INJECTOR FOR LOGGING OR INTERVENTION STRING
A well logging- or well intervention string injector includes two adjacent motorized endless chains with gripper elements for bearing against the string. The gripping elements have an engagement packer against the string. The gripping elements run over the back supporting rollers carried by separate back supporting roller brackets. The back supporting roller brackets further bear against an elongated hydrostatic pressure equalizing cushion with hydraulic fluid. The pressure equalizing cushion bears against a back supporting rail.
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The present invention relates to an injector for a logging- or intervention string for use in petroleum wells. The string, that is to be injected may be a logging string such as a wire, a plain string by metal or composite material or a coiled tubing, carrying a logging tool or an intervention tool that operates down in the petroleum well.
The injector is located at a lubrication central at a lock-chamber at the top of the well. The logging tool, is placed into the lock-chamber and connected to the logging- or intervention string. The string extends up through the lubrication central to the injector. The logging or intervention string, is fed to, or from a reel at the deck and will not be discussed further here.
The injector comprises two adjacent chains with gripper elements. The two chains with the gripper elements is pressed against the intermediate string supported by rollers that in general is back supported by the two adjacent rails assisted by the springs so that the desired pressure from the gripper elements comes to force.
PRIOR ART AND PROBLEMS RELATED TO THISU.S. Pat. No. 6,216,780B1 describes a coiled tubing string injector with two adjacent motorized endless chains with gripper elements for bearing against the coiled-tubing string, wherein the gripper elements have an engagement packer to the string (0), and wherein the gripper elements runs over back supporting rollers at back supporting roller brackets. The back supporting roller brackets bear against an elongated thin rubber beam, a resilient gasket that again bear against a back supporting rail. The elongated thin rubber beam will absorb uneven portions locally, but if the rubber beam is compressed, it will only be locally resilient. The local pressure to the coiled tubing will then increase, the back supporting bracket will move away from the string, with the disadvantages of that the pressure to the direct nearby back supporting roller bracket is reduced, and thus the total hold to the string. One may risk that the coiled tubing is locally deformed. The pressure to the string is local increased where an elevation to the string occurs. It is especially undesirable that the local pressure and then the local mechanical load to a coiled tubing occurs since this may damage the tubing. Thus, one have to operate with a somewhat lower total pressure to the coiled tubing string than what one optimal could have used if there had not been any unevenness to the tubing. That result in that one have to operate with a lower upper limit for the pull or push load to the tubing than what is possible at the maximum. This, to have a limit for unevenness that may cause an excess of the maximum allowable local pressure to the tubing. Such a limitation affects the operational use of the coiled tubing injection by lower max load or shorter logging and intervention depths, both vertically and horizontally.
SHORT SUMMARY OF THE INVENTIONA solution to the problems by the prior art is a well logging- or well intervention string (0) injector comprising two adjacent motorized endless chains (16) with gripper elements (2) for bearing against the string (0),
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- wherein the gripping elements (2) have an engagement packer against the string (0),
- wherein the gripping elements (2) runs over the back supporting rollers (3) carried by separate back supporting roller brackets (4),
characterized in - that the back supporting roller brackets(4) bear against an elongated hydrostatic pressure equalizing cushion (5) with hydraulic fluid (15),
- wherein the pressure equalizing cushion (5) further a bears against a back supporting rail (6).
Advantageous embodiments of the invention are given in the independent patent claims.
ADVANTAGES BY THE INVENTIONAny unevenness, with extension comparable to the gripping elements extension, in the diameter or the surface of the string (0), will immediately be absorbed by the local back supporting bracket (4), moving the back supporting roller (3), and by that, the gripper element a small distance in the direction away from, or towards the string (0), to compensate the unevenness. The change in pressure for the locally disturbed back support roller bracket will be distributed by the hydrostatic pressure equalizing cushion (5) at all the other back supporting roller brackets so that
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- a) the unevenness easier will pass
- b) the pressure against the string (0) will be held more even local
- c) the total pressure to the string (0) will be held generally constant, which may result in an increased total pressure to the string (0) an by that get a stronger gripping force and thus higher pull or push load than by prior art, without risking unevenness in the string (0) to bring along a locally to high pressure.
The pressure equalizing cushion (5) may be compared in the way of working to a local hydraulic piston placed behind every back support roller, and that the hydraulic cylinder is hydraulic connected to each other so the pressure is distributed. However, the pressure equalizing cushion of the invention is a much simpler component than such hydraulic pistons since it will distribute the hydrostatic pressure immediately in its length direction and further distribute the mechanical load from the back supporting roller bracket via the back supporting rollers and the gripper elements that holds by an even pressure to the string.
The rubber beam of the U.S. Pat. No. 6,216,780B1 is resilient. The pressure equalizing cushion (5), according to the invention, is practically non-resilient. Neither locally, nor as a whole. This comparing to the rubber beam in the known U.S. patent, where one may say that the rubber beam performs a local spring resistance, F=kd, where d is the height of the unevenness that passes. The cushion is only flexible locally, with a global pressure distribution, so that it adapt the pressure to be generally equal for all the road of the back supporting roller brackets, and by that, equal for all the gripper elements. One gain at least two advantages: first one prevent parts of deformation of the coiled tubing when the coiled tubing passes the injector since the local unevenness in the diameter of the coiled tubing are met by a transfer under even pressure locally under the roller. Second, due to the fact that better distributed pressure, without risk of pressure tops, is ensured along the part of the coiled tubing passing through the injector, one may increase the total pressure, and thus the total gripping force to the coiled tubing, resulting in that one may drive the coiled tubing in or out of the well with a higher force. Higher force by injection may give an easier access for the logging or intervention strings to the farther, often deviated drilled parts, of the well.
The invention is illustrated in the attached figures and sketches.
The invention is a well logging- or well intervention string (0) injector, with two adjacent motorized endless chains (16), with gripper elements (2) for bearing against the string (0), wherein the gripper elements(2) have an engagement packer to the string (0), wherein the gripper elements (2) runs over back supporting rollers (3), carried by separate back supporting roller brackets (4), please see
In the Injector according to the invention the back supporting rail (6) is forced in the direction towards the string (0), back supported by two or more springs (12). According to an embodiment of this it is arranged two adjacent back supporting rails mutual forced against each other by the springs (12). In an embodiment shown in
The force from a row (16) of gripper elements (2) against the string (0) may in the shown embodiment be adjusted to a larger degree by tightening or loosening the spring bolt (13), or by replacing the spring (12). This has to be carried out at the same time for the whole back supporting rail. Alternatively, one may adjust the hydraulic pressure via a valve (52, 51) in the pressure equalizing cushion (5), se
Every gripper element (2) is in the shown embodiment, se
In an embodiment of the invention, the pressure equalizing cushion (5) comprises a flexible metallic house. The flexible metallic house has, in an embodiment illustrated in the attached figures, see
The rear facing of every back supporting roller bracket (4) that faces toward the pressure equalizing cushion (5) are chamfered or rounded by the edges, especially where a back supporting roller bracket meets the next, please see
The back supporting roller (3) is in the shown embodiment arranged at roller shafts (31) in pairs of side members (42) at the back supporting roller bracket (4). The back supporting roller (3) rotates at a roller axle bearing (32) at a roller axle (31). In this shown embodiment, a roller axle is then static arranged in the side member. In the illustrated embodiment in
In an embodiment of the invention, the pressure equalizing cushion (5) is arranged with sealed ends. In an embodiment the pressure equalizing cushion (5) comprises an inlet valve for hydraulic fluid (15). In an embodiment of the invention a the pressure equalizing cushion (5) is arranged with a ventilation valve (51), See
Claims
1. A well logging- or well intervention string injector comprising two adjacent motorized endless chains with gripper elements for bearing against said string,
- wherein said gripping elements have an engagement packer against said string,
- wherein said gripping elements run over back supporting rollers carried by separate back supporting roller brackets,
- wherein said back supporting roller brackets further bear against an elongated hydrostatic pressure equalizing cushion with hydraulic fluid, and
- wherein further said pressure equalizing cushion bears against a back supporting rail.
2. The injector according to claim 1, wherein said back supporting rail presses in the direction towards said string back supported by two or more springs.
3. The injector according to claim 2, wherein two adjacent back supporting rails are arranged and mutual forced against each other by springs.
4. The injector according to claim 1, wherein said pressure equalizing cushion comprises a flexible metallic hose.
5. The injector according to claim 1, wherein the cross section of said pressure equalizing cushion is rectangular.
6. The injector according to claim 1, wherein said pressure equalizing cushion has sealing ends.
7. The injector according to claim 1, wherein said pressure equalizing cushion comprises a valve for supply of hydraulic fluid.
8. The injector according to claim 1, wherein said pressure equalizing cushion comprises a ventilation valve to drain possible gas from said hydraulic fluid.
9. The injector according to claim 2, wherein said pressure equalizing cushion comprises a flexible metallic hose.
10. The injector according to claim 3, wherein said pressure equalizing cushion comprises a flexible metallic hose.
11. The injector according to claim 2, wherein the cross section of said pressure equalizing cushion is rectangular.
12. The injector according to claim 3, wherein the cross section of said pressure equalizing cushion is rectangular.
13. The injector according to claim 4, wherein the cross section of said pressure equalizing cushion is rectangular.
14. The injector according to claim 2, wherein said pressure equalizing cushion has sealing ends.
15. The injector according to claim 3, wherein said pressure equalizing cushion has sealing ends.
16. The injector according to claim 4, wherein said pressure equalizing cushion has sealing ends.
17. The injector according to claim 5, wherein said pressure equalizing cushion has sealing ends.
18. The injector according to claim 2, wherein said pressure equalizing cushion comprises a valve for supply of hydraulic fluid.
19. The injector according to claim 3, wherein said pressure equalizing cushion comprises a valve for supply of hydraulic fluid.
20. The injector according to claim 4, wherein said pressure equalizing cushion comprises a valve for supply of hydraulic fluid.
Type: Application
Filed: Aug 27, 2013
Publication Date: Mar 6, 2014
Applicants: Stimline AS (Kristiansand S), C6 Technologies AS (Stavanger)
Inventor: Mads BJØRNENAK (Kristiansand)
Application Number: 14/011,408