GB2284839A - A control system - Google Patents

Abstract

A control system (1) controls an array of control devices, e.g. the valves of a subsea manifold. The control system (1) comprises a guide member (2) mounted on the manifold 3 which extends along and adjacent to the array of control devices. A control device actuator (7) is mounted on the guide member (2) and an indexing mechanism (15, 16) is coupled between the guide means (2) and the control device actuator (7). The indexing mechanism (15, 16) indexes the control device actuator (7) to predetermined positions on the guide member (2) in which the control device actuator (7) may be engaged with a control device in the array to actuate the control device. <IMAGE>

Description

"A Control Mechanism" The invention relates to a control mechanism.

Subsea manifolds are installed on the seabed and control the flow of produced fluid, such as liquids and/or gases, from a number of wells which are fed to the subsea manifold by pipelines.

Such manifolds have a number of valves to control the fluid produced from each well through the manifold and to control the ultimate destination of the produced fluid from the manifold. Hence, most subsea manifolds have a large number of valves which may typically number twenty or more. It may be necessary to operate these valves in order to close or open the flow of fluid either from a particular well or to a particular destination.

In order to control each valve on a subsea manifold it is provided with an individual actuator which is operated hydraulically from a remote control panel.

However, if there are a large number of valves on the subsea manifold, providing each valve with its own individual actuator increases both the cost and weight of the subsea manifold as well as increasing the complexity of the hydraulics necessary in order to control each valve actuator individually.

In accordance with the present invention, a control system for controlling an array of control devices comprises a guide means which extends along and adjacent to the array, a control device actuator mounted on the guide means and indexing means coupled between the guide means and the control device actuator, the indexing means indexing the control device actuator to predetermined positions on the guide means in which the control device actuator may be engaged with a control device in the array to actuate the control device.

Preferably, the indexing means comprises location means which engages with indexing formations on the guide means and typically, the indexing formations define the predetermined positions.

Typically, two location means may be provided which are movable relative to each other on the guide means.

Preferably, the control device actuator is mounted on one of the location means.

Preferably, the control device actuator is moved along the guide means by alternate movement of each of the location means along the guide means and preferably, the location means are coupled to each other, for example by a piston arrangement.

Typically, the control device actuator is movably mounted on the indexing means to permit the control device actuator to be moved relative to the guide means to engage and disengage a control device.

Preferably, the control system is operated by fluids under pressure and is typically hydraulically operated.

Preferably, the array of control devices is a linear array.

The invention is particularly advantageous where the array of control devices is located in an environment which makes human intervention to actuate the control device difficult or impossible. Examples of such an environment may be a hazardous environment which may have extremes of temperature or contain poisonous chemicals, or an underwater location. Alternatively, the array of control devices may be located in an area where human access is difficult.

In the preferred form of the invention, the array of control devices is located on a support member and the control system may be mounted on the support member.

Typically, the support member may be a framework, such as a metal framework.

Preferably, the control system is removably attached to the support member to permit recovery of the control system, if necessary.

Typically, the control devices may be valves and in an example of the invention, the control devices may be located on a manifold, such as a subsea manifold.

An example of a control system in accordance with the invention will now be described with reference to the accompanying drawings, in which: Fig. 1 is a plan view of a control system for a subsea manifold; Fig. 2 is an elevation view of the control system shown in Fig. 1; Fig. 3 is a detailed partial cross-sectional view of an indexing means shown in Fig. 1; and Fig. 4 is a partial cross-sectional view along the line BB of Fig. 2.

Fig. 1 shows a control system 1 for mounting on a subsea manifold 3 to operate a linear array of valves (not shown) mounted on the subsea manifold 3. The control system 1 comprises a guide rail 2 which is mounted on the subsea manifold 3 by releasable pins 4 at each end of the guide rail 2. Located above the guide rail 2 is a hose track 5 which is hollow and within which a hose reel 6 is located. Mounted on the guide rail 2 is a valve actuator unit 7 which is coupled to the hose reel 6 by a rotating coupling 8.

Mounted at the other end of the guide rail 2 is a valve actuator back-up unit 9 which is also coupled to a hose reel (not shown). The valve actuator back-up unit 9 is essentially the same as the valve actuator control unit 7 and will generally only be used in the event of failure of the valve actuator unit 7.

The valve actuator unit 7 comprises a torque tool 10 which is mounted on a slide 20 which can move along a projecting arm 21 which is mounted on a slide 11 on the guide rail 2. The slide 11 is coupled to another slide 12 on the guide rail 2 by means of a hydraulic piston assembly which comprises a piston housing 13 coupled to the slide 12 and a piston rod 14 coupled to the slide 11.

Each of the slides 11, 12 include a locating device 15, 16 respectively. The locating devices 15, 16 are shown in more detail in Fig. 3. The locating devices 15, 16 each comprise a housing 17 within which a hydraulically actuable piston 18 is located. As shown in Fig. 3, the pistons 18 can be actuated to protrude into or removed from indexing apertures 19 in the guide rail 2 (see also Fig. 2).

As shown in Figs. 2 and 4, the torque tool 10 is mounted on the slide 20 and may be moved along the projecting arm 21 by a hydraulic piston 22 mounted on the arm 21. The operating arm of the piston 23 is fixed to the slide 20.

In use, the control system 1 is fixed to the subsea manifold 3 by means of the releasable pins 4. The positions of the location apertures 19 are chosen so that when the location unit 15 is located in indexing apertures 19, extension of the slide 20 along the projecting arm 21 will cause the torque tool 10 to engage with a valve (not shown) on the subsea manifold 3.

In order to move the valve actuator unit 7 along the guide rail 2, the piston 18 in the location unit 16 is extended into an indexing aperture 19a and the piston rod 14 is extended in the direction of arrow 30 to move the location unit 15 along the guide rail 2 to the position shown in Fig. 3. When the slide 11 is at the ((3)) position shown in Fig. 3, the piston 18 in the location unit 15 is extended into aperture 19c and the piston 18 of location unit 16 is retracted, as shown in Fig. 3.

The piston rod 14 is then retracted into the piston housing 13 and as the location unit 15 is fixed with respect to the guide rail 2, this moves the location unit 16 to the position of indexing aperture l9b, as shown in phantom in Fig. 3; The process can then be repeated to move the valve actuator unit 7 along the guide rail 2 to the desired location. As the position of each indexing aperture 19 corresponds to the position of a valve on the subsea manifold 3, it is possible to accurately move the location unit 7 along the guide rail 2 in order to operate the correct valve by counting the number of moves which the valve actuator unit makes from the left hand end of the guide rail 2.

As the slide 12 moves along the guide rail 2 the hose reel 6 also moves in the direction of the arrow 30 and the hose carrying the hydraulic fluid unwinds from the reel 6, this is facilitated by means of the swivel connector 8 which permits rotation of the hose reel 6 in response to a linear movement of slide 12. The hydraulic hose is coupled to the piston 13, the torque tool 10, the location units 15, 16 and the piston 22 in order to operate the appropriate movements of the control system 1.

The back-up valve actuator unit 9 is identical to the valve actuator unit 7 except that the valve actuator unit 9 is the mirror image of the valve actuator unit 7. The valve actuator back-up unit 9 operates in a similar manner to the valve actuator unit 7, descirbed above.

When the slide 11 is located at the correct indexing aperture 19, the piston 22 is activated to extend the the piston rod 23 and move the torque tool 10 into engagement with the valve to be actuated. Once the torque tool 10 has engaged with the valve to be actuated, rotation of the engagement tip 31 in either a clockwise or anti-clockwise direction operates the valve.

For servicing purposes, or in the event that the control system 1 develops a fault, the control system 1 may be removed from the subsea manifold 3 by removing the locating pins 4 and recovering the control system 1 to the surface for servicing or adjustment as necessary.

Modifications and improvements may be incorporated without departing from the scope of the invention.

Claims (15)

1. Control system for controlling an array of control devices comprises a guide means which extends along and adjacent to the array, a control device actuator mounted on the guide means and indexing means coupled between the guide means and the control device actuator, the indexing means indexing the control device actuator to predetermined positions on the guide means in which the control device actuator may be engaged with a control device in the array to actuate the control device.

2. A control system according to Claim 1, wherein the indexing means comprises location means which engages with indexing formations on the guide means.

3. A control system according to Claim 2, wherein the indexing formations define the predetermined positions.

4. A control system according to Claim 2 or Claim 3, wherein two location means are provided, the location means being movable relative to each other on the guide means.

5. A control system according to Claim 4, wherein the control device actuator is moved along the guide means by alternate movement of each of the location means along the guide means.

6. A control system according to Claim 5, wherein the location means are coupled to each other.

7. A control system according to Claim 6, wherein the location means are coupled to each other by a piston arrangement.

8. A control system according to any of Claims 2 to 7, wherein the control device actuator is mounted on the indexing means.

9. A control system according to any of the preceding claims, wherein the control device actuator is movably mounted on the indexing means to permit the control device actuator to be moved relative to the guide means to engage and disengage a control device.

10. A control system according to any of the preceding claims, wherein the control system is fluid operated.

11. A control system according to any of the preceding claims, wherein the array of control devices is located on a support member and the control system is mounted on the support member.

12. A control system according to Claim 11, wherein the control system is removably attached to the support member.

13. A control system according to any of the preceding claims, wherein the control devices are located in a hazardous environment.

14. A control system according to Claim 13, wherein the hazardous environment is an underwater environment.

15. A control system substantially as hereinbefore described with reference to the accompanying drawings.