Fishing overshot tool   

BACKGROUND OF THE INVENTION

In the hydrocarbon recovery industry stuck tools are known to all but the very newest hands. Tools can become stuck in the downhole environment in more ways than one would be happy to recount and they occur often. For this reason “Fishing” has developed as an industry. Fishing tools are designed to be run in the hole to ultimately engage the stuck tool (“fish”) and pull it out of the hole. Over the years fishing has been very successful in developing tools to accommodate most every iteration of a stuck tool. In most cases however, the range of a specific tool with respect to the size fish it can engage is about plus or minus 1/16 inch. Due to the limited range of individual tools and the plethora of tool sizes that might and do become stuck, a great many fishing tools must be stocked to ensure that a right sized tool is available to retrieve whatever is stuck in the well. Having such a large number of tools at the ready can be expensive if an operator intends to stock his own and requires a lot of storage space, or in the event that a fishing operator will be engaged to bring tools to remove the stuck tool, can create undesirable delays. The art will therefore be receptive to alternatives to traditional fishing tools.

SUMMARY

A fishing tool gripper head including at least one moveable jaw of a set of jaws, a motivator including one or more of an SMA, SMP, or EAP material in operable communication with the at least one moveable jaw.

A method for engaging a fish in a wellbore including running a fishing tool with an adjustable gripper head and facilitating a threshold condition at the gripper head to cause a change in the dimension of the gripper head, the method further including engaging a fish.

BRIEF DESCRIPTION OF THE DRAWINGS

Referring now to the drawings wherein like elements are numbered alike in the several Figures:

FIG. 1 is a schematic side view of a wire wrapped gripping head as disclosed herein;

FIG. 2 is a schematic end view of torsion spring wrapped embodiment;

FIGS. 3A and 3B are sequential views (unactuated and actuated, respectively) of another embodiment.

DETAILED DESCRIPTION

A detailed description of one or more embodiments of the disclosed apparatus and method are presented herein by way of exemplification and not limitation with reference to the Figures.

An adjustable gripper head 10 as referred to herein may have one or more engagement jaws 12 that are movable radially inwardly or radially outwardly or both depending upon the construction and intent of the fishing tool of which they will be a part. In all cases, at least one of the set of engagement jaws will be mobile. For purposes hereof, the term set includes one or more. This will be the case whether or not one or more other of the segments (if more than one) are mobile. The mobility of the segments in conjunction with a motivator 14 to cause movement thereof is discussed further hereunder with reference to the figures.

Referring to FIG. 1, a plurality of segments or jaws 12 are illustrated with at least one of a shape memory alloy or polymer, or an electrically activated polymer wire 14 helically wrapped therearound. It is noted that the material can also be combined with other materials and remains within the scope of this disclosure. Because each of the materials noted has the capability of changing dimension upon a temperature change or upon the application of a voltage thereto, each can be configured to act as a motivator for the one or more mobile segments 12. In the particular embodiment illustrated in FIG. 1, the gripper head 10 comprises two jaws 12 that are illustrated as diametrically opposed to one another. This arrangement could have merely two jaws or could have another number of jaws that are positioned outside the plane of the cross section illustrated. Either or both of the illustrated jaws 12 can be configured to be movable as desired. In either case, the spacing between the jaws 12 is adjustable through actuation of the wire motivator 14 wrapped therearound, the wire being fixedly located at both longitudinal ends thereof (or some other spaced apart locus for affixation not necessarily at the end of the wire 14). As will be recognized, shape memory alloys, shape memory polymers and electrically activated polymers all can be configured to, under a temperature threshold or electrical input threshold, change their shape. One of the changes that is possible is length of the material in a wire form. This is the configuration employed in the embodiment illustrated in FIG. 1. When a temperature to which the motivator 14 is exposed or an electrical input to which the motivator 14 is exposed exceeds a selected value, the material will shorten axially of the wire material itself. This causes a shortening of the wire 14. Because the wire is affixed at its longitudinal ends or at least at some spaced apart location therealong, the shortening of the wire 14 causes an effective radial load to be placed upon the jaws or segments 12. This will cause the at least one mobile segment or jaw 12 to move radially inwardly thereby reducing the distance between the jaws 12. The reduction in distance makes the gripper head 10 more tolerant to different size fish. Rather than being restricted to a tolerance of about plus or minus 1/16 inch, the tolerance of the gripping head as disclosed is about plus or minus ⅛ inch. Further, while the illustration contemplates an adjustability from a rest position to an actuated position that is smaller than the rest position, it will be understood that the capability of shape memory alloys, shape memory polymers and electrically activated polymers or combinations including at least one of the foregoing (hereinafter SMA, SMP and EAP) is not limited to a shortening of the material but rather can also be configured to lengthen the material. Therefore it will be appreciated that the illustration of FIG. 1 can be reversed such that the restring position is the smallest position and the actuated position is a larger diametric position.

In a second embodiment, and referring to FIG. 2, a band 20 of SMA, SMP, EAP or combinations including at least one of the foregoing is positioned around a set of jaws or segments 12 similar to that of the foregoing embodiment of FIG. 1. Each of the operational features or the FIG. 1 embodiment applies to the embodiment of FIG. 2. In this embodiment, a greater actuation force is achievable due to the increase in amount of SMA, SMP, EAP or combinations including at least one of the foregoing employed. The greater force capability comes at the expense of increased material cost for manufacturing. Again, as in the embodiment of FIG. 1, the components may be reversed in operation to expand rather than contract the arrangement.

Referring to FIGS. 3A and 3B, a different configuration of is employed to directly act upon one of the jaws 12 at a time, one being shown. It will be understood that one or more jaws in a set of jaws may be configured as illustrated in FIG. 3. In this embodiment the shape change capability of SMA, SMP, EAP or combinations including at least one of the foregoing is being utilized differently than in the previously disclosed embodiments in that the shape change directly rather than a length change caused by the shape change is employed. A review of the difference between FIGS. 3A and 3B clearly illustrated the direct displacing action of the embodiment. As in the foregoing embodiments, the components may be easily reversed to cause the jaws 12 to move radially inwardly or radially outwardly depending upon the action desired in the tool.

While preferred embodiments have been shown and described, modifications and substitutions may be made thereto without departing from the spirit and scope of the invention. Accordingly, it is to be understood that the present invention has been described by way of illustrations and not limitation.