FIELD

The present invention relates to a wellbore tool and in particular to a tubing anchor catcher.

BACKGROUND

Various types of tubing anchor catchers have been devised for anchoring the tubing string and catching a string in the event that the tubing string is severed above the tubing anchor catcher.

SUMMARY

In accordance with a broad aspect of the present invention, there is provided a tubing anchor catcher comprising: a mandrel for connection to a tubing string, the mandrel having upper and lower ends each configured for connection into a tubing string, an enlargement on the upper end, an enlargement on the lower end and therebetween a smaller diameter necked region on the outer surface of the mandrel; a slip cage assembly carried on the mandrel necked region; and a J-slot mechanism between the mandrel and the slip cage assembly, the J-slot mechanism including a J- slot including a pathway of slots and a control pin over which the pathway of slots ride and wherein the J-slot mechanism is selectable between at least a run in position, a tubing anchoring position, a tubing catching position and a run out position relative by axial movement upwardly or downwardly of the mandrel through the slip cage.

It is to be understood that other aspects of the present invention will become readily apparent to those skilled in the art from the following detailed description, wherein various embodiments of the invention are shown and described by way of illustration. As will be realized, the invention is capable of other and different embodiments and its several details are capable of modification in various other respects, all within the present invention. Furthermore, the various embodiments described may be combined, mutatis mutandis, with other embodiments described herein. Accordingly, the drawings and detailed description are to be regarded as illustrative in nature and not as restrictive. BRIEF DESCRIPTION OF THE DRAWINGS

Referring to the drawings, several aspects of the present invention are illustrated by way of example, and not by way of limitation, in detail in the figures, wherein:

Figure 1 is a side, isometric view of a tubing anchor catcher.

Figure 2a (i) is a side elevation view of the tubing anchor catcher of Figure 1 in a run in position (Pos 1) in a wellbore;

Figure 2a (ii) is a side elevation view of the tubing anchor catcher of Figure 2a (i) in a tension anchoring position (Pos 2) in a wellbore;

Figure 2a (iii) is a side elevation view of the mandrel of the tubing anchor catcher of Figures 2a (i) and 2a (ii) showing the direction of mandrel movement required to move the tubing anchor catcher from Pos 1 to Pos 2 and the path through which the control pin of the outer slip cage moves through the control slots on the mandrel;

Figure 2b (i) is a side elevation view of the tubing anchor catcher of Figure 1 in a wellbore, the tubing anchor catcher is in an anchoring, tensioning position (Pos 2), which is the same as Figure 2a (ii);

Figure 2b (ii) is a side elevation view of the tubing anchor catcher of Figure 2b (i) in an anchor catching position (Pos 3) in a wellbore;

Figure 2b (iii) is a side elevation view of the mandrel of the tubing anchor catcher of Figures 2b (i) and 2b (ii) showing the direction of mandrel movement and the path for moving the tubing anchor catcher from Pos 2 to Pos 3;

Figure 2c (i) is a side elevation view of the tubing anchor catcher of Figure 1 in a transitional position near to Pos 3, but where the upper slips are not yet expanded;

Figure 2c (ii) is a side elevation view of the tubing anchor catcher of Figure 2c (i) in a run out position (Pos 4) in a wellbore; Figure 2c (iii) is a side elevation view of the mandrel of the tubing anchor catcher of Figures 2c (i) and 2c (ii) showing the direction of mandrel movement for moving the tubing anchor catcher from Pos 3 to Pos 4 and the path through which the control pin moves through the control slots during this movement;

Figure 3 is a side elevation of the tubing anchor catcher of Figure 1 in a run in position (Pos 1);

Figure 4 is a side, isometric view of another tubing anchor catcher;

Figure 5a (i) is a side elevation view of the tubing anchor catcher of Figure 4 in a run in position (Pos 1A);

Figure 5a (ii) is a side elevation view of the tubing anchor catcher of Figure 5a (i) in a tension anchor/rotation position (Pos 2A) in a wellbore;

Figure 5a (iii) is a side elevation view of the mandrel of the tubing anchor catcher of Figures 5a (i) and 5a (ii) showing the direction of mandrel movement required to move the tubing anchor catcher from Pos 1A to Pos 2A and the path through which the control pin of the outer slip cage moves by the indicated movement through the control slots of the mandrel;

Figure 5b (i) is a side elevation view of the tubing anchor catcher in a wellbore in a tension anchor/rotation position (Pos 2A), which is the same as Figure 5a (ii);

Figure 5b (ii) is a side elevation view of the tubing anchor catcher of Figure 5b (i) in an anchor catching position (Pos 3A) in a wellbore;

Figure 5b (iii) is a side elevation view of the mandrel of the tubing anchor catcher of Figures 5b (i) and 5b (ii) showing the direction of mandrel movement and the path for moving the tubing anchor catcher from Pos 2A to Pos 3A;

Figure 5c (i) is a side elevation view of the tubing anchor catcher of Figure 4 in a transition position near an anchor catching position (Pos 3A) in a wellbore;

Figure 5c (ii) is a side elevation view of the tubing anchor catcher of Figure 5c (i) in a run out position (Pos 4A) in a wellbore; Figure 5c (iii) is a side elevation view of the mandrel of the tubing anchor catcher of Figures 5c (i) and 5c (ii) showing the direction of mandrel movement for moving the tubing anchor catcher from Pos 3A to Pos 4A and the path through which the control pin moves through the control slots during this movement;

Figure 6 is a side elevation of the tubing anchor catcher of Figure 5a (i) in a run in position (Pos 1A); and

Figure 7 is a quarter section through the tubing anchor catcher of Figure 6.

DETAILED DESCRIPTION OF EMBODIMENTS

The detailed description set forth below in connection with the appended drawings is intended as a description of various embodiments of the present invention and is not intended to represent the only embodiments contemplated by the inventor. The detailed description includes specific details for providing a comprehensive understanding of the present invention. However, it will be apparent to those skilled in the art that the present invention may be practiced without these specific details.

Figures 1 to 3 illustrate a tubing anchor catcher according to one aspect of the present invention.

The tubing anchor catcher includes a mandrel 1 and a slip cage 3 carried rotatably and concentrically on the mandrel. In use, the tubing anchor catcher is intended to be coupled in line to a tubing string T. In particular, mandrel 1 has a tubing string tubular of the tubing string coupled, for example threaded, onto its upper threaded end 13a and another tubing string tubular coupled to its lower threaded end or lower sub 13b.

The mandrel includes a necked area la between an enlarged upper end lb and an enlarged lower end 1c. The necked area has an outer diameter smaller than the outer diameters at the enlarged ends. The slip cage 3 can ride up and down along the necked area, but cannot move upwardly past the upper enlarged end lb and cannot move downwardly past the lower enlarged end 1c.

There is an upper ramped frustoconical surface lb' in between the necked area la and enlarged upper end lb and there a lower ramped frustoconical surface 1c' in between the necked area la and enlarged lower end 1c. Slip cage 3 includes a cylindrical housing and a plurality of upper slips 4a carried on the cylindrical housing. There may also be a plurality of lower slips 4b carried on the cylindrical housing. The slip cage cylindrical housing also carries drag blocks 5 biased outwardly by springs 5a (Figure 7). A retainer clip 6 is coupled, as by a fastener 7, to the cylindrical housing and extends across an outward facing portion of each drag block 5 to act against the biasing springs 5a, to limit the outward extension of the drag blocks. In one embodiment, upper slips 4a are each configured integral with a drag block and the lower slips are each configured integral with a drag block. In such an embodiment, each retainer clip 6 can extend across the combined slip/drag block members between the slip outer facing surface and the drag block outer facing surface, such that the combined members can pivot around their retainer clips. For example, the combined members can rock back and forth, wherein each slip can pivot outwardly, while its attached drag block pivots inwardly and vice versa.

Drag blocks 5 permit relative movement between the slip cage and the mandrel. In particular, the drag blocks are selected to firmly drag along the wellbore wall when the tubing anchor is moved. This permits the slip cage 3 to remain in place in the well, while mandrel is moved up and down through it. However, if enough force is applied, the drag blocks do move with the tubing string. Normally, springs 5a bias the drag blocks out and ensure that the drags blocks are in contact with the wellbore wall.

The plurality of upper slips 4a, are normally retracted to a retracted diameter. In this embodiment, normally, springs 5a bias the drag blocks out, which pivots the toothed faces of the slips to be retracted. The upper set of slips 4a can, however, be expanded to an expanded diameter, which is larger than the retracted diameter. Expansion of the upper set of slips 4a occurs when frustoconical surface lb' of the enlarged upper end lb of the mandrel is moved down behind the backside 4a' of the slips 4a. Slips 4a are coupled to the slip cage and backsides 4a' are ramped in a reverse angle to frustoconical surface lb' so that when the mandrel is moved down while slip case is retained against movement by the drag blocks, frustoconical surface lb' is driven under the slips 4a and they expand radially outwardly. This is shown in Figure 2b (ii), and identified as Pos 3, Anchor Catcher Position. By selection of the retracted diameter to be less than an inner diameter of a wellbore wall W in which the tubing anchor is to be used, upper slips 4a do not hinder movement of the tubing anchor catcher through the well. This is shown in Figure 2a (i) and identified as Pos 1, Run in position and in Figure 2c (ii), Pos 4, Run out position. However, by selection of the expanded diameter across slips 4a to be more than the inner diameter of the wellbore wall W, upper slips 4a can be employed to catch a tubing string connected to the mandrel threaded ends 13a, 13b, should the tubing string start to fall within the well. This is shown in Figure 2b (ii) identified as Pos 3, Anchor Catcher Position. Figure 2c (i) shows a transitional position near to Pos 3, but where slips 4a remain spaced from the surface lb' and are therefore not expanded.

The tubing anchor catcher lower slips 4b act in a similar manner as upper slips but are expanded by lower frustoconical surface 1c' on the enlarged lower end 1c of the mandrel, to prevent selected instances of upward movement of the tubing string. Generally, this may be used to pull the anchor the tubing string and possibly to pull it into tension, which may be the normal set position of the tubing anchor catcher when it is in use downhole. This position is shown in Figure 2a (ii) and Figure 2b (i), and identified as Pos 2, Tension anchor position.

To control the movement of the tubing anchor between the various positions, the tubing anchor catcher further includes a J-slot mechanism between mandrel 1 and slip cage assembly 3. The J- slot mechanism includes a J-slot including a pathway of slots 2a and a control pin 2b that rides in the pathway of slots. The J-slot pathway 2a and control pin 2b cooperate such that tubing anchor catcher is configurable between at least the run in position Pos 1, the set, anchor catching position Pos 3 and the run out position Pos 4 by moving the pathway of slots 2a relative to the control pin 2b. This is achieved by axial movement upwardly and/or downwardly of the mandrel through the slip cage.

Generally, the pathway of slots 2a is a groove on the outer surface of mandrel 1 in the necked area la and control pin 2b is carried, inwardly extending on the inner facing surface of slip cage 3.

Movement of the mandrel is achieved by movement of the drill string in which the mandrel is coupled. The tubing anchor catcher is set and operated through the various positions by up and down motion of the mandrel relative to the slip cage. This up and down axially directed movement allows the control pin to initiate the rotation of the mandrel within the slip cage instead of by rotational motion of the tubing string, and thereby the mandrel, from surface. Setting and releasing the tubing anchor catcher through up and down motion is straightforward and easy to control. For moving the tubing anchor catcher from one position to another, there is no need to rotate the tubing string and thereby the mandrel from surface.

To further explain, the movement of the tubing anchor catcher from position to position is by interaction between the pathway of slots and the control pin. In particular, the pathway of slots 2a has a plurality of axially extending slots 2a 2a ₂ , 2a ₃ , 2a ₄ , which are each joined one to the next by an angled deflector 2ad. Angled deflectors 2ad are portions of the slot grooves that have side walls shaped with an angular surface leading from one slot to the next, always in one deflecting direction. All of the plurality of slots extend along a length of the mandrel, substantially parallel to the long axis of the mandrel. The distance that each of the axially extending slots stop relative to a frustoconical surface determines which position P os 1, P os 2, P os 3 or P os 4 the tubing anchor catcher will be in after the axial movement of the mandrel within the slip cage. More specifically, the pathway of slots has deflectors 2ad positioned about midway between the frustoconical surfaces. There is a short slot 2ai that extends from the midway point a length towards the upper end. An end wall 2a of slot 2ai creates a stop in the slot that spaces the slot a distance from upper frustoconical surface lb'. Joined to slot 2ai via an angled deflector is a long slot 2a ₂ that extends a distance from the angled deflector towards, and has its end wall close to, the frustoconical surface lc' on the lower end. Joined to slot 2a ₂ via another angled deflector is an upwardly extending long slot 2a ₃ . Long slot 2a ₃ extends parallel to slot 2a but has a length longer than slot 2ai such that its end wall 2a ₃ ' is close to frustoconical surface lb' on the upper end. Joined to slot 2a ₃ via another angled deflector is a downwardly extending short slot 2a ₄ . Slot 2a ₄ extends parallel to slot 2a ₂ , but has a length shorter than slot 2a ₂ .

It may be useful to have the pathway of slots continuous about the circumference of the mandrel. As such, another slot 2ai may be joined via an angled deflector after slot 2a ₄ . There may be a plurality of control pins on the slip cage, all of which ride in the pathway of slots and the pattern of slots in the pathway of slots may be duplicated around the circumference.

The control pin and pathway of slots are slidably locked together. Therefore, recalling that downhole slip cage assembly 3 is held in position by the drag blocks, movement of the mandrel up and down forces the slots to move past the control pin. Since the mandrel pathway of slots is restricted to ride over the control pin, movement of the mandrel up and down causes the mandrel to rotate slightly and move to ride over the control pin from slot to slot. The angled deflectors are axially aligned at the opening to each slot and the angled deflectors are angled to force the mandrel to rotate slightly upon moving a slot off the pin, such that the pin engages into the next slot. The mandrel cannot rotate backwards. In the illustrated embodiment, the mandrel is configured to move counterclockwise as the pathway of slots ride over the control pin.

The distances between the ends of the slots and the frustoconical surfaces determine how the slips will interact with mandrel. In particular, the end walls of slots 2ai and 2a ₄ are each spaced far enough from their adjacent frustoconical surfaces such that when those slots are riding on the control pin, the frustoconical surfaces cannot ride under and impact the slips. Thus, during run in (Pos 1, corresponding with slot 2aJ and during Run out (Pos 4, corresponding with slot 2a ₄ ) slips 4a, 4b remain retracted. However, the end walls of slots 2a2 and 2a ₄ are each close to their adjacent frustoconical surfaces such that when those slots are riding on the control pin, the frustoconical surfaces can ride under and expand the slips. Thus, when it is desired to anchor and tension the tubing anchor catcher (Pos 2, corresponding with slot 2a2), mandrel 1 can be pulled up with the slots moved along path P relative to control pin 2b until frustoconical surface lc' is pulled under slips 4b to bear against the backsides 4b' of the slips and expand those slips out. Slips 4b then jam in between wellbore wall W and the frustoconical surface lc' to allow the tubing string to be pulled up into tension.

Likewise, the tubing anchor catcher, of course, has a position Pos 3 where it can catch the tubing if the tubing starts to fall and forces the mandrel rapidly down through the slip cage, for example if the tubing is severed above the tubing anchor catcher. As such, should the tubing drop through the cage (Pos 3, corresponding with slot 2a ₄ ) frustoconical surface lb' is forced under slips 4a and they will expand out to hold the slip housing and thereby the mandrel and tubing string T from dropping. As in Figure 2b(iii), this happens when the mandrel drops (see arrow) and moves along a path P relative to control pin such that from slot 2a2 then slot 2a ₄ is located on the control pin.

Then, if it is desired to pull the tubing anchor catcher to surface, the mandrel can be pulled up to move slot 2a ₄ over the control pin. In this position, slip cage 3 is carried on the mandrel with slips 4b spaced from frustoconical surface lc' and the tubing anchor catcher is free to be pulled to surface with the tubing string.

If the tubing string never needed to be caught, the tubing string can be moved down to move the mandrel into a transitional position, as shown in Figure 2c(i) which is near to Pos 3, but where slips have not jammed against the frustoconical surface lb'. Then, the tubing string can be moved up to bring mandrel 1 into Pos 4, as shown in Figure 2c(ii) for running out.

The anchor anchor catcher also has a good annular bypass area between the slips. While there are a plurality of slips, the space between slips 4a, 4b is a relatively thin walled area 3a on the slip cage. Therefore, there is an open area A in the annular space about the tool, which is between each slip and drag block member around the anchor anchor catcher. The open area defines a fluid bypass for the tubing anchor catcher. The slip and drag blocks can be installed within raised sites on the slip cage and have an enlarged outer diameter compared to the smaller outer diameter across the thin walled area.

The anchor anchor catcher also has an additional shear out capability allowing the tool to be unset by pulling up until the shear out is achieved. This feature allows the tool to be unset and pulled to surface should any of the mechanisms plug or become seized during its engagement to the casing in the well. Shear pins 11 and shear ring 12, or other shear mechanisms, may be positioned adjacent lower sub 13 to allow the lower frustoconical surface lc' to be sheared away from slips 4b.

Figures 4 to 7 illustrate a rotatable version of the tubing anchor catcher.

This tubing anchor catcher is similar to the above-noted static tubing anchor catcher (Figures 1-3), but the embodiment of Figures 4-7 has a mandrel capable of rotating once set in Tension anchor position Pos 2 A in slot 2a _2A . This rotation allows tubing attached to the threaded ends of the mandrel to be rotated while the anchor catcher is set in the well. In particular, there is an annular area 2c below the J-slot mechanism pathway of slots 2a that has a uniform outer diameter. Slot 2a ₂ A opens into the annular area 2c. There are funneled guide walls 2c' that are raised, stepped up relative to annular area 2c. Funneled guide walls 2c' converge and lead from annular area 2c to slot 2a _2A . As such, should the mandrel begin to move down when the control pin 2d is in the annular area, the mandrel will readily move slot 2a ₂ A back over the control pin and rotate so that slot 2a _3A rides down along a path P over the control pin to the tubing catching position Pos 3A where control pin 2d is stopped against end wall 2a ₃ A . In so doing, slips 4a are expanded out over upper frustoconical surface lb' (Figure 5b(ii)) to prevent the tubing string from falling into the well.

The position of the lower limit 2c" of annular indented area 2c is close enough to lower frustoconical surface 1c' such that when slot 2a ₂ A is pulled up over control pin 2d, the slips 4b can be expanded out to tensioning position Pos 2 A and while the mandrel can be rotated.

The end wall 2a _4A ' of slot 2a _4A is separated from, not open to, annular indented area 2c. In other words, the groove of the slot does not extend down to area 2c and there is a raised portion of mandrel that forms end wall 2a ₄ A in between. Therefore, when the control pin is in slot 2a ₄ A and thereby in the run out position Pos 4A, slips 4b are maintained in a spaced position away from frustoconical surface 1c' and mandrel 1 cannot rotate within the slip cage 3 (Figure 5c (ii) and (iii)).

In such the embodiment of Figures 4-7, there may be a bearing 9 between the lower cone 8 that defines lower frustoconical surface 1c' and the mandrel. Thus, mandrel 1 can rotate even when lower cone 8 is engaged under slips 4b. Lower cone 8, which defines lower frustoconical surface lc', is an annular structure, installed encircling the mandrel and the bearing therefore accomodates rotation of the mandrel within the lower cone. Seals 10 may be installed to protect bearing 9 from fouling.

It will be understood by those skilled in the art that the drag and slip functions can be separated such that drag blocks can act independently of the slips and the slips can be help radially inward by springs or other means and forced outward by contact with the frustoconical surfaces in the upward or downward directions as explained previously.

Although specific embodiments of the invention have been described herein in some detail, this has been done solely for the purposes of explaining the various aspects of the invention, and is not intended to limit the scope of the invention as defined in the claims that follow. Those skilled in the art will understand that the embodiment shown and described is exemplary, and various other substitutions, alterations and modifications, including but not limited to those design alternatives specifically discussed herein, may be made in the practice of the invention without departing from its scope.