CONNECTORS FOR HIGH TEMPERATURE GEOTHERMAL WELLS

Abstract

The invention relates to a connector for connecting casing segments used in wells drilled in high temperature areas and for transport of high temperature media, the connector comprising: a hollow tubular main body 1 with a first tubular sleeve opening 2 to be attached to first casing 4 and a second tubular sleeve opening 3 to be attached to a second casing 5, an inwardly facing circumferential spacing 21 axially extending between an inwardly extending upper rim 11 in proximity to the first tubular sleeve opening 2 and an inwardly extending central rim 13, an inner tubular member 7 extending radially within the spacing 21, said inner tubular member comprising a first circumferential engaging zone 8 for engaging a mating engaging zone of an end of said first casing 4, a second circumferential engaging zone 10 in proximity to the second tubular sleeve opening 3, for engaging a mating engaging zone of an end of the second casing 5, characterised in that the inner tubular member 7 is shorter in the axial direction than the inwardly facing circumferential spacing 21 and is reversibly slidable within the inwardly facing circumferential spacing 21 between the inwardly extending upper rim 11 and the inwardly extending central rim 13.

Claims

1. A connector for connecting casing segments used in wells drilled in high temperature areas and for transport of high temperature media, the connector comprising: a hollow tubular main body 1 with a first tubular sleeve opening 2 to be attached to first casing 4 and a second tubular sleeve opening 3 to be attached to a second casing 5, an inwardly facing circumferential spacing 21 axially extending between an inwardly extending upper rim 11 in proximity to the first tubular sleeve opening 2 and an inwardly extending central rim 13, an inner tubular member 7 extending radially within the spacing 21, said inner tubular member comprising a first circumferential engaging zone 8 for engaging a mating engaging zone of an end of said first casing 4, a second circumferential engaging zone 10 in proximity to the second tubular sleeve opening 3, for engaging a mating engaging zone of an end of the second casing 5, wherein the inner tubular member 7 is shorter in the axial direction than the inwardly facing circumferential spacing 21 and is reversibly slidable within the inwardly facing circumferential spacing 21 between the inwardly extending upper rim 11 and the inwardly extending central rim 13.

2. The connector according to claim 1, further comprising a first sacrificial seal/gasket 14 between said inwardly extending central rim 13 and the inner tubular member 7.

3. The connector according to claim 1, wherein the longitudinal thickness of the first seal/gasket 14 is similar to the space between the connecting portion C of the inner tubular member 7 and the connecting portion D of the central rim 13, when the inner tubular member 7 sits in mounting seat A, in its most distal position.

4. The connector according to claim 1, wherein an outer surface of the inner tubular member 7 and an inwardly facing surface of the inwardly facing circumferential spacing 21 are essentially parallel to the axial direction.

5. The connector according to claim 1, wherein the inner tubular member 7 comprises an abutting inwardly extending rim 12 that contacts the peripheral end surface of the first casing 4 when the first casing 4 is fully attached.

6. The connector according to claim 1, wherein the high temperature media comprises one or more of oil, steam, water or brine.

7. The connector according to claim 1, wherein the circumferential engaging zones 8 and 10 comprise a screw thread.

8. The connector according to claim 7, wherein the circumferential engaging zone 8 extends essentially to the abutting inwardly extending rim 12 of the inner tubular member 7 and wherein the circumferential engaging zone 10 of the second tubular sleeve opening 3 extends to the inwardly extending central rim 13 of the second tubular sleeve opening 3.

9. The connector according to claim 1, wherein the outer surface 15 of the inner tubular member 7 and the inner surface 16 of the hollow tubular main body have restrictive structural formations to restrict rotation around the length of the casing.

10. The connector according to claim 1, wherein the structural formations to restrict rotation around the length of the casing comprise protrusions in one member and respective depressions in the other member or slight elliptical circumference in the mating surfaces of the two members.

11. A method for connecting casing segments used in drilling wells through in high temperature areas and transport of high temperature media through the casings using a connector, said method comprising: engaging a first casing 4 to a first tubular sleeve opening 2 of a connector having a hollow tubular main body 1 and engaging a second casing 5 to a second tubular sleeve opening 3 of the connector, wherein the first casing 4 is engaged to a mating circumferential engaging zone 8 in the inner tubular member 7 of the first tubular sleeve opening 2 and wherein the second casing 5 is engaged to a mating circumferential engaging zone 10 in the second tubular sleeve opening 3 wherein the inner tubular member 7 is shorter in the axial direction than the inwardly facing circumferential spacing 21 and is reversibly slidable within the inwardly facing circumferential spacing 21 between the inwardly extending upper rim 11 and the inwardly extending central rim 13 to take up expansion and contraction of the casings as a result of a temperature change.

12. The method according to claim 11, wherein an outer surface of the inner tubular member 7 and an inwardly facing surface of the inwardly facing circumferential spacing 21 contact to form a metallic sealing with sealing surfaces that are essentially parallel to the axial direction.

13. The method according to claim 11, further comprising providing a first seal/gasket 14 between second tubular sleeve opening 3 and the inner tubular member 7 within the hollow tubular main body 1 to prevent water or concrete will flow into a joint between the first and second casings 4, 5 during mounting and to keep a maximum distance between the casings during mounting.

14. The method according to claim 11, wherein the longitudinal thickness of the first seal/gasket 14 is similar to the distance E between the connecting portion C of the inner tubular member 7 of first tubular sleeve opening 2 and the connecting portion D of the second tubular sleeve opening 3, when the inner tubular member 7 of the first tubular sleeve opening 2 sits in mounting seat A and wherein the first seal/gasket 14 melts away due to heating of the casing and the connecting portion of the inner tubular member 7 of first tubular sleeve opening 2 is positioned in connecting seat B.

15. The method according to claim 14, wherein the distance E between the connecting portion C of the inner tubular member 7 of first tubular sleeve opening 2 and the connecting portion D of the second tubular sleeve opening 3 can account for the entire increase or decrease in length of the casings due to expansion or contraction as a result of temperature change.

16. The method according to claim 11, wherein the casings are attached to the connector by screwing the upper casing into a screw thread of the inner surface of the inner tubular member 7 and screwing the lower casing into a screw thread of the outer support member 9 before they are lowered down into a borehole using screw thread 8 and 10 in the connector.

17. The method according to claim 11, wherein the outer surface 15 of the inner tubular member 7 and the inner surface 16 of outer support member 6 form a metallic seal in an open mounting position.

18. The method according to claim 11, wherein the outer surface 15 of the inner tubular member 7 and the inner surface 16 of outer support member 6 together with the bottom surface 17 of the inwardly extending lower rim 12 of the inner tubular member 7 and the top surface 18 of the inwardly extending lower rim 13 of the outer support member 9 of the second tubular sleeve opening 3 form a metallic seal in a connecting positon.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0037] The skilled person will understand that the drawings, described below, are for illustration purposes only. The drawings are not intended to limit the scope of the present teachings in any way.

[0038] FIG. 1 shows a schematic layout of a vertical well with regular diameter used in geothermal drilling.

[0039] FIG. 2 shows the connector of the present invention in mounting position.

[0040] FIG. 3 shows a transection of two casings being connected by the connector of the invention in mounting position (FIG. 3A) and in connection position (FIG. 3B) outlining the individual parts of the connector.

[0041] FIG. 4 shows a transection of two casings being connected by the connector of the invention in mounting position (FIG. 4A) and in connection position (FIG. 4B) outlining the surfaces forming the sealing properties of the connector.

[0042] FIG. 5 shows the connector of the present invention in mounting position (FIG. 5A) and in connection position (FIG. 5B).

[0043] FIG. 6 shows a transection of the sliding member in mounting position.

[0044] FIG. 7 shows a transection of the sliding member in connecting position.

[0045] FIG. 8 shows a transection of the connecting portion C of the sliding member and the connecting portion D of the second tubular sleeve opening in mounting position.

[0046] FIG. 9 shows a transection of the gap between the connecting portion of the sliding member of first tubular sleeve opening and the connecting portion of the second tubular sleeve opening.

[0047] FIG. 10 shows two embodiments for providing restrictive structural formations to restrict rotation around the length of the casing.

DESCRIPTION OF VARIOUS EMBODIMENTS

[0048] In the following, exemplary embodiments of the invention will be described, referring to the figures. These examples are provided to provide further understanding of the invention, without limiting its scope.

[0049] It should be appreciated that the invention is applicable for connecting casing segments in general in borehole for utilizing high temperature media, such as oil and geothermal media. Further, the connector, a system and the method according to the invention is illustrated in the embodiments that follow with a preferred embodiment of geothermal borehole, but it should be appreciated that the invention is also applicable to drilling for other purposes such as oil wells.

[0050] For the drawings below the embodiments show a connector where the sliding inner member is attached to the upper casing during drilling and assembly. The skilled person will appreciate that the connector can be used such that the sliding inner member is attached to the lower casing during drilling and assembly.

[0051] Referring to FIG. 2A, there is schematically shown connector for connecting two casings. The drawing is a transactional view of a connector having a hollow tubular main body 1 with an upper tubular sleeve opening 2 and a lower tubular sleeve opening 3 to be attached to an upper casing 4 and a lower casing 5.

[0052] In FIG. 2B the connector for connecting casing segments is shown with a similar drawing as in FIG. 2A. Thea hollow tubular main body 1 having first tubular sleeve opening 2 being attached to the first casing 4 and a second tubular sleeve opening 3 being attached to a second casing 5. The drawing outlines how the connector can take up thermal expansion due to temperature change when high temperature media starts to flow through the casings and contraction when the well needs to be cooled down for maintenance. An axially extending inwardly facing circumferential spacing 21 is created by an inwardly extending upper rim 11 in proximity to the first tubular sleeve opening 2 and an inwardly extending central rim 13. An inner tubular member 7 is provided extending radially within the spacing 21. The inner tubular member has a first circumferential engaging zone for engaging a mating engaging zone of an end of said first casing 4 and a second circumferential engaging zone in proximity to the second tubular sleeve opening 3, for engaging a mating engaging zone of an end of the second casing 5. The drawing shows how the inner tubular member 7 is shorter in the axial direction than the inwardly facing circumferential spacing 21 and is therefore reversibly and slidable within the inwardly facing circumferential spacing 21 between the inwardly extending upper rim 11 and the inwardly extending central rim 13. A first seal or gasket 14 is shown in the drawing. The gasket is optional but when used it will fill the free space between the inwardly extending central rim 13 and the most distal part of the inner tubular member 7. When high temperature media starts to flow through the casings this gasket melts away and the inner tubular member 7 can slide freely in an axial direction within the spacing 21.

[0053] FIG. 3 shows in transection how two casings have been connected by the connector in an (open) mounting or maintenance position (FIG. 3A) and in a (closed) connecting or operating position (FIG. 3B). There the first or upper tubular sleeve opening 2 has two different mayor components, namely an outer support member 6 and an inner tubular member 7. The inner member has circumferential attaching zone 8 for attaching the upper casing 4 end to the connector, but this is done by attaching the casing 4 into the inner tubular member 7 of the upper tubular sleeve opening 2 using circumferential attaching zone 8 of the inner tubular member 7 and a matching outer circumferential attaching zone of the upper casing 4. In embodiments where the circumferential sealing means is a screw thread, both the outer end of the casing and the inner circumference of the connecting part of the connector have matching screw threads and the casing is screwed all the way into the connector to form a tight connection to the other casing. The second or lower tubular sleeve opening 3 comprises an outer support member 9 further comprising a circumferential attaching zone 10 for attaching the second casing 5 end to the connector. The outer support member 6 of the upper tubular sleeve opening 2 has an inwardly extending upper rim 11 extending inwardly the equivalent to the thickness of the upper opening of the inner tubular member 7. Additionally, the inner tubular member 7 of the upper tubular sleeve opening 2 has an inwardly extending lower rim 12 extending inwardly the equivalent to the thickness of the lower opening of the casing 4. Furthermore, the second tubular sleeve opening 3 comprises an inwardly extending upper rim 13 extending inwardly the equivalent to the thickness of the inwardly extending lower rim 12 of the inner tubular member 7. The inner tubular member 7 of the upper tubular sleeve opening 2 is shorter than the outer support member 6 of the upper tubular sleeve opening 2 and is slidably movable between the inwardly extending upper rim 11 of the outer support member 6 and the inwardly extending upper rim 13 of the second tubular sleeve opening 3. The distance, of which the inner member is slidable within the upper tubular sleeve opening 2 is calculated as the distance which one casing expands due to the temperature increase in the environment of pumping up geothermal media or oil. If the well needs to be cooled down for maintenance, the casings are able to contract back to the length during mounting due to the allowable sliding length within the connector.

[0054] When the connector of the present invention is being used, the casing segments are connected by screwing them into the connector before or as they are lowered down into a borehole using screw thread 8 and 10 in the connector. The upper casing 4 is secured to the upper tubular sleeve opening 2 of the connector and the lower casing 5 to a lower tubular sleeve opening 3 of the connector. The zigzag lines 8 and 10 define screw threads of the upper and lower casing 4, 5 matching the screw thread of the upper and lower tubular sleeve opening 2, 3 respectively. The first seal or gasket 14 (not shown in this drawing) between the casings in a mounting position prevent water, drilling mud or concrete from flowing into the joint between the upper and lower casing during mounting and to keep a maximum distance between the pipes during mounting. As the inner tubular member 7 of the upper tubular sleeve opening 2 is shorter than the outer support member 6 and is slidably movable within the outer support member 6 when the pipes heat up and expand due to the high temperature. This means that the inner member will slide into connection position when the well heats up due to hot steam. Furthermore, in cases when the well needs to be cooled down for maintenance or the like, the inner member can slide back into mounting position without disrupting the pipeline.

[0055] In FIG. 3A the space between the lowest part of the inner tubular member 7 of upper tubular sleeve opening 2 and the upper part of the lower tubular sleeve opening 3, defines the space where the first seal/gasket 14 during mounting and the distance of the space amounts to approximately the longitudinal thickness of the seal/gasket 14 when the inner tubular member 7 of the upper tubular sleeve opening 2 sits in mounting position.

[0056] In FIG. 3B there is no space between the lowest part of the inner tubular member 7 of upper tubular sleeve opening 2 and the upper part of the lower tubular sleeve opening 3 as the gasket 14 has been sacrificed and the two casings are connected in connecting position. A recess is shown in the upper part of the upper tubular sleeve opening 2 in FIG. 3B for housing a second seal/gasket in the upper rim 11 to prevent water, drill mud or cement to seep into the connector. This is an optional feature of the present invention although shown in the transactional drawings.

[0057] FIG. 4 outlines how the connector of the present invention forms a metallic seal by its components in both a mounting/maintenance position as well as in an operating position. In FIG. 4A the connector is in a mounting/maintenance position. The outer surface 15 (shown with a thick line in FIG. 4A) of the inner member 7 and the inner surface 16 (shown with a thick line in FIG. 4B) of outer support member 6 form a metallic seal in a mounting/maintenance position. In FIG. 4B, the connector is in an operating position. The outer surface 15 of the inner member 7 and the inner surface 16 of outer support member 6 together with the bottom surface 17 (shown with a thick line in FIG. 4A) of the inwardly extending lower rim 12 of the inner member 7 and the top surface 18 (shown with a thick line in FIG. 4A) of the inwardly extending lower rim 13 of the outer support member 9 of the second tubular sleeve opening 3 form a metallic seal in a connecting positon. As can be seen in FIG. 4 A and B, the circumferential sealing zone/means 8 extends essentially to the lowest part of the inner member 7 (to the inwardly extending lower rim 12) of upper tubular sleeve opening 2. In the same manner the circumferential sealing zone/means 10 of the lower tubular sleeve opening 3 extends essentially to the most upper part (to the rim 13) of the lower tubular sleeve opening 3.

[0058] FIG. 5 shows in a schematic drawing two casings being connected by a connector in mounting/maintenance position (FIG. 5A) and in connection/operating position (FIG. 5B). In the embodiment shown in FIG. 5A, a first sacrificial seal/gasket 14 is positioned between the upper tubular sleeve opening 2 and a lower tubular sleeve opening 3, but this gasket melts or disintegrates when hot steam and brine starts to flow up the casing. In FIG. 5A, the inner member 7 of the upper tubular sleeve opening 2 sits in mounting seat A, but in FIG. 5B it is in connecting seat B. This is also shown with transactional view in FIGS. 6 and 7.

[0059] FIG. 8 defines connection points C of the inner member 8 of first tubular sleeve opening 2 and connecting portion D of the second tubular sleeve opening 3, but the space between connecting portions C and D is similar to the longitudinal thickness of the first seal/gasket 14. When the well is activated and steam or brine of high temperatures enters the casing, the gasket melts away and the inner member 7 of the first tubular sleeve opening 2 slides from mounting seat A to connecting seat B where connecting portions C and D meet and form a tight connection. The space between connecting portions C and D is defined as distance E in FIG. 9

[0060] FIG. 10A shows a cross-sectional view of a first casing 4 being secured into the connector 1. The space between the casing and the inner member as well as the space between the sliding inner member 7 and the hollow tubular main body 6 is exaggerated to outline the restrictive structural formations to restrict rotation around the length of the casing. The outer surface 19 of the casing 4 is secured to the inner surface 20 of the sliding inner member 7 by a screw thread for example. The outer surface 15 of the inner member 7 and the inner surface 16 of outer support member 6 have an elliptical shape in this embodiment to prevent rotation around the length of the casing, whereas the outer surface 19 of the casing 4 and the inner surface 20 of the sliding inner member 7 are completely circular to provide connectivity by screwing the two components together. The outer circumference of the outer support member is also shown as circular. It should be noted that only a small degree of elliptical shape is required to prevent rotation around the length of the casing, but this is exaggerated in this drawing for demonstrational purposes.

[0061] In FIG. 10B, a different type of restrictive structural formations is shown. The mating surfaces of outer surface 15 of the inner member 7 and the inner surface 16 of outer support member 6 have mating protrusions 22 in the outer support member 6 and depressions 23 in the inner member 7.

[0062] As used herein, including in the claims, singular forms of terms are to be construed as also including the plural form and vice versa, unless the context indicates otherwise. Thus, it should be noted that as used herein, the singular forms a, an, and the include plural references unless the context clearly dictates otherwise.

[0063] Throughout the description and claims, the terms comprise, including, having, and contain and their variations should be understood as meaning including but not limited to, and are not intended to exclude other components.

[0064] The present invention also covers the exact terms, features, values and ranges etc. in case these terms, features, values and ranges etc. are used in conjunction with terms such as about, around, generally, substantially, essentially, at least etc. (i.e., about 3 shall also cover exactly 3 or substantially constant shall also cover exactly constant).

[0065] The term at least one should be understood as meaning one or more, and therefore includes both embodiments that include one or multiple components. Furthermore, dependent claims that refer to independent claims that describe features with at least one have the same meaning, both when the feature is referred to as the and the at least one.

[0066] It will be appreciated that variations to the foregoing embodiments of the invention can be made while still falling within the scope of the invention can be made while still falling within scope of the invention. Features disclosed in the specification, unless stated otherwise, can be replaced by alternative features serving the same, equivalent or similar purpose. Thus, unless stated otherwise, each feature disclosed represents one example of a generic series of equivalent or similar features.

[0067] Use of exemplary language, such as for instance, such as, for example and the like, is merely intended to better illustrate the invention and does not indicate a limitation on the scope of the invention unless so claimed. Any steps described in the specification may be performed in any order or simultaneously, unless the context clearly indicates otherwise.

[0068] All of the features and/or steps disclosed in the specification can be combined in any combination, except for combinations where at least some of the features and/or steps are mutually exclusive. In particular, preferred features of the invention are applicable to all aspects of the invention and may be used in any combination.