WO2002088515A1

WO2002088515A1 - Offshore delivery line support

Info

Publication number: WO2002088515A1
Application number: PCT/AU2002/000534
Authority: WO
Inventors: Kevin Gallagher; David Bond
Original assignee: Woodside Energy Ltd
Current assignee: Woodside Energy Ltd
Priority date: 2001-04-30
Filing date: 2002-04-30
Publication date: 2002-11-07
Anticipated expiration: 2003-10-30

Abstract

A support assembly for an underwater fluid delivery line interconnecting an underwater well with a surface platform delivery comprising a riser, a mudline riser-casing connecting assembly providing connection between the lower end of the riser and the well, said mudline riser-casing connecting assembly comprising a bore hole conductor casing adapted to be fixed in a bore hole in the mudline and terminating at its upper end at or in the region of the mudline and adapted to support the riser and well bore casing, the assembly further comprising an annular landing shoulder on the inner face of the bore hole conductor casing at a position spaced downwardly from the upper end of the bore hole conductor casing and an annular hanger assembly adapted to be mounted to the upper end of the well bore casing, said annular hanger assembly being engagable with the landing shoulder to support the well bore casing from the landing shoulder, the mudline riser-casing connecting assembly further comprising a connector adapted at one end to be connected with the hanger assembly and adapted to be connected at the other end to the lower end of the riser, the connector being capable of selective engagement and disengagement with the hanger, said connector being supported in the bore hole conductor casing in the region of the upper end of the bore hole conductor casing through a support assembly to prevent radial movement of the connector within the bore hole conductor casing, the upper end of the connector extending above the support assembly and including a stress joint which is adapted to be fixed to the lower end of the riser, said stress joint being adapted to accommodate the stress arising from the movement of the lower end of the riser relative to that part of the mudline riser-casing connecting assembly within the bore hole conductor casing. A mud-line riser-casing support system and surface blow-out prevention support system is also claimed.

Description

Offshore Delivery Line Support

Field of the Invention

This invention relates to a support assembly for a delivery line of an underwater well.

Background

In providing a connection between an underwater well and a drill rig, it is conventional practice to provide a blow-out prevention system at the mudline or seabed which serves to control any excessive pressure within the borehole during the drilling of the borehole. In the event of there being excessive pressure in the borehole which could result in a blow-out, the blow-out prevention system is designed to shut the borehole off. However, a difficulty with such an arrangement relates to the servicing of the blow-out prevention system and the well in deep water drilling conditions. Therefore in at least some instances it can be advantageous to locate the blow-out prevention system in the region of the surface, however this can cause a difficulty as a result of the need to accommodate for the relative movement between the seabed and the platform which support the delivery line.

In some circumstances, it has been known to support the blow-out prevention system from the rig where the blow-out prevention system is supported by the support rig to be able accommodate for relative longitudinal movement between the riser and the rig. However, the degree of movement which is available to the blow-out prevention system relative to the structure or rig is extremely limited which results in considerable stresses being applied to the riser.

Disclosure of the Invention

Accordingly the invention resides in a support assembly for an underwater fluid delivery line interconnecting an underwater well with a surface platform delivery comprising a riser, a mudline riser-casing connecting assembly providing connection between the lower end of the riser and the well, said mudline riser- casing connecting assembly comprising a bore hole conductor casing adapted to be fixed in a bore hole in the mudline and terminating at its upper end at or in the region of the mudline and adapted to support the riser and well bore casing, the assembly further comprising an annular landing shoulder on the inner face of the bore hole conductor casing at a position spaced downwardly from the upper end of the bore hole conductor casing and an annular hanger assembly adapted to be mounted to the upper end of the well bore casing, said annular hanger assembly being engagable with the landing shoulder to support the well bore casing from the landing shoulder, the mudline riser-casing connecting assembly further comprising a connector adapted at one end to be connected with the hanger assembly and adapted to be connected at the other end to the lower end of the riser, the connector being capable of selective engagement and disengagement with the hanger, said connector being supported in the bore hole conductor casing in the region of the upper end of the bore hole conductor casing through a support assembly to prevent radial movement of the connector within the bore hole conductor casing, the upper end of the connector extending above the support assembly and including a stress joint which is adapted to be fixed to the lower end of the riser, said stress joint being adapted to accommodate the stress arising from the movement of the lower end of the riser relative to that part of the mudline riser-casing connecting assembly within the bore hole conductor casing.

According to a preferred feature of the invention the support assembly further comprises a surface blow- out prevention support system between the upper end of the riser and the platform.

According to a further preferred feature of the invention the surface blow-out prevention support system comprises a support accommodating the blow-out preventer which is adapted to be supported from an associated support structure, the support facilitating connection between the blow-out prevention system and a riser extending from an underwater well, a connector providing a fluid connection between the blow-out preventer and the associated support structure, said support comprising a plurality of suspension members extending between the associated support structure and the support, said suspension members being mounted to the support at substantially angularly equidistant position around the central axis of the support, each suspension member comprising a flexible cord member extending between the support and the associated support structure through a sheave arrangement, said sheave arrangement including a resilient tensioning member which is capable of resilient longitudinal extension to cause the spacing between the support and the associated support structure to be varied.

According to a further preferred feature of the invention the support assembly further comprises a support accommodating the blow-out preventer which is adapted to be supported from an associated support structure, the support facilitating connection between the blow-out prevention system and a riser extending from an underwater well, a connector providing a fluid connection between the blow-out preventer and the associated support structure, said support comprising a plurality of suspension members extending between the associated support structure and the support, said suspension members being mounted to the support at substantially angularly equidistant positions around the central axis of the support, each suspension member comprising a flexible cord member extending between the support and the associated support structure through a sheave arrangement, said sheave arrangement including a resilient tensioning member which is capable of resilient longitudinal extension to cause the spacing between the support and the associated support structure to be varied, wherein the connector is adapted to provide fluid connection between the blow-out preventer and a fluid line provided on the associated support structure, said connector having an elongate tubular body, the body having a first end adapted to be mounted to the blow-out prevention means and the body having a second end adapted to be connected to the fluid line where the connector accommodates for relative longitudinal movement between the riser and the associated support structure, said body comprising a plurality of tubular portions which are telescopically and sealingly interengaged to enable the spacing between the ends to be varied, one of said ends having an engagement member adapted to be fixed to said blow-out prevention means or to said support structure, said engagement member being pivotally mounted to the one end of said ends to be rotatable about the longitudinal axis of the body and to be pivotable about the transverse axis of the body.

According to another aspect the invention resides in a mudline riser-casing connecting assembly for an underwater well said mudline riser-casing connecting assembly comprising a bore hole conductor casing adapted to be fixed in a bore hole in the mudline and terminating at its upper end at or in the region of the mudline and adapted to support a fluid conveying riser and well bore casing, the assembly further comprising an annular landing shoulder on the inner face of the bore hole conductor casing at a position spaced downwardly from the upper end of the bore hole conductor casing and an annular hanger assembly adapted to be mounted to the upper end of the well bore casing, said annular hanger assembly being engageable with the landing shoulder to support the well bore casing from the landing shoulder, the mudline riser-casing connecting assembly further comprising a connector adapted at one end to be connected with the hanger assembly and adapted to be connected at the other end to the lower end of the riser, the connector being capable of selective engagement and disengagement with the hanger, said connector being supported in the bore hole conductor casing in the region of the upper end of the bore hole conductor casing through a support assembly to prevent radial movement of the connector within the bore hole conductor casing, the upper end of the connector extending above the support assembly and including a stress joint which is adapted to be fixed to the lower end of the riser, said stress joint being adapted to accommodate the stress arising from the movement of the lower end of the riser relative to that part of the mudline riser-casing connecting assembly within the bore hole conductor casing.

According to a preferred feature of the invention, said connector comprises a first portion extending between the hanger and the upper end of the bore hole conductor, said support assembly comprising an annular support provided at the upper end of the first portion and receivable in the upper end of the bore hole conductor casing to resist relative radial movement between the connector and the upper end of bore hole conductor, said connector comprising a second portion extending between the upper end of the first portion and the riser said second potion providing the stress joint.

According to a preferred feature of the invention a stabiliser element is located between the outer radial face of the first portion and the inner face of the bore hole conductor casing at a position intermediate of the hanger and the upper end of the bore hole conductor, said stabiliser being adapted to resist relative radial movement between the first portion and the upper end of bore hole conductor at said position. According to one embodiment the stabiliser element comprises an annular element fixed to the first portion.

According to a further preferred feature of the invention, the mudline riser-casing connecting assembly incorporates a disconnect facility which enables remote interengagement and disengagement of the lower end of the connector with the hanger assembly.

According to another aspect the invention resides in a surface blow-out prevention support system comprising a support accommodating the blow-out preventer which is adapted to be supported from an associated support structure, the support facilitating connection between the blow-out prevention system and a riser extending from an underwater well, a connector providing a fluid connection between the blow-out preventer and the associated support structure, said support comprising a plurality of suspension members extending between the associated support structure and the support, said suspension members being mounted to the support at substantially angularly equidistant position around the central axis of the support, each suspension member comprising a flexible cord member extending between the support and the associated support structure through a sheave arrangement, said sheave arrangement including a resilient tensioning member which is capable of resilient longitudinal extension to cause the spacing between the support and the associated support structure to be varied. According to a preferred feature of the invention at least three suspension members are provided between the support and the associated support structure. According to one embodiment four suspension members are provided between the support and the associated support structure.

According to a preferred feature of the invention, each suspension member comprises a sheave block mounted to the support and a further sheave block mounted to the associated support structure, one end of said cord being fixed to the associated support structure or the support. According to one embodiment the other end of the cord is connected to the associated support structure through the tensioning member.

According to a preferred feature of the invention the connector is adapted to provide fluid connection between the blow-out preventer and a fluid line provided on the associated support structure, said connector having an elongate tubular body, the body having a first end adapted to be mounted to the blow-out prevention means and the body having a second end adapted to be connected to the fluid line where the connector accommodates for relative longitudinal movement between the riser and the associated support structure, said body comprising a plurality of tubular portions which are telescopically and sealingly interengaged to enable the spacing between the ends to be varied, one of said ends having an engagement member adapted to be fixed to said blow-out prevention means or to said support structure, said engagement member being pivotally mounted to the one end of said ends to be rotatable about the longitudinal axis of the body and to be pivotable about the transverse axis of the body.

According to a preferred feature of the invention, the said one end of the body is provided with an annular collar having an outer face which is of a part spherical configuration, said collar being received within a socket of complementary configuration within the engagement member to permit said rotatable and pivotal relative movement between the body and the engagement member. The invention will be more fully understood in the light of the following description of one specific embodiment.

Brief Description of the Drawings

The description is made with reference to the accompanying drawings of which:

Figure 1 is a sectional elevation illustrating the mudline riser-casing connecting assembly according to the embodiment;

Figure 2 is a sectional elevation of the mudline riser-casing connecting assembly according to the embodiment illustrating a drill rod accommodated within the riser and the well bore casing accommodating the mechanical disconnect tool;

Figure 3 is a sectional elevation of the mudline riser-casing connecting assembly according to the embodiment illustrating the disconnection of the riser from the upper end of the casing; and

Figure 4 is a sectional elevation of the mudline riser-casing connecting assembly according to the embodiment illustrating the mounting of a Christmas tree assembly to the well for production purposes;

Figure 5 is a schematic illustration of a support for a blow-out protector according to the embodiment; and

Figure 7 is a schematic sectional elevation of the connector according to the embodiment.

Detailed Description of Specific Embodiment

The embodiment is directed to delivery line of an underwater well where the lower end is provide with a mudline riser-casing connecting assembly as shown at Figures 1 to 4 providing connection between the riser and the casing of an underwater well in circumstances where the blowout preventer is at or about the surface of the water and is supported by an arrangement as shown at Figures 5 and 6. The mudline riser-casing connecting assembly according to the embodiment serves to provide a connection between the riser and casing which will accommodate for the suspension loads exerted by the casing to isolate the suspension loads from the riser, whilst allowing for the relative movement of the riser without causing resultant movement of the casing within the bore hole.

The mudline riser-casing connecting assembly according to embodiment comprises a borehole conductor casing 11 which is receivable in a borehole. The borehole conductor casing 11 provides support for both the riser 27 and the well bore casing 23 of the well. Such support is in part provided by a landing shoulder 13 which comprises an inwardly directed annulus provided in the inner face of the bore hole conductor casing at a position spaced downwardly from the upper end of the bore hole conductor casing. Support for the riser is provided by an enlarged support housing 15 which is provided at the upper end of the bore hole conductor casing in the region of the mudline.

The mudline riser-casing connecting assembly further comprises a hanger 17 which is engageable with the landing shoulder 13 and which comprises a central tubular portion 19 and an annulus 21 where the annulus 21 is adapted to be engageable with the landing shoulder to prevent movement of the hanger 17 past the landing shoulder 13. The hanger 17 is adapted to be fixed to the upper end of the well bore casing 23 to enable the well bore casing 23 to be supported from the landing shoulder 13.

The upper end of the hanger 17 is engageable with a connector assembly 25 which extends between the hanger 17 and the lower end of the riser pipe 27. The connector assembly comprises a first portion 29 which extends between the hanger 17 and the support housing 15 of the bore hole conductor casing and a second portion which comprises a tapered stress joint 31 located between the upper end of the first portion 29 and the lower end of the riser 27. The upper end of the first portion is formed with an annular flange 33 which is receivable with the support assembly 15 of the support housing of the bore hole conductor casing to be incapable of relative radial movement within the bore hole conductor casing 11. In addition, an annular stabiliser 35 is mounted to the first portion to be receivable within the bore hole conductor casing 11 at a position intermediate of the length of the first portion 29 to prevent flexure of the first portion between its ends.

The stress joint 31 is configured to accommodate for the relative movement of the lower end of the riser 27 to the bore hole conductor casing and to accommodate the stresses which are the result of such relative movement.

The lower end of the first portion 29 accommodates a mechanical disconnect tool 37 which is of a substantially conventional form and through which the lower end of the first portion 29 can be remotely engaged with and disengaged from the upper end of the hanger 17 whereby the riser can be disconnected from the casing as illustrated at Figure 3 when it becomes necessary to decommission a well and/or it becomes necessary for the rig associated with the well to move out of station.

The mudline riser-casing connecting assembly of the embodiment ensures that no bending loads which are exerted upon the riser are transmitted to the casing below the mudline. Furthermore, the mudline riser-casing connecting assembly provides a means of supporting the casing within the borehole from the mudline in order to isolate the loading exerted by the weight of the casing from the riser. Furthermore, the embodiment enables the use by a semi-submersible drilling rig of a blowout preventer located at or about the surface of the water by virtue of its capacity to accommodate the flexure of the riser. In addition, the embodiment provides a means of selectively connecting and disconnecting the riser from the casing as required without permanently decommissioning the well. This is enabled by the circumstance that the weight of the casing is accommodated by the bore hole conductor casing. This latter feature enables the temporary suspension of drilling and/or draw off activities from a well in the event that the supporting rig is required to move off station from the well. Furthermore, the disconnect and reconnect facility enables an exploration well to be converted to a production well as required.

The embodiment connection arrangement according to the embodiment further comprises a surface blow-out prevention system located at the upper end of the delivery line as shown at Figures 5 and 6 where the arrangement comprises a blow-out preventer 51 and connector 53 supported from a rig 69 where the lower most end of the blow-out preventer is connected via a hydraulic connection to a tapered stress joint 55 connected to the riser 27 of an underwater well at a position located in the vicinity of the surface of the water. The upper end of the blow-out protector 51 is connected to a conduit (not shown) provided on the rig through the connector 53 which extends between the blow-out protector and the conduit.

The blow-out protector 51 of the embodiment is supported from the rig 69 through a support frame 59 which accommodates the blow-out protector and which is supported from the rig through a set of four suspension members 61. The suspension members 61 are spaced at angularly equidistant intervals around the central longitudinal axis of the blow-out protector. Each suspension member comprises a first sheave block 63 which is supported from the upper end of the support frame 15 through a link member 65 which is pivotally supported from the frame 59. Each suspension member further comprises a second sheave block 67 which is supported from the rig 69. A cable or like flexible cord member 71 is fixed at one end 73 to the rig 69 and extends from the one end 73 over the first sheave block 63 and the second sheave block 67. The other end (not shown) of the flexible cord member 71 is fixed to the rig 69 through a tensioning member 75 which is capable of resilient extension to allow for relative movement between the support frame 59 and the rig 69.

The arrangement according to the embodiment enables the blow-out protector system to be supported from underneath the rig in a manner whereby the support arrangement will resiliently accommodate for relative movement between the rig and the riser 27 without inducing any significant undue stresses on the support arrangement.

The connection between the blow-out protector and the rig 69 is effected through the connector 53 which is able to accommodate for relative longitudinal rotational and pivotal movement between the blow-out protector and the rig. The connector 53 facilitates the transfer of fluid from the well to the conduit 83 while accommodating for relative movement between the rig and the riser pipe 27 which will arise from relative movement of the platform or rig as a result of variations in the water level which can arise from tidal movements and/or wave action. The connector 53 comprises a telescopic elongate body 81 which enables connection between the blow-out protector 51 and the conduit 83 provided on the rig 69. The body has a first end 85 which is adapted to be sealingly engaged with the outlet of the blow-out protector system and the body has a second end 87 which is adapted to be fixed to the conduit 83. The body 81 comprises 3 tubular portions A, B and C. The lower most portion A provides the first end 85 of the body and is dimensioned to receive the intermediate portion B. The lower most portion A is provided at its other end with a first seal 89 which is slidably and sealingly received over the outer surface of the intermediate portion B to enable relative elongate movement between the lower most portion A and the intermediate portion B. The end of the intermediate portion B which is received within the lower most portion A is provided on its outermost surface within a first annular collar 91 which is intended to be sealingly and slidingly received with the internal face of the lower most portion A. In addition the first annular collar 91 is intended to be engageable with the first seal 89 provided on the lower most portion A to prevent the axial movement of the intermediate portion B out of engagement with the lower most portion A. The intermediate portion B is dimensioned to receive the upper most portion C and the outer end of the intermediate portion B is provided with a second seal 93 which is slidably and sealingly received over the outer surface of the upper most portion C. The end of the upper most portion within the intermediate portion B is provided with a second annular collar 95 which is intended to be sealingly and slidingly received with the internal face of the intermediate portion B. In addition the second annular collar 95 is intended to be engageable with the second seal 93 provided on the intermediate portion B to prevent the axial movement of the upper most portion C out of engagement with the intermediate portion B. .

The second end 87 of the body is adapted to be able to accommodate for pivotal and rotational movement between the connector and the rig 69. This is effected by providing an annular flange member 95 which is adapted to be fixed to the rig 69 and which has an interior which is formed as a socket 97 which receives the outer end of the upper most portion C of the body 81. The lowermost portion of the internal face of the socket is formed as a concave part spherical surface. The outer end of the upper most portion C is provided with an annular sealing collar 97 which has a spherical outer configuration where the socket defined by the annular flange member which accommodates the outer end of the upper most portion C is of complementary configuration to the outer surface of the annular sealing collar 97 (i.e.: is of a part spherical configuration) to enable the annular sealing collar 97 to be both rotatably received within the flange member 95 and to be pivotable about the transverse axis of the flange 95. Suitable seals are provided between the annular sealing collar 97 and the socket of the flange member 95 to provide a fluid tight connection.

The connector of the embodiment enables the connection between the blow-out protector and the rig to accommodate relative movement there between without inducing excessive or undue stresses on the interconnection.

Throughout the specification, unless the context requires otherwise, the word "comprise" or variations such as "comprises" or "comprising", will be understood to imply the inclusion of a stated integer or group of integers but not the exclusion of any other integer or group of integers.

It should be appreciated that the scope of the present invention need not be limited to the particular scope of the embodiment as described above.

Claims

The claims defining the invention are as follows:

1) A mudline riser-casing connecting assembly for an underwater well, said mudline riser-casing connecting assembly comprising a bore hole conductor casing adapted to be fixed in a bore hole in the mudline and terminating at its upper end at or in the region of the mudline and adapted to support a fluid conveying riser and well bore casing, the assembly further comprising an annular landing shoulder on the inner face of the bore hole conductor casing at a position spaced downwardly from the upper end of the bore hole conductor casing and an annular hanger assembly adapted to be mounted to the upper end of the well bore casing, said annular hanger assembly being engagable with the landing shoulder to support the well bore casing from the landing shoulder, the mudline riser-casing connecting assembly further comprising a connector adapted at one end to be connected with the hanger assembly and adapted to be connected at the other end to the lower end of the riser, the connector being capable of selective engagement and disengagement with the hanger, said connector being supported in the bore hole conductor casing in the region of the upper end of the bore hole conductor casing through a support assembly to prevent radial movement of the connector within the bore hole conductor casing, the upper end of the connector extending above the support assembly and including a stress joint which is adapted to be fixed to the lower end of the riser, said stress joint being adapted to accommodate the stress arising from the movement of the lower end of the riser relative to that part of the mudline riser-casing connecting assembly within the bore hole conductor casing.

2) A mudline riser-casing connecting assembly as claimed at claim 1 wherein, said connector comprises a first portion extending between the hanger and the upper end of the bore hole conductor, said support assembly comprising an annular support provided at the upper end of the first portion and receivable in the upper end of the bore hole conductor casing to resist relative radial movement between the connector and the upper end of bore hole conductor, said connector comprising a second portion extending between the upper end of the first portion and the riser said second potion providing the stress joint.

3) A mudline riser-casing connecting assembly as claimed at claim 1 or 2 wherein, a stabiliser element is located between the outer radial face of the first portion and the inner face of the bore hole conductor casing at a position intermediate of the hanger and the upper end of the bore hole conductor, said stabiliser being adapted to resist relative radial movement between the first portion and the upper end of bore hole conductor at said position.

4) A mudline riser-casing connecting assembly as claimed at claim 3 wherein, the stabiliser element comprises an annular element fixed to the first portion.

5) A mudline riser-casing connecting assembly as claimed at claim 1 ,2 3 or 4 wherein, the mudline riser-casing connecting assembly incorporates a disconnect facility which enables remote interengagement and disengagement of the lower end of the connector with the hanger assembly.

6) A mudline riser-casing connecting assembly substantially as herein described.

7) A surface blow-out prevention support system comprising a support accommodating the blow-out preventer which is adapted to be supported from an associated support structure, the support facilitating connection between the blow-out prevention system and a riser extending from an underwater well, a connector providing a fluid connection between the blow-out preventer and the associated support structure, said support comprising a plurality of suspension members extending between the associated support structure and the support, said suspension members being mounted to the support at substantially angularly equidistant position around the central axis of the support, each suspension member comprising a flexible cord member extending between the support and the associated support structure through a sheave arrangement, said sheave arrangement including a resilient tensioning member which is capable of resilient longitudinal extension to cause the spacing between the support and the associated support structure to be varied.

8) A surface blow-out prevention support system as claimed at claim 7 wherein at least three suspension members are provided between the support and the associated support structure.

9) A surface blow-out prevention support system as claimed at claim 7 wherein four suspension members are provided between the support and the associated support structure.

10) A surface blow-out prevention support system as claimed at claim 7, 8 or 9 wherein, each suspension member comprises a sheave block mounted to the support and a further sheave block mounted to the associated support structure, one end of said cord being fixed to the associated support structure or the support.

11 ) A surface blow-out prevention support system as claimed at claim 10 wherein the other end of the cord is connected to the associated support structure through the tensioning member.

12) A surface blow-out prevention support system comprising a support accommodating the blow-out preventer which is adapted to be supported from an associated support structure, the support facilitating connection between the blow-out prevention system and a riser extending from an underwater well, a connector providing a fluid connection between the blow-out preventer and the associated support structure, said support comprising a plurality of suspension members extending between the associated support structure and the support, said suspension members being mounted to the support at substantially angularly equidistant position around the central axis of the support, each suspension member comprising a flexible cord member extending between the support and the associated support structure through a sheave arrangement, said sheave arrangement including a resilient tensioning member which is capable of resilient longitudinal extension to cause the spacing between the support and the associated support structure to be varied, wherein the connector is adapted to provide fluid connection between the blowout preventer and a fluid line provided on the associated support structure, said connector having an elongate tubular body, the body having a first end adapted to be mounted to the blow-out prevention means and the body having a second end adapted to be connected to the fluid line where the connector accommodates for relative longitudinal movement between the riser and the associated support structure, said body comprising a plurality of tubular portions which are telescopically and sealingly interengaged to enable the spacing between the ends to be varied, one of said ends having an engagement member adapted to be fixed to said blow-out prevention means or to said support structure, said engagement member being pivotally mounted to the one end of said ends to be rotatable about the longitudinal axis of the body and to be pivotable about the transverse axis of the body.

13) A surface blow-out prevention support system as claimed at claim 12 wherein the said one end of the body is provided with an annular collar having an outer face which is of a part spherical configuration, said collar being received within a socket of complementary configuration within the engagement member to permit said rotatable and pivotal relative movement between the body and the engagement member. 14) A surface blow-out prevention support system as claimed at claim 12 or 13 wherein at least three suspension members are provided between the support and the associated support structure.

15) A surface blow-out prevention support system as claimed at claim 12 or 13 wherein four suspension members are provided between the support and the associated support structure.

16) A surface blow-out prevention support system as claimed at claim 12, 13, 14 or 15 wherein, each suspension member comprises a sheave block mounted to the support and a further sheave block mounted to the associated support structure, one end of said cord being fixed to the associated support structure or the support.

17) A surface blow-out prevention support system as claimed at claim 16 wherein the other end of the cord is connected to the associated support structure through the tensioning member.

18) A surface blow-out prevention support system substantially as herein described.

19) A support assembly for an underwater fluid delivery line interconnecting an underwater well with a surface platform delivery comprising a riser, a mudline riser-casing connecting assembly providing connection between the lower end of the riser and the well, said mudline riser-casing connecting assembly comprising a bore hole conductor casing adapted to be fixed in a bore hole in the mudline and terminating at its upper end at or in the region of the mudline and adapted to support the riser and well bore casing, the assembly further comprising an annular landing shoulder on the inner face of the bore hole conductor casing at a position spaced downwardly from the upper end of the bore hole conductor casing and an annular hanger assembly adapted to be mounted to the upper end of the well bore casing, said annular hanger assembly being engagable with the landing shoulder to support the well bore casing from the landing shoulder, the mudline riser-casing connecting assembly further comprising a connector adapted at one end to be connected with the hanger assembly and adapted to be connected at the other end to the lower end of the riser, the connector being capable of selective engagement and disengagement with the hanger, said connector being supported in the bore hole conductor casing in the region of the upper end of the bore hole conductor casing through a support assembly to prevent radial movement of the connector within the bore hole conductor casing, the upper end of the connector extending above the support assembly and including a stress joint which is adapted to be fixed to the lower end of the riser, said stress joint being adapted to accommodate the stress arising from the movement of the lower end of the riser relative to that part of the mudline riser-casing connecting assembly within the bore hole conductor casing.

20) A support assembly for an underwater fluid delivery line as claimed at claim 19 further comprising a surface blow- out prevention support system between the upper end of the riser and the platform.

21 ) A support assembly for an underwater fluid delivery line as claimed at claim 20 wherein the surface blow-out prevention support system comprises a support accommodating the blow-out preventer which is adapted to be supported from an associated support structure, the support facilitating connection between the blow-out prevention system and a riser extending from an underwater well, a connector providing a fluid connection between the blow-out preventer and the associated support structure, said support comprising a plurality of suspension members extending between the associated support structure and the support, said suspension members being mounted to the support at substantially angularly equidistant position around the central axis of the support, each suspension member comprising a flexible cord member extending between the support and the associated support structure through a sheave arrangement, said sheave arrangement including a resilient tensioning member which is capable of resilient longitudinal extension to cause the spacing between the support and the associated support structure to be varied.

22) A support assembly for an underwater fluid delivery line as claimed at claim 21 wherein at least three suspension members are provided between the support and the associated support structure.

23) A surface blow-out prevention support system as claimed at claim 21 wherein four suspension members are provided between the support and the associated support structure.

24) A surface blow-out prevention support system as claimed at claim 21 , 22 or 23 wherein, each suspension member comprises a sheave block mounted to the support and a further sheave block mounted to the associated support structure, one end of said cord being fixed to the associated support structure or the support.

25) A surface blow-out prevention support system as claimed at claim 24 wherein the other end of the cord is connected to the associated support structure through the tensioning member.

26) A support assembly for an underwater fluid delivery line as claimed at claim 19 further comprising a support accommodating the blow-out preventer which is adapted to be supported from an associated support structure, the support facilitating connection between the blow-out prevention system and a riser extending from an underwater well, a connector providing a fluid connection between the blow-out preventer and the associated support structure, said support comprising a plurality of suspension members extending between the associated support structure and the support, said suspension members being mounted to the support at substantially angularly equidistant positions around the central axis of the support, each suspension member comprising a flexible cord member extending between the support and the associated support structure through a sheave arrangement, said sheave arrangement including a resilient tensioning member which is capable of resilient longitudinal extension to cause the spacing between the support and the associated support structure to be varied, wherein the connector is adapted to provide fluid connection between the blow-out preventer and a fluid line provided on the associated support structure, said connector having an elongate tubular body, the body having a first end adapted to be mounted to the blow-out prevention means and the body having a second end adapted to be connected to the fluid line where the connector accommodates for relative longitudinal movement between the riser and the associated support structure, said body comprising a plurality of tubular portions which are telescopically and sealingly interengaged to enable the spacing between the ends to be varied, one of said ends having an engagement member adapted to be fixed to said blow-out prevention means or to said support structure, said engagement member being pivotally mounted to the one end of said ends to be rotatable about the longitudinal axis of the body and to be pivotable about the transverse axis of the body.

27) A support assembly for an underwater fluid delivery line as claimed at claim 26 wherein the said one end of the body is provided with an annular collar having an outer face which is of a part spherical configuration, said collar being received within a socket of complementary configuration within the engagement member to permit said rotatable and pivotal relative movement between the body and the engagement member.

28) A support assembly for an underwater fluid delivery line as claimed at claim 26 or 27 wherein at least three suspension members are provided between the support and the associated support structure. 29) A support assembly for an underwater fluid delivery line as claimed at claim 26 or 27 wherein four suspension members are provided between the support and the associated support structure.

30) A support assembly for an underwater fluid delivery line as claimed at claim 26, 27, 28 or 29 wherein, each suspension member comprises a sheave block mounted to the support and a further sheave block mounted to the associated support structure, one end of said cord being fixed to the associated support structure or the support.

31) A support assembly for an underwater fluid delivery line as claimed at claim 30 wherein the other end of the cord is connected to the associated support structure through the tensioning member.

32) A support assembly for an underwater fluid delivery line as claimed at any one of claims 26 to 31 wherein, said connector comprises a first portion extending between the hanger and the upper end of the bore hole conductor, said support assembly comprising an annular support provided at the upper end of the first portion and receivable in the upper end of the bore hole conductor casing to resist relative radial movement between the connector and the upper end of bore hole conductor, said connector comprising a second portion extending between the upper end of the first portion and the riser said second potion providing the stress joint.

33) A support assembly for an underwater fluid delivery line as claimed at any one of claims 26 to 32 wherein, a stabiliser element is located between the outer radial face of the first portion and the inner face of the bore hole conductor casing at a position intermediate of the hanger and the upper end of the bore hole conductor, said stabiliser being adapted to resist relative radial movement between the first portion and the upper end of bore hole conductor at said position. 34) A support assembly for an underwater fluid delivery line as claimed at claim 33 wherein, the stabiliser element comprises an annular element fixed to the first portion.

35) A support assembly for an underwater fluid delivery line as claimed at any one of claims 26 to 34 wherein, the mudline riser-casing connecting assembly incorporates a disconnect facility which enables remote interengagement and disengagement of the lower end of the connector with the hanger assembly.

36) A support assembly for an underwater fluid delivery line substantially as herein described.