GB2459488A

GB2459488A - Wired communication with acoustic communication backup

Info

Publication number: GB2459488A
Application number: GB0807467A
Authority: GB
Inventors: Theresa Joyce Rebours
Original assignee: Vetco Gray Controls Ltd
Current assignee: Baker Hughes International Treasury Services Ltd
Priority date: 2008-04-24
Filing date: 2008-04-24
Publication date: 2009-10-28
Also published as: GB0807467D0

Abstract

A method of enabling data transmission between an underwater well installation and a remote location separated by a body of water, comprises the steps of:during a first, normal mode of operation, transmitting a first set of data from the installation via an umbilical cable, andin the event of a malfunction such that transmission via the umbilical cable fails, switching to a second mode of operation comprising transmitting a second set of data from the installation as acoustic signals.

Description

Communication system and method for an underwater well installation This invention relates to method of enabling data transmission between an underwater well installation and a remote location separated by a body of water, a communication system for an underwater well installation, an underwater well installation and a hydrocarbon production facility. Such well installations may comprise subsea hydrocarbon production wells for example.

In hydrocarbon production facilities, subsea hydrocarbon production installations, which may comprise a one or a plurality of individual wells, are typically maintained in communication with a remote location, separated therefrom by a body water, for example a sea-surface platform, or a shore-based plant. Such communication is effected by means of one or several umbilical cables connected between the surface and the installation, the umbilical carrying conductive and/or fibre-optic cables. These enable monitoring data concerned with the status and performance of devices at the installation to be sent from the installation to the surface, and also enable control signals to be sent from the surface to the installation. In practice. these umbilical cables may be very long, for example several kilometres, and subject to stresses caused by sea currents and heave. In addition, severe weather conditions may sometimes cause movement or even destruction of surface fluid extraction platforms. Both of these can result in damage or breakage of the umbilical cables, Normally, if such damage occurs, the loss of control signals causes automatic shut down of the subsea wells, to prevent pollution in the possible situation that the fluid extraction flowline is also damaged. This may be effected using a Hydraulic Pipe Protection System (HIPPS), which is a primary shutdown system that not only prevents overpressure and thus damage to the production fluid extraction pipeline, but also prevents pollution from the continued flow of extracted fluid if it is severed or fractured. However, breakage of the monitoring signal links through the umbilical cable means that the well operator is unable to ascertain the status of devices on the well, which include valves forming part of the HIPPS. This means that the operator is unable to ascertain whether shutdown has been successful, or whether the installation has been damaged. Generally, it has been necessary to use a Remotely Operated Vehicle (ROV) to inspect the situation externally. Furthermore, the loss of the communication link also prevents such valves being actuated by the operator, which could be vital in an emergency.

It is an aim of the present invention to provide a system for enabling the status of all such valves to be monitored in the event of failure of the umbilical. It is an additional aim of the invention to provide a system for enabling these valves to be controlled in the event of such a failure. This includes for example the valves operated by a Subsea Electronic Module (SEM) typically mounted on the well tree such as process control valves which also act as HIPPS valves. Other valves that may need to be monitored include those mounted on manifolds often remote from the well tree and typically controlled by a manifold mounted SEM, and external valves which are occasionally part of the fluid production flowline.

The present invention achieves these aims by providing an additional communication link between the installation and the surface, which link is enacted using the transmission of acoustic signals through the body of water between the installation and surface.

A communication system for subsea wells using acoustic signalling is known from US 2002/0154572. In this system, acoustic signalling is the only communication means provided, there is no umbilical link. Such a system is impractical since the bandwidth available using available acoustic transmitters is considered too small to enable full operation of the installation.

In accordance with a first aspect of the present invention, there is provided a method of enabling data transmission between an underwater well installation and a remote location separated by a body of water as set out in the accompanying claims.

In accordance with a second aspect of the present invention there is provided a communication system for an underwater well installation as set out in the accompanying claims.

In accordance with a third aspect of the present invention, there is provided an underwater well installation as set out in the accompanying claims.

In accordance with a fourth aspect of the present invention, there is provided a hydrocarbon production facility as set out in the accompanying claims.

The invention will now be described, by way of example, with reference to the accompanying drawing. in which:-Figure 1 schematically shows a subsea well installation in accordance with an embodiment of the present invention.

It will be appreciated by those skilled in the art that the configuration of a production fluid extraction installation may vary considerably. Such variations may comprise for example a single well tree, which may have a dedicated Subsea Control Module (SCM) incorporating a Subsea Electronics Module (SEM), which includes the electronics to control and monitor a HIPPS system. More complex configurations may for example comprise a multiplicity of wells, each feeding production fluid to a manifold and thus a single production flowline. This manifold may incorporate an SCM and SEM to control all of the well trees. For the purpose of illustration, Fig. 1 shows a configuration comprising a multiplicity of wells feeding a manifold, the manifold housing a single HIPPS system.

Production fluid from individual wells flows to a manifold 4 along flowlines 16, in the present example there are four individual wells, and so four lines 16 are shown. These flowlines are connected to the manifold 4 via respective control valves 5, 6, 7 and 8. At the manifold 4, the fluid from flowlines 16 is combined into a single flow, which exits the manifold through main production fluid flowline 1. The exiting fluid flow is controlled by HIPPS valves 2 and 3 housed in the manifold 4. A Subsea Control Module (SCM) 9 is mounted on the manifold 4 which houses a plurality of directional control valves (not shown for clarity). A Subsea Electronics Module (SEM) 10 is provided on the SCM 9, and is connected to an umbilical cable 11 which leads to a surface control platform (not shown). Each of the valves 2, 3, 5, 6, 7, and 8 have sensors (not shown) on them which indicate the position of the respective valve, e.g. fully open or fully closed. These sensors are connected and output to the SEM 10 via electrical connections 12, in the case of well valves 5, 6, 7 and 8, and connections 13 and 14 respectively in the case of HIPPS valves 2 and 3. The positional data output from the sensors may thus be fed from SEM 10 to the control platform via the umbilical cable 11. The sensors An acoustic modem 15 is mounted on the manifold 4 and connected electrically to the SEM 10. The acoustic modem iSis capable of transmitting data by modulation of an acoustic signal into the water.

Both the sensors and the acoustic modern 15 receive power from a source local to the installation, so that they are not reliant on power being supplied via the umbilical cable 11. In a preferred embodiment, each of the sensors and the acoustic modem includes a battery (not shown), such as a rechargeable NiMH battery.

Using this system, communication may be provided in two diverse ways, as described below.

During normal operation, the valves 2, 3, 5, 6, 7, and 8, which are typically hydraulically operated, are controlled by directional control valves housed in the SCM 9. Valves 5, 6, 7 and 8 are, in turn, operated by electrical signals from the SEM 10, generated from control signals fed by the umbilical 11 from the control platform. Positional data from the respective valves' sensors is fed via the umbilical 11 to the control platform for monitoring by the well operator. Thus, during normal operation, monitoring signals from the installation are transmitted to the surface via the umbilical, and control signals are transmitted from the surface also via the umbilical. The transmitted data typically includes data relating to all the various sources and devices at the installation in order to run the whole installation effectively, and not just the particular valves discussed above.

In the event of failure of the communications system, for example damage or severance of the umbilical such that it cannot be used for data transmission, the operator is unable to monitor the position of the valves. In this case, the communications system is switched to an emergency operation state. This may be effected automatically at the installation, or manually by the well operator.

In this emergency state, safety critical information is transmitted from the installation to the surface using acoustic signalling, by means of the acoustic modem 15. The acoustic signals are received by a complementary acoustic modem at the control platform enabling the operator to assess the risk of pollution if the production flowline is damaged.

Acoustic modems are available commercially with ranges of at least 3 km and data rates of between 100 and 480 bits per second, This range and data rate is more than adequate for most installations, Such acoustic modems are two way devices, and although only one way communication i.e. from the manifold to the platform, is required, the facility of two way communication may be useful to operate further emergency protection devices on the wells.

Under normal operating conditions the bandwidth available from an acoustic link is too small to handle the full monitoring requirements of a modern well, but is adequate to handle the relatively small amount of data needed to monitor safety-critical devices, for example the status of valves 2, 3 and 5-8. In other words, the data transmitted acoustically in the emergency mode is a subset of the data transmitted via the umbilical during normal operation. Typically the well operator needs to know that valves that must be shut are fully closed and have not stuck partly open. As well as the HIPPS valves 2, 3 and process control valves 5-8, other safety critical valves that may need to be monitored may include those mounted on manifolds, which are often remote from the well tree and typically controlled by a manifold mounted SEM, and external valves which are occasionally part of the fluid production flowline. The choice of valves, and any other devices, to be monitored using acoustic signalling will therefore be dependent on the configuration of the particular installation.

As mentioned above, the acoustic modems allow bi-directional acoustic communication, so that in addition to the monitoring of the valves and other safety-critical devices at the installation, the system may also enable control or actuation of such valves and devices by an operator from the surface. This may be useful for safely effecting shutdown in an emergency for example.

It can be seen that the inventive system enables a well operator to know the status of the well control valves and indeed any other subsea devices deemed important, in the event of a serious well malfunction resulting in failure of communication via the umbilical.

Thus the major cost of having to deploy a Remotely Operated Vehicle (ROV) to inspect the installation for damage is avoided. Furthermore, the use of acoustic modems enabling bi-directional communication provides the additional facility of being able to operate other devices, such as additional valves in an emergency.

The above described embodiments are exemplary only, and various alternatives may be envisioned within the scope of the claims.

For example, the sensors and acoustic modem may be powered by a generator located at the subsea installation.

Claims

CLAIMS1. A method of enabling data transmission between an underwater well installation and a remote location separated by a body of water, comprising the steps of: during a first, normal mode of operation, transmitting a first set of data from the installation via an umbilical cable, and in the event of a malfunction such that transmission via the umbilical cable fails, switching to a second mode of operation comprising transmitting a second set of data from the installation as acoustic signals.
2. A method according to claim 1, wherein the first set of data comprises data from a plurality of sources at the well installation, and the second set of data comprises a subset of the first set of data, from selected sources of the plurality of sources.
3. A method according to claim 2, wherein the selected sources comprise devices vital to the functioning of the well.
4. A method according to any preceding claim, wherein the acoustic signals are transmitted via an acoustic modem located at the installation.
5. A method according to claim 4, wherein the acoustic modem is adapted to receive acoustic control signals from the remote location, for controlling the selected devices.
6. A communication system for an underwater well installation comprising first and second means for communicating with a location remote from the installation, through a body of water, the first means comprising a connection for an umbilical cable arranged for carrying information from said installation through said body of water, and the second means comprising an acoustic modem for transmitting acoustic signals to said body of water.
7. An underwater well installation comprising the communication system of claim 6.
8. An underwater well installation according to claim 7, further comprising a plurality of actuators.
9. An installation according to claim 8, wherein the actuators comprise valves.
10. An installation according to claim 9, wherein the valves comprise HIPPS valves.
11. An installation according to any of claims 8 to 10, wherein the acoustic signals comprise data relating to the status of the actuators.
12. An installation according to any of claims 8 to 12, wherein the acoustic modem is arranged to receive acoustic control signals from the body of water which signals effect operation of the actuators.
13. An installation according to any of claims 7 to 12, wherein the acoustic modem is mounted on a well tree.
14. An installation according to any of claims 7 to 13, wherein the acoustic modem is mounted on a manifold.
15. A hydrocarbon production facility comprising an underwater well installation according to any of claims 7 to 14, a location remote from the underwater well installation separated therefrom by a body of water, and an umbilical cable connected between the remote location and the installation, wherein the remote location comprises an acoustic modem for receiving acoustic signals from said body of water.
16. A method of enabling data transmission between an underwater well installation and a remote location separated by a body of water substantially as herein described with reference to the accompanying figure.
17. A communication system for an underwater well installation substantially as herein described with reference to the accompanying figure.
18. An underwater well installation substantially as herein described with reference to the accompanying figure.