WO2001007751A1

WO2001007751A1 - A wellhead arrangement

Info

Publication number: WO2001007751A1
Application number: PCT/GB2000/002790
Authority: WO
Inventors: Bernard Herman Van Bilderbeek
Original assignee: Plexus Ocean Systems Limited
Priority date: 1999-07-22
Filing date: 2000-07-24
Publication date: 2001-02-01
Also published as: AU6170400A; GB2352258B; GB2352258A; GB9917074D0

Abstract

A wellhead (10) with a side mounted production outlet (18) has an internal tubing hanger (22, 28). The hanger supports the tubing (16) within a wellhead housing (12) and is formed in two sections. One section is a lower hanger body (22) which carries the tubing loads, is supported on a shoulder in the wellhead and is sealed in the wellhead below the position of the production outlet port (18). The other section is an upper hanger body (28) which is sealed in the wellhead, independently of the lower body, at a position above the production outlet port. The upper body may overlap the port and have its own side outlet aperture (30) (Figure 1) or it may be positioned wholly above the production outlet port (Figure 2).

Description

A Wellhead Arrangement

This invention relates to a wellhead arrangement for use in an oil or gas well (surface or subsea) where the production fluid from the well is to be taken out from the wellhead at one side.

Wellheads with a side production outlet port are known and are referred to as, for example, "lateral", "horizontal" or "cantilever" tree wells. In such wells the production fluid reaches the wellhead through tubing which is supported in the wellhead by a tubing hanger. It is necessary to develop a reliable and easy to operate manner of setting and sealing the tubing hanger in the well in such a way that seals both above and below the production outlet are properly formed, and so that the production outlet bore is properly ported.

Conventionally the tubing is supported at its top end in a tubing hanger which has seals which will be located above and below the production outlet, and also has a side port which is to be aligned with the production outlet port in the wellhead through which production fluid is to flow into the Christmas tree valve assembly which controls flow.

According to the invention, there is provided a wellhead arrangement comprising a tubing housing, a production outlet which exits from a side of the housing and a tubing hanger for location in the housing to provide a production fluid passage communicating directly with the production outlet, the hanger comprising a lower hanger body adapted to be supported in the housing, to be sealed to the housing below the production outlet and to support the tubing load, and an upper hanger body separate from the lower body and adapted to seal with the housing above the production outlet.

For the purposes of this patent specification, tubing housing shall mean any housing in which a tubing hanger is placed. This includes a tubing spool, tubing head or tree spool attached to a wellhead or wellhead housing designed to accept a tubing hanger.

By separating the uppermost tubing hanger into a lower body and an upper body, it is possible for each body to be optimised according to the function which it has to perform and for the seals above and below the production outlet to be set independently.

Both the lower and the upper hanger bodies are preferably fitted with metal to metal seals between the bodies and the internal wall of the wellhead. Metal to metal seals require careful and accurate setting if they are to function correctly, and it is advantageous to be able to run the lower hanger body into place, set the seal associated with that body and test it before running in the upper body and setting and testing the seal associated with the upper body.

The upper hanger body can have an upper region for receiving a tree cap to close the tubing bore, and the lower hanger body can be externally fitted with a preloaded lock down mechanism for securing the body within the wellhead housing.

The upper hanger body may extend axially past the side production outlet port, with its own side outlet aperture which has to be set to register with the production outlet port. The lower body which has to carry the loads associated with the tubing extending down the well can be set in any angular orientation within the wellhead housing. On the other hand the upper hanger body has to be set in one specific orientation where the side opening is aligned with the production outlet port. This correct rotational alignment is greatly simplified through the separation of the upper and lower hanger bodies because the upper hanger body can be relatively lightweight. It is then easy to manoeuvre the upper body into the correct angular position because it is not necessary at the same time to rotate the tubing load.

If a detent or similar is provided to give a positive angular location of the upper hanger body in the wellhead, then the orientation step can be still further simplified. The detent may be a spring-loaded key mounted in the external circumferential surface of the upper hanger body and a recess in the wellhead wall arranged so that the key can be biased outwardly to engage in the recess when the upper hanger body is in the correct orientation in the wellhead. Alternatively the key may be in the wellhead wall and the recess in the upper hanger body.

The lower end of the upper hanger body can have a stab coupling to engage in a corresponding stab pocket in the lower hanger body, and stab coupling vent passages can be provided both in the lower and upper hanger bodies. A control line port preferably extends through both the upper and lower hanger bodies .

The upper hanger body can extend radially to the wellhead wall at the position of the side opening, to allow the use of automatic seals above and below the side opening.

In another embodiment, the upper and lower hanger bodies may be entirely unconnected with one another and may be separated by a gap with the production outlet port opening into that gap and thus communicating with the production bore through the top of the lower hanger body. The upper hanger body will then be adapted to receive a wellhead cap to close the wellhead.

The invention also extends to a two-part side-port tubing hanger for use in the wellhead arrangement set forth above, and thus according to another aspect of the invention, there is provided a side port tubing hanger for location in a tubing housing to provide a passage for production fluid from a well, the hanger comprising a lower hanger body adapted to be supported in the wellhead housing, to be sealed to the tubing housing below the production outlet and to support the tubing load, and an upper hanger body separate from the lower body and adapted to seal with the wellhead above the production outlet.

In yet another aspect, the invention extends to a two-part side-port tubing hanger which comprises a lower hanger body and an upper hanger body separate from the lower body, wherein the upper hanger body is rotatable relative to the lower body, and carries a side production outlet.

The invention will now be further described, by way of example, with reference to the accompanying drawings, in which:

Figure 1 is a cross-section through a wellhead forming a first embodiment of the invention; and

Figure 2 is a cross-section through a wellhead forming a second embodiment of the invention.

Figure 1 shows a wellhead generally designated 10 located above a wellhead housing 12 and with a cantilever tree block 14 mounted on one side. Within the wellhead 10 is tubing 16 up which production fluid will flow from the well. This fluid is to exit the wellhead through a side port 18 through which it flows into the block 14 with the flow being controlled by valves 20.

The tubing 16 is supported below a lower hanger body 22 which itself is supported, in a conventional manner, on a shoulder in the wellhead housing 12.

Above the wellhead housing 12 is a tree spool 24, and the lower hanger body 22 is sealed to the interior of the tree spool by a metal-to-metal annular seal 26. This seal prevents the fluid passing up the tubing 16 from passing back down the well around the outside of the tubing 16. The seal 26 also isolates any build up of pressure in the production annulus 56.

Above the lower hanger body 22, there is an upper hanger body 28 which has a side aperture 30. The upper hanger body 28 is also sealed to the tree spool 24, this time by a metal-to-metal seal indicated at 32. Above the upper body 28 a well cap 34 is fitted to close off the top of the well, this cap being of a conventional nature.

The upper hanger body 28 has a stab collar 36 at its lower end which fits into a stab pocket 38 on the lower hanger body 22. A protective cap 40 guides the collar 36 into the pocket 38, when the two bodies are run together.

A control line 42 extends through the joint between the upper and lower hanger bodies and is accessible through the top of the well through a valve 44.

In operation, when the well is being set up the lower hanger body 22 with the tubing 16 is run into the wellhead in the conventional manner and the seal 26 is set by use of a suitable tool which is introduced down the well bore. A conventional lockdown mechanism and a running thread are provided in a known manner to correctly locate and secure the lower hanger body in position. Once the seal 26 has been set, it is tested.

After setting of the seal 26, the upper hanger body 28 is independently run into the well, and the stab collar 36 enters the pocket 38. It will be seen that seals 46 are provided on the interface between the collar 36 and pocket 38 to prevent leakage where the control line 42 passes from the pocket 38 to the collar 36.

It is important that the side aperture 30 in the upper body 28 registers accurately with the side port 18 in the spool 24. The body 28 can be rotated about the vertical axis without disturbing the positioning or the sealing of the lower body 22, until the two apertures are lined up. Lining up of the apertures will be confirmed by the engagement of a spring-loaded anti-rotation key 48 in a suitably positioned recess 50 in the tree spool 24. Once the upper hanger body 28 has been correctly positioned, the seal 32 is set, and tested, in a manner similar to that previously carried out in respect of the seal 26.

Finally, the cap 34 is positioned above the hanger body 28 to close the internal bore of that body. If appropriate, plugs such as 52 can be mounted in the internal bore.

Trash seals 54 are provided between the hanger body 28 and the side apertures 30, 18 to prevent escape of production fluid at the position where it passes from the aperture 30 to the aperture 18. Other components shown in the drawing but not specifically referenced are conventional wellhead structural features, the nature of which will be apparent to the skilled man.

Figure 2 shows an alternative embodiment in which similar components have similar reference numerals. In particular the wellhead 10 is the same as the wellhead shown in Figure 1.

In Figure 2, a lower tubing hanger 122 supports the tubing 16. The hanger 122 is sealed with a metal-to-metal seal 126, in the same way as the hanger body 22 of Figure 1. However the hanger body 122 does not have a stab pocket 38, as there will be no direct contact between the lower hanger body 122 and the upper hanger body 128. In fact the upper and lower hanger bodies 122, 128 are spaced apart and this leaves a gap 129 between the two bodies, from which the fluid flows out through the production outlet port 18.

The upper body 128 is however sealed in the tree spool 24, by metal-to-metal seals 132 corresponding to the seals 32 of Figure 1.

It will be apparent that in this embodiment, the upper and lower bodies will be run into the well independently and their seals will be set independently, as already described with reference to Figure 1. However in Figure 2, there is no need to rotationally align the upper body 128 with the outlet port 18 which will further simplify set up of the well .

The wellhead arrangements described here greatly simplify the well set up of a side-port production wellhead, because the seals above and below the production outlet port can be separately set and separately tested so that their functions are independently assured. the step of aligning a side port in the wellhead housing with a side aperture in the hanger is either greatly simplified (because the part of the hanger which needs to be rotated for such alignment is relatively small and light in weight) or is avoided entirely.

Claims

1. A wellhead arrangement comprising a tubing housing, a production outlet which exits from a side of the housing and a tubing hanger for location in the housing to provide a passage communicating directly with the production outlet, the hanger comprising a lower hanger body adapted to be supported in the housing, to be sealed to the housing below the production outlet and to support the tubing load, and an upper hanger body separate from the lower body and adapted to seal with the housing above the production outlet.

2. A wellhead arrangement as claimed any preceding claim, wherein the lower hanger body is sealed within the tubing housing through a metal to metal seal.

3. A wellhead arrangement as claimed in any preceding claim, wherein the upper hanger body is sealed within the tubing housing by a metal to metal seal positioned above the production outlet.

4. A wellhead arrangement as claimed in any preceding claim, wherein the upper hanger body has an upper region for receiving a tree cap to close the tubing bore.

5. A wellhead arrangement as claimed in any preceding claim, wherein the lower hanger body is externally fitted with a preloaded lock down mechanism for securing the body within the tubing housing.

6. A wellhead arrangement as claimed in any preceding claim, wherein the upper hanger body is adapted to seal with the lower hanger body, the upper hanger body having a side opening for communication with the production outlet in the tubing housing.

7. A wellhead arrangement as claimed in Claim 6, wherein the upper hanger body has means for locating the side opening in a specific angular orientation relative to the wellhead.

8. A wellhead arrangement as claimed in Claim 6 or Claim 7, wherein the lower end of the upper hanger body has a stab coupling to engage in a corresponding stab pocket in the lower hanger body.

9. A wellhead arrangement as claimed in Claim 8, wherein stab coupling vent passages are provided both in the lower and upper hanger bodies.

10. A wellhead arrangement as claimed in any preceding claim, wherein a control line port extends through both the upper and lower hanger bodies.

11. A wellhead arrangement as claimed in any one of Claims 6 to 10, wherein the upper hanger body extends radially to the wellhead wall at the position of the side opening to allow the use of automatic seals above and below the side opening.

12. A wellhead arrangement as claimed in Claim 11, wherein trash seals are fitted above and below the side opening, between the tubing housing inner wall and the outer wall of the upper hanger body.

13. A wellhead arrangement as claimed in any one of Claims 7 to 12, wherein the means for locating the side opening in a specific angular orientation relative to the wellhead comprises a spring-loaded key mounted in the external circumferential surface of the upper hanger body and a recess in the wellhead wall arranged so that the key can be biased outwardly to engage in the recess when the upper hanger body is in the correct orientation in the wellhead.

14. A wellhead arrangement as claimed in any one of Claims 6 to 12, wherein the means for locating the side opening in a specific angular orientation relative to the wellhead comprises a spring-loaded key mounted in the wellhead wall and a recess in the external circumferential surface of the upper hanger body arranged so that the key can be biased inwardly to engage in the recess when the upper hanger body is in the correct orientation in the wellhead.

15. A wellhead arrangement as claimed in any one of Claims 1 to 5, wherein the lower hanger body is sealed to the wellhead below the production outlet, the upper hanger body is sealed to the wellhead above the production outlet, and the bodies are not sealed to one another.

16. A wellhead arrangement as claimed in Claim 15, wherein the upper hanger body is adapted to receive a wellhead cap to close the wellhead.

17. A side-port tubing hanger for use in the wellhead arrangement of any preceding claim.

18. A wellhead arrangement substantially as herein described with reference to any one embodiment shown in the accompanying drawings.

19. A two-part side-port tubing hanger which comprises a lower hanger body and an upper hanger body separate from the lower body, wherein the upper hanger body is rotatable relative to the lower body, and carries a side production outlet.

20. A side-port tubing hanger substantially as herein described with reference to any one embodiment shown in the accompanying drawings.

21. A wellhead arrangement as claimed in any preceding claim and adapted for use in a subsea environment .