Downhole tractor
By designing two sets of walking mechanisms and arc-shaped elastic foot plates, the problem of insufficient friction in electric wheeled downhole tractors is solved, enabling stable forward movement and reliable operation of the downhole tractor in complex wellbores.
Patent Information
- Application Number
- CN202210252173.7
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- Filing Date
- 2022-03-15
- Publication Date
- 2025-12-05
- Estimated Expiration
- 2042-03-15
AI Technical Summary
Existing electric wheeled downhole traction devices have a small contact area between the wheels and the well wall, resulting in insufficient friction, easy slippage, and increased complexity of the mechanism or travel resistance.
It employs two sets of walking mechanisms, including a first crank and a second crank, a gear system with a central shaft and an eccentric shaft, combined with an arc-shaped elastic foot plate and a needle structure. Through alternating expansion or contraction, it forms a continuous walking cycle, increasing the contact area and friction with the well wall and preventing slippage.
It enables the downhole traction device to move stably in complex wellbores, avoids slippage, improves friction and operational reliability, and is suitable for complex wellbores such as horizontal wells, highly deviated wells, and ultra-deep wells.
Smart Images
Figure CN114517651B_ABST
Abstract
Description
TECHNICAL FIELD
[0001] The present application relates to the field of oil field, in particular to a downhole tractor. BACKGROUND
[0002] At the early stage of oil and gas resource development, most of the oil and gas wells are vertical wells, and the downhole tools, logging instruments, perforating equipment and other operation tools are dropped to the bottom of the well by gravity, and the recovery is realized through the winch driven cable or steel wire drum. However, with the increasing number of horizontal wells, highly deviated wells, ultra-deep wells, small diameter wells and complex path wellbores, gravity alone cannot transmit the downhole operation tools to the target layer. In view of this situation, downhole tractors are widely used at home and abroad. The downhole tractor relies on the power provided by the electromechanical hydraulic system to drive the walking mechanism to grip the well wall and crawl, so it is also called crawler. The tractor is usually installed at the front end of the logging tool string, and pulls the entire tool string through the horizontal, ascending well section or complex wellbore. According to the driving mode, the tractor is divided into telescopic (crawling) tractor, wheel type well tractor, high pressure jet recoil type well tractor and propeller propulsion type well tractor.
[0003] For wireline logging, the most commonly used in China at present is the electric wheel type downhole tractor, which relies on the motor to drive multiple wheels close to the well wall to drive the tractor forward. In order to adapt to the uneven well wall, the wheels are usually installed at the end of a rocker arm, and the pre-tightening force in the radial direction of the well wall is used to open the rocker arm to ensure that the wheels are always pressed against the well wall. However, due to the limited space in the well, and in order to adapt to the uneven path in the wellbore, the wheels need to be installed at the movable end of the expandable rocker arm, so the diameter of the wheels used for driving cannot be too large, resulting in a small contact area between the wheels and the well wall, and insufficient friction, which is easy to slip. In order to increase the friction, the common solution is to increase the number of wheels, but this makes the mechanism complex; or increase the pressure of the wheels on the well wall, but this will increase the resistance of the travel. SUMMARY
[0004] In order to overcome the deficiency of the existing electric wheel type downhole tractor that the wheels have a small contact area with the well wall and are easy to slip, the present application provides a downhole tractor which has a large friction between the tractor and the well wall, avoids slipping and runs reliably.
[0005] The technical scheme of the present application is: a downhole tractor, comprising a body, a power source is arranged inside the body, the power source is connected with a transmission mechanism at both ends, the other end of the two transmission mechanisms is connected with a walking gear respectively, and a walking mechanism is connected with the walking gear at both sides respectively.
[0006] The walking mechanism comprises a first crank and a second crank, the first crank is respectively provided with a first central shaft and a first eccentric shaft, the first central shaft is connected with a first crank gear, and the first eccentric shaft is connected with a first guide rod, the first crank gear is engaged with a walking gear, and one end of the first guide rod is connected with a short foot plate through a rotating shaft, and the other end is connected with the body through a first sliding pin;
[0007] The second crank is respectively connected with a second central shaft and a second eccentric shaft, the second central shaft is connected with a second crank gear, the second eccentric shaft is connected with a second rod, the second crank gear is engaged with the first crank gear, one end of the second guide rod is connected with a long foot plate through a rotating shaft, and the other end is connected with the body through a second sliding pin;
[0008] The outer surfaces of the short foot plate and the long foot plate are located outside the body, and the two are parallel to the body axis and symmetrical along the body axis.
[0009] The inner part of the long foot plate and the short foot plate is a rigid skeleton, and the outer surface is an arc-shaped elastic block, and the arc-shaped outer diameter is not greater than the inner diameter of the wellbore.
[0010] The outer surfaces of the long foot plate and the short foot plate are respectively provided with a plurality of rearward inclined thorn needles.
[0011] The body is provided with a first sliding groove corresponding to the first sliding pin, one end of the first sliding pin is located in the first sliding groove, and the other end is connected with the first guide rod; the body is provided with a second sliding groove corresponding to the second sliding pin, one end of the second sliding pin is located in the second sliding groove, and the other end is connected with the second guide rod.
[0012] The transmission mechanism comprises a power gear connected with a power source, the power gear is engaged with a transmission gear, the transmission gear is connected with a worm through a transmission shaft, the worm is engaged with a turbine, and the turbine is connected with the walking gear through an intermediate shaft.
[0013] The first crank gear, the second crank gear and the walking gear are located on a straight line parallel to the body axis.
[0014] The first crank gear and the second crank gear have the same number of teeth and the same module.
[0015] The underground traction device can be applied to various complex wellbores such as horizontal wells, high-deviation wells, ultra-deep wells and small-diameter wells, and is reliable in operation. BRIEF DESCRIPTION OF DRAWINGS
[0016] Figure 1is a structural schematic diagram of the present application;
[0017] Figure 2 is a front view of the present application;
[0018] Figure 3 is a bottom view of the present application;
[0019] Figure 4 is a sectional view along Figure 3 A-A of the middle;
[0020] Figure 5 is a structural schematic diagram of the present application removing the first section body;
[0021] Figure 6 is a front view of the present application; Figure 2
[0022] is an enlarged view of C in the middle; Figure 7 Figure 4 is an enlarged view of E in the middle;
[0023] Figure 8 Figure 5 is a schematic diagram of the long foot plate;
[0024] Figure 9 is a sectional view along D-D of the middle;
[0025] Figure 10 Figure 9 is an enlarged view of F in the middle.
[0026] Figure 11 is a front view of the present application; Figure 10
[0027] Figure 1 - body, 2 - walking gear, 3-1 - first crank gear, 3-2 - second crank gear, 4-1 - first guide rod, 4-2 - second guide rod, 5-1 - first crank, 5-2 - second crank, 6 - short foot plate, 7 - long foot plate, 9 - turbine, 10 - worm, 11 - transmission shaft, 12 - transmission gear, 13 - power gear, 14 - power source, 101 - first section body, 102 - second section body, 103 - first sliding chute, 104 - second sliding chute, 105 - transmission line, 701 - lancet. DETAILED DESCRIPTION
[0028] The present application is further described below in conjunction with the accompanying drawings:
[0029] The present application is further described below in conjunction with the accompanying drawings: Figures 1 to 11 As shown, a downhole tractor comprises a body 1 connected by two sections, a first section body 101 and a second section body 102, and connected with downhole testing tools at both ends. The body 1 is internally provided with a power source 14, and both ends of the power source 14 are connected with transmission mechanisms, which are symmetrically arranged along the center of the power source 14. One end of the transmission mechanism is connected with the power source 14, and the other end is connected with a walking gear 2, and both sides of the walking gear 2 are connected with walking mechanisms.
[0030] The walking mechanism comprises a first crank 5-1 and a second crank 5-2, and the first crank 5-1 is respectively provided with a first center shaft and a first eccentric shaft. The first center shaft is connected with a first crank gear 3-1, and the first crank gear 3-1 is engaged with the walking gear 2. The first eccentric shaft is connected with a first guide rod 4-1 at the middle part, and one end of the first guide rod 4-1 is connected with a short foot plate 6 through a rotating shaft, and the other end is connected with the body 1 through a first sliding pin. The body 1 is provided with a first sliding groove 103 corresponding to the first sliding pin, and one end of the first sliding pin is located in the first sliding groove 103, and the other end is connected with the first guide rod 4-1. The first sliding pin can move back and forth in the first sliding groove.
[0031] The second crank 5-2 is respectively provided with a second center shaft and a second eccentric shaft. The second center shaft is connected with a second crank gear 3-2, and the second eccentric shaft is connected with a second guide rod 4-2. The second crank gear 3-2 is engaged with the first crank gear 3-1, and one end of the second guide rod 4-2 is connected with a long foot plate 7 through a rotating shaft, and the other end is connected with the body 1 through a second sliding pin. The first crank gear 3-1 and the second crank gear 3-2 have the same number of teeth and the same module, that is, all the crank gear structures are completely the same. The first crank gear 3-1, the second crank gear 3-2 and the walking gear 2 are located on a straight line parallel to the axis of the body 1. The body 1 is provided with a second sliding groove 104 corresponding to the second sliding pin, and one end of the second sliding pin is located in the second sliding groove 104, and the other end is connected with the second guide rod 4-2.
[0032] The outer surfaces of the short foot plate 6 and the long foot plate 7 are located outside the body 1, and they are parallel to and symmetric to the axis of the body 1. The body 1 is provided with oblong holes corresponding to the short foot plate 6 and the long foot plate 7, so that the short foot plate 6 and the long foot plate 7 can be extended from the holes and move. The long foot plate 7 and the short foot plate 6 can have two structures. One is that the inside is a rigid skeleton, and the outer surface is an arc-shaped elastic block, and the arc-shaped outer diameter is not greater than the inner diameter of the wellbore, so that the elastic block can better fit the inner wall of the wellbore. The other is that the outer surface of the long foot plate 7 and the short foot plate 6 is provided with a plurality of backward inclined thorn needles, that is, the inclined direction of the thorn needle is the rear of the running direction. Figure 11As shown, the spike needle 701 can be made of thin steel wire, and the spike needle is in an inclined or curved state in a natural state, and the inclined or curved direction is opposite to the forward direction of the tractor. In this way, at the moment when the short foot plate 6 or the long foot plate 7 steps down, the inclined or curved spike needle will convert the radial pressure of the wellbore into a force in the forward direction of the tractor, increasing the forward thrust, and also increasing the holding force on the well wall. At the same time, for uneven well walls, the spike needle will be deformed under pressure, and all the spike needles will adapt to the shape of the well wall as a whole, maintaining the holding on the well wall.
[0033] The transmission mechanism includes power gears 13, two power gears 13 are connected at both ends of the power source 14, the power gears 13 are engaged with the transmission gears 12, the transmission gears 12 are connected with the worm 10 through the transmission shaft 11, the worm 10 is engaged with the turbine 9, and the turbine 9 is connected with the walking gear 2 through the intermediate shaft, so that the power provided by the power source 14 is transmitted to the walking gear 2.
[0034] The working process of the downhole tractor is as follows: after the power source 14 is started, the power gears 13 are driven to rotate, and the power is transmitted to the walking gear 2 through the transmission gears 12, the transmission shaft 11, the worm 10 and the turbine 9 in turn. The walking gear 2 drives the two first crank gears 3-1 engaged therewith to rotate, and the first crank gears 3-1 drive the second crank gears 3-2 to rotate, so that the directions of rotation of the two second crank gears 3-2 are opposite to those of the two first crank gears 3-1. The first crank gears 3-1 drive the first cranks 5-1 to rotate, the first crank gears 5-1 drive the first guide rods 4-1 connected therewith to move up, down, left and right, and the sliding pins on the first guide rods 4-1 slide in the first sliding grooves 103 and are constrained by the first sliding grooves 103. The two first guide rods 4-1 simultaneously drive the short foot plates 6 to move up, down, forward and backward, forming a movement track close to the foot during walking.
[0035] Similarly, the second crank gears 3-2 drive the second cranks 5-2 to rotate, the second crank gears 5-2 drive the second guide rods 4-2 connected therewith to move up, down, left and right, and the sliding pins on the second guide rods 4-2 slide in the second sliding grooves 104 and are constrained by the second sliding grooves 104. The two second guide rods 4-2 simultaneously drive the long foot plates 7 to move up, down, forward and backward, forming a movement track close to the foot during walking. The positions of the long foot plates 7 and the short foot plates 6 are symmetrical along the axis, and the two simultaneously expand outward and support the well wall, and then simultaneously push backward to move the tractor forward; then simultaneously contract inward and then step forward, forming a continuous walking cycle, so as to reciprocatingly push the tractor to continuously move forward.
[0036] Since the downhole tractor is provided with two sets of running mechanisms, respectively located in the first body 101 and the second body 102, as long as the movement trajectories of the two sets of running mechanisms are adjusted to be 180° different, that is, when the first set of running mechanisms pushes the tractor outward to move forward, the second set of running mechanisms is inwardly retracted; when the second set of running mechanisms pushes the tractor outward to move forward, the first set of running mechanisms is inwardly retracted. The two sets of running mechanisms cooperate with each other to make the movement of the tractor more continuous, and the tractor will not slide down due to the loss of support for the well wall.
[0037] The downhole tractor can be used in series or multiple downhole tools can be used at different positions in the string to obtain greater traction.
Claims
1. A downhole tractor comprising a body (1) having a power source (14) housed therein, characterised in that: The power source (14) is connected with two transmission mechanisms, and the other ends of the two transmission mechanisms are connected with walking gears (2), and the walking gears (2) are connected with walking mechanisms on both sides. The walking mechanism comprises a first crank (5-1) and a second crank (5-2), the first crank (5-1) is provided with a first central shaft and a first eccentric shaft, the first central shaft is connected with a first crank gear (3-1), and the first eccentric shaft is connected with a first guide rod (4-1); the first crank gear (3-1) is engaged with the walking gear (2), and the first guide rod (4-1) is connected with a short foot plate (6) through a rotating shaft at one end and connected with the body (1) through a first sliding pin at the other end. The second crank (5-2) is provided with a second central shaft and a second eccentric shaft, the second central shaft is connected with a second crank gear (3-2), and the second eccentric shaft is connected with a second guide rod (4-2); the second crank gear (3-2) is engaged with the first crank gear (3-1), and the second guide rod (4-2) is connected with a long foot plate (7) through a rotating shaft at one end and connected with the body (1) through a second sliding pin at the other end. The body (1) is provided with a first sliding groove (103) corresponding to the first sliding pin, the first sliding pin is located in the first sliding groove (103) at one end and connected with the first guide rod (4-1) at the other end; the body (1) is provided with a second sliding groove (104) corresponding to the second sliding pin, the second sliding pin is located in the second sliding groove (104) at one end and connected with the second guide rod (4-2) at the other end. The outer surfaces of the short foot plate (6) and the long foot plate (7) are located outside the body (1) and are parallel to and symmetrical to the axis of the body (1). The outer surfaces of the long foot plate (7) and the short foot plate (6) are provided with a plurality of backward inclined needles (701), the needles (701) are thin steel wires, and the needles (701) are in an inclined or curved state in a natural state, and the inclined or curved direction is opposite to the forward direction of the tractor.
2. The downhole tractor of claim 1, wherein: The inner parts of the long foot plate (7) and the short foot plate (6) are rigid frames, and the outer surfaces are arc-shaped elastic blocks, and the arc-shaped outer diameters are not greater than the inner diameters of the shafts.
3. The downhole tractor of claim 2, wherein: The transmission mechanism comprises a power gear (13), the power gear (13) is connected with the power source (14), the power gear (13) is engaged with a transmission gear (12), the transmission gear (12) is connected with a worm (10) through a transmission shaft (11), the worm (10) is engaged with a turbine (9), and the turbine (9) is connected with the walking gear (2) through an intermediate shaft.
4. The downhole tractor of claim 3, wherein: The first crank gear (3-1), the second crank gear (3-2) and the walking gear (2) are located on a straight line parallel to the axis of the body (1).
5. The downhole tractor of claim 4, wherein: The first crank gear (3-1) and the second crank gear (3-2) have the same number of teeth and the same modulus.
Citation Information
Patent Citations
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