AU658239B2 - Flowline connection system - Google Patents

Description

AUSTRALIA

PATENTS ACT 1990 COMPLETE SPECIFICATION FOR A STANDARD PATENT

ORIGINAL

S F Ref: 226733

D

Name and Address of Applicant: Actual Inventor(s): Address for Service: Invention Title: Sonsub Services Pty. Ltd.

106-108 Kurnall Road Welshpool Nestern Australia 6106

AUSTRALIA

Christopher Glen Sutherland Spruson Ferguson, Patent Attorneys Level 33 St Martins Tower, 31 Market Street Sydney, New South Wales, 2000, Australia Flowline Connection System ASSOCIATED PROVISIONAL [31] Application No(s) PK9555 APPLICATION DETAILS [33] Country

AU

[32] Application Date 18 November 1991 The following statement is a full description of this invention, including the best method of performing it known to me/us:- 5815/3 2 BACKGROUND OF THE INVENTION This invention relates to a system for connecting a flowline, and more particularly for remotely connecting a flowline to a wellhead connection.

In order to connect a flowline for oil to an appropriate connection in an undersea wellhead, the flowline is first laid on the sea bed to within a short distance, for example to within approximately 50 metres of the wellhead and then the end of the flowline is pulled along the sea bed and engaged to the wellhead connection. Since the flowline, although flexible, is relatively rigid at the end thereof, it is necessary that the end of the flowline be brought into proximity with the wellhead connection at the correct angle so that accurate engagement can take place. Generally, saturation divers are used to carry out the connection procedure, who require support from a dive support vessel, which can be 15 costly.

It is also known for the divers to attach a winch line to the wellhead, pay out the winch line as they move to the flowline and then winch in the winch line so as to pull the end of the flowline towards the wellhead. Although the flowline is thereby easily moved towards the wellhead, the lateral accuracy thereof cannot be easily adjusted so that the correct angle for engagement is not easily achieved.

It is therefore an object of the present invention to provide a system which will overcome, or at least reduce, some of the 2. abovementioned disadvantages.

25 It is therefore an object of the present invention to provide a system which will overcome, or at least reduce, some the abovementioned disadvantages.

BRIEF SUMMARY OF THE INVENTION According to one aspect of the present invention there is disclosed a module for connection to a remotely operated undersea vehicle, the module comprising means for maintaining an end of a flowline in a predetermined orientation with respect to the module, a winch including a winch line for attachment to a wellhead to which the flowline is to be connected such that as the winch pulls in the winch line, the module is pulled towards the wellhead, and means for laterally adjusting the position of the module as it approaches the wellhead.

STA/0561E 3- Preferably, the means for laterally adjusting the position of the module comprisesione lateral thruster. The means for maintaining the end of the flowline in a predetermined orientation, preferably comprises one clamp or more clamps for holding the end of the flowline in the predetermined orientation.

In the preferred embodiment, one or more guide posts are provided on the wellhead for engagement with suitable recesses on the module such that when the guide posts engage the recesses, the end of the flowline is automatically in the correct position for connection with a flowline connector on the wellhead. Preferably, the end of the flowline is connected to the flowline connector on the wellhead by means of a collet connector. Furthermore, the guide posts are preferably provided with S* stabbing cones to firmly engage the wellhead when the guide posts have engaged with the respective recess in the wellhead.

S 15 Preferably, the module is adapted to be attached to the remotely operated vehicle by means of bolts.

According to a second aspect of the present invention there is disclosed a method a method of connecting one end of a flow line to an underwater wellhead connection, said method comprising the steps of attaching a winchline from a remotely operable undersea vehicleAas necessary to attach said vehicle to said flowline end, drawing said winchline in to move said vehicle towards said wellhead whilst simultaneously maintaining a predetermined orientation of said vehicle, and inter-connecting said flowline end and wellhead connection.

25 BRIEF DESCRIPTION OF THE DRAWINGS One embodiment of the invention will now be more fully described, by way of example, with reference to the drawings, of which: Figure 1 is a perspective view of a module according to the invention in position attached to a remotely operated vehicle adjacent a wellhead; Figure 2 is a side elevational view of the module, remotely operated vehicle and wellhead shown in Figure 1; Figure 3 is a plan view of the module and remotely opnwated vehicle shown in Figure 2; and Figure 4 is an end elevation of the module and remotely, operated vehicle of Figure 2.

Vr s- STA/0561E 4 DETAILED DESCRIPTION OF THE DRAWINGS The flowline connection system shown in the drawings comprises a module 1 shown connected below a remotely operated vehicle (ROV) 2 commonly used in offshore construction.

The system consists of a bolt-on module, which is attached to the underside of a standard work class (50 HP) ROV.

The bolt-on module 1 consists of a submersible hydraulic power unit which provides hydraulic power to a number of thrusters 3, a 5 to 10 ton pull-in winch 4, a hot stab hydraulics to activate a flowline or umbilical connection and a hydraulic clamp 5 to lock the flowline to the underside of the module 1.

Thus, only electrical cabling is required to interface between the module 1 and the ROV 2. The flowline connection operation consists of the following steps: 1. Laying of the flowline 6 in a controlled manner, such that the flowline pull-in head 7 is located within a planned target zone near the wellhead 8.

2. The ROV 2 is then deployed and confirms by survey fix (via an acoustic transducer (not shown) mounted on the ROV 2 that the pull-in head 7 is in the correct location and that the or each flowline 6 (if there are more than one) is free of entanglement.

3. The ROV 2 then moves to the wellhead 8, and attaches a Kevlar winch line 9 to an attachment point 10 on the wellhead 8. The ROV 2 then returns to the flowline pull-in head 7 whilst paying out the winch line 9.

25 4. The flowline pull-in head 7 is then engaged through the hydraulic clamp 5 located on the underside of the module 1.

The winch 4 then pulls in the winch line 9 so that the ROV 2, together with module 1, is pulled towards the wellhead 8. At the same *c C 3 cy c time, the if use to provide any lateral correction in the alignment of the flowline head 7 with a flowline connector 12 on the wellhead 8. The adjustment is carried out remotely due to cameras or other sensors positioned on the ROV 2 which allow a remote operator to accurately determine the relative positions of the ROV 2 and the wellhead 8.

L 9 STA/0561E 6. Conically shaped guide post receivers 14 provided on the module 1 are used to accurately mate the module 1 with the wellhead 8.

The guide post receivers 14 engage guide posts 13 on the wellhead 8.

When fully engaged, the flowline head 7 is correctly aligned with flowline connector 12 on wellhead 8.

7. Hydraulic stabs are then introduced from the ROV 2, by means of manipulator arm 11, to provide hydraulic power to engage a hydraulic flowline connector (for example a collet type connector) to connect the flowline head 7 to wellhead 8.

8. The connection is then tested for leaks, together with a visual confirmation of the test gauge by the ROV 2.

9. The ROV 2 then disengages from the wellhead 10 and is recovered to the surface.

Although only one embodiment of the present invention has been particularly described, it will be apparent to a person skilled in the art that various modifications and alterations can be made without departing from the scope of the invention.

SFor example, the guide posts can be located on the ROV and the recesses on the wellhead.

STA/0561E

Claims (11)

1. A module for connection to a remotely operated underspi vehicle, the module comprising means for maintaining an end of a flowline in a predetermined orientation with respect to the module, a winch including a winch line for attachment to a wellhead to which the flowline is to be connected such that as the winch pulls in the winch line, the module is pulled towards the wellhead, and means for laterally adjusting ani PrIoci to r\ the position of the module as it approachesAthe wellhead.

2. A module as claimed in claim 1, wherein the means for laterally adjusting the position of the module comprises at least one V.9. lateral thruster.

3. The module as claimed in claim 1 or 2, wherein the means for maintaining the end of the flowline in a predetermined orientation, comprises at least one clamp for holding the end of the flowline, each said clamp being secured to said module.

4. The module as claimed in any one of claims 1 to 3, wherein at least one guide post is provided on either the wellhead or the module for inter-engagement with a corresponding recessed guide post receiver mounted on said module or wellhead respectively. poe.

The module as claimed in claim 4, wherein each said?~anessd ie r comprises a stabbing cone.

6. The module as claimed in any one of claims 1 to 5, wherein the end of the flowline is connected to the flowline connector on the wellhead by means of a collet connector.

7. The module as claimed in any one of claims 1 to 6, and being adapted to be attached to the remotely operated vehicle by means of bolts.

8. A module for connection to a remotely operated undersea vehicle, said module being substantially as described with reference to the drawings.

9. A method of connecting one end of a flow line to an underwater wellhead connection, said method comprising the steps of attaching a to o. w e.hnd." winchline from a remotely operable undersea vehicle, playing out said winchline as necessary to attach said vehicle to said flowline end, drawing said winchline in to move said vehicle towards said wellhead whilst simultaneously maintaining a predetermined orientation of said vehicle, and inter-connecting said flowline end and wellhead connection.

A method of connecting one end of a flowline to an underwater wellhead connection, said method being substantially as described with reference to the drawings.

11. A module for connection to a remotely operated undersea vehicle, said module being substantially as hereinbefore described with reference to the accompanying drawings. Dated 16 September, 1994 Sonsub Services Pty. Ltd. Patent Attorneys for the Applicant/Nominated Person SPRUSON FERGUSON o o *oo o o [N:\LIBTTI00261:vgs