WO2008091157A1

WO2008091157A1 - Device for transport of tools in wellbores and pipelines

Info

Publication number: WO2008091157A1
Application number: PCT/NO2008/000018
Authority: WO
Inventors: Lars Raunholt
Original assignee: WELLBORE SOLUTIONS AS
Current assignee: WELLBORE SOLUTIONS AS
Priority date: 2007-01-23
Filing date: 2008-01-22
Publication date: 2008-07-31
Anticipated expiration: 2009-07-23
Also published as: EP2106493A4; EP2106493A1

Abstract

The present invention relates to a pulling tool for transporting tools in a wellbore or pipeline comprising at least one cylindrical module (1) comprising a number of drive wheels (5) mounted on one or more lever arms (4), said lever arms being adapted for forcing the drive wheels (5) radially out against the wall of the wellbore or pipeline (6). The invention is characterized in that the drive wheels (5) are interlocked by way of a shaft (7) and an angular gear (11, 12), as well as a gear transmission comprising a number of cog wheels (13, 14, 15, 17, 21) forward to the drive wheels (5), the shaft (7) being eccentrically positioned relative to a center line of the modules (1).

Description

Device for transport of tools in wellbores and pipelines

The present invention relates to a device for transporting various types of tools into and within substantially circular and extended reach wellbores or pipelines.

hi connection with maintenance and inspection operations in substantially horizontal pipelines and wellbores for the recovery of oil/gas/water, it is often necessary to use a pulling tool in order to reach sufficiently far into the wellbore with tools for carrying out various work, maintenance, or inspection operations.

Particularly in oil and gas wells comprising a lot of sophisticated equipment for optimizing the recovery of oil and gas, various complicated maintenance operations must be performed, hi connection with such operations, there is a need for reliable and cost efficient tool carriers.

Currently, pulling tools of various configurations are used. Most such tools are electro- hydraulic devices comprising advancing mechanisms that are driven by hydraulic motors mounted directly to the drive wheels. Alternatively, the hydraulic power is transferred to the drive wheels by way of various types of gear systems.

For relatively small diameter (about 70 mm, for example) wellbores / pipes, the allowed dimensions of the drive wheels and motors are very limited, necessitating the use of smaller component dimensions which result in a significant loss of flow in the hydraulic motors as well as fragile structures.

The patents US 5,184,676, US 5,736,821, and WO 2005/116484 disclose various exemplary implementations of pulling tools for use in horizontal wells.

US 5,184,676 relates to a pulling tool comprising to parallel arms. Drive wheels are forced against the wellbore wall by means of a trapezoidal lever arm arrangement. This arrangement is considered to be relatively complex, and includes a number of failure-prone components. US 5,736,821 relates to a two- wheel robot that is capable of operating in a pipeline. The wheels are forced against the pipe wall by their own weight and, additionally, the wheels are provided with magnets to create friction against the pipe wall.

WO 2005/116484 relates to a pulling tool comprising two drive shafts used for driving a chain. The drive shafts are eccentrically positioned relative to the tool centre line, but the use of two drive shafts is necessary, one at each side of the chain, in order for the design to work.

The market increasingly demands efficient, reliable, and cost-saving equipment. The current conventional solutions are considered to be complicated, expensive, and too vulnerable to component failure and downtime.

A challenge associated with pulling tools of the above type is to avoid torsional moments that either cause the pulling tool to progress along a helical path, and/or to assume a crooked position relative to the direction of movement of the pulling tool. Such torsional moments may result in that connected lines/coiled tubing become undesirably twisted, that the pulling tool loses traction, or that the tool jams. In order to overcome this well-known problem, it is necessary to create symmetrical pulling tools wherein the drive wheel surfaces that are to engage the inside surface of the wellbore or pipeline are not parallel- displaced relative to each other. US 5,184,676 tries to solve this problem, and achieves a lower torsional moment. However, the solution involves several components that are prone to failure and wear.

Moreover, it has been a problem that one or more drive wheels of a pulling tool starts/start to spin freely if such wheel(s) loses/lose the traction/grip. Wellbores and pipelines may exhibit very rough surfaces and frictional conditions. Besides the fact that the pulling tool may get stuck because all the rotation is transferred to the spinning wheel, the rotational velocity of the wheel may become so large that the drive wheel effectively operate as a circular saw. This may cause severe damage to a pipeline.

The present invention provides a pulling tool of the above kind that avoids a number of the disadvantages from which the conventional solutions suffer. The present invention provides a pulling tool comprising advancement means yielding a high efficiency and a large pulling/pushing force.

It is an object of the present invention to provide a symmetric pulling tool, the configuration of which does not cause unnecessary torsional moments, while at the same time the design is simple and robust.

It is a further object of the present invention to provide a pulling tool in which an even and equal pulling force is transferred to each drive wheel at any time, wherein the loss of traction for one or more wheels does not cause such wheel(s) to spin nor change the rotational velocity of any of the remaining wheels that have not lost their traction.

According to the present invention, these and other objects are achieved by means of a device of the above kind that is characterized in the features set forth in the characterizing part of the accompanied, independent claim. Further advantageous embodiments and features are set forth in the dependent claims.

In the following, a detailed description of preferred embodiments of the present invention is provided with reference to the attached drawings, in which:

Fig. Ia shows an embodiment comprising two separate modules, wherein each separate module includes to lever arms, each arm having one drive wheel,

Fig. Ib shows an alternative embodiment comprising to separate modules, wherein each separate module includes one lever arm, the lever arm being centrally supported and having two drive wheels, one at each end of the lever arm,

Fig. 2a shows a design of a gear system and a drive shaft that may be used in the embodiment shown in fig. Ia,

Fig. 2b shows a design of a support that may be used in connection with the embodiment shown in fig. Ib comprising one lever arm, the lever arm being supported in the center thereof and having two drive wheels, one at each end of the lever arm, Fig. 2c shows a design of a support of a lever arm having two drive wheels, with the figure also showing a design of a drive line forward to the driving wheels, cf. fig. Ib,

Fig. 3 shows a design of a gear transmission between the drive shaft and wheels, cf. fig. Ia,

Fig. 4a shows a section and a cross-section of a lever arm support, cf. fig. Ic^

Fig. 4b _! shows a section of a lever arm support, cf . fig. 1 \©

Fig. 5a shows an embodiment of a device for actuating a lever arm having one drive wheel, cf. fig. Ia, and

Fig. 6 shows an example of how a drive wheel may be supported.

Figs. Ia and Ib show two different pulling tools according to the present invention comprising two separate modules, each of which includes two drive wheels. Fig. Ia shows an embodiment wherein each drive wheel 5 is mounted on a separate lever arm 4, whereas fig. 2a shows an embodiment wherein each drive wheel 5 is mounted at each end of one lever arm 4. The pulling tool is assembled using a desired number of separate modules 1 needed to obtain a sufficient axial pulling/pushing force by means of suitable threaded connections or adaptor means/elements. Figs. Ia and Ib show exemplary embodiments comprising two separate modules 1, although it is understood that any suitable number of separate modules 1 may be used. Each separate module 1 has a given pulling/pushing force, so that a desired total pulling/pushing force can be achieved by assembling a sufficient number of separate modules 1.

The advancement of the pulling tool is effected by causing a drive shaft 7 to rotate, whereupon the rotational force from drive shaft 7 is transferred to drive wheels 5 via a number of cog wheels 12, 11 and cog wheel gears 21, 13, 14, 15, and 16 while at the same time drive wheels 5 are forced against the wellbore/pipe wall 6 by lever arms 4, cf. fig. 2a.

According to the present invention, all drive wheels are mechanically interlocked through a common drive line, which ensures that all wheels are engaged at the same time, which in turn prevents the uncontrolled wheel rotation should any wheel lose its grip on the wellbore/pipe wall.

According to one embodiment, each separate module 1 includes two drive wheels, and one or two respective lever arms 4, depending on whether or not these are end supported with one drive wheel 5 at the one end, or centrally supported with one drive wheel 5 at each end. The drive wheels 5 of each separate module 1 are separated by 180° relative to each other.

In the front of the pulling tool, a connector adapter 3 is provided for connecting tools thereto.

According to one embodiment, a control and drive section 2 is disposed at the end of the pulling tool, which communicates with the surface through a cable or coiled tubing 29.

The rotational moment to driving wheels 5 is applied through cog wheel 9, which is centrically mounted on the longitudinal axis of the pulling tool. That is, the rotational moment is transferred from cog wheel 9, through cog wheel 8 and shaft 7, to an angular gear comprising cog wheels 11 and 12, and then through cog wheel gears 21, 13, 14, 15, and 16, which transfer the rotational moment to drive wheels 5. Figs. 2a and 3 detail this arrangement in the case of two lever arms 4 each having its own single drive wheel 5.

hi the case of centre-supported lever arms 4 (cf. fig. Ib) having two drive wheels 5 on the same lever arm, the rotational moment is transferred from a drive shaft 7 according to the same principle as explained above, except that the moment transferred from the drive shaft to cog wheels 12 and 11 applies forces to both drive wheels 5 simultaneously through the respective cog wheel connections 20, 35, 25, and 20, 22, 25 according to fig. 2c.

An overload connection 17 is provided in conjunction with angular gear 12 and shaft 7, with pretension being adjusted by a spring 18, cf. fig. 2a. Cog wheel gears 8 and 9 are provided at each end of the through drive shaft 7, so that the transfer of moment from one individual module to the next is accomplished centrically through a cog wheel gear 9, cf. figs. 2a and 2b.

Angular gear 11 (cf. fig. 4a) may be supported by a ball-bearing 23, with lever arm 4 being supported by circular sliding surfaces 26. A similar principle may be used for centrally supported lever arms 4 having one drive wheel at each end thereof (ref. fig. 4b), in which case angular gear 12 may be supported by a ball-bearing 23 and lever arms 4 is supported by circular sliding surfaces 26.

According to one embodiment, lever arm 4 may be actuated by means of a hydraulic fluid pressure acting on pistons 25 engaged with a cogging element 32 connected to lever arm 4, cf. fig. 5a. A similar principle may be used for a center-supported lever arm 4 having two wheels, in which case lever arm 4 may be actuated by means of a hydraulic fluid pressure acting on pistons 28 in meshed engagement 32 with cog wheel shaft 32, cf. fig. 2b.

Drive wheels 5 may be supported by a ball-bearing 36 of lever arm 4, cf. fig. 6. A similar principle may be used for center-supported lever arms 4 having one drive wheel 5 at each end.

According to one embodiment, the pulling tool may include an overload connection that switches off the power to a drive wheel without significantly affecting the power to the remaining drive wheels. The lever arm still will force the wheel against the wellbore or pipe wall and make sure that the pulling tool remains centered in the wellbore/pipeline. According to one embodiment, such an overload connection may include a conical member 24 with an associated spring 18 (cf. fig. 4a).

As mentioned above, the pulling tool according to one embodiment may be assembled from a number of separate modules 1, it being understood that each separate module 1 may include one or more drive wheels. Hence, the necessary pulling/pushing force may be provided by putting together a sufficient number of individual modules 1. If more than one separate module 1 is used, the drive wheels 5 of each separate module 1 may be positioned so as to form an angle of 90°, for example, to the drive wheels 5 of the previous and/or following separate module 1. Such a configuration may help improving the ability of the pulling tool to self-center within the substantially circular and extended reach wellbore or pipeline, as well as significantly improve the traction. It is understood that other angles may also be used, e.g. 45°, 60°, 120°, etc.

Each separate module 1 is configured so that adaptor elements for transferring rotational forces and carrying lines and liquid across angles of 45°, 60°, 90°, 120°, etc., for example, may be provided between modules 1, with the separate modules being more or less identical and the adaptor elements determining the radial angles of the drive wheels of each following separate module.

Power may be supplied through electric cables from the surface and through an electro motor for the gear transmission, or alternatively by means of a liquid motor/turbine driven by drilling fluid in connection with coiled tubing operations, for example.

While the pulling tool according to the present description has been described mainly with reference to wellbore operations, it is understood that the device may be equally applicable to other types of pipe systems, such as water pipelines or buried or surface oil and gas pipelines, for example.

It is also understood that the size may be adapted and configured according to the particular needs. The functioning of the lever arms as such gives the pulling tool a relatively wide area of application with respect to the inner dimension of the wellbore or pipeline. According to one embodiment, it is also possible to use articulated adaptor elements between individual modules 1, so that the pulling tool is able to get past bends in a pipeline. Also, in such an embodiment, the function of the lever arm will help allowing for relatively sharp bends to be traversed by means of a device according to the present invention, without the device getting stuck. Reference numerals of the drawings:

1 Drive section including drive wheel

2 Controller

3 Adapter for auxiliary tools

4 Moment arm

5 Drive wheel

6 Pipe / Wellbore wall

7 Drive shaft

8 Cog wheel

9 Cog wheel

10 Bore/Cylinder for hydraulic fluid

11 Angular gear

12 Angular gear

13 Cog wheel

14 Cog wheel

15 Cog wheel

16 Cog wheel

17 Friction sleeve

18 Spring

19 Cover plate/ Bonnet

20 Cog wheel

21 Cog wheel

22 Cog wheel

23 Bearing

24 Conical end piece

25 Cog wheel

26 Sliding surface

27 Bore for electric power or hydraulics

28 Pistons with cogging

29 Power cable or Coiled tubing

30 Sliding surface/ Control

31 Moment arm support

32 Cogged center shaft

33 End abutment for friction connection of drive shaft

34 Spacer/Slide bearing

35 Cog wheel

36 Ball bearing

Claims

1. A pulling tool for transporting tools in a wellbore or pipeline comprising at least one cylindrical module (1) comprising a number of drive wheels (5) mounted on one or more lever arms (4), said lever arms being adapted for forcing said drive wheels (5) radially out against the wall of said wellbore or pipeline (6), characterized in that said drive wheels (5) are interlocked by way of a shaft (7) and an angular gear (11, 12) as well as a gear transmission comprising a number of cog wheels (13, 14, 15, 17, 21) forward to said drive wheels (5), said shaft (7) being eccentrically positioned relative to a center line of said modules (1).

2. The pulling tool of claim 1, characterized in that each lever arm (4) extends through and is centrally supported in said module (1) having one drive wheel (5) at each end.

3. The pulling tool of claim 1, characterized in that each lever arm (4) is end supported in said module (1) having one drive wheel (5) at the other and outer end of said lever arm (4).

4. The pulling tool of any of the preceding claims, characterized in that the pulling tool further comprises an overload connection consisting of a conical element (24) with an associated spring (18).

5. The pulling tool of any of the preceding claims, characterized in that said lever arms (4) are actuated by fluid pressure through hydraulic cylinders engaged with one cogging element (32) connected to said lever arm (4).