GB2228961A - Modularized tool carrier for diverless underwater operations - Google Patents

Abstract

A modularized tool carrier for diverless underwater work operations such as inspection, installation, repair, component replacement, and so on, of seabed-based installations comprises a frame-like stand (1) with legs (2) and is provided with an operating unit (9), a control unit (10) and a power supply unit (11). With the aid of a lifting wire (6a) and guide wires (4) the tool carrier can be brought down to and be positioned at a predetermined location on the seabed. A variety of different work tools (12) are locatable on the tool carrier below the stand (1) and between the legs (2). <IMAGE>

Description

MODULARIZED TOOL CARRIER FOR DIVERLESS UNDERWATER OPERATIONS The present invention relates to a tool carrier for different work operations in connection with diverless underwater work.

In the offshore extraction of oil and gas from wells on the seabed, with increasing water depths the extraction will be performed from bottom-based installations. Alternatively, it may be economically advantageous to connect peripheral deposits to an existing platform with the aid of bottom-based satellite installations. In bottom-based installations it is in many respects advantageous to use diverless equipment for both mounting and maintenance of the installations. At large depths it may be essential to use diverless equipment for mounting and maintenance of the bottom-based installations for the extraction of oil and gas.

A large number of different systems, serving the above purpose, exist. As examples a few embodiments disclosed in US patent specifications will be briefly described.

US 3,461,777 describes a method and a device for work on subsea pipelines. The device comprises a framework provided with certain clamping devices and working chambers. The framework is arranged so as to straddle those sections of the pipeline which are to be attended to. A number of clamping devices engage the pipe sections whereupon these are moved with the aid of the clamping devices so that the pipe sections are centred with respect to each other. The working chamber is placed over the aligned pipe sections, to which a controlled, relatively dry atmosphere is then led, where pipe repair, joining, or other work operations can be carried out.

US 3,717,000 discloses a jig or a guide tool for work in a weightless medium. The jig is used to position a work tool in such a way in relation to an existing installation that a specified task can be carried out. This may be, for example, the replacement of a valve in a subsea pipeline system. The jig is here provided withmeans for fixing it against the existing installation, for moving the jig, and for holding and operating replacement components.

US 4,030,309 discloses a system of working arms extending from a chamber submerged on the seabed. Extending from the chamber, the arms can be rotated in various directions and the length of the arms can also be adjusted.

At the ends of the arms, tools of various kinds are attached to be able to carry out a number of different work operations. The chamber is anchored to the seabed by means of articulated arms and guides surrounding guide wires.

US 4,786,209 discloses a method for replacement of a valve forming part of a subsea production system for oil and gas. A manipulator is guided with the aid of guide wires down towards a definite location on the seabed. The manipulator is provided with a telescopic arm in the end of which there is a tool for alignment against the valve as well as tools for detaching an existing valve and attaching a replacement valve.

To be able to perform several different diverless work operations offshore in connection with bottom-based installations for extracting oil and gas, a flexible and modularized tool carrier has been produced. It is intended to be used in connection with inspection, installation, repair, component replacement, control and maintenance, etc., of bottom-based installations. What constitutes the invention is defined in the following claim 1.

The tool carrier mainly comprises a framelike stand with legs and attachments and holders for guide wires between a surface installation and a bottom-based installa tion. Further, the tool carrier is provided with an operating, a control and a power supply system and has a launching system placed on the surface installation. With the aid of a lifting wire between the tool carrier and the surface installation, the tool carrier can be moved between the surface and the bottom. By means of a control line (or umbilical) between surface-based control equipment and tool carrier-based equipment, the work operations of the tool carrier can be controlled.

The frame-like stand portion with its legs has a large open area in the forward and downward directions such that, with the tool carrier in position, different work operations can be carried out within a large working range.

The legged stand portion can be dimensioned for carrying large loads and arranged so as to allow a flexible location of tools and their supply system.

Especially characteristic of a tool carrier according to the invention is the modularized structure formed by the frame-like stand with legs, attachments, holders, etc.

Further, the modularization is made so as to allow great flexibility for adaptation to existing and different possible subsea installations and structures.

Any heave of the sea experienced by the surface installation connected to the guide wires can be compensated for within wide limits by means of operating systems located on the surface installation.

An advantage of this type of tool carrier is that, with the guide wires connected to the bottom-based installation, it may be given an accurate positioning to the installation for carrying out a work operation. A freely moving tool carrier unit has great limitations as regards manoeuvrability due to underwater currents despite the arrangement of thrusters. The lifting capacity is also greatly limited, since ample floats are required for heavy lifting operations. With lifting and guide wires a tool carrier unit will be easily manoeuvrable within the range and may have a great lifting capacity.

The invention will now be further described, by way of example, with reference to the accompanying drawings, in which: Figure 1 shows a tool carrier according to a basic embodiment, Figure 2 shows the tool carrier of Figure 1 provided with a tool for replacement of an insert unit in a bottombased valve, and Figure 3 shows the tool carrier of Figure 1 provided with a tool device for pulling in a pipe to a template (or Xmas tree).

A tool carrier according to the invention comprises a frame-like stand portion with legs connected thereto. The stand portion supports an operating unit and a power supply unit. Guide wire funnels are detachably connected to the stand portion or, alternatively, to the legs. Manipulator arms may be connected to the legs. The stand portion may include means for connection of tool packages and multiconnectors for signal and power transmission to the tools.

The legs are adapted such that tools and an extra supporting leg can be attached thereto.

Using the tool carrier with a range of different tool packages, enables a variety of different work operations to be carried out, for example mounting and dismantling of horizontally and vertically arranged valves, mounting and dismantling of control units, inspection, pressure testing, machining, interconnection of pipes, cutting of pipes, pulling-in of pipes or umbilicals, removal of cement around pipes and certain handling of different parts, for example for an Xmas tree. The tool carrier is adapted and dimensioned such that, together with the different tools, it is capable of lifting and handling units within a large weight range.

On the associated surface ship or platform, the tool carrier is provided with a tool package suitable for the intended task. Then the tool carrier with the tool is sent down to the bottom installation. With control equipment on the surface ship or the platform, the work operation at depth can be controlled and monitored with the umbilical connected to the tool carrier. After completion of the work, the tool carrier with its umbilical is returned to the surface ship or the platform.

Figure 1 shows a basic embodiment of a tool carrier according to the invention. The basic embodiment comprises a generally horizontally-extending frame-like stand portion 1 to which two parallel, generally vertically-extending legs 2 are connected. The distance between the legs 2 may be varied for adapting the tool carrier to different bottom-based installations. The legs 2 of the tool carrier are provided with outwardly directed open guides 3 for guide wires 4 extending between the bottom-based installation and a surface-based platform or corresponding surface ship. The guide wire system also includes a docking tube 5 at the lower part of each leg 2. The lower part of each docking tube 5 is formed as a funnel to simplify the positioning of the tool carrier agai nst -cor respond i ng , bottom-based guide posts.

With the aid of a lifting wire 6a, centrally connected to the stand portion 1 of the tool carrier, the entire device may be lowered down from the surface installation to the bottom-based installation and raised back up to the surface installation again.

The basic embodiment also comprises a plate 8 anchored to the stand portion 1 by means of screws 7 and serving as a base for different tool packages. By means of the screws 7 the plate 8 can be moved in parallel relative to the stand portion 1.

The basic design further comprises, connected to the stand portion 1, an operating unit 9, a power supply unit 10 and a hydraulic unit 11, all these units being adapted together with the different tools, to control current work operations and processes. An umbilical 6b is connected to the operating unit 9 for the transmission of control signals between the surface installation and the tool carrier.

The basic design of the tool carrier also includes devices for monitoring work operations, positioning, and so on, in the form of TV cameras, position transducers of various kinds, lighting, and so on. These auxiliary devices can be placed at a variety of different locations on the tool carrier and are therefore not shown in Figure 1. The umbilical 6b can be utilized for the powering and control of such devices.

The need to carry out a number of different work operations on a bottom-based oil and gas extraction installation is very great. Some of these needs are mentioned above. These operations require a variety of different specially-designed tools which are to be placed on and operated from the tool carrier. In addition, there is a requirement and a need to be able to apply the tool in the correct position in relation to that part of the bottombased installation which is to be attended to. Although certain standardisation efforts have been made, aimed at designing the bottom-based installations with respect to Xmas trees, the laying of pipes, guide posts, etc., as identical as possible, there are, however, a plurality of different designs.

To be able to serve different bottom-based installations with their respective different parts, a tool carrier of a highly flexible design is required. It should therefore also be built up in a modular manner from replaceable parts starting from a basic design.

Prior to a work operation on the seabed, the actual tool carrier is first prepared on the surface-based ship or the platform. The final composition of the tool carrier is determined by the exact location on the seabed of the work operation and by what tools are to be used. Then the relevant tool package is connected, and operating and control lines are connected to the tool package.

The tool carrier with tool package is now prepared to be lowered down to the seabed.

The modularization according to the invention substantially comprises, according to Figure 1, the frame-like stand portion 1, the legs 2, the tool holder plate 8, units placed on the stand for operation 9, power supply 10, and hydraulics 11.

The modularization serves three purposes. First, it is to make it possible to adapt the tool carrier to different bottom-based installations; second, it is to make it possible to reach different parts of a bottom-based installation; and third, it is to make it possible to attach a plurality of different work tools to the tool carrier.

The modularization of the stand portion 1 requires a plurality of different stand lengths, and allowing the legs 2 to have different distances from each other by being adjustably attached to the stand portion 1. The modularization also requires different possibilities of positioning on the stand portion 1 different optional designs of operating units 9, power supply units 13 and hydraulics units 11. The lifting wire 6a and the umbilical power and control line 6b may consist of different parts or an integrated lifting and control function in a common wire (umbilical), and the stand portion 1 is therefore adapted for attachment thereto not only of a pure lifting wire and a pure control line, but also of a combined lifting and control wire.

The plate 8 with its adjusting screws 7, shown in the basic design of Figure 1, can be replaced by other holders and/or lifting devices which may be hydraulically operable.

The units for operation and power supply with hydraulic pressure/flow, positioned on the stand portion 1, can be designed and used differently depending on the need for manoeuvrability, electric power and hydraulic pressure/flow, and the like, for different tools and work operations.

The bottom-based installation is likely to include devices having widely varying heights above the seabed. To be able to carry out work operations at any of these heights, it is therefore necessary to be able to mount the tools on the tool carrier within a relatively large height range. Therefore, as far as the legs 2 are concerned, the modularization concept means that legs of a number of different lengths should be available.

Figure 2 shows a tool carrier unit provided with a tool package 12 for replacement of an insert unit for a valve. The plate 8 and its screws 7 shown in Figure 1 are here replaced by a tool holder 13 which is guided by carriages 14 running on the legs 2 and can be operated in the vertical direction by meansof screws 15 (only one of which is shown).

Figure 3 shows a tool carrier provided with a tool package for pulling-in a pipe or a cable towards, and attaching it to, a template with Xmas trees. The pullingin is carried out by means of a hauling rope 16 and a winch system 17. This work often requires the generation of very large tension in the rope and the tool package must therefore be anchored in a reliable manner to the bottom structure so as to be able to absorb the lateral forces that may arise. To this end a heavy frame 18 is provided. The docking funnels 5 are here disposed on the upper part of guide posts 19. The lower part of each guide post 19 is locked against the legs 2 of the tool carrier with the aid of gripping arms 20. To protect the parts included, the winch arrangement 17, spotlights 21 and other vulnerable parts are surrounded by arched bumper guards 22.

When there is a need for greater freedom of movement of the tool carrier than what is permitted by bottom-based guide posts, the tool carrier can be released from the guide wires and be provided with a thruster unit for steered movement over the seabed. The tool carrier can also be supplemented with an extra leg of telescopic design to be able to land on the seabed, for example over a pipeline without any prepared landing place.

Claims (10)

1. A modularized tool carrier for diverless underwater work, which comprises a generally horizontallyextending stand portion, two spaced-apart parallel, generally vertically-extending, horizontally adjustable legs, depending from the stand portion, guides to engage guide wires extending between an upper installation and a bottombased installation, replaceable docking means for connection to bottom-based guide posts, the stand portion supporting connection means for a lifting wire/umbilical line, an operating unit, a power supply unit, and a hydraulic unit, and the carrier including at least one operating tool located below the stand portion and between the legs.

2. A tool carrier according to claim 1, in which the docking means are funnels which can be placed at different locations on the tool carrier.

3. A tool carrier according to claim 1 or claim 2, in which the connection means for the lifting wire/umbilical line is arranged as a replaceable connection for different designs of wires and/or lines.

4. A tool carrier according to any preceding claim, in which a plate is secured adjustably to the stand portion to support tool-holding devices or lifting elements.

5. A tool carrier according to any preceding claim, in which the operating unit is adapted to be replaced by at least one different operating unit to adapt the tool carrier for different operating tools.

6. A 1tool carrier according to any preceding claim, in which the power supply unit is adapted to be replaced by at least one different power supply unit necessary for powering different operating tools.

7. A tool carrier according to any preceding claim, in which the hydraulic unit is adapted to be replaced by at least one different hydraulic unit necessary for powering different operating tools.

8. A tool carrier according to any preceding claim, in which a range of different length legs are provided for connection to the stand portion.

9. A modularized tool carrier substantially as herein described with reference to Figure 1 of the accompanying drawings.

10. A modularized tool carrier substantially as herein described with reference to Figure 2 or Figure 3 of the accompanying drawings.