Not Applicable
1. Field of the Invention
The present invention is in the field of tools used to retrieve lodged or stuck items, called fish, from a well bore or casing.
2. Background Art
In the art of well drilling and workover, it is common to have a need to retrieve a stuck tool or other item from the well bore or casing. For the purposes of describing the invention herein, the terms casing and bore hole should be understood to mean any well bore, casing, or other tubing within which items may be lodged or stuck. Stuck items are commonly called fish. The fish may be a broken tool which has inadvertently stuck in the casing, or it may be a tool such as a whipstock, which is intentionally installed in the casing, to be removed or fished out later. Some types of fish have specially designed fishing tools which are suitable for latching onto a fishing contour on the uphole end of the fish. Others may be retrievable with a more general purpose fishing tool which is designed to latch onto many different configurations of fish. One example is a latch mechanism made up of a collet and a central spear, in which the central spear assists the collet in latching onto the fish.
Regardless of whether the fish is to be retrieved with a specially designed fishing tool or with a general purpose fishing tool, it is necessary for the tool to align with the fish, to a greater or lesser degree, depending upon the particular fish and the particular fishing tool. In some cases, as the fishing tool is run into the hole, the latch mechanism may be generally aligned with the center of the casing or bore hole, and the upper end of the fish may be aligned to one side, or vice versa. Such misalignment can make it very difficult to latch onto the fish with the fishing tool.
The possibility for such misalignment is even more likely to occur when the fish lies in a highly deviated or horizontal hole. In such situations, the operator usually relies upon gravity to deflect the fishing tool toward the same side of the casing as the uphole end of the fish. However, where an inflation element or whipstock is lodged in a highly deviated bore hole or casing, the uphole end of the fish may be positioned in the center of the hole, or even near the upper side of the deviated hole. Where gravity deflects the latch mechanism of the fishing tool toward the lower side of the deviated hole, latching onto this type of fish may be impractical at best. Since the present invention addresses the alignment of fish and fishing tools in deviated holes as well as vertical holes, the terms uphole and downhole will generally be used herein, it being understood that these terms mean the same as the terms upper and lower, respectively, in a vertical hole.
The currently known fishing tool may have bow centralizers installed to position the latch mechanism, or bent subs may be used to orient the latch mechanism properly via a trial and error type operation. These methods can be less than satisfactory, and they can consume valuable time.
The present invention provides a method and apparatus for guiding a latch mechanism and a fish into engagement, regardless of their relative positions in the bore hole or casing. The fishing tool is lowered downhole on a work string, until it is positioned just above a fish. The work string can be a wire line, where appropriate. In the running position, a plurality of guide fingers on the downhole end of the tool are retracted radially inwardly, minimizing the overall diameter of the tool. This can be accomplished with a sleeve at least partially surrounding the guide fingers, for example, contacting the outer edges or surfaces of the fingers to hold them radially inwardly. When the tool is just above the fish, a mechanical or hydraulic actuation mechanism shifts the sleeve longitudinally and expands the downhole ends of the guide fingers until the fingers contact the casing. The sleeve can have slots which contact radially extending tangs on the upper ends of the fingers to rotate the lower ends of the fingers radially outwardly.
In this expanded configuration, the guide fingers are arrayed in a basically frusto-conical array, with the base of the frusto-conical array downhole and the apex of the frusto-conical array uphole. A latch mechanism, such as a collet and spear assembly, is mounted on the fishing tool near the downhole end of the mandrel, and near the uphole ends of the guide fingers. Other types of latch mechanisms may also be used. The guide fingers are spaced as close together as possible to improve the guiding performance of the conical array, and minimize the likelihood of the uphole end of the fish passing between two guide fingers.
When the fingers are expanded, further lowering of the tool causes the conical array of expanded guide fingers to guide the uphole end of the fish and the latch mechanism into engagement with each other. More specifically, the combined inner surfaces of the guide fingers form a substantially conical guide cage for guiding the fish and the latch mechanism into engagement with each other. This may involve guiding the downhole end of the fishing tool toward the location of the uphole end of the fish, or vice versa, or a combination of both. After engagement of the fish with the latch mechanism, the fishing tool may be pulled uphole, retrieving the fish. During retrieval, the fingers can be retracted to some extent by shifting the sleeve relative to the mandrel, depending upon the type of latch mechanism used and upon the type of fish. Where a mechanically actuated guide mechanism is used, re-entry of the tool into a smaller tubular can reverse the action of the actuation mechanism, to shift the sleeve downwardly, thereby retracting the fingers.
The novel features of this invention, as well as the invention itself, will be best understood from the attached drawings, taken along with the following description, in which similar reference characters refer to similar parts, and in which:
As shown in
A longitudinal fluid bore 13 within the mandrel 19 and one or more main ports 15 through the spear 34 form a fluid passage provided to conduct pressurized fluid, from a pump (not shown) at the well site, through the tool 10 to the space below the lower end of the mandrel 19. The main ports 15 could alternatively be provided through other latch mechanisms or through the lower end of the mandrel 19 itself. The bore 13 and one or more actuation ports 36 through the wall of the mandrel 19 also form a fluid passage to conduct pressurized fluid into an annular space or chamber 38 between the mandrel 19 and the hollow piston 14. A tell-tale hole 40 can also be provided through the spear 34, or alternatively through the lower end of the mandrel 19, from the bore 13 to the space below the lower end of the mandrel 19. A spring such as a wave spring 42 can be provided in a space between the uphole end of the collet 32 and the downhole end of the mandrel 19, to force the collet 32 downwardly against the fluid backpressure, into abutment with the uphole end of the finger cage 20. This keeps the collet 32 longitudinally aligned with the tell-tale hole 40 regardless of increased fluid pressure, to block the tell-tale hole 40 until latching occurs, as described below.
When the tool 10 has been lowered into the bore hole in the running configuration shown in
As better seen in
The embodiment shown in
Preferably, the inner or outer surfaces of the downhole ends 30 of the fingers 18 can be beveled, so that the downhole ends 30 of the fingers 18 present a low profile as they lie against the casing C. This provides a relatively thin wedge shape to wedge between the casing C and almost any shape of fish F that may be encountered, regardless of the positioning of the fish relative to the casing C. Alternatively, the downhole ends 30 of the fingers 18 could be shaped as appropriate to surround a particular fish that is to be removed. In any case, as shown in
As shown in
When the fish F is latched, a shoulder on the fish F is captured by one or more shoulders on the interior of the collet 32, to securely engage the fish F to the collet 32. During pulling, the weight of the fish F pulls the collet 32 downwardly to abut the upper end of the finger cage 20, and the weight of the fish F is borne by the mandrel 19, the mandrel skirt 21, the finger cage 20, and the collet 32. One or more of the fingers 18 may become free to rotate slightly in its respective sleeve slot 46 during pulling, depending upon the angle between the fish F and the tool 10, and depending upon the relative position of the finger sleeve 16. Further, fluid pressure may be dropped by the operator during pulling, allowing the piston 14 and the sleeve 16 to be shifted downwardly by the spring 22, thereby allowing one or more of the fingers 18 to pivot toward its retracted position. The degree to which any of the fingers 18 retract may be determined by the degree of interference, if any, between the fish F, and the fingers 18.
In accordance with the present invention, a second embodiment of the tool 10′ is shown in
In
When the tool 10′ has been lowered into the bore hole in the running configuration shown in
When the fish F is latched, as explained above, a shoulder on the fish F is captured by one or more shoulders on the interior of the collet 32, to securely engage the fish F to the collet 32. During pulling, the weight of the fish F pulls the collet 32 downwardly to abut the upper end of the finger cage 20, and the weight of the fish F is borne by the mandrel 19, the mandrel skirt 21, the finger cage 20, and the collet 32. One or more of the fingers 18 may become free to rotate slightly in its respective sleeve slot 46 during pulling, depending upon the angle between the fish F and the tool 10′, and depending upon the relative position of the finger sleeve 16. Further, as the tool 10′ withdraws into the tubular element T during pulling, the bow spring 50 is forced back to its smaller diameter constrained condition, forcing the lower end 54 of the bow spring 50 downwardly, causing the sleeve 16 to be shifted downwardly, thereby allowing one or more of the fingers 18 to pivot toward its retracted position. The degree to which any of the fingers 18 retract may be determined by the degree of interference, if any, between the fish F, and the fingers 18.
It can be seen that the fingers 18 can be either mechanically expanded or mechanically retracted, or both, by the action of the bow spring 50 as it interacts with the smaller diameter tubular element T. Further, it can be seen that, where both the bow spring 50 and the piston 14 are included in the tool 10′, expansion of the fingers 18 can be hydraulically accomplished or assisted. In an application where hydraulic actuation is planned, the bow spring 50 can be constrained to its retracted condition during run-in, for example, by restraining the piston 14 in its lower position by means such as a shear pin (not shown). Hydraulic actuation of the tool 10′ will then shear the pin, and thereafter the tool 10′ functions as explained above. In an application where mechanical actuation is planned, removal of the shear pin before running the tool 10′ downhole allows mechanical actuation of the tool 10′ by means of the action of the bow spring 50, as the tool 10′ exits the tubular element T.
While the particular invention as herein shown and disclosed in detail is fully capable of obtaining the objects and providing the advantages hereinbefore stated, it is to be understood that this disclosure is merely illustrative of the presently preferred embodiments of the invention and that no limitations are intended other than as described in the appended claims.
This is a continuation-in-part patent application of U.S. patent application Ser. No. 10/260,211, filed on Sep. 26, 2002, now U.S. Pat. No. 6,719,052 and entitled “Latch Mechanism Guide.”
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Number | Date | Country | |
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20040262005 A1 | Dec 2004 | US |
Number | Date | Country | |
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Parent | 10260211 | Sep 2002 | US |
Child | 10823384 | US |