NO20240074A1

NO20240074A1 - Wellhead port plug assembly

Info

Publication number: NO20240074A1
Application number: NO20240074A
Authority: NO
Inventors: Rylan Paul D'souza; Pedro Patela
Original assignee: Interwell Norway As
Priority date: 2024-01-26
Filing date: 2024-01-26
Publication date: 2025-07-28
Also published as: NO349143B1

Description

5 Wellhead port plug assembly

Field of the invention

The present invention relates to a wellhead port plug assembly suitable for being sealingly and removably mounted in a port of a wellhead of a hydrocarbon well, i.e. an oil and/or gas well.

10 The invention also relates to a wellhead of a hydrocarbon well comprising such a plug assembly.

Background

It is common to provide a wellhead of a hydrocarbon well with ports allowing the mounting of devices for monitoring the annuli of the well. For example, such a 15 device is disclosed in WO 2013/056857 A1, which is hereby incorporated by reference. Generally, a system for monitoring an annulus via a wellhead port comprises a plug body which is positioned in the port and comprises at least one sensor for measuring and monitoring at least one parameter in the annulus, e.g. pressure or temperature. In addition to provide a measuring or monitoring function, 20 the plug body must provide a sealing function to prevent leakage to or from the annulus.

Prior art which may be useful for understanding the background includes WO 2013/056857, US 2012/012341,WO 2001/57360, WO 2006/061645, and WO 2011/093717.

25

With the serious consequences that may result from a potential leakage of hydrocarbon fluids, there is a continuous need for improved systems and methods for measuring and monitoring well operational parameters (such as annulus pressures). The present invention has the objective to provide a wellhead port plug

30 assembly and associated method which provides advantages over known solutions and techniques with regards to the above mentioned or other aspects.

Summary of the invention

Embodiments of the present invention relate to a wellhead port plug assembly

35 according to claim 1 suitable for being sealingly and removably mounted in a port 5 of a wellhead of a petroleum well. Embodiments also relates to a wellhead of a petroleum well comprising such a plug assembly.

Further embodiments are set out and specified in the appended claims.

10 Description of the drawings

In the following, embodiments of the invention will be disclosed in more detail with reference to the appended drawings.

Fig. 1 discloses a wellhead structure of an offshore hydrocarbon well.

Fig. 2 discloses a sectional side view of an embodiment of a plug assembly 15 according to the present invention mounted to a wellhead, which plug assembly comprises a measuring or monitoring system.

Detailed description of the invention

Fig. 1 schematically discloses a typical wellhead structure that is used in connection with a hydrocarbon well. The wellhead structure comprises a wellhead 20 1 which is positioned on a base formation O. The wellhead 1 comprises a housing H and a first casing 3, a second casing 5, a third casing 6 and a fourth 7 casing which extend coaxially a distance down into the base formation O such that a first annular space A, or annulus, is formed between the first casing 3 and the second casing 5, a second annulus B is formed between the second casing 5 and the third 25 casing, and a third annulus is formed C between the fourth casing 6 and the third casing 7. Sealing devices 4, in the form of packers, are arranged between the housing H and the casings 3, 5, 6, 7 such that pressure tight connections between the housing H and the casings 3, 5, 6, 7 are obtained.

When the hydrocarbon well is in production, a production tubing (not illustrated) 30 will be arranged inside the fourth casing 7.

In order to monitor the wellhead 1, i.e. to detect an increased or a decreased of pressure indicative of pressure leaks, at least one plug assembly according to a first embodiment of the invention, which comprises a measuring and monitoring system, is arranged in the wellhead 1 such that well parameters can be measured 35 and monitored. Such parameters may, for example, include the pressure and/or the temperature in one of annuli A-C of the wellhead 1. The wellhead 1 will then be configured with a through-bore or channel (not disclosed in Fig.1) leading into the annulus to be monitored, to which channel the plug assembly is connected.

5 In order to get a more complete overview of the performance of the well, it may be advantageous to provide the wellhead 1 with more than one plug assembly, e.g. one plug assembly for each annulus.

The measurements made by the measuring and monitoring system may advantageously be transmitted to an external location for processing and analysis.

10 Fig. 2 shows an embodiment of a plug assembly 20 according to the invention comprising a measuring or monitoring system. The assembly 20 is mounted to a wellhead 21 which comprises a bore or channel 22 leading to an annulus of the wellhead 21. An outermost section of the channel 22 forms an opening or port of the channel 22 and has a diameter which is slightly larger than a neighbouring 15 section such that an annular shoulder 19 is formed within the channel.

The assembly 20 comprises a spool unit assembly comprising a spool unit 24 and a spool end unit 50, in which is mounted first plug unit 23, a second plug unit 25, and a third plug unit 26.

The first plug unit 23 comprises a plug body 27 which has a generally cylindrical 20 form and comprises at least one sensor 27b for measuring a physical parameter related to a fluid in the channel 22. Such sensors are known as such and will not be discussed further here. As is known in the art, the parameters may comprise temperature and pressure. The plug body 27 comprises external threads 28 for cooperation with corresponding internal threads 29 of the channel 22 (cf. Fig.10).

25 The plug body 27 is threaded into the channel 22 and abuts the shoulder 19 such that a fluid-tight metal-to-metal connection or seal is formed between the plug body 27 and the inside wall of the channel 22.

The first plug unit 23 further comprises a connector element 30 for connecting the first senor unit 23 to the second plug unit 25 such that electrical signals can be 30 transmitted between the units 23 and 25. The first plug unit 23 also comprises a tool engagement element 31 for cooperation with a plug installation and removal tool.

The spool unit 24 has a through-bore or channel 32 which runs in the longitudinal or axial direction between a first end and a second end of the spool unit 24. The 35 spool unit 24 comprises a housing 35 which is generally circular symmetric about the longitudinal axis of the spool unit 24. At the first end, the housing is provided with a first flange 33, and at a second end the housing is provided with a second flange 34. The first flange 33 is connected to the wellhead 21 by means of fastening means in the form of bolts 36 such that the channel 32 of the spool unit 40 24 is coaxial with the channel 22 of the wellhead 21. An annular sealing element 37 is positioned between the first flange 33 and the wellhead 21 to ensure a fluidtight connection between the spool unit 24 and the wellhead 21. A first section of 5 the channel 32, which is adjacent to the wellhead 21, has a diameter which is less than a second section which is distal to the wellhead 21 such that that an annular shoulder 38 is formed within the channel 32. The diameter of the first section of the spool unit channel 32 is generally the same as the diameter of the outermost section of the wellhead channel 22.

10 The second plug unit 25 has a plug body 42 which comprises external threads 43 for cooperation with corresponding internal threads 44 of the channel 32. The plug body 42 is threaded into the channel 32 and abuts the shoulder 38 such that a fluid-tight metal-to-metal connection or seal is formed between the plug body 42 and the inside wall of the channel 32. The second plug unit 25 further comprises a 15 first connector element 45 for connecting the second plug unit 25 to the connector element 30 of the first plug unit 27 such that electrical signals can be transmitted between the first plug unit 23 and the second plug unit 25. In the disclosed embodiment, the first connection element 45 of the second plug unit 25 is connected to the connector element 30 of the first plug unit 23 by means of an 20 axial release coupling, i.e. a coupling which allows the connector element 45 to be connected and disconnected from the first connector element 30 upon a movement of the second connector element 45 in the longitudinal or axial direction of the spool unit 24.

The second plug unit 25 further comprises a second connector element 46 for 25 connecting the second plug unit 25 to the third plug unit such that electrical signals can be transmitted between the first and third plug units 23, 26 via the second plug unit 25.

The second plug unit 45 also comprises a tool engagement element 48 for cooperation with the above-mentioned plug installation and removal tool (to be 30 discussed below).

The housing 35 is provided with radial, through-bores or channels 39 connecting the channel 32 with an outer, annular surface 40 of the housing 35. These channels 39 may be used to provide a fluid communication conduit to the channel 32, e.g. to monitor the pressure in or vent the channel 32, but are plugged by 35 plugging elements or valves 41 at the outer surface 40 when not in operation.

In this embodiment, a spool end unit 50 is connected to the second flange 34 of the spool unit 24 by means of fastening means in the form of bolts 52. The spool end unit 50 has a through-bore or channel 54 which runs in the longitudinal or axial direction between a first end and a second end of the spool end unit 50. The 40 spool end unit 50 comprises a housing 56 which is generally circular symmetric about the longitudinal axis of the spool end unit 50. At the first end, the housing 56 is provided with a flange 58. The flange 58 is connected to the spool unit 24 wellhead 21 by means of the bolts 52 such that the channel 32 of the spool unit 24 5 is coaxial with the channel 54 of the spool end unit 50. An annular sealing element 60 is positioned between the second flange 34 of the spool unit 24 and the flange 58 of the spool end unit 50 to ensure a fluid-tight connection between the spool unit 24 and the spool end unit 50. A first section of the channel 54, which is adjacent to the spool unit 24, has a diameter which is greater than a second 10 section which is distal to the spool unit 24 such that that an annular shoulder 62 is formed within the channel 54. The diameter of the first section of the spool end unit channel 54 is generally the same as the diameter of the outermost section of the channel 32 of the spool unit 24.

The housing 56 of the spool end unit 50 is provided with radial, through-bores or 15 channels 64 connecting the channel 54 with an outer, annular surface of the housing 56. These channels 64 may be used to provide a fluid communication conduit to the channel 54, e.g. to monitor the pressure in or vent the channel 54, but are plugged by plugging elements or valves 66 at the outer surface when not in operation.

20 The third plug unit 26 comprises a plug body 68 which has a generally cylindrical form and comprises electronics 69, which could comprise a printed circuit board. The electronics 69 are connected to the second connector element 46 of the second plug unit 25, and therefore may receive signals from the sensors of the first unit 23, and forwarding the signals to a signal transmission unit of the

25 assembly. The third plug unit 26 may also comprise electronics 69 for processing the signals prior to forwarding them, and electronics 69 for communicating with the sensors. The plug body 68 comprises external threads 70 for cooperation with corresponding internal threads 72 of the channel 54. The plug body 68 is threaded into the channel 54 and abuts the shoulder 62 such that a fluid-tight 30 metal-to-metal connection or seal is formed between the plug body 68 and the inside wall of the channel 54.

An end cap 74 is mounted on the second end of the spool end unit 50 to close the channel 54.

The end cap 74 comprises a lead-through 76 which, on the inside of the end cap 35 74, comprises a connector element 78 which is connected to the corresponding connector element 80 of the third unit 26, by means of which the electronics 69 may communicate with the lead-through 76. The connector element 80 is connected to the third plug unit 26 by means of an axial release coupling, i.e. a coupling which allows the connector element 80 to be connected and

40 disconnected from the third unit 26 upon a movement of the connector element 80 in the longitudinal or axial direction of the spool end unit 50. Sensor signals from the first plug unit 23 may therefore be communicated to the lead-through 76 via the connector element 30 of the first plug unit 23, the first and second connector 5 elements 45, 46 of the second plug unit 25, the connector element 80 of the third plug unit 26, and the connector element 78 of the lead-through 76.

On the outside of the spool end unit 50, the lead-through 76 is connected to a signal transmission unit for forwarding the signals to said external location. In this embodiment, the signal transmission unit comprises a communication cable 82.

10 Power for operating the sensors and the sensor electronics may be provided to the assembly 20 via the same cable 82.

In an alternative embodiment, the sensor signals are transmitted wirelessly to the external location. In such an embodiment, the cable may be substituted for wireless transmission means such as an antenna which advantageously is 15 positioned on the outside surface of the end cap 74. Also, in such an embodiment, a power supply, e.g. an electric battery, is advantageously arranged in the assembly, e.g. in the third unit 24, to provide power to the sensors and to the associated electronics and signal transmission means.

Whilst in this embodiment, the third plug unit 26 is mounted in a separate spool 20 end unit 50, this need not be the case. The third plug unit 26 could, instead, be mounted in the channel 32 of the spool unit 24 between the second plug unit 25 and the second end of the spool unit 24. In this case, the end cap 74 would be mounted directly on the spool unit 24 to close the channel 32 at the second end thereof.

25 The plug bodies 27 and 42 provide three independent barriers preventing flow of fluid out of the wellhead 21 via the assembly and, consequently, out of the annulus the assembly 20 is set to monitor. Should the spool unit 24 be knocked of the wellhead 21, e.g. due to a falling load hitting the spool unit 24, the connector elements 30 and 45 will separate and the first plug body 27 will remain in the 30 channel 22, thus preventing fluid in the annulus from escaping via the channel 22.

Equally, should the spool end unit 50 be knocked off the spool unit 24, the first plug unit 23 and second plug unit 25 will remain in place providing two barriers to flow of fluid out of the annulus.

Claims

5 Claims

1. A wellhead port plug assembly (20), comprising:

- a first plug unit (23) comprising a first plug body (27) comprising connection elements (28) allowing the first plug body (27) to be sealingly and removably mounted in a port (22) of a wellhead (21) of a hydrocarbon well, 10 which port (22) is in fluid communication with a channel (22) leading to an annulus of the wellhead (21) and which first plug body (27) comprises a sensor (27b) for measuring a physical parameter related to a fluid in the channel (22);

- a spool unit assembly (24, 50) having an axial channel (32, 54) extending 15 between a first end and a second end of the spool unit (24), which spool unit assembly (24, 50) comprises a first flange (33) arranged at the first end for sealingly mounting the spool unit (24) to the wellhead (21) aligning the channel (32) with the channel (22);

- a second plug unit (25) comprising a second plug body (42) comprising 20 connection elements (43) allowing the second plug body (42) to be sealingly and removably mounted in the channel (32, 54);

- a third plug unit (26) comprising a third plug body (68) comprising connection elements (70) allowing the third plug body (68) to be sealing and removably mounted in the through-channel (32.54), the third plug unit (26) 25 further comprising electronics for receiving signals from the sensor (27b);

and

- connection elements (30, 45, 46) which provide a conduit for transmission of electrical signals from the sensor (27b) to the electronics of the third plug unit (26).

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2. A plug assembly (2) according to claim 1, wherein the channel (32, 54) comprises first annular shoulder (38) for co-operation with the second plug body (42) for providing a metal-to-metal seal between the spool unit assembly (24, 50) and the second plug body (42), and a second annular shoulder (62) 35 for co-operation with the third plug body (68) for providing a metal-to-metal seal between the spool unit assembly (24, 50) and the third plug body (68).

3. A plug assembly (20) according to any preceding claim wherein the spool unit assembly comprises a spool unit (24) having a through-channel (32), and a 40 spool end unit (50) having a through-channel (54), the spool unit (24) having a first end on which is provided the first flange (33) and a second end, the spool end unit (50) being sealingly secured to the second end of the spool unit so that the through-channel (32) of the spool unit (24) is aligned with the throughchannel (54) of the spool end unit (50), the through-channels (32, 54) together 45 forming the channel of the spool unit assembly, wherein the second plug unit 5 (25) is mounted in the through-channel (32) of the spool unit (24) and the third plug unit (26) is mounted in the through-channel of the spool end unit (50).

4. A plug assembly according to claim 3, wherein the through channel (32) of the spool unit (24) comprises a first channel section and a second channel section which has a diameter which is larger than the diameter of the first channel 10 section (32a).

5. A plug assembly according to claim 5, wherein the diameter of the first channel section (32a) is sufficient to allow the transport of the first plug body (27) therethrough.

15 6. A plug assembly (20) according to any preceding claim wherein the connection elements (30, 45, 46) comprise a connection element (30) of the first plug unit, and a first and second connection element (45, 46) of the second plug unit (23), the connection element (30) of the first plug unit (23) extending from the sensor (27b) and being releasably connected to the first connection element 20 (45) of the second plug unit (25), and the second connection element (46) of the second plug unit (25) being releasably connected to the electronics of the third plug unit (26).

7. A plug assembly according to any preceding claim further comprising a signal transmission unit for forwarding signals form the sensor (27b) to a location 25 separate from the plug assembly.

8. A plug assembly according to any one of the preceding claims, wherein the signal transmission unit comprises a communication cable.

9. A plug assembly according to any one of the preceding claims, wherein the signal transmission unit comprises wireless transmission means.

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10. A plug assembly according to the preceding claim wherein the third plug unit (26) comprises a connector element (80) which provides a conduit for transmission of signals from the electronics of the third plug unit (26) to the signal transmission unit.

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11. A plug assembly according to any one of claims 9 or 10 further comprising an end cap (74) which is mounted on the spool unit assembly (24, 50) to close the channel (32, 54) at the second end thereof, the signal transmission unit being mounted on the end cap (74).

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12. A plug assembly according to the preceding claim wherein the signal transmission unit comprises a lead-through (76) having a connector element which is releasably connected to the connector element (80) of the third plug 5 unit (26) to provide a conduit for transmission of signals from the electronics of the third plug unit (26) to the lead-through (76).

13. The plug assembly according to any preceding claim wherein the plug assembly comprises a power supply to provide power to said sensor.

14. A wellhead of a hydrocarbon well, characterised in that it comprises a plug 10 assembly according to any one of claims 1-13.