the bottom of the return spring 8, and a support 3 provided at the front end of the housing 9. When pressurized, the pressurized hydraulic oil enters the housing 9 to push the push rod 4 to move forward. When the pressure is relieved, the push rod 4 moves backward and resets under the action of the return spring 8.

[0029] The rear end of the support arm 6 is hinged to the support 3 at the front end of the hydraulic push rod assembly. A damping roller 7 is provided at the front end. Preferably, the damping roller is a hexagonal roller, and damping is provided at the hinged portion of the hexagonal roller and the support arm. A guiding groove is axially formed on the support arm 6. The front end of the push rod 4 passes through the housing 9 and the support 3 and extends out, and a slider 10 is provided. Guide blocks 11 are symmetrically provided on both sides of the slider 10. The guide blocks 11 are located in the guiding grooves 12 of the corresponding side support arm 6. The rear section of the guiding groove 12 is an inclined line segment 14 that slopes upward, and the front section is a straight line segment 13 parallel to the axis of the support arm 6.

[0030] It further includes a safety lock assembly 1 for locking the support arm in the pressure relief state. Specifically, the safety lock assembly 1 includes a safety rod 5 and a tension spring 15 installed on the front support of the hydraulic push rod assembly 1. The middle section of the safety rod 5 is hinged to the support 3, and one end of the safety rod 5 is connected to the tension spring 15, and the end face of the other end is a flat surface. A safety groove 16 corresponding to the safety rod 5 is formed on the push rod 4. The bottom surface of the safety groove 16 is provided with adjacent first flat surface 17 and second flat surface 18 from front to back. The shortest distance from the first flat surface 17 to the hinge point of the safety rod 5 is equal to the distance from the hinge point of the safety rod 5 to the end face of the other end of the safety rod 5. The shortest distance from the second flat surface 18 to the hinge point of the safety rod is greater than the maximum radius from the hinge point of the safety rod 5 to the other end of the safety rod 5.

[0031] The support 3 is sleeved on the front section of the push rod 4. A positioning groove 19 is axially formed on the support 3. A positioning screw 20 is correspondingly provided on the push rod 4. The head of the positioning screw 20 is located in the positioning groove 19 and can move axially along the positioning groove 19 but cannot rotate, so as to realize the limit of the rotation direction of the push rod 4.

[0032] The device of the present invention is usually installed at the tail end of the hydraulic tractor, and the oil circuit shares with the tractor. When the tractor works, there is hydraulic pressure inside the system, and the traction arm of the tractor will open. At this time, the support arm of the device of the present invention is in the retracted state, thus forming a movement mode that is exactly opposite to that of the tractor, namely pressure suppression and recovery, pressure relief and opening. The specific working principle is as follows:

[0033] I. Pre-lock: When the hydraulic tractor is about to lower the downhole instrument string for operation, the instrument string is not powered on, that is, in the non-pressure-suppression state. At this time, the two side support arms 6 are pushed to overcome the reset spring 8 to retract them. At this time, the flat end of the other end of the safety rod 5 just contacts the first flat surface 17 of the safety groove 16. Limited by the first flat surface 17, the safety rod 5 can effectively prevent the displacement of the push rod 4. At this time, the guide blocks 11 of the slider 10 are exactly located at the rear end of the straight line segment 13 of the corresponding side guiding groove 12. The support arm 6 is kept in the retracted and locked state, and under the action of the reset spring 28, it will be clamped tighter and tighter, and there will be no problem of coming out. See Figure 2 .

[0034] II. Unlocking: After reaching the underground, when the internal pressure of the hydraulic tractor reaches the set value (the corresponding set value can be set by selecting an appropriate limit spring, which is set to 5 MPa in this embodiment), the push rod 4 can move forward against the force of the limit spring 8, so that the second plane 18 of the safety groove 16 moves below the plane at the other end of the safety rod 5. Since the second plane 18 is lower than the first plane 17 and meets the space requirement for the rotation of the safety rod, the safety rod 5 is no longer limited. Under the action of the tension spring 15, the other end of the safety rod 5 rotates and leaves the area of the safety groove 16, no longer limiting the push rod 4, achieving the purpose of unlocking the safety lock. At this time, the guide block 11 of the slider 10 is located at the front end of the straight section 13 of the guide groove 12 on the corresponding side arm 6, and the side arm 6 is in the pressure-receiving and folding state. See Figure 4 .

[0035] III. Braking: When it is necessary to lift the downhole tool through the cable and the traction wheel of the hydraulic tractor is depressurized and retracted, the hydraulic push rod assembly is also depressurized accordingly. The push rod 4 moves backward under the action of the return spring, driving the guide block 11 of the slider 10 to slide from the straight section 13 of the guide groove 12 to the inclined section 14 until the rear end of the inclined section 14, so that the side arm 6 is opened to the set angle under the action of the push rod 4, and the damping roller 7 is closely attached to the cylinder wall 21 (see Figure 1 ); when the downhole tool slides down rapidly, on the one hand, the damping roller 7 will generate resistance when rolling on the cylinder wall, achieving the purpose of deceleration; on the other hand, the damping roller 7 adopts a hexagonal wheel structure and will vibrate when rotating, which will drive the return spring 28 to fluctuate accordingly. The return spring 28 will also apply a force to the damping roller 7 accordingly, so that it also applies a certain force to the cylinder wall, also having a certain braking effect; under the combined action, it can effectively prevent the problem of the instrument string sliding down too fast, and at the same time, there will be no problem of brake locking, and it can also ensure the normal lifting of the downhole tool.

Claims

1. A hydraulic downhole brake device for a cable logging tractor, comprising a hydraulic push rod assembly connected to the oil circuit of the tractor and a support arm, characterized in that, The support arms are symmetrically arranged on both sides of the push rod of the hydraulic push rod assembly. The rear end of the support arm is hinged to the support on the front end of the hydraulic push rod assembly, and a damping roller is provided at the front end. A guiding groove is axially formed on the support arm. A slider is provided at the front end of the push rod, and guiding blocks are symmetrically arranged on both sides of the slider. The guiding blocks are located in the corresponding guiding grooves on one side. It further includes a safety lock assembly for locking the support arm in a pressure-relieved state. The safety lock assembly includes a safety rod and a tension spring installed on the front support of the hydraulic push rod assembly. The middle section of the safety rod is hinged to the support, and one end of the safety rod is connected to the tension spring, and the end face of the other end is a flat surface. A safety groove corresponding to the safety rod is formed on the push rod. The bottom surface of the safety groove is provided with adjacent first and second flat surfaces from front to back. The shortest distance from the first flat surface to the hinge point of the safety rod is equal to the distance from the hinge point of the safety rod to the end face of the other end of the safety rod. The shortest distance from the second flat surface to the hinge point of the safety rod is greater than the maximum radius from the hinge point of the safety rod to the other end of the safety rod. The hydraulic push rod assembly includes a housing connecting the oil circuit of the tractor, a push rod installed in the housing at the rear section, a return spring sleeved on the rear section of the push rod, a sealing seat located at the bottom of the return spring, and a support provided at the front end of the housing. The damping roller is a hexagonal roller, and damping is provided at the hinge of the hexagonal roller and the support arm.

2. The hydraulic downhole brake device for a cable logging tractor according to claim 1, characterized in that, The guiding groove has an inclined upward slant segment.

3. The hydraulic downhole brake device for a cable logging tractor according to claim 2, characterized in that, The rear section of the guiding groove is an inclined upward slant segment, and the front section is a straight segment parallel to the axis.

4. The hydraulic downhole brake device for cable logging tractor according to claim 1, characterized in that, The support is sleeved on the front section of the push rod. A positioning groove is axially formed on the support, and a positioning screw is correspondingly provided on the push rod. The head of the positioning screw is located in the positioning groove.

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