GB2421524A

GB2421524A - Subsea well control system with electrical or optical signals actuating remote hydraulics

Info

Publication number: GB2421524A
Application number: GB0428001A
Authority: GB
Inventors: Christopher David Baggs
Original assignee: Vetco Gray Controls Ltd
Current assignee: Baker Hughes International Treasury Services Ltd
Priority date: 2004-12-22
Filing date: 2004-12-22
Publication date: 2006-06-28
Anticipated expiration: 2024-12-22
Also published as: GB0428001D0; BRPI0506085A; BRPI0506085A8; GB2456442A; US7650943B2; NO336511B1; US8096365B2; GB0907246D0; GB2456442B; GB2421524B; US20100078175A1; NO20056045L; US20060157254A1; DE102005058058A1

Abstract

A subsea control module (SCM) 2 is mounted at a tree 1 and has electrical or optical cables 9 which communicate with a control pod 8 at a remote manifold 3. The control pod 8 controls directional control valves 4 at the manifold via hydraulic lines 10. Long hydraulic control lines (figure 1) are avoided or replaced by the electrical or optical signal cables 9 communicating with the control pod 8 to hydraulically actuate control valves 4. In an alternative embodiment (figure 4) the control pod 8 is mounted at the tree or downhole from the tree where it controls downhole valves.

Description

ilydraulic Control System The present invention relates to a hydraulic

control system and a well installation incorporating the control system.

In fluid extraction well installations there is a frequent requirement to control a small number of subsea hydraulic devices, typically valves for example, on a manifold or other structure from a well head tree, located typically I 00m distant from the manifold / structure. The traditional method of implementing this requirement is to install a hydraulic jumper between the tree and the manifold I structure hydraulic devices and use a tree subsea control module' (SCM) to control these devices.

Fig. I illustrates a traditional arrangement for control of hydraulic devices, in this example valves on a remote manifold. A tree 1 houses an SCM 2, which is connected to the manifold 3. Each valve 4 on the manifold 3 is led via a hydraulic control line 5 such that a directional control valve (DCV) in the SCM 2 controls the operation of one valve 4. Each tree around the manifold would be connected similarly to a respective set of three valves. I-listorically, hose-type jumpers 5 have been employed to link the hydraulic control from the SCM to the manifold valves. However, with the current trend for subsea wells to be at greater depths, fluid well installation companies are specifying steel tube jumpers, which are extremely expensive, both to buy and to install.

The requirement to operate hydraulic devices remote from the well head means that additional DCVs have to be integrated into the SCM. In general, SCMs are designed and manufactured as common' in that they contain sufficient DCVs to meet the requirement of a typical well. However, when further remote devices have to he operated, the common' SCM has to be modified which incurs substantial design costs. If, on the other hand, the common' SCM is designed to accommodate additional remote devices, then in many straightforward' applications the surplus capacity makes the SCM more expensive.

Intelligent downhole systems are becoming more common and generally require three hydraulic functions, operating at high pressure (typically 10 k tolS k psi), inside the SCM.

Not all wells need an intelligent completion. It is usual to have a common' design of SCM, so in many cases these three functions are unused. Typically, an intelligent well system will also need an additional high pressure (HP) accumulator to ensure that operating the intelligent well does not adversely affect the surface controlled sub-surface safety valve' (SCSSV) which is also on the HP supply and vice versa.

Fig. 2 illustrates a traditional arrangement for the control of downhole hydraulic devices, in this example valves 6. The tree I carries an SCM 2, which is connected to the downhole valves 6 via hydraulic feeds 7.

It should be noted that such systems are not the only systems available, for example British Patent Application No. GB 0319622.7 describes a decentraljsed control system which does not use an SCM. Likewise the system as described in British Patent No. GB 2264737 describes a further system in which the SCM is replaced by a multiplicity of integrated electronic and hydraulic functions in modules, such as smaller and dedicated electronic units and hydraulic units. In contrast to these two described systems, while this invention also employs modules that contain electrically operated hydraulic functions and perhaps electronic functions in some embodiments, in the present invention they are under the control of an SCM.

It is an aim of the present invention to obviate the need for steel tube jumpers and to allow standard minimum SCMs to be employed when there is a requirement to operate additional remote hydraulic devices.

This aim is achieved by the removal of the hydraulic controls for remote hydraulic devices, e.g. DCVs, from the tree mounted SCM and housing them instead in a separate pod' which is then located external to the SCM and in some applications close to the remote devices.

In accordance with a first aspect of the present invention, there is provided a hydraulic control system for controlling an external device at a well installation, comprising a control module for generating electrical and / or optical control signals, a control pod for receiving said control signals, the control pod comprising control means for controlling the external device, and a hydraulic line for linking the control means to said external device for the control thereof.

The control signals may be transmitted from the module to the pod via an electrically conductive coupling, e.g. via a serial data link, or via optical fibre.

A plurality of control means may be provided, linked to respective external devices by respective hydraulic lines.

The or each control means may be a valve, for example a directional control valve.

Preferably, the control pod is adapted to receive hydraulic fluid from a supply.

According to a second aspect of the present invention, there is provided a well installation for location underwater, comprising a well tree, a well, an external device and the hydraulic control means according to the first aspect of the present invention, wherein the control module is located at the tree.

The control pod may be located at a structure remote from the tree, for example a manifold.

The external device may also be located at the structure. The pod may further receive low pressure hydraulic fluid from a supply located at the structure.

Alternatively, the control pod may be located at the tree. The pod may receive hydraulic fluid from a high pressure supply via the control module.

As a third alternative, the control pod may be mounted at or within the well.

The external device may be located within the well.

The external device may be a valve.

Fig. 3 illustrates a first embodiment of the invention relating to the control of valves on a remote manifold I structure. In this embodiment, replacement of the hydraulic control lines from the tree with an electric or a fibre optic cable is achieved so that the need to modify or expand a minimal common' SCM is removed. An SCM 2 is housed on tree I and is connected either electrically or optically via a cable 9 to a pod 8, which is mounted on the remote manifold / structure 3. Each valve 4 on the manifold / structure 3 is fed via a hydraulic control line 10 from the pod 8. Electrical or optical signals from the SCM 2 operate DCVs in the pod 8 which in turn control the hydraulic power from a local source, designated LP (low pressure) supply' in Fig. 3, to each valve 4 via hydraulic feeds 10 internal to the manifold / structure 3. Thus the cost of steel hydraulic tubing from the SCM to the manifold / structure is obviated as is the need to add additional DCVs to the SCM.

Fig. 4 illustrates a second embodiment of the invention relating to the control of downhole valves. In this embodiment, a pod can be located on the tree but external to the SCM thus avoiding the need to modify or expand a minimal standard SCM. An SCM 2 is housed on tree I and is connected either electrically or optically via cable 9 to the pod 8. In this embodiment, the pod 8 is also mounted on the tree 1. The pod 8 feeds downhole valves 4 via respective hydraulic control lines 7. Electrical or optical signals from the SCM 2 operate DCVs in the pod 8, which in turn control the hydraulic power from the SCM, designated HP (high pressure) supply' in Fig. 4, to each valve 4, via the hydraulic control lines 7. Thus the need to add additional DCVs to the SCM is obviated.

As an alternative form of this embodiment, a pod may be located downhole and the hydraulic feeds, which could be several kilonietres long, replaced by a much cheaper electric or fibre optic cable, similar to the arrangement used in the first embodiment of Fig. 3.

In all these embodiments, the pod contains, as a minimum, electrically operated DCVs to provide hydraulic operation of the hydraulic devices at the location, powered from a local hydraulic source. When more than one device is to be operated it may be cost effective to replace the individual wires that provide electric control of each DCV with a serial data link, transmitting on its own separate pair of wires, or superimposed on the electric power, with decoding electronics incorporated in the pod. Alternatively the digital message could be transmjfted to the pod via an optical fibre with a single pair of wires to provide electric power.

It will be apparent that the described systems provide the following advantages over the prior art systems: 1) Removal of both the need for long expensive steel hydraulic tubing, when used between a tree and a remote manifold / structure and the cost of installation which is expensive because of the need for special remotely operated vehicle (ROV) tools and facilities to install it.

2) Removal of the need to modify a common' SCM when used to control hydraulic devices remote from the tree. Normally the pod would only be fitted to trees that need it.

Although the consequence of this is that all trees would still need a mounting plate for it to be plugged into, these are relatively cheap.

3) Enables replacement of the remote hydraulic device control i.e. a pod (e.g. by an Roy), without disrupting the operation of the SCM.

4) Provides the opportunity, when applied to intelligent wells, of having just one pod and deploying it when needed and then recovering it afterwards, since an intelligent well operation is often only needed only a few times in the system's approximate 25 year life.

5) For control of downhole hydraulic devices, the pod offers the opportunity to mount a small additional hydraulic accumulator inside the pod, although this may well have to sit on an auxiliary stab plate. Such an application may provide isolation of the SCM hydraulic fluid from the downhole hydraulic control system which, in terms of prevention of fluid contamination of the SCM hydraulics from the downhole hydraulics, is attractive to well installers.

Claims

Claims 1. A hydraulic control system for controlling an external device at

a well installation, comprising a control module for generating electrical and / or optical control signals, a control pod for receiving said control signals, the control pod comprising control means for controlling the external device, and a hydraulic line for linking the control means to said external device for the control thereof.
2. A control system according to Claim 1, wherein the control signals are transmitted from the module to the pod via an electrically conductive coupling.
3. A control system according to Claim 2, wherein the control signals are transmitted from the module to the pod via a serial data link.

1 5
4. A control system according to Claim I, wherein the control signals are transmitted from the module to the pod via optical fibre.
5. A control system according to any preceding claim, wherein a plurality of control means are provided, linked to respective external devices by respective hydraulic lines.
6. A control system according to any preceding claim, wherein the or each control means is a valve.
7. A control system according to Claim 6, wherein the or each control means is a directional control valve.
8. A control system according to any preceding claim, wherein the control pod is adapted to receive hydraulic fluid from a supply.
9. A well installation for location underwater, comprising a well tree, a well, an external device and the hydraulic control means according to any preceding claim, wherein the control module is located at the tree. 4 I 7..
10. An installation according to Claim 9, wherein the control pod is located at a structure remote from the tree.
II. An installation according to Claim 10, wherein the structure is a manifold.
12. An installation according to either of Claims 10 and 11, wherein the external device is located at the structure.
13. An installation according to any of claims 10 to 12, wherein the pod receives low pressure hydraulic fluid from a supply located at the structure.
14. An installation according to Claim 9, wherein the control pod is located at the tree.
15. An installation according to Claim 14, wherein the pod receives hydraulic fluid from a high pressure supply via the control module.
16. An installation according to Claim 9, wherein the control pod is mounted at or within the well.
17. An installation according to either of claims 15 and 16, wherein the external device is located within the well.
18. An installation according to any of claims 9 to 17, wherein the external device is a valve.
19. A control system as herein described with reference to Figs. 3 or 4 of the accompanying drawings.
20. A well installation as herein described with reference to Figs. 3 or 4 of the accompanying drawings.