TOGGLE OVERSHOT
An overshot includes a sleeve. A coupling member having a latched state and an unlatched state is disposed at a first end of the sleeve. A load-responsive toggle mechanism for alternating the coupling member between the latched state and the unlatched state is disposed at a second end of the sleeve.
This application claims benefit of U.S. Provisional Application No. 61/040,981 filed Mar. 31, 2008.
STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENTNot Applicable.
BACKGROUND OF THE INVENTION1. Field of the Invention
The invention relates generally to a wireline overshot for connecting a wireline to an article within a borehole (or within a downhole tool in the borehole) and/or for retrieving an article from a borehole (or from a downhole tool disposed in the borehole).
2. Related Art
A “wireline” overshot is used to connect a wireline to an article within a drill string. The article can be, but need not be limited to, a wireline coring inner barrel, a soft material sampling tool, a data gathering assembly, or an optional portion of a downhole drilling assembly. The wireline overshot may also be referred to as a fishing tool. In one example, the wireline overshot connects to the article within the drill string by latching over a spearhead coupled to the article. In another example, the wireline overshot may latch onto the article within the drill string by engaging a circular (or receiving) portion of the article. The wireline is commonly a flexible wire rope but may also be a solid wire (or “slickline”), synthetic braided rope, or small-diameter, flexible tubing. The wireline is typically lowered and raised by a winch.
In a typical core barrel retrieval operation, a wireline overshot is lowered on the end of a wireline down the drill string, where it latches onto an inner tube assembly of a core barrel disposed within the drill string. The wireline overshot is then pulled back to the surface with the attached inner tube assembly. At the drill floor, the inner tube assembly is held in a clamp or lowered onto the drill floor. An operator releases the wireline overshot from the inner tube assembly manually and sets the wireline overshot aside. In cases where the wireline overshot needs to be unlatched from the inner tube assembly while still within the drill string, the method of unlatching the wireline overshot is commonly one of free-falling a release sleeve onto the wireline overshot, tensioning and releasing the wireline to ratchet a release pall, and repeated pulling or releasing of the wireline to shear a release pin. All of these operations require the wireline overshot to be reconfigured or rebuilt at the surface before it can function as an overshot again.
SUMMARYIn a first aspect of the invention, an overshot comprises a sleeve, a coupling member having a latched state and an unlatched state disposed at a first end of the sleeve, and a load-responsive toggle mechanism for alternating the coupling member between the latched state and the unlatched state disposed at a second end of the sleeve.
In a second aspect of the invention, an overshot comprises an outer sleeve and a coupling member disposed a first end of the outer sleeve. A first rotator is disposed within the outer sleeve and configured to alternately engage and disengage from the coupling member, thereby toggling the coupling member between an unlatched state and a latched state. A second rotator is disposed within the outer sleeve and configured to selectively displace and rotate the first rotator in response to an applied load. A weight member is disposed at a second end of the outer sleeve for applying a load to the second rotator.
In a third aspect of the invention, a method of connecting or disconnecting a wireline from an article comprises providing an overshot comprising a sleeve, a coupling member having a latched state and an unlatched state disposed at a first end of the sleeve, and a load-responsive mechanism for alternating the coupling member between the latched state and the unlatched state disposed at a second end of the sleeve. The method includes coupling a wireline to the load-responsive mechanism, aligning the article with the coupling member, and selectively activating the load-responsive mechanism to alternate the coupling member between the latched state where it engages the article and the unlatched state where it disengages from the article.
Other aspects of the invention will be apparent from the following description and the appended claims.
The accompanying drawings, described below, illustrate typical embodiments of the invention and are not to be considered limiting of the scope of the invention, for the invention may admit to other equally effective embodiments. The figures are not necessarily to scale, and certain features and certain views of the figures may be shown exaggerated in scale or in schematic in the interest of clarity and conciseness.
For the purpose of engaging an article of interest, the coupling member 14 is configured to mate with a coupling member on the article of interest, or vice versa. The coupling member 14 and the coupling member on the article of interest may have several different configurations suited for the intended purposes. In the example shown in
Returning to
The toggle mechanism includes an upper rotator 40 disposed about the shaft 24. The upper rotator 40 is held in place above the lower rotator 34 (and about the shaft 24) by a spring 42. The term “rotator,” as used herein and above, means a part that can rotate or that can rotate another part. In one example, the upper rotator 40 is configured to rotate the lower rotator 34. The upper rotator 40 is slidable along the shaft 24 upon application of a load to the upper rotator 40 by the weight jar assembly 44. For the upper rotator 40 to be slidable, the load applied by the weight jar assembly 44 must be sufficient to overcome the biasing force of the spring 42 holding the upper rotator 40 in place. As will be further explained below, the load should also be sufficient to overcome the biasing force of the spring 38 holding up the lower rotator 34, or the biasing force of the spring 38 holding up the lower rotator 34 should be less than that of the spring 42 holding up the upper rotator 40. A wireline (not shown) coupled to the weight bar 19 through the cap 60 is used to control the position of the jar stem 23 (of the weight jar assembly 44) within the sleeve 22. The jar stem 23 is movable between an upper position limited by the jar bushing 27 (at the upper end of the sleeve 22) and a lower position limited by the upper rotator 40. When the weight jar assembly 44 rests on the upper rotator 40, it applies a load to the upper rotator 40. As will be explained below, this load assists in shifting the lifting dogs 18 between the latched and unlatched states. Contact is required between the jar stem 23 and the upper rotator 40 to allow the weight jar assembly 44 to apply a load to the upper rotator 40. Contact can be achieved in one of two ways. One way is by letting go of tension in the wireline (not shown) coupled to the weight bar 19 so that the jar stem 23 slides down the shaft 24 to contact the upper rotator 40. The other way is by moving the overshot 10 upwardly so that the upper rotator 40 slides up the shaft 24 to contact the jar stem 23. A jar bushing 51 is disposed within the sleeve 22 and locked to the sleeve 22 by fasteners 53. A key holder sleeve 46 is mounted inside the sleeve 22 and attached to the jar bushing 51. The key holder sleeve 46 is generally concentric with the upper rotator 40, the lower rotator 34, and the shaft 24. The jar stem 23 is sized to slide through the jar bushing 51 into the key holder sleeve 46 as needed to contact the upper rotator 40. The jar stem 23 includes a bore 47 which fits over the shaft 24, thereby allowing the jar stem 23 to travel along the shaft 24.
In
To release the lifting dogs 18 from the spearhead 16, the weight jar assembly 44 is again brought into contact with the upper rotator 40 to apply a load to the upper rotator 40, as shown in
The overshot 10 can be used to connect a wireline to an article, such as an oilfield tool, either at the surface or in a borehole. The overshot 10 can be disconnected from the article by the same action used in connecting the overshot 10 to the article, as described above. The overshot 10 can be used in any drilling or wireline operation. For illustration purposes,
While the invention has been described with respect to a limited number of embodiments, those skilled in the art, having benefit of this disclosure, will appreciate that other embodiments can be devised which do not depart from the scope of the invention as disclosed herein. Accordingly, the scope of the invention should be limited only by the attached claims.
Claims
1. An overshot, comprising:
- a sleeve;
- a coupling member having a latched state and an unlatched state disposed at a first end of the sleeve; and
- a load-responsive toggle mechanism for alternating the coupling member between the latched state and the unlatched state disposed at a second end of the sleeve.
2. The overshot of claim 1, wherein the load-responsive mechanism comprises a first rotator for selectively engaging the coupling and a second rotator for selectively displacing and rotating the first rotator.
3. The overshot of claim 2, wherein the load-responsive mechanism further comprises a weight member for applying a load to the second rotator that causes the second rotator to selectively displace the first rotator.
4. The overshot of claim 3, further comprising a first spring member supporting the second rotator, and wherein the load is selected to overcome a biasing force of the first spring member.
5. The overshot of claim 4, further comprising a second spring member supporting the first rotator, and wherein the load is selected to overcome a biasing force of second spring member.
6. The overshot of claim 3, wherein the weight member is selectively movable relative to the sleeve to contact the second rotator and apply the load to the second rotator.
7. The overshot of claim 3, wherein the second rotator is selectively movable relative to the sleeve to contact the weight member and receive the load from the weight member.
8. The overshot of claim 3, further comprising a wireline connector coupled to the weight member.
9. The overshot of claim 2, wherein the first rotator engages the coupling when the coupling is in the unlatched state and disengages from the coupling when the coupling is in the latched state.
10. An overshot, comprising:
- an outer sleeve;
- a coupling member disposed at a first end of the outer sleeve;
- a first rotator disposed within the outer sleeve and configured to alternately engage and disengage from the coupling member, thereby toggling the coupling member between an unlatched state and a latched state; and
- a second rotator disposed within the outer sleeve and configured to selectively displace and rotate the first rotator in response to an applied load; and
- a weight member disposed at a second end of the outer sleeve for applying a load to the second rotator.
11. The overshot of claim 10, further comprising an inner sleeve disposed within the outer sleeve.
12. The overshot of claim 11, wherein the inner sleeve comprises a plurality of keys and the first rotator comprises a plurality of keys, and wherein the keys on the inner sleeve and the keys on the first rotator selectively come into contact to rotate the first rotator relative to the inner sleeve.
13. The overshot of claim 11, further comprising a mechanism for selectively locking the first rotator to the inner sleeve.
14. The overshot of claim 13, wherein the mechanism comprises a plurality of key slots on one of the inner sleeve and first rotator and a plurality of keys on the other of the inner sleeve and first rotator.
15. The overshot of claim 13, wherein the mechanism further comprises at least one stop member coupled to the inner sleeve for selectively restricting motion of the first rotator.
16. The overshot of claim 10, wherein the coupling member comprises a pair of lifting dogs pivotally mounted on an axle.
17. The overshot of claim 16, wherein each of the lifting dogs has a first end for selectively engaging an article and a second end for selectively engaging the first rotator.
18. The overshot of claim 17, wherein the coupling member further comprises a spring disposed between the second ends of the lifting dogs for biasing the second ends in opposing directions.
19. The overshot of claim 10, further comprising a wireline connector coupled to the weight member for coupling the weight member to a wireline.
20. A method of connecting or disconnecting a wireline from an article, comprising:
- providing an overshot comprising a sleeve, a coupling member having a latched state and an unlatched state disposed at a first end of the sleeve, and a load-responsive mechanism for alternating the coupling member between the latched state and the unlatched state disposed at a second end of the sleeve;
- coupling a wireline to the load-responsive mechanism;
- aligning the article with the coupling member; and
- selectively activating the load-responsive mechanism to alternate the coupling member between the latched state where it engages the article and the unlatched state where it disengages from the article.
21. The method of claim 20, wherein activating the load-responsive mechanism comprises applying or releasing tension from the wireline.
22. The method of claim 20, wherein activating the load-responsive mechanism comprises moving the overshot upwardly.
Type: Application
Filed: Mar 30, 2009
Publication Date: Oct 1, 2009
Inventor: Harold M. Pardey (Sarasota, FL)
Application Number: 12/414,053
International Classification: E21B 31/18 (20060101); E21B 31/12 (20060101);