GB2527109A

GB2527109A - Pipe coupling

Info

Publication number: GB2527109A
Application number: GB1410489.7A
Authority: GB
Inventors: Neil Thomson; William Luke Mcelligott
Original assignee: Meta Downhole Ltd
Current assignee: Meta Downhole Ltd
Priority date: 2014-06-12
Filing date: 2014-06-12
Publication date: 2015-12-16
Also published as: GB201410489D0; WO2015189622A1

Abstract

A coupling system between tubulars such as tubing, pipes, casing and liner for location in a well bore in which the ends of each tubular 12, 14 are expanded and have cooperating profiled sections 62, 80 on the expanded surfaces, the profiled sections are arranged coaxially and a radially applied inward force is applied to form a metal to metal sealed connection, the resulting connection has the substantially the same inner diameter 22 and outer diameter 26 as the tubulars. The force may be applied by a swaged die. The profile sections may include grooves, rims, pins jaws or sawtooth arrangements. The profile sections may be tapered. Additional sections may be provided to prevent relative rotation of the tubular using a lug 102 (see Figure 5) and notch.

Description

PIPE COUPLING

The present invention relates to a coupling system between tubulars such as tubing, pipes, casing and liner for location in a well bore. In particular, s though not exclusively, the invention relates to a coupling system in which swaged profiled sections on the tubulars are connected using a radially applied force to form a metal to metal sealed connection providing a substantially continuous tubular.

ao In the exploration and production of oil and gas wells, tubulars in the form of tubing, pipe, casing and liner are run into the well bore. As the depth of each well bore can be hundreds of metres, the tubulars are manufactured in fixed lengths and then they require to be joined together. A typical method of joining tubulars together is to use a screw threaded connection to form a tubular string for insertion in a well bore.

In order to achieve this type of connection each tubular member is manufactured with a box section at a first end and a pin section at the opposing end having respective male and female screw threads. The outer surface at the ends of the tubulars are keyed to allow one tubular to zo be held in place while the second tubular is turned so as to mate with the first and make-up the threaded connection. A known disadvantage of such a connection is that if the tubular string becomes stuck in the well bore, the string cannot be rotated counter to the direction of the screw thread as the connection may come apart. Standard screw threaded connections may also not provide a reliable seal between the inside of the tubulars and the outside of the tubulars at the connection as a fluid path can exist along the helical screw thread. Additionally the threads can be prone to make up problems, require the use of dope (lubricant and sealant) and can have a complex supply chain.

To overcome these disadvantages, the present applicants have proposed a pipe coupling described in G62503344 as a coupling system between tubulars such as tubing, pipes, casing and liner for location in a well bore in which profiled sections on the tubulars are connected using a radially applied force to form a metal to metal sealed connection. Embodiments are provided in which the profiled sections are grooved and/or tapered, s additional profiles are provided to prevent relative rotation of the tubulars, the radial force is applied inwardly, outwardly or in both directions, and a connector is used as an additional tubular member to form the coupling.

A disadvantage in this coupling arrangement has been found when the radial force is applied. If the tubular members are of a significant length, such as drill pipe, liner and casing sections used in the oil and gas industry, there is insufficient space on a drilling rig to insert an expansion tool through the tubular members to the coupling point. This leads to use of an inwardly applied radial force. Use of hydraulic fluid pressure directly against the outer surface of the coupling will cause both profiled sections to elastically deform and, as this is difficult to control, the connection may be formed with a reduced inner and, potentially, outer diameter compared to the tubulars. Such narrowing of the throughbore of the tubulars is zo undesirable and limits usefulness of the coupled tubulars.

It is therefore an object of at least one embodiment of the present invention to provide a coupling system between tubulars which mitigates at least some of the disadvantages of the prior art.

According to a first aspect of the present invention there is provided a coupling system between first and second tubular members comprising: a first tubular member having: a cylindrical body with an inner body diameter and an outer body diameter substantially along its length; a first end with a first end inner diameter and a first end outer diameter, the first end including a first profiled section extending circumferentially and continuously around an outer surface; a second tubular member having: s a cylindrical body with the inner body diameter and the outer body diameter substantially along its length; a second end with a second end inner diameter and a second end outer diameter, the second end including a second profiled section extending circumferentially and continuously around an inner surface; wherein: ao the first and second end inner diameters are greater than the inner body diameter; the first and second end outer diameters are greater than the outer body diameter; and the first end of the first tubular member being inserted within the second end of the second tubular member so that the profiled sections are coaxial and by application of a radially inward force creating a connection having a metal to metal seal between the tubular members at the profiled sections with the connection having substantially the inner body diameter and the outer body diameter.

In this way, the tubular members can be coupled directly together by an interference fit creating a connection which has the same inner and outer diameter as the tubular members, providing a substantially continuous tubular.

Preferably the first tubular member has the second end opposite the first end. Preferably also, the second tubular member has the first end opposite the second end. In this way, the first and second tubular members may be identical. This provides a coupling system suitable for use in providing tubular strings as are known in the oil and gas industry.

Preferably the inner and outer body diameters are selected to match standard diameters of tubulars used in downhole oil and gas exploration and production. In this way, a tubular string can be made-up without requiring box sections at the coupling points.

Preferably the force is applied radially inwards over the ends of the tubulars. More preferably, the force is applied by a swaged die being driven over the outer surface of the second tubular towards the first tubular. In this way, the force is applied to an outer surface of the second ao tubular to cause it to move radially inwards and contact the inner surface of the first tubular, both ends are elastically deformed and morphed to have the outer body diameter. In this way, an interference is created between the first and second profiled sections on each tubular member.

By applying a radial force to make-up the coupling, the tubular members do not have to be turned as would be required for a screw-thread.

Preferably, the first profiled section comprises one or more circumferential grooves formed on the outer surface of the first end. Preferably also, the zo second profiled section comprises one or more circumferential grooves formed on the inner surface of the first end. More preferably, a continuous annular rim is formed between each pair of grooves.

In an embodiment, grooves are formed on the first and second profiled sections. More preferably, each groove on the first and second profiled section is arranged to mate with a rim on the opposing second and first profiled section, respectively. In this way, the first profiled section is a reverse of the second profiled section so that the sections perfectly mate causing an interference fit when the force is applied. When a plurality of grooves are present, the coupling may be considered as a meshed teeth arrangement.

Preferably, the first profiled section is tapered. In this way, the thickness of the tubular wall reduces across the first end being narrowest at a distal end. Preferably also, the second profiled section is tapered. In this way, the thickness of the tubular wall reduces across the first end being s narrowest at a distal end. Tapering the ends provides a combined wall thickness which, when morphed, has the inner body diameter and the outer body diameter.

Preferably, a wall thickness of the first end is substantially the same as the wall thickness of the second end. Preferably also, the wall thickness of the first and second ends is substantially the same as the wall thickness of the body of the first and second members. In this way, wall thickness across the connection is maintained.

Preferably, the first tubular member includes a third profiled section at an end face and the second tubular member includes a fourth profiled section at an end face wherein the third and fourth profiled sections mate to prevent relative rotation of the tubular members. In an embodiment, the third profiled section comprises at least one lug on the end face and the zo fourth profiled section comprises at least one notch, each notch being sized to receive a lug when the force is applied. Alternatively, the fourth profiled section comprises at least one lug on the end surface and the third profiled section comprises at least one notch. By keying the facing ends of the tubular members, relative rotation of the tubular members is prevented.

Further features are embodied in the description.

In the description that follows, the drawings are not necessarily to scale.

Certain features of the invention may be shown exaggerated in scale or in somewhat schematic form, and some details of conventional elements may not be shown in the interest of clarity and conciseness. It is to be fully recognized that the different teachings of the embodiments discussed below may be employed separately or in any suitable combination to produce the desired results.

s Accordingly, the drawings and descriptions are to be regarded as illustrative in nature, and not as restrictive. Furthermore, the terminology and phraseology used herein is solely used for descriptive purposes and should not be construed as limiting in scope. Language such as "including," "comprising," "having," "containing," or "involving," and ao variations thereof, is intended to be broad and encompass the subject matter listed thereafter, equivalents, and additional subject matter not recited, and is not intended to exclude other additives, components, integers or steps. Likewise, the term "comprising" is considered synonymous with the terms "including" or "containing" for applicable legal purposes.

All numerical values in this disclosure are understood as being modified by "about". All singular forms of elements, or any other components described herein including (without limitations) components of the zo apparatus are understood to include plural forms thereof.

Embodiments of the present invention will now be described, by way of example only, with reference to the accompanying drawings of which: Figure 1 is a half cross-sectional view of a coupling system according to an embodiment of the present; Figure 2 is a half cross-sectional view of the coupling system of Figure 1 as a made-up joint; Figure 3 is a side view of a first profiled section of the first tubular member of Figure 1; Figure 3 is a schematic illustration of a portion of first and second profiled sections of the first and second tubular members, respectively, of Figure 1; and Figure 4 is a schematic illustration of an anti-rotation fitting in a coupling system according to a further embodiment of the present invention.

Referring initially to Figure 1 of the drawings there is provided a coupling system, generally indicated by reference numeral 10, providing a connection between a first tubular member 12 and a second tubular member 14 according to an embodiment of the present invention.

The first tubular member 12 has a substantially cylindrical body 16 having a bore 18 therethough providing an inner surface 20 with a first diameter 22 and an outer surface 24 with a second diameter 26 along a majority of it's length. Note that the Figure marks the diameters to the longitudinal axis 32 of the bore 18, the distance representing the radius. The body 16 of first tubular member 12 is of metal construction and has dimensions zo typical of tubulars found in the oil and gas industry as used in tubing strings, casings and liners. The first tubular member 12 has a first end 28 with an annular end face 30 which is substantially perpendicular to the longitudinal axis of the bore 18.

The first end 28 is radially expanded from the body 16 providing an increased inner diameter 34 to the inner surface 36 of the first end 28 and an increased outer diameter 36 to the outer surface 40 of the first end 28. Preferably the wall thickness at the first end 28 is the same or substantially similar to the wall thickness of the body 16.

The second tubular member 14 has a substantially cylindrical body 42 having a bore 18 therethough providing an inner surface 46 with the first diameter 22 and an outer surface 48 with the second diameter 26 along a majority of it's length. Thus the body 16 of the first tubular member 12 and the body 42 of the second tubular member 14 have the same dimensions. The body 42 of the second tubular member 14 is also of s metal construction and has dimensions typical of tubulars found in the oil and gas industry as used in tubing strings, casings and liners. The second tubular member 14 has a second end 50 with an annular end face 52 which is substantially perpendicular to the longitudinal axis 32 of the bore 44. It is noted that the bores 18,44 are collinear on the longitudinal axis 32.

The second end 50 is also radially expanded from the body 42 providing an increased inner diameter 54 to the inner surface 56 of the second end and an increased outer diameter 58 to the outer surface 60 of the second end 50. Preferably the wall thickness at the second end 50 is the same or substantially similar to the wall thickness of the body 42.

On the outer surface 40 of the first end 28 of the first tubular member 12 there is a first profiled section 62. Profiled section 62 is a shape machined zo into the outer surface 40. The shape is entirely circumferential in that, a cross-sectional view as shown in Figure 1, would be identical for every cross-section around the tubular 12. Profiled section 62 is tapered. In this way the outer surface 40 reduces from the outer diameter 38 towards the inner diameter 22, leaving a wall thickness of the annular end face 30 at the distal end 64. The taper is gradual and thus easily machined on the end 28 of the tubular 12. While this embodiment shows a taper it will be appreciated that a taper is not essential, but merely preferred.

The profiled section 62 of the first tubular member 12 is provided with grooves 66 having rims 68 there between. The grooves 66 and rims 68 are arranged along the tapered edge. Note that the depths of the grooves 66 and the respective heights of the rims 68 are small in relation to the thickness of the wall of the first tubular member 12. This is done to provide maximum strength at the end 28.

The grooves 66 and rims 68 provide a sawtooth arrangement. On the s tapered outer surface 40 there are arranged a parallel series of grooves 66. Each groove 66 has a tapered base 70 with sloping side walls 72,74.

The side wall 74 closer to the end face 30 is sloped at an angle which is closer to perpendicular to the bore 18 than the side wall 72. This assists in loading when the coupling 10 is made up. Between each groove 66 there is provided a rim 68. The side walls 72,74 match those of the grooves bounding the rim 68. The rim 68 is trapezoidal in shape so that its top 76 is substantially parallel to the bore 18. It will be appreciated that the grooves/rims can be of any complementary shape, for example trapezoidal or triangular. Equally the sides need not be straight, they may be curved or have any profile which increases the potential surface area or number of points of contact to make a seal.

A side view of the first tubular member 12 is shown in Figure 3. It can be seen that the second groove 82 from the end face 30 has an increased zo slope on the taper. This provides a pilot end to the member 12 and an increased surface area over which contact can be made at a point on the first end 28 where the wall will be particularly thin. The arrangement of parallel grooves 66, being perpendicular to the bore 18 and providing a continuous circumferential profile on the outer surface 40, can be clearly seen. This is in direct contrast to the screw thread arrangement which would provide a single groove helically wound on the outer surface.

On the inner surface 56 of the second end 50 of the second tubular member 14 there is a second profiled section 80. Profiled section 80 is a shape machined into the inner surface 56. The shape is entirely circumferential in that, a cross-sectional view as shown in Figure 1, would be identical for every cross-section around the tubular 14.

The profiled section 80 of the second tubular member 14 is also provided with grooves 82 having rims 84 there between. However the grooves 82 and rims 84 are the inverse of the grooves 66 and rims 68. In this way, the rims 68,84 lie within the opposing grooves 82,66, respectively when s the first 28 and second 50 ends are arranged coaxially together as per Figure 1. The profiled section 80 is tapered so that the thickness of the wall of the tubular member 14 reduces towards a distal end 86 to provide an annular end face 88. The grooves 82 and the rims 84 are arranged on the tapered surface 56. Contrary to the first tubular member 12, each rim 844 has a tapered top 90 with sloping side walls 92,94. The side wall 92 furthest from the end face 88 is sloped at an angle which is closer to perpendicular to the bore 44 than the side wall 94. The side walls 92,94 match those of the grooves bounding the rim 68. The groove 82 is trapezoidal in shape so that its base 96 is substantially parallel to the bore 44.

If desired, although probably not necessary as the seal is made up outside the well bore, the grooves 66,82 may be filled with a compliant material being a sealant, foam or gel which may be compressed when the zo coupling 10 is made-up as will be described hereinafter.

In use, the first end 28 of the first tubular member 12 is inserted into the second end 50 of the second tubular member 14 until the profiled sections 62,80 are coaxially arranged and the bores 18,44 are collinear.

This is the arrangement shown in Figure 1. A metal to metal seal is created between the profiled sections 62,80 at the first end 28 of the first tubular member 12 and the second end 50 of the second tubular member 14. This is achieved by applying force to the outer surface 60 at the second end 50 of the second tubular member 14.

This inward radial force can be applied by a swage die as is known in the art. The swage die (not shown) is fitted around the outer surface 48 of :ii the second tubular member 14 on the body 42. The tubulars 12,14 are then moved relative to the swage die to cause the die to move over the outer surface 60 of the second end 60. As the inner diameter of the swage die is fixed to the diameter 26 of the body 42, the second end 50 S will be elastically deformed and move radially inwards so that the second profiled section is progressively pressed into the first profiled section 62 with the respective rims 68,84 locating in the opposing grooves 82,66 and creating a mesh arrangement. As a metal to metal seal is created between the elastically deforming ends 28,50 of the first and second tubular members 12,14, the first end 28 of the first tubular member 12 is also moved radially inwards.

When the die has passed over the ends 28,50 it can pass onto body 16 of the first member 12 as the outer diameter of body 16 is the same as that of body 42.

Referring now to Figure 2, the made-up connection of coupling system 10 can be seen. The outer surfaces 24,40,60,48 are now substantially continuous with a diameter 26 matching the bodies 16,42 of the tubular zo members 12,14. Ideally, the inner surfaces 20,36,56,46 are now substantially continuous with a diameter 22 matching the bodies 16,42 of the tubular members 12,14. As the ends 28,50 have been brought together each rim 68,84 to be forced into the corresponding groove 82,66. The contact between a rim 68 and a groove 82 is shown in Figure 4 where the rim 68 has made an interference fit within the groove 82 and the side walls 72,74 are in contact to provide a metal to metal seal. This produces a very high contact pressure which elastically deforms both the first 12 and second 14 tubular members at the contact point. Pressure can be applied to plastically deform the member exposed to the radial force while the opposite member will elastically contract and tighten the seal by placing tension on the member when the pressure is released.

It will be readily apparent that the tubular members 12,14 may be identical with each having a first end 28 and a second end 50. By coupling successive tubular members 12,14 together a tubing string can be formed. If the body 16,42 of the identical tubular members 12,14 is s selected to be a standard size used in the oil and gas exploration and production, the tubing string can then be used as a drill string, casing string or liner string. The resulting string will have a continuous inner and outer surface with a uniform bore therethrough. The use of pin and box sections is removed so that there are no protrusions from the cylindrical body of the string.

Reference is now made to Figure 5 of the drawings which illustrates an anti-rotation fitting, generally indicated by reference numeral 100, for use in a coupling system 10 according to an embodiment of the present invention.

Fitting 100 comprises a lug 102 located on the end face 104 of the second tubular member 14 which is located within a recess 106 machined in the end face 30 of the first tubular member 12. Lug 102 provides first 108a zo and second 108b surfaces which are not parallel to the end faces 30,104 and each does not extend circumferentially around the tubular member 14. Similarly, the recess 106 provides first llOa and second hUb abutting surfaces for contact with the first 108a and second 108b surfaces respectively. First llOa and second hUb abutting surfaces do not extend circumferentially around the tubular member. In the embodiment shown the surfaces 108,110 are perpendicular to the end faces 30,104. The fitting 100 prevents the tubular member 12,14 rotating with respect to the other tubular member 14,12 at the coupling 10.

so The principle advantage of the present invention is that it provides a coupling system for connecting two tubular members which provides a joint having the same inner and outer diameter as the body of the tubular members.

A further advantage of the present invention is that it provides a coupling s system for connecting two tubular members with a metal to metal seal between the members without requiring a screw thread.

A yet further advantage of at least one embodiment of the present invention is that it provides a coupling system for connecting two tubular ao members which prevents relative rotation of the tubular members when joined together.

It will be appreciated by those skilled in the art that modifications may be made to the invention herein described without departing from the scope thereof. For example, while the tubular members have been described as metal structures, only the end portions need to have metal to form the seal and thus the tubular members may be of composite form with metal ends. While a single lug is described as being located on the second tubular member, any number of lugs may be used and the one or more lugs can be located on the first tubular member. Additionally the lug may take any shape provided it has the required surface for preventing rotation.

Claims

CLAIMS1. A coupling system between first and second tubular members comprising: s a first tubular member having: a cylindrical body with an inner body diameter and an outer body diameter substantially along its length; a first end with a first end inner diameter and a first end outer diameter, the first end including a first profiled section extending circumferentially and continuously around an outer surface; a second tubular member having: a cylindrical body with the inner body diameter and the outer body diameter substantially along its length; a second end with a second end inner diameter and a second end outer diameter, the second end including a second profiled section extending circumferentially and continuously around an inner surface; wherein: the first and second end inner diameters are greater than the inner body diameter; zo the first and second end outer diameters are greater than the outer body diameter; and the first end of the first tubular member being inserted within the second end of the second tubular member so that the profiled sections are coaxial and by application of a radially inward force creating a connection having a metal to metal seal between the tubular members at the profiled sections with the connection having substantially the inner body diameter and the outer body diameter.
2. A coupling system according to claim 1 wherein the first tubular member has the second end opposite the first end and the second tubular member has the first end opposite the second end.
3. A coupling system according to claim 1 or claim 2 wherein the inner and outer body diameters are selected to match standard diameters of tubulars used in downhole oil and gas exploration and production.s
4. A coupling system according to any preceding claim wherein the force is applied radially inwards over the ends of the tubulars.
5. A coupling system according to claim 4 wherein the force is applied by a swaged die being driven over the outer surface of the second tubular towards the first tubular.
6. Preferably, the first profiled section comprises one or more circumferential grooves formed on the outer surface of the first end.Preferably also, the second profiled section comprises one or more is circumferential grooves formed on the inner surface of the first end.More preferably, a continuous annular rim is formed between each pair of grooves.
7. A coupling system according to any preceding claim wherein the first profiled section comprises one or more circumferential grooves formed on the outer surface of the first end.
8. A coupling system according to any preceding claim wherein the second profiled section comprises one or more circumferential grooves formed on the inner surface of the first end.
9. A coupling system according to claim 7 or claim 8 wherein a continuous annular rim is formed between each pair of grooves.
10. A coupling system according to claim 9 wherein grooves are formed on the first and second profiled sections and each groove on the first and second profiled section is arranged to mate with a rim on the opposing second and first profiled section, respectively.
11. A coupling system according to any preceding claim wherein the first profiled section is a reverse of the second profiled section so that the sections perfectly mate causing an interference fit when the force is applied.
12. A coupling system according to any preceding claim wherein the first profiled section is tapered.
13. A coupling system according to any preceding claim wherein the second profiled section is tapered.
14. A coupling system according to any preceding claim wherein the first tubular member includes a third profiled section at an end face and the second tubular member includes a fourth profiled section at an end face wherein the third and fourth profiled sections mate to prevent relative rotation of the tubular members.
15. A coupling system according to claim 14 wherein the third profiled section comprises at least one lug on the end face and the fourth profiled section comprises at least one notch, each notch being sized to receive a lug when the force is applied.
16. A coupling system according to claim 14 wherein the fourth profiled section comprises at least one lug on the end surface and the third profiled section comprises at least one notch.