Downhole tool and method for perforating a downhole tubular

Abstract

A downhole tool, having an elongate tool housing, a collapsible sting (1), a press device, and a bending arm (2). The downhole tool may be run longitudinally in a bore of a downhole tubular arranged within a borehole in the Earth. The sting is pivotably mounted on a distal end of the bending arm, such that it can transition between a lying position and an erect position. With the sting in lying position, the downhole tool has a smaller lateral size than with the sting in erect position. In the erect position, the distal end of the sting laterally extends outside contours of the tool housing, whereas in the lying position the sting, including the base, may be fully within a lateral outer contour of the tool housing. The downhole tool can be used to perforate a wall of a downhole tubular arranged within a borehole in the Earth.

Description

[0001] DOWNHOLE TOOL AND METHOD FOR PERFORATING A DOWNHOLE TUBULAR

[0002] FIELD OF THE INVENTION

[0003] In a first aspect, the present invention relates to a downhole tool for perforating a downhole tubular installed in a borehole in the Earth. In another aspect, the invention relates to method of perforating a dow nhole tubular arranged within a borehole in the Earth.

[0004] BACKGROUND TO THE INVENTION

[0005] In the operation of oil / gas wells or other cased boreholes in the Earth, it can often become necessary' or beneficial to punch one or more holes through, or perforate, the casing which lines the well bore, or a production tubing or liner within the casing. Tools have been proposed to perforate the casing, and to subsequently inject sealing material into the space between the Earth formation around the bore hole and the casing through the perforation or perforations formed therein. Tools have also been proposed to perforate the casing and to arrange an insert in the perforation. Typical inserts include functional plugs, such as an orifice and / or a nozzle, a check valve (also called: non-retum valve), an unloading valve for gas lift, or a sensor unit.

[0006] WO 2023 / 083946 Al, for example, discloses a downhole tool for perforating a dow nhole tubular with a sting. A distal end of the sting may comprise an insert that stays behind in the wall of the downhole tubular as a functional plug, even after the downhole tool has been retrieved to surface. The sting is housed in an elongate tool housing, together with a press device, and a bending arm. The housing extends around a central longitudinal tool axis. The press device acts on the sting, to force the sting in radially outward direction, upon relative movement of the press device, in longitudinal direction, with respect to the sting whereby the sting may extend outside the tool housing. The sting is mounted on a distal end of the bending arm. At its proximal end the bending arm is longitudinally secured stationary' relative to the tool housing. The sting and the distal end of the bending arm are movable in unison in a longitudinal-radial plane from the central longitudinal tool axis.

[0007] A problem associated with the downhole tool of WO 2023 / 083946 Al is that the radial reach of the end face of the sting (or the insert) outside of the tool housing is limited. In practice, this translates in that the outer diameter of the elongate tool housing cannot be much smaller than the inner diameter of the downhole tubular which is to be perforated. Another consequence is that there is a limit to how much the sting or the insert can extend radially outward from the downhole tubular once it has perforated the tubular wall. In some instances, there may be a need for a longer insert that extends deeper into the space around the downhole tubular, for example so that it may house more or larger components inside.

[0008] SUMMARY OF THE INVENTION

[0009] In accordance with the invention there is provided a downhole tool for perforating of a tubular installed in a borehole in the Earth, comprising:

[0010] - an elongate tool housing extending around a central longitudinal tool axis;

[0011] - a sting comprising a sting distal end for perforating a wall of the tubular, whereby the sting further comprises, a sting proximal end and a base at the sting proximal end, having a base surface facing away from the sting;

[0012] - a bending arm having an arm distal end on which the sting is mounted, wherein the arm distal end comprises an wedge-facing surface, and an sting-facing surface facing away from the wedge-facing surface, whereby the bending arm at an arm proximal end is secured stationary relative to the elongate tool housing, and said bending arm is bendable relative to the arm proximal end in a longitudinal-radial plane encompassing the central longitudinal tool axis and the arm proximal end;

[0013] - a press device comprising a wedge movable relative to the elongate tool housing in a protracting direction that is parallel to the central longitudinal tool axis, said wedge being configured to push, in a direction parallel the longitudinal-radial plane, against the wedgefacing surface of the bending arm, upon relative movement of the wedge in said protracting direction and in sliding engagement with the wedge-facing surface of the arm distal end over at least part of a stroke, causing the sting and the arm distal end to move in unison in the longitudinal-radial plane; wherein the sting at the base is hinge-mounted on the arm distal end, pivotable about a hinge axis between a lying position relative to the sting-facing surface, and an erect position relative to the sting-facing surface, whereby in the erect position the base surface is in parallel contact with the sting-facing surface of the bending arm. In a further aspect, there is provided a method of perforating a wall of a dow nhole tubular arranged within a borehole in the Earth, said method comprising:

[0014] - providing a downhole tool as defined above;

[0015] - lowering the downhole tool into the borehole through the downhole tubular to a selected depth;

[0016] - at the selected depth, activating longitudinal relative movement of the wedge in the protracting direction, whereby pivoting the sting from lying position to erect position, in which erect position the base surface is in parallel contact with the sting-facing surface of the bending arm, and engaging a wedge glide surface in sliding contact with the wedgefacing surface at the arm distal end, whereby forcing the sting distal end in the direction parallel the longitudinal-radial plane through a wall of the downhole tubular whereby perforating said wall of said downhole tubular with said sting distal end;

[0017] - retrieving the downhole tool from the downhole tubular comprising pulling the downhole tool in upward direction through to borehole towards surface.

[0018] These and other features, embodiments and advantages of the method, and of suitable expansion devices, are described in the accompanying claims, abstract and the following detailed description of non-limiting embodiments depicted in the accompanying drawings, in which description reference numerals are used which refer to corresponding reference numerals that are depicted in the drawings.

[0019] BRIEF DESCRIPTION OF THE DRAWINGS

[0020] The drawing figures depict one or more implementations in accordance with the present teachings, by way of example only, not by way of limitation. In the figures, like reference numerals refer to the same or similar elements.

[0021] Fig. 1 is cross sectional view of a first embodiment of a collapsible sting, in lying position;

[0022] Fig. 2 is a cross sectional view of the collapsible sting of Fig. 1 in pivoting position;

[0023] Fig. 3 is a cross sectional view of the collapsible sting of Fig. 1 in erect position;

[0024] Fig. 4 is a longitudinal sectional view cut in plane B-B as indicated in Fig. 8, of a dow nhole tool disposed in a tubular, comprising the collapsible sting of Fig. 1 in lying position;

[0025] Fig. 5 is a longitudinal sectional view of the tubular and downhole tool of Fig. 4 with the collapsible sting in pivoting position; Fig. 6 is a longitudinal sectional view of the tubular and downhole tool of Fig. 4 wi th the collapsible sting in erect position, as cut on plane D-D indicated in Fig. 9;

[0026] Fig. 7 is a cross sectional view of the tubular and dow nhole tool of Fig. 4 after a perforation has been punched in the tubular;

[0027] Fig. 8 is a cross sectional view of the downhole tool in the tubular viewed against plane A-A as shown in Fig. 4;

[0028] Fig. 9 is a cross sectional view of the downhole tool in the tubular viewed against section plane C-C as shown in Fig. 6;

[0029] Fig. 10 shows a perspective view of a wedge block for use in the downhole tool of Fig. 4;

[0030] Fig. 11 shows a perspective view of the wedge block as embedded in the downhole tool with the sting in erect position as shown in Fig. 6;

[0031] Fig. 12 show s a perspective view of the collapsible sting of Fig. 1 mounted on a bending arm;

[0032] Fig. 13 is a central longitudinal sectional view of the w edge block of Fig. 10;

[0033] Fig. 14 is a cross sectional view7of the dow nhole tool, through the w edge block, on plane E-E shown in Fig. 5 (the wellbore tubular is excluded from the view);

[0034] Fig. 15 shows a perspective view on a longitudinal section of the downhole tool provided with a collapsible sting according to a second embodiment, cut along plane F-F shown in Fig. 16;

[0035] Fig. 16 is a front view of the downhole tool of Fig. 15 and Fig. 20 with the sting in erect position;

[0036] Fig. 17 is a longitudinal sectional view of a downhole tool comprising the collapsible sting according to the second embodiment of Fig. 15, in lying position;

[0037] Fig. 18 is a longitudinal sectional view7of the downhole tool of Fig. 17 with the collapsible sting in pivoting position;

[0038] Fig. 19 is a longitudinal sectional view of the downhole tool of Fig. 17, as cut on plane F-F indicated in Fig. 16, with the collapsible sting in erect position;

[0039] Fig. 20 shows a perspective view7on a longitudinal section of the downhole tool provided with a collapsible sting according to a third embodiment, cut along plane F-F shown in Fig. 16;

[0040] Fig. 21 is a longitudinal sectional view of a downhole tool compnsing the collapsible sting according to the third embodiment of Fig. 20, in lying position; Fig. 22 is a longitudinal sectional view of the downhole tool of Fig. 21 with the collapsible sting in pivoting position;

[0041] Fig. 23 is a longitudinal sectional view of the downhole tool of Fig. 21, as cut on plane F-F indicated in Fig. 16, with the collapsible sting in erect position;

[0042] Fig. 24 shows a perspective view on a longitudinal section of the downhole tool of Fig. 15, wherein the sting is provided with a sleeve;

[0043] Fig. 25 is a longitudinal sectional view of the downhole tool of Fig. 24, with the collapsible sting in erect position;

[0044] Fig. 26 shows a perspective view on a longitudinal section of the downhole tool of Fig. 20, wherein the sting is provided with a clamp;

[0045] Fig. 27 shows a perspective view on a longitudinal section of the downhole tool of Fig. 26 configured in a tubular while the sting distal end is being punched into the wall;

[0046] Fig. 28 shows the perspective view of Fig. 27 at a later stage where the sting distal end has been punched into the wall and is ready for release from the sting;

[0047] Fig. 29 shows the perspective view of Figs. 27 and 28 after the sting distal end has been released from the base of the sting; and

[0048] Fig. 30 shows an example gas lift system comprising sensor units and unloading valves punched into a production tubing.

[0049] All view s are schematic and not necessarily to-scale. Similar reference numerals in different figures denote the same or similar objects. Objects and other features depicted in the figures and / or described in this specification, abstract and / or claims may be combined in different ways by a person skilled in the art. Unless otherwise indicated, the term longitudinal is used herein to express the direction parallel to the central longitudinal tool axis, and the term transverse is used to express any direction normal (perpendicular) to the central longitudinal tool axis.

[0050] DETAILED DESCRIPTION OF THE INVENTION

[0051] Proposed is a downhole tool for perforating a downhole tubular. The downhole tool has an elongate tool housing that extends around a central longitudinal tool axis, a sting, a press device, and a bending arm. The downhole tubular may be arranged within a borehole in the Earth. The downhole tool may be run longitudinally in a bore of the downhole tubular. The downhole tool can be used in a method of perforating a wall of the downhole tubular. The sting is collapsible, which allows to maintain a relatively slim tool housing compared to the inside diameter of the tubular to be perforated. The sting is pivotably mounted on a distal end of the bending arm, such that it can transition between a lying position and an erect position. Suitably, the sting is mounted on a hinge. With the sting in lying position, the downhole tool has a smaller lateral size than with the sting in erect position. In the erect position, the distal end of the sting laterally extends outside the proj ected lateral contour of the tool housing, whereas in the lying position the sting, including the base, may be fully within the lateral outer contour of the tool housing. This way. it is possible to run the downhole tool through narrower openings, such as inner restrictions within a w ellbore tubular (for example subsurface safety valve) with the sting in its lying position than would be possible if the sting were in the erect position or not collapsible.

[0052] With the sting in its erect position, the sting’s distal end is movable in a radially outw ard direction, and capable of perforating the wall of the wellbore tubular. The tool housing may be kept stationary during this phase. The press device acts on the sting, to force the sting in the radially outw ard direction upon relative movement of the press device, in longitudinal direction. Suitably, the press device comprises a wedge, which may be moved by hydraulic pressure acting for example on a piston that is connected to the wedge. By ensuring that in the erect position the base surface of the sting is in parallel contact (preferably, abutting) with the sting-facing surface of the bending arm, it is achieved that the compressive pressure exerted on the bending arm during the perforating phase can be fully transmitted via the contacting surfaces without subjecting the hinge to any significant mechanical loading or any excessive loading.

[0053] At its proximal end, the bending arm is secured longitudinally stationary relative to the tool housing. How ever, the sting and the distal end of the bending arm are movable in unison in a longitudinal-radial plane, which includes the central longitudinal tool axis. Any axial (longitudinal) force transmitted from the glide surface of the longitudinally moving wedge to the arm distal end and the sting is thus balanced exclusively by tension in the bending arm, whereby the arm distal end is free to move in lateral / radial direction.

[0054] In use, the tool may be lowered into the borehole through the bore of the downhole tubular, to a selected depth. At the selected depth, the sting is pivoted about the hinge, from the lying position to the erect position, in which erect position the base surface of the sting is in parallel contact (abutment) with the sting-facing surface of the bending arm. With the sting in erect position, and while the tool housing may be kept stationary, the press device may be activated to act on the arm distal end. Thus, the sting distal end with the sting in erect position is forced in the radially outward direction from the tool housing, whereby bringing the sting distal end into contact with the wall of the downhole tubular and subsequently perforating the wall of the downhole tubular with the same sting distal end. At least part of the sting may be subsequently retracted, and the downhole tool may then be retrieved from the downhole tubular.

[0055] Examples of downhole tubulars include w ellbore tubulars, such as, for example, casing, liner, or production tubing.

[0056] The method and downhole tool described herein can be used to perforate and install an insert in a wall of a downhole tubular (e.g. casing or production tubing). Such insert may be a blind plug or a functional plug. Such functional plug may for example be a circulation-modifying insert, capable of passing a fluid through the wall from the inside of the tubular to the surrounding and / or in the other direction. Examples include an orifice, a nozzle, a flow rate limited valve and / or a non-retum valve. Functional plugs may include a sensor, such as a pressure sensor, a temperature sensor and / or a chemical sensor. These may be referred to as sensor inserts. Sensor inserts and circulation-modifying inserts may be combined in a single insert if the available space can accommodate the necessary elements for that. Applications for functional plugs include (gas) lift operations and injecting of a treatment fluid such as a sealant. Functional plugs may include a filter mechanism or material, to promote the pass-through of a certain substance over another, for example promoting the pass through of hydrocarbons over alternative products such as sand or water from a wellbore. These may be referred to as production inserts.

[0057] The method and downhole tool described herein may be used for subsequently injecting a treatment fluid in an annulus surrounding the downhole tubular.

[0058] Fig. 1 provides a schematic cross-sectional view of a first embodiment of a sting 1 mounted on a distal end of a bending arm 2. The distal end of the bending arm 2 will hereinafter be referred to as arm distal end 4, to distinguish it from a sting distal end 3 on the sting 1. The sting 1 further comprises a sting proximal end 7 and a base 8 at the sting proximal end 7. The base 8 comprises base surface 9 that faces away from the sting 1. In the figure, the base 8 is schematically depicted monolithically integral with the sting 1. However, the base 8 may be a separate piece on which the sting 1 is mounted or the base 8 may be part of the sting 1. The arm distal end 4 comprises a sting-facing surface 5 for engaging with the base surface 9 of the sting 1. A wedge-facing surface 6 of the arm distal end is oriented away from the sting-facing surface 5, and adapted for engaging with a glide surface 22 of a wedge 21 (as will be shown and explained in more detail hereinbelow). The sting 1, at the base 8, is hinge-mounted on the arm distal end 4. for example by means of a hinge 10. The hinge 10 is disposed along a hinge axis, whereby the sting 1 can pivot about the hinge axis. In Fig. 1, the hinge axis is perpendicular to the plane of view (i.e. the plane of cross section). Fig. 1 depicts the sting 1 in a lying position, whereby a longitudinal sting axis 11 is parallel to the bending arm 2 or close to parallel.

[0059] Figs. 2 and 3 illustrate the sting 1 is pivotable between the lying position of Fig. 1 and an erect position as depicted in Fig. 3. In the erect position, the base surface 9 is in parallel abutting contact with the sting-facing surface 5 of the bending arm 2. The parallel contact ensures that compressive force can be effectively transferred from the sting-facing surface 5 of the bending arm to the sting distal end 3. without having to expose the hinge 10 to any compressive load. This has as advantage that the hinge 10, including any construction that holds the hinge 10 in place relative to the arm distal end 4, can be as strong or as weak as desired. By comparing distances di in Fig. 1 and d2 in Fig. 3, it can be seen that the sting distal end 3 extends further away from the sting-facing surface 5 of the bending arm 5 in the erect position, than the entire sting 1, including its base 8, does in the lying position.

[0060] In the embodiment as illustrated in Figs. 1 to 3, the hinge 10 is held in place relative to the arm distal end 4 by means of a construction comprising a bracket 12, which is secured to a front side 13 of the arm distal end 4. for example by means of one or more screws, bolts, rivets, or similar fastening means 14. The hinge 10 may extend between two open arms of the bracket 12. Alternative constructions are within reach of the person skilled in the art.

[0061] Figs. 4-7 show a downhole tool provided with pivotable sting 1, for example according to the embodiment as described above, in various stages of operation. The downhole tool is deployed in a downhole tubular 15, which may be installed in a borehole in the Earth. Only a short section of tubular 15 is shown in the figures; the tubular may extend further on either end. Fig. 8 provides a cross-sectional view of the tool in the tubular along A-A as indicated in Fig. 4. Fig. 9 provides a similar cross-sectional view along C-C as depicted in Fig. 6. The downhole tool comprises an elongate tool housing 16 extending around a central longitudinal tool axis 17. A proximal end 19 of the bending arm 2 is secured to the elongate tool housing 16 and stationary7relative thereto. The bending arm 2 is bendable relative to the arm proximal end 19 in a longitudinal -radial plane encompassing the central longitudinal tool axis 17 and the arm proximal end 19. In Fig. 4, the bending is the most pronounced in the area identified by reference number 20. The longitudinal-radial place coincides with the plane of view.

[0062] The downhole tool further comprises a wedge 21 having a glide surface 22 facing the bending arm 2. The wedge 21 is movable relative to the elongate tool housing 16 in a direction that is parallel to the central longitudinal tool axis 17. The glide surface 22 has a normal direction 25 in the longitudinal-radial plane, which extends at a non-perpendicular angle relative to the central longitudinal tool axis 17. A backside of the wedge 21, w hich faces away from the glide surface 22, preferably has a flat surface 41 that is perpendicular to the longitudinal-radial plane and parallel to the central longitudinal tool axis 17.

[0063] In a preferred embodiment, the downhole tool further comprises a buffer arm 38, which in construction is similar to the bending arm 2, but has a different function. The construction is similar in that it has a buffer arm distal end 39 and a buffer arm proximal end 40, which is secured to the elongate tool housing 16 in a similar manner as the bending arm proximal end 19. The buffer arm distal end is opposite to the bending arm distal end and configured to allow7the w edge 21 to be inserted betw een the bending arm distal end 4. The function of the buffer arm 38 is to provide a buffer between the backside of the wedge 21 and the tubular 15, to allow the wedge 21 to slide when it is being moved in longitudinal direction relative to the tool housing 16 while the buffer arm 38 is stationary relative to the tubular 15.

[0064] The tool housing 16 optionally has a cylindrical section with a circular outer contour having a maximum outer diameter D. This is also illustrated in Fig. 8, which shows a cross sectional view along A-A. The sting 1 is provided at the arm distal end 4. As explained above, the sting 1 is pivotable about hinge 10, which extends perpendicular to the longitudinal plane of view7. In Fig. 4 the sting 1 is seen in lying position, w hereas in Fig. 6 the sting is seen in erect position. It can be seen in Figs. 4 and 8 that the sting 1 in the lying position fully fits within the cross-sectional outer contour of the tool housing 16. Thus, the outer diameter D in this embodiment determines the smallest inner diameter through which this downhole tool can pass. This would be a smaller inner diameter than would be possible with the sting 1 in the erect position, as illustrated in Fig. 9.

[0065] In the erect position, illustrated in Figs. 6 and 9, at least a part of the sting distal end extends outside of the tool housing. The sting distal end 3 will ultimately be perforating a wall 18 of the tubular 15. The remaining distance between the end face 24 of the sting 1 and the wall 18 is less than it would have been if the sting 1 were permanently in the erect position and within the outer contour of the tool housing.

[0066] The outward facing surface of the buffer arm 38, particularly at its distal end 39, is preferably cylindrically shaped with a contour that approximates the inside contour of the wall 18 of the tubular 15. Preferably, the radius of curvature of the cylindrical contour is larger than that of the circular outer contour of the tool housing 16.

[0067] With the sting 1 in its erect position, the longitudinal sting axis 11 extends in the longitudinal-radial plane and substantially perpendicular to the central longitudinal tool axis 17. In this condition, the downhole tool is ready for the next phase of operation, which is laterally moving the sting outward towards the tubular 15 whereby the bending arm 2 holds the sting 1 in position in the longitudinal direction. It follows from Figs. 4-6 that the pivoting of the sting 1 to the erect position is completed prior to the glide surface 22 engaging in sliding contact with the wedge-facing surface 6 at the arm distal end 4.

[0068] The wedge 21 is movable in a protracting direction 23 wherein, when contact is established between the glide surface 22 and the wedge-facing surface of the bending arm 2 the wedge 21 pushes against the wedge-facing surface 6 of the bending arm 2 with the glide surface 22 in sliding engagement with the wedge-facing surface 6. The back surface 41 is in sliding engagement with the distal end 39 of the buffer arm 38, which in turn is supported by the tubular 15 diametrically opposite to where the sting 1 interacts with the inside surface of the wall 18 of the tubular 15. The arm distal end 4 thus undergoes a push in a direction parallel the longitudinal-radial plane. This causes the sting 1 and the arm distal end 4 to move in unison in the longitudinal-radial plane. The contact between the buffer arm 38 distal end 39 and the tubular 15 provides counter force against the resistance that the sting distal end 3 experiences from the tubular 15 as the end face 24 interacts with the wall 18 of the tubular 15. As the surface area of the end face 24 of the sting 1 is small compared the contact surface of the buffer arm 38, and the end face 24 of the sting 1 may have a well-defined outer contour edge, the protracting movement of the wedge 21 ultimately causes the sting 1 to perforate the wall 18 of the tubular 15. The end result of this phase is illustrated in Fig. 7.

[0069] In Fig. 7, the wedge block is fully protracted and the sting distal end 3 is maximally extended outward. The sting distal end 3 has been forced through the wall 18 thereby- perforating it. The sting distal end 3 stays behind in the wall 18 of the downhole tubular 15 after retrieving the downhole tool back to surface. US 2024 / 0076950 A shows one example of how that can be done by using a frangible zone in the sting. Alternative ways are contemplated.

[0070] As can be seen in the sequence of Figs. 4 to 7, a stroke of the wedge 21 has two phases. In a pivoting part of the stroke, the sting 1 transitions to the erect position. The pivoting phase is followed by the punching part of the stroke, wherein glide surface 22 of the wedge 21 starts to push the arm distal end 4 and the sting 1 towards the wall 18. This can be done with any suitable choice of mechanisms or activators. However, in the embodiment shown in these figures, the mechanism is integrated with the wedge 21 so that the longitudinal movement of the wedge 21 in the protracting direction 23 causes the sting 1 to pivot from the lying position to the erect position. Fig. 5 shows the downhole tool in an intermediate position w here the wedge block 29 is in its initial phase of the protracting stroke where the sting 1 transitions between the lying position and the erect position. In this case, the glide surface 22 of the wedge 21 has closed in on the bending arm 2 but is not yet quite in contact with the w edge- facing surface 6 of the arm distal end 4.

[0071] In the particular embodiment described here, the wedge glide surface 22 and the bending arm 2 are both sandwiched between two opposing longitudinal walls 26 as can be seen in the perspective views provided in Figs. 10 and 11. Fig. 10 shows the wedge block 29 including these walls. The two opposing longitudinal walls 26, which mutually face each other and may be referred to as “inside w alls", are rigidly joined to the wedge 21 and oriented parallel w ith the longitudinal-radial plane. The thus formed wedge block 29 is provided with a connector 30 to join it with a movement actuator, such as an end of a hydraulic piston 31 (visible in Figs. 4-7). Fig. 11 shows how the wedge block 29 is fitted on the piston end 31 and around the bending arm 2 and sting 1. At least one, preferably both, of the two opposing longitudinal walls 26 comprise a track 27. The track 27 can suitably be a continuous groove, such as shown, or a rail. The track 27 engages slidingly with the sting 1. with a slider 32 (shown in Fig. 12) provided at a finite non-zero distance r from the hinge axis 33. Relative longitudinal movement of the wedge block 29 past the bending arm 2 and sting 1 causes the slider 32 to follow the path of the track 27. which in turn causes the sting 1 to pivot between the lying position and the erect position. An embodiment of such slider 32 is illustrated in Fig. 12.

[0072] The piston 31 may be actuated hydraulically by means of pressurized fluid such as pressurized hydraulic oil. A suitable design is presented in WO 2023 / 083946 Al, which is incorporated herein by reference.

[0073] Fig. 12 also illustrates the bracket 12 and the fastening means 14. The fastening means 14 preferably serve as shear pins, which are adopted to break when an axial tension force the direction of the longitudinal tool axis exceeds a break limit. This might occur, for example, when the wedge block 29 for some reason stalls and cannot be retracted after the sting 1 has been punched into the wall 18 of the tubular 15. In such a case, the tool can be retrieved to surface with the wedge block 29 in protracted position, by severing the entire sting from the bending arm 2 by breaking the fastening means 14 under influence of the pulling force of the downhole tool towards surface. In some embodiments, the hinge itself may serve as shear pin, such that the sting breaks loose from hinge in case the sting remains stuck somewhere in the tubular while the downhole tool is subject to being pulled back to surface, while the wedge block is still in protracted position and / or the sting has not been sufficiently retracted back into the tool housing.

[0074] Preferably, to facilitate proper retraction of the sting 1 upon retracting the wedge block 29, the wedge 21 and the arm distal end 4 may be provided with a slider 34 (Fig. 12) and groove 35 (Fig. 13) connection to preserve close vicinity' of the arm wedge-facing surface 6 to the glide surface 22 of the wedge 21. The slider and groove connection may suitably have a trajectory section that stretches parallel to the wedge glide surface 22, to keep the w edge-facing surface 6 of the bending arm 6 in sliding contact with the wedge glide surface 22 during at least part of the stroke, as the w edge 21 moves longitudinally in a retracting direction opposite to the protracting direction. The slider and groove connection may extend ahead of the wedge glide surface 22, as indicated at 36, to guide the arm distal end 4 in a first part of the stroke, prior to the glide surface 22 engaging in sliding contact with the arm distal end 4 wedge-facing surface 6. This allow s a part of the stroke of the w edge block 29 can be used to actuate transition of the sting 1 betw een the lying position and the erect position, prior to or after contact between the glide surface 22 and the arm distal end 4 wedge-facing surface 6. In the discussed embodiment, the track 27 and the groove 35 coincide over part of the trajectories. Fig. 14 shows a cross sectional view of the downhole tool cut as indicated by E-E in Fig. 5. This shows the wedge block 29 in cross section. The inside wall 26 is parallel to the view direction. Track 27, which guides sliders 32 of the sting, cuts to a depth ds into the inside wall 26 whereas the groove 35 which guides the bending arm slider 34 cuts to a depth d4 into the same side wall 26. In this case d4 < d3 and accordingly the guide sliders 32 of the sting can be longer (i.e. can extend further out from the central longitudinal tool plane) than the arm sliders 34. This way, the track 27 and groove 35 can coincide over part of the trajectories, while the guide sliders 32 can be picked up by the. deeper, diverting part of the track 27 to cause the transition between the lying and erect positions.

[0075] In the first embodiment, the sting 1 is collapsible in rearward direction, whereby the end face 24 is directed toward the bending arm proximal end 19 when the sting 1 is in lying position. In such instance, the longitudinal component of movement of the sting distal end 3, as it pivots about the hinge 10 from lying position to erect position, is co- directional with the movement of the w edge block 29. Now will be discussed an example of a second embodiment, wherein the sting 1 is collapsible in forward direction whereby the end face 24 is directed away from the bending arm proximal end 19 when the sting 1 is in lying position. In such design, the longitudinal component of movement of the sting distal end 3, as it pivots about the hinge 10 from lying position to erect position, is counterdirectional w ith the movement of the wedge block 29.

[0076] Fig. 15 shows a perspective view of a tool with such an embodiment of a forward- collapsible sting 1, with a cut plane F-F as indicated in Fig. 16. In this view, the sting 1 is already in erect position. The hinge 10 on the side of the base 8 which is furthest removed from the arm proximal end 19; the sting slider 32 is on the side of the base 8 which is closest to the arm proximal end 19. Track 27 in wall 26 has been adapted to facilitate the reverse pivoting direction of the sting 1 compared to the longitudinal movement 23 of the wedge block 29. A different trajectory of the track 27 compared to the rearward collapsing version facilitates smooth pivoting transition. This is best illustrated in Figs. 17-19, which show' the sting’s transition from lying position (Fig. 17) to erect position (Fig. 19) as the wedge block 29 is moved in the protracting direction as indicated by arrow 23. These figures also show an optional buffer shder 42, which is provided on the buffer arm distal end 39, and is adapted to cooperate with a buffer arm track 43 provided in the wall 26 of the wedge block 29 to guide the buffer arm 38 during the relative longitudinal (protracting and retracting) movements of the wedge block 29 during operation.

[0077] The slider 34 of the arm distal end 4 cooperates with a separate groove 35, which extends into part 36. In this second embodiment, the slider 32 of the sting 1 is transversely separated from the slider 34 of the arm distal end 34. Hence, groove 35 and track 27 do not coincide in this particular design. Accordingly, one does not have to be cut deeper into the inside walls than the other (i.e. ds can be equal to ds) although a different choice may be made.

[0078] With the sting 1 in erect position, the base surface 9 of the sting 1 is in parallel abutting contact with the sting-facing surface 5 of the bending arm 2. Further operation of the tool is identical to the first embodiment, including further moving the wedge block 29 in the protracting direction and thereby forcing the sting’s distal end in the radially outward direction to ultimately perforate the wall 18 of the wellbore tubular 15.

[0079] Figs. 20-23 illustrate another embodiment of a forward-collapsible sting 1, seen on the cut plane F-F as indicated in Fig. 1 . As with the embodiment of Fig. 15, the hinge 10 is provided on the side of the base 8 which is furthest removed from the arm proximal end 19. However, in this version the sting sliders 32 are provided on an extension winglets 44 extending from the base 8 away from the arm proximal end 19. These winglets 44 may have rounded contours around the hinge axis 33 to provide continuous sliding support with the arm distal end 4 during transition between lying and erect positions.

[0080] Still another different trajectory' of the track 27 compared to the version of Fig. 15 is employed. This track 27 has a section running parallel to the groove 35 for the arm slider 34 (adjacent to the glide surface 22 of the wedge 21). further displaced from each other than in the embodiment of Fig. 15. Also, both the track 27 and the groove 35 in this embodiment have longitudinally directed parallel end parts 36, which both control the bending arm 2 and keep the sting lin lying position, prior to wedge 21 being close.

[0081] Figs. 21-23 show the sting’s transition from lying position (Fig. 21) to erect position (Fig. 23) as the wedge block 29 is moved in the protracting direction as indicated by arrow 23.

[0082] In any of the embodiments contemplated herein, the insert, which forms the sting distal end, may be provided with a chamfer as explained in more detail in WO 2024 / 013225 Al. incorporated herein by reference. An example of such chamfer 37 is included in Fig. 12. Any of the downhole tools described above may be employed as follows in a method of perforating a wall of a downhole tubular arranged within a borehole in the Earth. In such method, the downhole tool is lowered into the borehole through the downhole tubular to a selected depth which is the target depth. During this phase, the downhole tool may pass one or more restrictions where the inner diameter of the borehole passage is smaller than the inner diameter at the target depth. At the selected depth, a longitudinal relative movement of the wedge in the protracting direction is activated, whereby the sting pivots from lying position to erect position, in which erect position the base surface is in parallel contact with the sting-facing surface of the bending arm. In addition, the relative movement of the wedge brings a wedge glide surface in sliding contact with the w edgefacing surface at the arm distal end, whereby the sting distal end is forced in the direction parallel the longitudinal -radial plane through a wall of the downhole tubular. Tow ards the end of the stroke, the wall of the downhole tubular is perforated by the sting distal end.

[0083] Subsequently, the downhole tool is retrieved from the downhole tubular, by at least pulling the downhole tool in upward direction through to borehole towards surface. Preferably, prior to retrieving the downhole tubular and pulling the tool upward, the wedge is moved in a protracting direction relative to the bending arm, causing at least part of the sting 1 to be retracted from the tubular.

[0084] The sting distal end 3 (the insert) may stay behind in the wall of the downhole tubular during and when retrieving the downhole tool back to surface. One example of how that can be done, as mentioned hereinabove, is by using a frangible zone in the sting 1, to provide a shearing zone in the sting 1 allowing to sever the sting distal end 3 from a baseportion of the sting 1. Figs. 24-29 illustrate alternative ways of how this can be done using an external body.

[0085] Referring first to Figs. 24 and 25, the base 8 comprises a cylindrical sting body 23. The sting distal end 3 is a separate substantially cylindrical insert body, which extends around the longitudinal sting axis 11. The substantially cylindrical insert body abuts the cylindrical sting body 23 at an interface 45, and is secured to the cylindrical sting body 23 by an external body 49 that snuggly surrounds the interface 45. The external body 49 is slidable onto the cylindrical sting body 23 by application of a force along the longitudinal sting axis 11 directed from the sting distal end 3 to the sting base 8, which overcomes a static longitudinal frictional force between the external body 49 and the sting 1 by which the external body 49 is held in place. Once the external body 49 has been moved far enough onto the cylindrical sting body 23, the interface 45 becomes exposed, and the sting distal end 3 is then readily releasable from the cylindrical sting body 23. 1.e. at this stage, the external body 45 no longer contributes to securing the substantially cylindrical insert body in place on the cylindrical sting body 23.

[0086] As the sting distal end 3 is intended to stay behind in the wall of the tubular, it is effectively an insert as mentioned hereinabove.

[0087] The external body 49 as illustrated in Figs. 24-25 is embodied as a snugly fitting sleeve, which is positioned as a cylindrical mantle around a part of the sting 1. Figs. 26-29 illustrate an alternative, whereby the external body 49 is embodied by a clamp. The specifically shown example comprises two clamp halves, brought together with two screws or bolts 44. There are many variations that can be contemplated, including models having only one bolt, and model designs based on pipe clamps, hose clamps, bicy cle seat-post clamp. These can be generally ring shaped or rectangular such as shown in the example of Fig. 26. An advantage of clamps is that the static friction is adjustable by adjusting the clamping force. In an advantageous embodiment, the clamp includes a clamp bolt with a torque spec, to have a predictable static friction. The elongate generally rectangular shape of the external body of Fig. 26 facilitates the application of clamp bolts. Moreover, this shape facilitates a relatively large surface area of the rim 43 of the external body 19. which comes into contact with the wall of the dow nhole tubular 15, while at the same being accommodated within the available gap betw een the two opposing longitudinal walls 26 of the w edge block 29.

[0088] It will be readily obvious that the clamp variant can be applied on the tool of Figs. 24-25 and the sleeve variant of Figs. 24-25 can be applied on the tool of Fig. 26. Moreover, for either variant, the external body 49 is preferably' sufficiently tight around the sting 1 to keep the sting distal end 3 in place during the initial phases of the operation of running the punching tool into the downhole tubular 15 and initiating the outward movement of the sting 1 in the punch direction 46. The surface area of the rim 43 may be curved cylindrically convex to match the concave cylindrical profile of the wall of the downhole tubular 15.

[0089] Fig. 27 illustrates a stage of the perforation operation, where the sting distal end 3 has perforated the downhole tubular 15 and continuing movement of the wedge 21 in the protracting direction 23 causes the sting distal end 3 to move in the punch direction 46. The external body' 49 is just in contact with the inside of the wall of the dowTihole tubular 15. As the external body 49 exceeds the outer diameter (OJ)) of the sting distal end 3. it will not fit in the perforation that has been created by the sting distal end 3. When the wedge 21 device continues to push the sting 1 through the perforation, the wall of the downhole tubular 15 will exert a force along the longitudinal sting axis 11 in the direction from the sting distal end 3 to the base 8 (i.e. opposite to the punch direction 46). This force may exceed the static frictional force by which the external body 49 is held in place on the sting 1. This results in the external body 49 sliding onto the cylindrical sting body 23.

[0090] There is enough distance available on the cylindrical sting body 23, to accommodate the sliding movement by the external body 49 as pushed by the contact with the inside wall of the dow nhole tubular 15. Fig. 28 shows the situation where external body 49 has completely slided over the cylindrical sting body 7, after the w edge 21 has moved further in the protracting direction 23. The interface 45 is now fully exposed to release the sting distal end 3 from the cylindrical sting body 23.

[0091] Subsequently, the wedge 21 is moved in retracting direction 28 to withdraw the base 8 of the sting 1. Fig. 29 shows how the sting distal end 3 can stay behind in the downhole tubular 15, while the cylindrical sting body 23, preferably with the external body 49 still on it, is moved away from the sting distal end 3. The sting distal end 3 is substantially aligned flush with the inside of the wall of the downhole tubular 15.

[0092] Further details relevant to application of the external body 49 on the sting 1 are described in European patent application No. 24186573.2 filed on 4 July 2024.

[0093] In one example, the presently proposed tool and method can be applied to install a retrofittable gas lift system. Fig. 30 schematically shows a cross section view of a production tubing 52 in a typically cased section of a well bore. Several inserts comprising sensor units 54 and unloading valves 51 have been installed at various depths in the side wall of the production tubing 52. The inserts are substantially flush with the inside wall surface of the production tubing 52, whereby none of the inserts cause any pertinent inner diameter restrictions. This minimizes any restrictions for future tool access through the production tubing 52 to lower parts of the well. Moreover, unnecessary additional pressure drop of the flow of produced fluids 55 in the tubing is thereby avoided as well.

[0094] An open annulus may surround the production tubing 52, which is typically sealed at the bottom with a production packer 47. The bottom of the open annulus, and the production packer 47. may be located near a lower end of the production tubing 52. A tubing nipple profile 53. shown at the lower end of the production tubing 52. may not be necessary when the method of the invention is employed.

[0095] The present disclosure is not limited to the embodiments as described above and the appended claims. Many modifications are conceivable, and features of respective embodiments may be combined. The particular embodiments disclosed above are illustrative only, as the present invention may be modified, combined and / or practiced in different but equivalent manners apparent to those skilled in the art having the benefit of the teachings herein. Furthermore, no limitations are intended to the details of construction or design herein shown, other than as described in the claims below. It is therefore evident that the particular illustrative embodiments disclosed above may be altered, combined and / or modified and all such variations are considered within the scope of the present invention as defined in the accompanying claims.

Claims

C L A I M S1. A downhole tool for perforating of a tubular installed in a borehole in the Earth, comprising:- an elongate tool housing extending around a central longitudinal tool axis;- a sting comprising a sting distal end for perforating a wall of the tubular, whereby the sting further comprises, a sting proximal end and a base at the sting proximal end, having a base surface facing away from the sting;- a bending arm having an arm distal end on which the sting is mounted, wherein the arm distal end comprises an wedge-facing surface, and an sting-facing surface facing away from the wedge-facing surface, whereby the bending arm at an arm proximal end is secured stationary' relative to the elongate tool housing, and said bending arm is bendable relative to the arm proximal end in a longitudinal-radial plane encompassing the central longitudinal tool axis and the arm proximal end;- a press device comprising a wedge movable relative to the elongate tool housing in a protracting direction that is parallel to the central longitudinal tool axis, said wedge being configured to push, in a direction parallel the longitudinal-radial plane, against the w edgefacing surface of the bending arm, upon relative movement of the wedge in said protracting direction and in sliding engagement with the wedge-facing surface of the arm distal end over at least part of a stroke, causing the sting and the arm distal end to move in unison in the longitudinal-radial plane; wherein the sting at the base is hinge-mounted on the arm distal end. pivotable about a hinge axis between a lying position relative to the sting-facing surface, and an erect position relative to the sting-facing surface, whereby in the erect position the base surface is in parallel contact with the sting-facing surface of the bending arm.

2. The downhole tool of claim 1, wherein a longitudinal sting axis extends from the base to the sting distal end, and wherein in the erect position the longitudinal sting axis extends in the longitudinal-radial plane essentially perpendicular to the central longitudinal tool axis.

3. The downhole tool of claim 1 or 2, wherein the hinge axis extends perpendicular to the longitudinal-radial plane.

4. The downhole tool of any one of claims 1 to 3. wherein the sting is releasably mounted on the arm distal end with at least one shear pin.

5. The downhole tool of any one of claims 1 to 4. wherein the wedge comprises a glide surface for engaging in sliding contact with the wedge-facing surface of the bending arm, whereby the glide surface has a normal direction in the longitudinal-radial plane in a nonperpendicular angle relative to the central longitudinal tool axis.

6. The downhole tool of claim 5, wherein the wedge and the arm distal end are provided with a slider and groove connection having a trajectory section parallel to the wedge glide surface, to keep the wedge-facing surface of the bending arm in sliding contact with the wedge glide surface during at least part of the stroke as the wedge moves longitudinally in a retracting direction opposite to the protracting direction.

7. The downhole tool of claim 6, wherein the slider and groove connection extends ahead of the w edge glide surface to guide the arm distal end in a first part of the stroke, prior to the glide surface engaging in sliding contact with the arm distal end.

8. The downhole tool of any one of claims 5 to 7, wherein the wedge glide surface and the bending arm are sandwiched between two opposing longitudinal walls that face each other, whereby the two opposing longitudinal walls are rigidly joined to the wedge and oriented parallel with the longitudinal-radial plane.

9. The downhole tool of claim 6 or 7, combined with claim 8, wherein part of the slider and groove connection is formed in at least one, preferably both, of the two opposing longitudinal walls.

10. The downhole tool of claim 8 or 9, w herein at least one, preferably both, of the tw o opposing longitudinal w alls comprise a track, which slidingly engages with the sting at a finite non-zero distance from the hinge axis, and which causes the sting to pivot between the lying position and the erect position upon the relative movement of the wedge.11 . The downhole tool of claim 10, w herein the sting is in the erect position before the glide surface engages in sliding contact with the w edge-facing surface of the bending arm.

12. The dow nhole tool of any one of claims 1 to 11, when in the erect position, the sting distal end laterally extends outside of the tool housing whereas in the lying position the sting, including the base, are within a lateral outer contour of the tool housing.

13. A method of perforating a wall of a downhole tubular arranged within a borehole in the Earth, said method comprising:- providing a downhole tool as claimed in any one of the preceding claims;- lowering the downhole tool into the borehole through the downhole tubular to a selected depth;- at the selected depth, activating longitudinal relative movement of the wedge in the protracting direction, whereby pivoting the sting from lying position to erect position, in which erect position the base surface is in parallel contact with the sting-facing surface of the bending arm, and engaging a wedge glide surface in sliding contact with the wedge- facing surface at the arm distal end. whereby forcing the sting distal end in the direction parallel the longitudinal-radial plane through a wall of the dow nhole tubular w hereby perforating said wall of said downhole tubular with said sting distal end;- retrieving the downhole tool from the downhole tubular comprising pulling the downhole tool in upward direction through to borehole towards surface.

14. The method of claim 14, wherein the pivoting of the sting to the erect position is completed prior to the glide surface engaging in sliding contact with the w edge-facing surface at the arm distal end.

15. The method of claim 13 or 14, wherein the sting distal end stays behind in the wall of the downhole tubular after retrieving the downhole tool.

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