EP3388616A1

EP3388616A1 - Anchor system

Info

Publication number: EP3388616A1
Application number: EP17166613.4A
Authority: EP
Inventors: Cornelus Josef Castelein; Antonius Leonardus Maria Wubben
Original assignee: Shell Internationale Research Maatschappij BV
Current assignee: Shell Internationale Research Maatschappij BV
Priority date: 2017-04-13
Filing date: 2017-04-13
Publication date: 2018-10-17

Abstract

An anchor system (10) for anchoring an expandable tubular in a borehole is proposed, which has one or more anchor members ( 1,1') that at a fixed end (40) thereof are secured to the expandable tubular with a securing system (50) that uses a tongue-and-groove connection (9). The tongue-and-groove connection makes use of an interlocking profile between one or more tongues (6) configured as ridges protruding outward from one surface and one or more grooves (7) formed as recesses in a mating surface. One groove, which may be formed by a recess in the outer surface of the cylindrical wall, receives a tongue which may be formed by a ridge on an engagement surface of the anchor members (facing toward the outer surface of the expandable tubular). The tongue and groove are thus interlocked, and prevent sliding movement of the fixed end of the anchor member relative to the expandable tubular (20).

Description

Field of the Invention

In a first aspect, the present invention relates to an anchor system for anchoring an expandable tubular to a borehole wall.

Background of the Invention

Expandable tubulars such as casing and liners are finding increasing application in the context of hydrocarbon wellbore drilling for exploration and production. A main advantage of deployment of expandable tubulars in wellbores is a larger internal diameter becomes available for production of hydrocarbons and for passage of tools as compared to conventional setting of nested casing. Typically, an expandable tubular is installed by lowering the expandable tubular into the wellbore, and subsequently pushing or pulling an expansion tool (usually comprising an expansion cone) through the expandable tubular in longitudinal direction whereby expanding the tubular in lateral direction. Generally, the expandable tubular tends to contract in longitudinal direction.
In order to keep the expandable tubular in place during the expansion process, anchor systems have been proposed which are configured on the outside of the expandable tubular and which are activated before or during the expansion process. Such anchor systems are often particularly desired to keep the expandable tubular reliably in place where it extends into an open borehole section. This is because the distance between the outside surface of the expandable tubular (even after expansion) and the open borehole wall is often too large to provide sufficient friction.
US patent No. 8,997,856 shows various embodiments of a system for anchoring an expandable tubular to a borehole wall, which are activated by the expansion process itself. The system comprises a ramping surface arranged on the cylindrical outer surface of the expandable tubular. An anchor member is fixed relative to the outside of the tubular at a fixed end of the anchor member. A loose end of the anchor member extends toward the ramping surface, and is movable relative to the outside of the expandable tubular. The ramp surface tapers inwardly in the direction of the anchor member. Radial outward expansion of the expandable tubular, which may be accomplished for instance by passing an expanding cone through the expandable tubular in longitudinal direction, causes the tubular wall to shorten in longitudinal direction. This, in turn, causes the loose end of the anchor member to slide up the ramp surface and move radially outward to and engage the borehole wall as a result of engagement with said ramping surface.
The fixed end of the anchor member is affixed to the expandable tubular by welding. However, welding may be undesired any one of various reasons. Such reasons can for instance include deterioration of the metal alloy quality of the expandable tubular, particularly in the heat-affected zone, which could be caused by welding. There is therefore a need to find other means of affixing the fixed end of the anchor member to the expandable tubular that prevents relative movement between the fixed end and the expandable tubular.

Summary of the invention

The invention provides an anchor system for anchoring an expandable tubular to a borehole wall, comprising:

an expandable tubular comprising a cylindrical wall extending around a longitudinal axis and having a cylindrical outer surface facing away from the longitudinal axis;
an anchor member, comprising a fixed end and a loose end arranged on the outer surface of the expandable tubular whereby the loose end is positioned longitudinally displaced from the fixed end, which fixed end is secured to the expandable tubular against sliding movement of the fixed end of the anchor member relative to the expandable tubular, and which loose end is movable in a direction away from the longitudinal axis whereby bending the anchor member between the fixed end and loose end;

Brief description of the drawing

The appended drawing, which is non-limiting, comprises the following figures:

FIG. 1 schematically shows a projected side view of a proposed anchor system configured on an expandable tubular;
FIG. 2 schematically shows a longitudinal sectional view of the proposed anchor system along D-D as indicated in FIG. 1;
FIG. 3 schematically shows an enlarged cut from FIG. 2 of the area marked 50 in FIG. 2;
FIG. 4A schematically shows an enlarged side view of a pliable link in collapsed condition; and
FIG. 4B schematically shows an enlarged side view of the pliable link of FIG. 4A in expanded condition.

The figures are schematic of nature, and not to scale. Like reference numbers are used for like features.

Detailed description of the invention

The invention will be further illustrated hereinafter by way of example only, and with reference to the non-limiting drawing. The person skilled in the art will readily understand that, while the invention is illustrated making reference to one or more specific combinations of features and measures, many of those features and measures are functionally independent from other features and measures such that they can be equally or similarly applied independently in other embodiments or combinations.
The presently proposed anchor system comprises one or more anchor members that at a fixed end thereof are secured to an expandable tubular with a securing system that comprises a tongue-and-groove connection. The tongue-and-groove connection comprises an interlocking profile between one or more tongues configured as ridges protruding outward from one surface and one or more grooves formed as recesses in a mating surface. One groove, which may be formed by a recess in the outer surface of the cylindrical wall, receives a tongue which may be formed by a ridge on an engagement surface of the anchor members (facing toward the outer surface of the expandable tubular). The tongue and groove are thus interlocked, and prevent sliding movement of the fixed end of the anchor member relative to the expandable tubular.
The grooves are suitably provided as concentrically arranged circumferencing grooves in the outer surface of the expandable tubular. However different groove forms are contemplated, including one or more pitched grooves and/or segmented grooves that are segmented around the circumference of the expandable tubular.
When the anchor members are activated and engaged with the open borehole wall, the expandable tubular will be better locked into position. The groove is preferably oriented in a circumferencing direction around the longitudinal axis, to provide maximum anchoring force in the longitudinal direction.
FIG. 1 shows a projected side view of an anchor system 10 configured on an expandable tubular 20, such as a casing or a liner or other expandable tubular for use in a borehole. The expandable tubular 20 generally has a circular cross section having a circumference. FIG. 2 shows longitudinal sectional view D-D as indicated in FIG. 1. The expandable tubular 20, which has a cylindrical wall 21 that extends around a longitudinal axis A, has a cylindrical outer surface 22 facing away from the longitudinal axis A. The anchor system 10 comprises a plurality of the anchor members (1, 1') arranged side by side distributed around the circumference of the expandable tubular 20. The anchor members 1, 1' may be provided in the form of strips, suitably metal strips, which can bend or hinge outward, as indicated by arrow 25 in FIG. 2, at a loose end 30 of the anchor members 1, 1'.
The anchor members 1, 1' are secured to the expandable tubular 20 at a fixed end 40, which for each anchor member is longitudinally displaced from the loose end 30 of the same anchor member. In both the fixed and loose ends the anchor members 1, 1' are arranged on the outer surface 22 of the expandable tubular 20. The anchor member 1 has an engagement surface 12 that faces toward the outer surface 22 of the expandable tubular 20, and a borehole-facing surface 13 which generally faces away from the outer surface 22 of the expandable tubular 20.
As briefly stated above, the loose end 30 of each anchor member 1, 1' is movable in a direction 25 away from the longitudinal axis A, suitably by bending the anchor member between the fixed end and loose end. Bending may also involve hinging. To facilitate said bending each anchor member may be provided with one or more hinges 31, as for instance described in US Pat. No. 8,997,856 , in which hinges the bending moment required to bend the anchor member outward is smaller than the bending moment required to bend other portions of the anchor members outward.
The fixed end 40 of each anchor member 1 is secured to the expandable tubular 20 with a securing system 50. The securing system 50 is better visible in FIG. 3 which shows an enlarged view. The securing system 50 comprises a tongue-and-groove connection 9, comprising a tongue 6 and a groove 7 that receives the tongue 6. The groove 7 is suitably formed by a recess in the outer surface of the cylindrical wall 21. Each groove 7 is suitably oriented in a circumferencing direction around the longitudinal axis A. The tongue 6 is suitably formed by a ridge on an engagement surface in the fixed end 40 of each anchor member 1.
Preferably, the tongue-and-groove connection 9 for each anchor member comprises a plurality of tongues and grooves, such as in the example shown in the drawings which has four tongues and grooves. The tongue-and-groove connection 9 prevents each anchor member 1, 1' against sliding movement of the anchor member relative to the expandable tubular 20 in longitudinal direction. The tongue-and-groove connection 9 provides a geometric lock that secures the anchor member(s) in longitudinal direction to the expandable tubular.
The securing system 50 further suitably comprises a squeeze sleeve 3 that is slidably arranged around the expandable tubular 20. The squeeze sleeve 3 can slide in longitudinal over at least part of the fixed end 40 of the anchor member 1, to maintain the tongue(s) 6 inside the groove(s) 7 and avoid inadvertent disengagement of the anchor member 1 from the expandable tubular 20. Suitably, at the fixed end 40 the borehole-facing surface 13 is tapered inwardly toward the longitudinal axis A to form a squeeze-sleeve engagement surface 14. The squeeze sleeve has a squeeze surface facing toward the outer surface 22 of the expandable tubular 20, which is a preferably angled parallel to the tapered sleeve engagement surface 14. Herewith a tight engagement can be achieved between the anchor member 1 and the expandable tubular 20. Suitably, a locking spring 5, such as a C-ring, may be provided to snap the squeeze sleeve into position. This facilitates assembly of the anchoring system 10, and is a safeguard against undesired release of the squeeze sleeve 3 during handling of the expandable tubular 20 and during running the expandable tubular 20 into the borehole.
The anchor members 1, 1' may be interconnected with each other by pliable links 8 to essentially form a circular sleeve of the anchor members around the expandable tubular 20 which can easily be slid into position during assembly. The pliable links 8 also prevent the individual anchor members 1 from prematurely bending outward before an expansion tool (such as an expander cone) is translated through the expandable tubular.
The sleeve of anchor members may suitably be machined out of a cylindrical mantle, by cutting a predetermined pattern of longitudinal slots 17 in the mantle which define the anchor members 1, 1' or parts of the anchor members. When produced this way, the anchor members together form a segmented sleeve or partially segmented sleeve. The longitudinal slots 17 may be intermittently interrupted to leave one or more bridges 11 of mantle material between adjacent anchor members 1 and 1'.
The pliable links 8 may be integral with the anchor members 1, 1'. As illustrated in FIG. 4A, the pliable links 8 may for instance be created by cutting additional longitudinal slots 18 and 18' circumferentially adjacent to each bridge 11, which additional slots 18, 18' at the extremities thereof extend side-by-side with the longitudinal slots 17 on either side of the bridge 11. The additional slots 18, 18' can be parallel to each other, and longitudinally oriented. Alternatives can easily be contemplated without departing from the inventive concept, including geometric variants, as well as variants involving pliable links that are not integral to the mantle but provided as separate parts, such as a (possibly elastic) ring or a band around the anchor members 1, 1'.
FIG. 4B illustrates the same pliable link 8 as shown in FIG. 4A, but in expanded condition. It can be seen that the slots 17 and 18, 18' become wider allowing the spacing between the adjacent anchor members 1, 1' to increase. During assembly of the anchor system 10, the anchor sleeve is in the expanded condition as illustrated in FIG. 4B conveniently slid over the expandable tubular, and then locked in place by collapsing it to the collapsed condition shown in FIG. 4A. During collapsing the tongues are suitably mated with the grooves, after which the optional squeeze sleeve can be brought into position.
To facilitate activation of the anchor system 10 running an expansion tool though the expandable tubular 20, a ramp member 4 may be provided longitudinally adjacent to the loose end 30 of the anchor member 1. The ramp member 4 is secured to the outer surface 22 of the expandable tubular 20 for engaging with the loose end 30 of the anchor member 1 during use. Such ramp member 4 suitably has an inclined surface 45 facing the loose end 30 of the anchor member 1 to guide it away from the longitudinal axis A upon longitudinal contraction of the expandable tubular 20. Such contraction in longitudinal direction accompanies the radial expansion of the tubular wall 21 caused by the expansion tool.
The ramp member 4 is optionally connected to the expandable tubular 20 with another tongue-and-groove connection. For clarity reasons, the tongue-and-groove connection for the anchor member(s) is referred to in the appended claims as "first" tongue-and-groove connection and the optional tongue-and-groove connection for the ramp member 4 is referred to as "second" tongue-and-groove connection. Likewise, the respective securing systems will be referred to as "first" securing system (squeeze sleeve) and "second" securing system (squeeze sleeve). The ramp members 4, 4' may be embodied in the form of strips, suitably metal strips, similar to the anchor members 1, 1', which are secured to the expandable tubular 20 at second fixed ends 60. A second squeeze sleeve 2 may be employed, with similar functionality as the squeeze sleeve 3 described above.
Alternatively, the ramp member may be formed by a (segmented) ring circumventing the expandable tubular. A separate support ring may optionally be provided on the expandable tubular 20 at the interface between the ramp members 4, 4' and the anchor members 1, 1' to further assist the proper activation of the anchor system 10. such support ring may be welded to the expandable tubular 20, but preferably, it is secured to the expandable tubular 20 in a welding-less manner as well such as by forging, for example.
A test has been performed using a carbon steel liner (OD 155 mm, ID 135 mm) on which a sleeve of anchor members was secured using a tongue-and-groove connection as described above. The securing system included a tongue-and-groove connection of four tongues and four circumferential concentric grooves of 3 mm depth and 4.5 mm axial width machined into the liner, and a squeeze sleeve locked into place. After expanding the expandable tubular by longitudinally forcing a 155 mm OD cone through the expandable tubular, an axial load of 160 metric Tonnes was applied to the sleeve of anchor members. Inspection indicated that the connection was still intact and no failure occurred. The integrity of the tongue-and-groove connection has also been investigated and confirmed using finite element computational analysis.
Although the invention is not limited to any particular size, by way of example one anchor member may be formed of a metal strip of approximately 50 cm long and approximately 30 mm wide. The thickness of the strip may be approximately 6 mm to 8 mm. The ramp member may be manufactured from the same metal strips, but at a length of approximately 20 cm.
It will be clear to the person skilled in the art that welding can be avoided. This is generally advantageous as welding requires a specialist to do the welding and when not performed according to specifications there is a risk of failure of the anchoring system down hole. The proposed securing systems generally make it easier to manufacture and assemble the anchor system on the expandable tubular. It is nearly impossible to incorrectly assemble this anchor system.
The anchor system proposed herein may be used to anchor an expandable tubular in an open hole section of a borehole in an earth formation, regardless of which type of material is used for the liner. For example, such anchoring can be used to keep an expandable liner in place by anchoring the liner at one end thereof in the open hole section to allow moving an expansion cone through the liner towards the other end, such as shown in US Pat. Appl. Publ. No. US 2013/0312954 A1 and/or International Publication No. WO 2017/01662 A1 . Alternatively, the anchor system proposed herein can be used to anchor a tool or a plug in an open hole section, such as but not limited to a whip stock, or a plug to isolate a lower part of the borehole from a higher part of the borehole. The latter may for instance be used to set a plug to avoid (hydrostatically driven) salt ingress into the bore hole in the course of hydrocarbon production, which may occur on occasion when the hydrocarbon rich formations are located above a salt dome. The anchor system described herein may be particularly suitable for salt-control plugs as avoiding of welding is particularly suited to a variety of corrosion-resistant alloys.
The person skilled in the art will understand that the teachings described in the present paper can be applied to advantageously modify any of the embodiments described in US patent Nos. 8,522,866 ; 8,973,654 ; 8,997,856 ; 8,997,857 ; all of which are incorporated herein by reference. This includes modifying the anchor systems as described in these US patents, or similar alternatives, welded or otherwise joined to the expandable tubular element, for use as tool-supporting anchor and/or open-hole plug.
The person skilled in the art will understand that the present invention can be carried out in many various ways without departing from the scope of the appended claims.

Claims

1. An anchor system for anchoring an expandable tubular to a borehole wall, comprising:

- an expandable tubular comprising a cylindrical wall extending around a longitudinal axis and having a cylindrical outer surface facing away from the longitudinal axis;

- an anchor member, comprising a fixed end and a loose end arranged on the outer surface of the expandable tubular whereby the loose end is positioned longitudinally displaced from the fixed end, which fixed end is secured to the expandable tubular against sliding movement of the fixed end of the anchor member relative to the expandable tubular, and which loose end is movable in a direction away from the longitudinal axis whereby bending the anchor member between the fixed end and loose end;

wherein the fixed end is secured to the expandable tubular with a first securing system that comprises a first tongue-and-groove connection comprising a tongue and a groove that receives the tongue.

2. The anchor system of claim 1, wherein the groove for said first tongue-and-groove connection is formed by a recess in the outer surface of the cylindrical wall.

3. The anchor system of claim 2, wherein said groove is oriented in a circumferencing direction around the longitudinal axis.

4. The anchor system of any one of the preceding claims, wherein the anchor member comprises an engagement surface facing toward the outer surface of the expandable tubular, wherein the tongue is formed by a ridge on the engagement surface.

5. The anchor system of any one of the preceding claims, wherein the anchor member comprises a borehole-facing surface facing away from the outer surface of the expandable tubular, which borehole-facing surface is tapered inwardly toward the longitudinal axis at the fixed end.

6. The anchor system of claim 5, wherein the tapered borehole-facing surface forms a squeeze-sleeve engagement surface, wherein the first securing system further comprises a first squeeze sleeve that is slidably arranged around the expandable tubular which first squeeze sleeve has a squeeze surface facing toward the outer surface of the expandable tubular and engaging with the squeeze-sleeve engagement surface.

7. The anchor system of any one of the preceding claims, comprising a plurality of the anchor members arranged side by side distributed around the circumference of the expandable tubular.

8. The anchor system of claim 8, wherein the anchor members are interconnected with each other by pliable links, whereby the plurality of the anchor members form a sleeve around the expandable tubular.

10. The anchor system of any one of the preceding claims, further comprising a ramp member secured to the outer surface of the expandable tubular for engaging with the loose end of the anchor member during use.

11. The anchor system of claim 10, wherein the ramp member is connected with a second securing system, said second securing system comprising a second tongue-and-groove connection.