SPOOLABLE RISER HANGER

Abstract

A coil tubing riser hanger (32) for use with a coil tubing riser (27) comprises gripping means (54a, 54b) for engaging the coil tubing riser to suspend and support the coil tubing in the hanger (32). In one embodiment the riser hanger (32) comprises a sealing arrangement for retaining bore pressure on the coil tubing riser when suspended in the hanger (32). In one embodiment the riser hanger (32) is adapted to be coupled to a compensated frame (18).

Description

FIELD OF THE INVENTION

The present invention relates to a spoolable riser hanger for supporting spoolable media and, particularly but not exclusively, to a hanger for use with spoolable coil tubing. The invention is particularly suitable for use with coil tubing when the coil tubing is used as a riser.

BACKGROUND TO THE INVENTION

In the oil and gas industry, risers are well known and are used to couple a wellhead to a platform work surface. When a platform is floating, vertical movement is compensated by well-known compensation mechanisms so that stresses on the riser due to ocean movement do not cause the riser to break or otherwise become damaged. Risers can be very large, heavy and expensive. In many cases the riser diameter can be of the order of 36 inches or more. These risers are difficult to manoeuvre particularly from floating vessels because of the size and weight of the riser. In applicant's WO 2009/016346, there is disclosed a novel coil tubing riser system which obviates various problems with the traditional types of risers.

In order to be able to use a spoolable riser offshore at depths greater than the depth of one roll of coil tubing, the coil tubing must be joined in the riser system, which will typically require the deployed riser section to be suspended and supported while a further riser section is connected thereto.

SUMMARY OF THE INVENTION

An aspect of the present invention relates to a spoolable riser hanger which engages the spoolable medium which passes through the riser hanger and suspends the medium therein.

In one aspect the spoolable medium comprises coil tubing and the hanger defines a coil tubing hanger which is used to suspend the coil tubing.

The coil tubing is used as a coil tubing riser and when the coil tubing riser is deployed from a floating vessel, the tubing hanger is supported in a compensated frame which is also located on the vessel.

Alternatively, the tubing hanger may be used on a land well where the coil tubing does not need to function as a riser.

The hanger may be retrievable and may be used to permit lengths of coil tubing to be joined to make a longer riser.

The tubing hanger may comprise actuatable gripping means which are moveable to engage and grip the coil tubing and suspend said tubing within the coil tubing hanger. The actuatable gripping means may comprise slips which are vertically and axially moveable to grip the coil tubing within the hanger.

The coil tuning riser hanger may comprise a sealing arrangement for engaging the coiled tubing being supported by the hanger. The sealing arrangement may be adapted to retain fluid pressure associated with the coil tubing. The sealing arrangement may be adapted to retain fluid pressure within a region defined between the riser hanger and the coil tubing, such as an annular region. The sealing arrangement may be adapted to retain fluid pressure within the coil tubing.

The tubing hanger may comprise seals for retaining fluid pressure within the coil tubing, i.e., within the internal tubing bore, when the coil tubing is being suspended, for example when being suspended in preparation for or while being joined to a further length of coil tubing.

The tubing hanger may comprise a bend stiffener stress joint adapted to minimise stress points on an associated tubing, for example when the tubing is being deployed through the hanger or when the tubing is supported by the hanger. The bend stiffener may be secured to the hanger via a support frame, such as a compensated support frame.

In another aspect of the present invention, there is provided a coil tubing riser hanger for use with a coil tubing riser, said coil tubing riser hanger being adapted to be coupled to a compensated frame and having gripping means for engaging the coil tubing riser to suspend and support the coil tubing in the hanger and seal means for retaining bore pressure on the coil tubing riser when suspended in the hanger.

BRIEF DESCRIPTION OF THE DRAWINGS

These and other aspects of the present invention will now be described, by way of example only, with reference to the accompanying drawings, in which:

FIG. 1 is a schematic diagram of the coil tubing riser system used with a vessel and incorporating a coil tubing hanger, in accordance with an embodiment of the invention, and

FIG. 2 is an enlarged longitudinal sectional view of part of the FIG. 1 illustrating the coil tubing hanger with a coil tubing riser suspended in the hanger.

DETAILED DESCRIPTION OF THE DRAWINGS

Reference is first made to FIG. 1 of the drawings which depicts part of a coil tubing riser system, generally indicated by reference numeral 10, used on a floating vessel 12 with a moon pool 14 beneath a moveable vessel floor 16. The entire coil tubing riser system is not described but it includes a compensated frame 18 which is coupled via cable 20 to a compensator (not shown) for compensating for vessel movement. The complete coil tubing riser system is disclosed in more detail in applicant's WO 2009/016346, the description of which is not essential to the understanding of the present invention.

The frame 18 supports an injection head 22 which is coupled by a connector 24 to a coil tubing make-up window 25 which depicts free ends 26,28 of coil tubing 27 to be connected by a coil tubing connector (not shown) to allow longer coil tubing risers to be made up in deep water, i.e. water of such a depth that a single spool of coil tubing cannot operate satisfactorily as a riser and requires to be joined to another length of coil tubing. A connector for this purpose is disclosed in applicant's co-pending UK patent application no. 0811638.6, but a detailed description of this connector is not essential for the understanding of the present invention.

The coil tubing make-up window 25 is coupled to the top 30 of the tubing hanger 32. The tubing hanger 32 includes a hanger housing portion 34 connected to the frame 18 and a lower stress joint 36 for minimising the stress on the coil tubing riser as will be later described in detail.

The coil tubing 27 is fed through an umbilical feeding device 40 and through the vessel floor 16 into the moon pool 14. The umbilical feeding device 40 is rotatable about a vertical axis 42 to feed umbilicals 44 around the coil tubing 27 as it is injected by the injector head 22 into the ocean to provide a composite riser 46 formed of the coil tubing 27 and the umbilicals 44.

Reference is now made to FIG. 2 of the drawings which depicts an enlarged longitudinal sectional view of the tubing hanger 32 mounted on the compensated frame 18. The tubing hanger main housing 34 is coupled to the frame 18 by a flange 46, and is coupled to a top connector 48 and to the lower bend stiffener stress joint 36. The connector 48 has two parts: a lower connecting joint 48a which is coupled to the housing 34 by nuts 50; and a top connecting joint 48b which is coupled to the lower joint 48a and which is adapted, in use, to be coupled to the bottom of the injector 22. Connectors 48a,48b, main housing 34 and stress joint 36 all have separate bores which are coaxially aligned to form a common bore 52, when assembled as shown in FIG. 2. The bore 52 receives coil tubing 27 from the injector head.

The main housing 34 contains a coil tubing gripping arrangement which is provided by a pair of slips 54a,54b which are located in respect of chambers 56a,56b. One of the slips 54a is shown in the upper position in chamber 56a and in this position is spaced from the wall of the coil tubing 27 and the other of the slips 54b is shown in a lower position in chamber 56b where it is engaged with the wall of the coil tubing 27. The slips 54a,54b may be actuated hydraulically to move between the upper and lower positions.

A safety collar 58 is shown which is axially secured relative to the string 27 and which, in use, moves downwardly with the string 27 so that the bottom of the collar 58 engages the top of the slips 54a and 54b and moves the slips 54a,54b from the disengaged position (slip 54a) to the engaged position (slip 54b) to suspend the coil tubing. Thus, in the event of the slips failing to actuate to engage the string 27, the string 27 will begin to fall through the hanger until the safety collar 58 engages the slips 54a,54b to initiate engagement.

Therefore, in slip position 54b the coil tubing is suspended in the coil tubing hanger 32. To ensure that bore pressure is retained in the bore 52 a seal block 60 with seals 62 is located within connector 48a and seals 64 are also located between the upper and lower connectors 48a and 46b. Thus, it will be understood from the foregoing description that the coil tubing hanger can be actuated to support the weight of the coil tubing in the slips and the seals 62,64 retain bore pressure while an additional length of coil tubing is connected to the suspended portion in the coil tubing hanger to allow the appropriate length of coil tubing riser to be made up.

Various modifications may be made to the embodiment hereinbefore described without departing from the scope of the invention. For example, the coil tubing hanger need not be used with a compensated frame and the hanger can be used with any spoolable medium, for example, plastic or a metal/plastic composite, other than coil tubing. The collar 58 can be actuated by any suitable means other than hydraulic means, for example electrical or mechanical means. Moreover, the bend stiffener stress joint 36 may be provided by a single piece or by a two-piece split connector as shown in FIG. 2.

Advantages of the invention are that the coil tubing hanger permits coil tubing to be used as a riser and made up into lengths suitable for deep water use. The coil tubing hanger can support the weight of the riser and allows the riser to be retrievable as well, the bore 50 being large enough to accommodate the width of the joint making up the longer riser. The spoolable riser hanger may be used with spoolable media, other than coil tubing, for example plastic and the hanger can be used in other applications other than floating vessels, for example on land. The riser provides an efficient way of suspending the spoolable medium/coil tubing and the design allows for bore pressure to be suitably sealed whilst riser joints are being made up.

Claims

1. A coil tubing riser hanger adapted to engage a coil tubing which passes through the riser hanger to suspend said tubing therein.

2. The coil tubing riser hanger according to claim 1, wherein the tubing hanger is adapted to be supported in a vessel mounted compensated frame.

3. The coil tubing riser hanger according to claim 1, wherein the hanger is retrievable and is used to permit lengths of coil tubing to be joined to make a longer riser.

4. The coil tubing riser hanger according to claim 1, comprising actuatable gripping means which are moveable to engage and grip the coil tubing and suspend said tubing within the coil tubing hanger.

5. The coil tubing riser hanger according to claim 4, wherein the actuatable gripping means comprise slips which are vertically and axially moveable to grip the coil tubing within the hanger.

6. The coil tuning riser hanger according to claim 1, comprising a sealing arrangement for engaging the coiled tubing being supported by the hanger.

7. The coil tubing riser hanger according to claim 6, wherein the sealing arrangement is adapted to retain fluid pressure associated with the coil tubing.

8. The coil tubing riser hanger according to claim 6, wherein the sealing arrangement is adapted to retain fluid pressure within a region defined between the riser hanger and the coil tubing.

9. The coil tubing riser hanger according to claim 6, wherein the sealing arrangement is adapted to retain fluid pressure within the coil tubing.

10. The coil tubing riser hanger according to claim 1, comprising a bend stiffener stress joint adapted to minimise stress points on an associated tubing.

11. The coil tubing riser hanger according to claim 10, wherein the bend stiffener is secured to the hanger via a support frame.

12. The coil tubing riser hanger according to claim 11, wherein the support frame comprises a compensated support frame.

13. A coil tubing riser hanger for use with a coil tubing riser, said coil tubing riser hanger being adapted to be coupled to a compensated frame and having gripping means for engaging the coil tubing riser to suspend and support the coil tubing in the hanger and seal means for retaining bore pressure on the coil tubing riser when suspended in the hanger.