CONNECTORS FOR HIGH TEMPERATURE GEOTHERMAL WELLS

Abstract

The invention relates to connectors for casings used in high temperature wells. The connectors of the present invention may be used for connecting casing segments of geothermal or oil wells. The connector is simple in design and able to take up thermal expansion due to temperature change when high temperature media starts to flow through the casings and when the well needs to be cooled down for maintenance. The connector of the present invention uses a new sealing mechanism for preventing leaking during operation.

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) a hollow tubular main body with an upper portion comprising a first tubular sleeve opening for receiving and engaging to a first casing and a lower portion comprising a second tubular sleeve opening for receiving and engaging to a second casing, an annular spacing in the upper portion axially extending between an inwardly extending upper rim of the upper portion in proximity to the first tubular sleeve opening and an inwardly extending central rim formed in the upper part of the lower portion of the hollow tubular main body, a) a slidable connection member extending radially within the annular spacing, said slidable connection member comprising a first circumferential engaging zone for engaging a mating engaging zone, of an end of said first casing, wherein the slidable connection member comprises an abutting inwardly extending rim that contacts the peripheral end surface of the first casing when the first casing is fully attached, and wherein the slidable connection member is shorter in the axial direction than the annular spacing and is reversibly slidable within annular spacing between the inwardly extending upper rim and the inwardly extending central rim, b) a second circumferential engaging zone in the lower portion of the hollow tubular main body in proximity to the second tubular sleeve opening, for engaging a mating engaging zone of an end of the second casing, wherein the upper portion and the lower portion of the hollow tubular main body are connected by at least two parallel surfaces as the connector is assembled, said at least two parallel surfaces being: i) first axial mating surfaces being where the upper portion meets the inwardly extending central rim formed in the upper part of the lower portion of the hollow tubular main body, when the upper portion and the lower portion are secured or fixed together during assembly, and ii) first radial facing surfaces adjacent to the first axial mating surfaces forming a spacing between the first radial facing surfaces, wherein a metal seal ring is positioned in the spacing between the first radial facing surfaces for forming a seal when axial pressure is applied to the connector during assembly and when high temperature media starts to flow through the connector.

2. The connector according to claim 1, wherein the first portion and the second portion of the hollow tubular main body are connected by further two parallel surfaces, said two parallel surfaces being: iii) second axial mating surfaces below the first radial mating surfaces, said second axial mating surfaces extending diagonally away from the first radial mating surfaces, and iv) second radial facing surfaces below the second axial mating surfaces forming a spacing between the facing surfaces opening out to the exterior of the hollow tubular main body.

3. The connector according to claim 1, wherein the attachment or fixing of the first axial mating surfaces during assembly is facilitated by welding, dovel pins or other means to prevent movement between the first and the second (5 portions along the first axial mating surfaces after assembly.

4. The connector according to claim 1, wherein the melting point of the metal seal ring is higher than 600° C.

5. The connector according to claim 1, wherein the metal seal ring is made from aluminium.

6. The connector according to claim 1, wherein the circumferential engaging zones of the upper portion and of the lower portion are screw threads.

7. The connector according to claim 1, further comprising a sacrificial seal/gasket between said inwardly extending central rim and the slidable connection member.

8. The connector according to claim 1, wherein the outer surface of the slidable connection member and the inner surface of upper portion of the hollow tubular main have restrictive structural formations to restrict rotation between the connection member and the upper portion around the length of the casing.

9. The connector according to claim 1, wherein the structural formations to restrict rotation between the connection member and the inner surface of upper portion 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.

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

11. The connector according to claim 1, wherein the seal material used in the metal seal ring is selected from the group of, but not limited to: Aluminium, Zink, Copper, Magnesium or alloys thereof.

12. The connector according to claim 11, wherein the seal material used in the metal seal ring is Aluminium alloy ASTM 1100 (99% aluminium).

13. The connector according to claim 1, wherein high axial pressure is applied to the connector during assembly.

14. A method for producing a connector for connecting casing segments used in wells drilled in high temperature areas and for transport of high temperature media, the method comprising: a) providing a hollow tubular main body further comprising i)an upper portion comprising a first tubular sleeve opening for receiving and engaging to a first casing, said upper portion further comprising an annular spacing axially extending between an inwardly extending upper rim of the upper portion in proximity to the first tubular sleeve opening and an inwardly extending central rim formed in the upper part of the lower portion of the hollow tubular main body, ii) a lower portion comprising a second tubular sleeve opening for receiving and engaging to a second casing, said lower portion further comprising a second circumferential engaging zone in proximity to the second tubular sleeve opening for engaging a mating engaging zone of an end of the second casing, b) radially positioning a slidable connection member within the annular spacing, said slidable connection member comprising a first circumferential engaging zone for engaging a mating engaging zone of an end of said first casing, said slidable connection member further comprising an abutting inwardly extending rim, that contacts the peripheral end surface of the first casing when the first casing is fully attached, and wherein the slidable connection member is shorter in the axial direction than the annular spacing and is reversibly slidable within annular spacing between the inwardly extending upper rim and the inwardly extending central rim, c) connecting the upper portion and the lower portion of the hollow tubular main body by engaging at least two parallel surfaces of the connector and applying an axial force onto the connector during assembly, wherein the at least two parallel surfaces engaged are: first axial mating surfaces where the upper portion meets the inwardly extending central rim (10 formed in the upper part of the lower portion of the hollow tubular main body, when the upper portion and the lower portion are secured or fixed together during assembly, and first radial facing surfaces adjacent to the first axial mating surfaces forming a spacing between the first radial facing surfaces, d) placing a metal seal ring in the spacing between the first radial facing surfaces prior to assembly for forming a seal when the axial pressure is applied to the connector and when high temperature media starts to flow through the connector.

15. The method according to claim 14, wherein the assembly and connection of the upper portion and the lower portion of the hollow tubular main body further comprises securing or fixing of the first axial mating surfaces together by welding, dovel pins or other securing/fixing means.

16. The method according to claim 14, wherein the method further comprises connecting further two parallel surfaces of the upper portion and the lower portion of the hollow tubular main body, said two parallel surfaces being: iii) second axial mating surfaces below the first radial mating surfaces, said second axial mating surfaces extending diagonally away from the first radial mating surfaces, and iv) second radial facing surfaces below the second axial mating surfaces forming a spacing between the facing surfaces opening out to the exterior of the hollow tubular main body.

17. The method according to claim 14, wherein the axial force applied to the connector during assembly is in the range of 10-150 ton.

18. The method according to claim 14, wherein the outer surface of the hollow tubular main body is kept cold and the inner surface of the hollow tubular main body is kept warm to ensure better connection of the axial mating surfaces during assembly.

19. The method according to claim 16, wherein the assembly and connection of the upper portion and the lower portion of the hollow tubular main body further comprises securing or fixing the second axial mating surfaces together by dovel pins or other securing/fixing means.

20. The method according to claim 14, further comprising the step of placing a sacrificial seal/gasket between said inwardly extending central rim and the slidable connection member during assembly.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0056] 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.

[0057] FIG. 1 shows a transection of two casings being connected by the connector of the invention in a connection position outlining the individual parts of the connector.

[0058] FIG. 2 shows a transection of two casings being connected by the connector of the invention in a connection position outlining the engaging zones of the connector.

[0059] FIG. 3 is a transection of the four mating zones where the upper and lower portions of the connector are joined.

[0060] 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) showing the sacrificial gasket.

[0061] FIG. 5 shows two embodiments for providing restrictive structural formations to restrict rotation around the length of the casing.

DESCRIPTION OF VARIOUS EMBODIMENTS

[0062] 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.

[0063] 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.

[0064] 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.

[0065] FIG. 1 is a schematic drawing of a connector for connecting two casings. The drawing is a transactional view of a connector having a hollow tubular main body 1 with an upper portion 2 having a first tubular sleeve opening 3 to be attached to first casing 4 and a lower portion 5 having a second tubular sleeve opening 6 to be attached to a second casing 7. An annular spacing 8 is formed in the upper portion 2 of the hollow tubular main body 1 axially extending between an inwardly extending upper rim 9 in at the first tubular sleeve opening 3 and an inwardly extending central rim 10 formed in the upper part of the lower portion 5 of the hollow tubular main body 1. A slidable connection member 11 is arranged and extending axially within the spacing 8. The slidable connection member 11 comprises an abutting inwardly extending rim 14 that makes contact with the peripheral end surface of the first casing 4 when the first casing 4 is fully attached. The slidable connection member 11 is shorter in the axial direction than the annular spacing 8 and is reversibly slidable within annular spacing 8 between the inwardly extending upper rim 9 and the inwardly extending central rim 10 when the casing extends and retracts due to temperature change.

[0066] FIG. 2 shows the engaging zones for connecting two casings into the connector of the present invention. The slidable connection member 11 comprises a first circumferential engaging zone 12 for engaging a mating engaging zone 13 of the connecting end of the first casing 4. The lower portion 5 of the hollow tubular main body 1 comprises a second circumferential engaging zone 15 for engaging a mating engaging zone 16 at the end of the second casing 7.

[0067] FIG. 3 is a schematic drawing showing the connecting surfaces of the first portion 2 and the second portion 3 of the hollow tubular main body 1. The first 2 and the second 5 portions are connected by four mating surfaces. The first mating surfaces are axial mating surfaces 17, 18 where the upper portion 2 meets the inwardly extending central rim 10 formed in the upper part of the lower portion 5 of the hollow tubular main body 1. The part of the connector, where the axial mating surfaces 17 and 18 connect is a part of the connector where there is now axial sliding between the first portion 2 and the second portion 3 of the hollow tubular main body 1. Therefore, the upper portion 2 and the lower portion 5 are secured or fixed together by means of pins or welding. In the embodiment shown in FIG. 3, the axial movement between the first portion 2 and the second portion 3nd attachment between them is secured by pins 28. Below the first axial mating surfaces, which are parallel to the direction of the casing the inner surface of the upper portion 2 and outer surface of the lower portion 5 take a 90° turn outwardly to form first radial facing surfaces 19 and 20 which form a spacing 21 between the facing surfaces 19 and 20. Thereafter, the inner surface of the upper portion 2 and outer surface of the lower portion 5 take an approximately 90° turn in an axial direction down the connector forming second axial mating surfaces 22, 23 below the first radial facing surfaces 19, 20. The second axial mating surfaces 22, 23 extending diagonally away from the first radial mating surfaces 19, 20 in the direction towards of the exterior of the connector. Finally, the inner surface of the upper portion 2 and outer surface of the lower portion 5 take an approximately 90° turn second radial facing surfaces 24, 25 below the second axial mating surfaces 22, 23 forming a spacing 26 between the facing surfaces 24, 25 opening out to the exterior of the hollow tubular main body 1. The drawing also shows a metal seal ring 27 is positioned in the spacing 21 for forming a seal in the axial direction of the connector during expansion of the casing. When the casing to take up thermal expansion due to temperature change when high temperature media starts to flow through the casings the upper portion 2 and presses against the lower portion 5 and the metal seal ring 27 in the spacing 21 forms a seal between the two portions making up the connector.

[0068] FIG. 4 shows in transection how two casings have been connected by the connector in an (open) mounting or maintenance position (FIG. 4A) and in a (closed) connecting or operating position (FIG. 4B). The drawing shows casing 4 and 7 being attached to the upper 2 and the lower 5 portions of the connector, where the upper casing is attached to the slidable connection member 11 of the upper portion 2. In FIG. 4 the slidable connection member 11 is in the mounting position and as it is shorter than the annular spacing 8 formed in the upper portion 2 of the hollow tubular main body 1, a gap is formed between the abutting inwardly extending rim 14 of the slidable connection member 11 and the inwardly extending central rim 10 of the lower portion 5. The drawing shows a sacrificial seal/gasket 29 in the gap formed between the abutting inwardly extending rim 14 of the slidable connection member 11 and the inwardly extending central rim 10 of the lower portion 5 which melts away when hot media starts to flow through the casing. In FIG. 4B the sacrificial seal/gasket 29 has melted and the slidable connection member 11 has been pushed towards the inwardly extending central rim 10 of the lower portion 5.

[0069] FIG. 5A 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 slidable connection member 11 and the upper portion 2 of the hollow tubular main body is exaggerated to outline the restrictive structural formations to restrict rotation around the length of the casing. The outer surface 30 of the casing 4 is secured to the inner surface 31 of slidable connection member 11 by a screw thread for example. The outer surface 32 of the slidable connection member 11 and the inner surface 33 of upper portion 2 of the hollow tubular main body have an elliptical shape in this embodiment to prevent rotation around the length of the casing, whereas the outer surface 30 of the casing 4 and the inner surface 31 of the slidable connection member 11 are completely circular to provide connectivity by screwing the two components together. The outer circumference 34 of the upper portion 2 of the hollow tubular main body 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.

[0070] In FIG. 5B, a different type of restrictive structural formations is shown. The mating surfaces of outer surface 32 of the slidable connection member 11 and the inner surface 33 of upper portion 2 of the hollow tubular main body by providing mating protrusions 35 in the inner surface 33 of upper portion 2 and to depressions 36 in the outer surface 32 of the slidable connection member 11.

[0071] In FIG. 6 it is demonstrated how the components of the connectors are secured together in the assembly process and connection of the upper portion and the lower portion of the hollow tubular main body. In order to further ensure no leaking through the connector the first axial mating surfaces 17,18 by dovel pins 28 in the embodiment shown in FIG. 6. During the assembly the outer surface of the hollow tubular main body is kept cold and the inner surface of the hollow tubular main body is kept warm to facilitate the fitting of the lower portion into the upper portion and to better ensure connection of the axial mating surfaces. The assembly process further comprises applying axial force to the connector in the range of 10-150 ton, preferably around 100 ton. The tightness of the connector can be secured even more during assembly by securing or fixing the second axial mating surfaces 22, 23 together by dovel pins 28.

[0072] 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.

[0073] 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.

[0074] 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).

[0075] 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”.

[0076] 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.

[0077] 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.

[0078] 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.