PLC Based Offshore Platform Monitoring & Control System

The Application

eP has provided a complete turnkey control system for two offshore platforms. The contract was awarded to eP from ABB Lummus Crest. These platforms will assist Chevron in the production of offshore oil fields in Angola.

eP provided controls from the wellhead out to the host computers as a turnkey project. Each platform control system consisted of an eP 16-well wellhead control panel, a well test panel, field interface panels, a safety system hot backup PLC, a process system hot backup PLC, and hot backup host computers running BJ Software's RealFlex software.

The System

Project Management/Engineering

eP provided project management and engineering, programming, configuration, packaging, factory acceptance testing, system documentation, training and installation assistance for a complete solution.

Pneumatic/Hydraulic Wellhead Control Panels

The customer chose the eP stainless steel 16-well modular design for maximum flexibility for future upgrades. The modular design allows for the purchase of 12 well control modules now, with room for expansion at a future date when new wells are drilled, completed and put on-line. This lowers up-front capital costs at project inception, and allows system expansion for future field developments.

Field Interface Panels

A total of 19 field interface panels were provided for the project. These panels perform a variety of functions including local control of skid mounted equipment, manual process bypass control, process indicator lights and marshalling racks. These interface panels include pneumatic and electronic controls.

Hot Backup Allen Bradley PLC Systems

eP mounted and wired the hot backup PLCs, light box annunciators and power supplies in free standing, painted NEMA 4 enclosures. The PLC relay ladder logic programming was done in-house by eP engineers for safety emergency shutdown control and process platform control. In addition, a Micromotion Net Oil Computer communication driver was written to provide automatic well testing capability.

PLC Networking

The safety PLCs, process PLCs, and solar turbine gen-set PLCs are networked for linking to BJ Software's RealFlex real-time, multi-tasking, multi-user SCADA software package which provides total platform monitoring and control.

Hot Backup RealFlex Computer System

ABB Lummus Crest and Chevron jointly chose RealFlex because of its reliability, flexibility, speed, and ease of use and expansion. The system design is based on placing a hot backup RealFlex host system on each platform. The main platform also has three additional operator workstations connected by a LAN. The RealFlex system runs on PCs which offer low hardware costs and accessible spare parts availability around the world. The key to RealFlex performance is the QNX operating system. QNX turns the PC hardware into a real-time, interrupt driven, SCADA host which outperforms any other system in its class.

The RealFlex DDE interface to DOS on one of the workstations, provides a DOS interface which allows production reporting in DOS based spreadsheet formats. Platform communications will be performed by RealFlex's BJScan report by exception communications protocol. This protocol provides a high degree of communication flexibility and efficiency.