PLATFORM AUTOMATION Remote control checklist for new or converted unmanned platforms

Phil Heathcote
Siemens Industrial & Building Systems

The move towards unmanned platforms is rapidly increasing as offshore operators recognize the important benefits offered in terms of cost savings, efficiency and above all safety. As the number of unmanned platforms increases, so too does the demand for remotely operated control systems.

Control systems are now available in two forms, designed to offer local and remote control. Before deciding on the most suitable system, a number of important issues should be considered, such as the budget available, and whether the installation is purpose-built for unmanned operation or a conversion of an existing manned platform.

Remote monitoring systems are most appropriate for platform conversions. Designed as a real alternative to 'swapping out' the existing solid state control system, a front end PLC is simply added and connected to the existing control room panels, thereby minimizing down time and cost. This allows the control room functions, normally carried out on site, to be transferred to another platform for remote monitoring.

An installation of this kind recently completed by Siemens was at Phillips Petroleum's West Ekofisk platform in Norway which was converted from a manned to an unmanned platform. The reduction in operating costs achieved through the adoption of remote control technology meant that the working life of the platform was significantly extended.

Conversely for full remote control, a fully equipped instrumentation system including telecommunications interface function is required - this standard telecoms interface is based on radio links or fibre optic cables without restricting system operation. This system requires a local VDU based operator station and control unit for process/utility control, MCC/ switchboard, emergency shutdown, fire and gas.

An installation recently completed for Phillips Petroleum's Embla platform was a purpose-built unmanned remote controlled wellhead platform (15 well slots). The control system developed was an extremely compact solution, with all necessary functions, including process control, ESD, HVAC, fire and gas, integrated into four controllers.

Dual challenge

The implementation of both types of system have brought their own set of challenges for remote control system developers and operators. Typically, suppliers have been faced with two major concerns from offshore oil companies - interfacing and reliability.

Successful interfacing is the key to the successful remote control of unmanned platforms. Systems based on an open architecture and which adhere to international standards are key requirements which should be demanded by offshore operators. Without either of these, they can expect problems later on.

Reliability was originally a major concern, but as more and more remote control installations enjoy long-term trouble-free service, this concern has quietly faded. Systems developed by Siemens carry integral self-diagnostics to detect and locate faults quickly and easily through a UNIX or Windows based operator station without the need for complicated engineering tools. As a result, several installations have enjoyed up to 10 years of fault-free service.

As remote control system suppliers push to grow their business on the back of an increase in the popularity of unmanned platforms, the issue of the benefits provided by single sourcing the complete system package from one supplier has come to the fore. Opposing views see this as either `placing all your eggs in one basket' or as a major way of saving costs and increasing reliability.

The single sourcing ethos is now commonplace in many other process and production industries. The benefits of choosing one supplier to be ultimately accountable to the customer has proved extremely successful.

Using one supplier can reduce interface problems - one company responsible for the total control package ensures the compatibility of all systems supplied. In addition, in maintenance terms, consistency in the technology deployed means servicing is more cost effective and straightforward.

It also offers a notable reduction in the number and variety of spare parts and therefore the storage space required. For example, a particular CPU may be common to several parts of the system - this means that one spare unit for every one installed may not be entirely necessary.

Having examined the current status of remote control technology for unmanned platforms, what are the trends for the future? Satellite installations are growing in popularity - several smaller, unmanned platforms are controlled and monitored remotely from a central, larger platform. Whilst the larger platform may be manned, the smaller versions benefit from significant staff cost savings.

Another recent development is unmanned floating production, storage and offloading systems (FPSO). These systems are designed as an alternative to fixed leg platforms and in response to the discovery of oil in deeper water conditions, such as around the Shetland Islands in the UK, where water depth typically reaches 400-600 metres.

The Petrojarl IV vessel used for Foinaven phase I - part ship, part crude oil and gas processing plant, part storage unit - was fitted with a complete integrated control and safety system from Siemens. At the heart of the vessel is a large moving turret around which the vessel weathervanes.

One of the challenges was to provide full process control of this turret without hard wiring. Instead, radio communications links were employed ensuring the vessel's operation as a fully remote controlled installation when it goes into service next year.