The Gladstone Liquefied Natural Gas (GLNG) project is a pioneering venture set to produce natural gas from Queensland’s coal seams and convert it into liquefied natural gas (LNG) for sale to world markets for many years to come. It relies on ongoing gas field development in the Surat and Bowen Basins, a 420-kilometre gas transmission pipeline, and the construction of LNG plants on Curtis Island, near Gladstone. GLNG is one of those plants, setup by Australian company Santos in partnership with other world leading energy companies.
Westside and GLNG have an agreement for Westside to supply gas to GLNG via the Queensland Gas Pipeline (QGP) or the GLNG Gas Transmission Pipeline (GTP).To facilitate this a new gas facility to provide Gas Metering was required to transfer the gas from Westside (the supplier) to QGP (the transmission company). Sometimes called a transfer station, the GLNG facility is a controlled “Gateway” between the two companies. Managed transfer of operational control and monitoring status between the Meridian and Santos facilities is required for safe and measured contract performance.
The conceptual design for the “GLNG” solution included;
• Independent 10 day battery backed powered solution using solar for the facility – no dependency on a mains powered connection.
• Minimum Safety Integrity Level (SIL) of 2
• DNP3 RTU Data Acquisition device to support event logging and minute to minute data back loading of information to the Westside SCADA System and Historian.
• 30 days of synchronised data storage
• Communication to Westside Moura SCADA System using 3G.
• Read only Modbus TCP communications between GLNG and Santos.
• Local display of data and control inputs for managing valve actuation and ESD resets
Westside and GLNG had negotiated a formal go to market contract. This meant to avoid contract default, gas had to be available on the go live specified date. The contract contained penalty clauses and either party would be penalised should the delivery date not be met. It was imperative that Westside (Parasyn’s customer) had their facility commissioned to avoid these penalties.
The project was kept on track using standard project management approach and the end result was the facility was ready on time. The design was chosen using proven and readily available equipment and the use of established system configuration practices. This avoided unnecessary risk associated with a customised site which already had its own unique peculiarities and special requirements.
SCOPE OF DELIVERY
The scope of works for this project included the design, fabrication and supply of two panels, one for the control system and one for the battery backup system. The scope also included supply and installation of the electrical and instrumentation cabling and installation of an earthing system consisting of earth stakes, a 70sqmm bearer and 35sqmm bonding cables. The solar panels were fitted to the roof of the panel structure and all field instrumentation connected to the RTU. The RTU is interfaced to the Westside SCADA System. On site commissioning was also part of the scope including sufficient resources to ensure the deadline was met and all electrical installation work had to meet Hazardous Area (HA) standards and be signed off by an authorised HA certifier.
Our detailed activities were;
• Drawings (GA, Schematics, Cable Schedules and Terminations)
• Design and Conformance to SIL 2 rating
• Material Take off list (materials required for installation)
• Updated Site Definition Matrix (site information and IO List)
• Material Certificates for isolators/barriers as needed for the HA audit dossier
• Quality Test Plans with Test Procedures
• Installation Works including Hazardous Area installation
• Software Development
• Factory Testing
• Site Testing
• Assembly and provision of HA Dossier.
The GLNG facility is required to shut down using strategically located activation points (ESDs). The Emergency Shut Down system conforms to SIL 2. To achieve SIL 2, the ESD circuits including valve shutdown solenoids could not be routed through the RTU. They had to be routed through a certified self-monitored SIL rated hardware relay. This means ESD is available even if the RTU has failed. A signal from the relay is connected to the RTU for monitoring purposes.
The GLNG facility contains instrumentation located in an area that has a risk of flammable gas presence. This required all design and installation to conform to specific HA standards (AS/NZ 60079.14). In addition, the HA installation required certification by an independent body prior to the site being put into operation. To meet requirements establishing and maintaining the site safely Parasyn produced the HA dossier, which is a record of all HA equipment and their HA certifications used on the site.
SCADA SYSTEM INTERFACES
The GLNG Facility has two separate interfaces to SCADA systems. One link is to the Westside main SCADA system and this is achieved over a 3G communications median using the DNP3 protocol. The other is to the SANTOS DeltaV DCS which is via a read only Modbus TCP using an RS485 serial communications link. The DCS interface is a real time poll only system meaning data is polled at regular intervals only. The Westside 3G interface uses DNP3 which allows for data storage ensuring data excursions are not missed and no data is lost if the communication link fails.
BENEFITS TO WESTSIDE
Apart from meeting contractual requirements, Westside (Westside) have benefited from this facility by having access to additional gas composition data made available over the Santos – GLNG communications link. This allows Westside to monitor the quality of the gas they produce not only to ensure they are meeting gas quality contractual requirement, but also to allow them to better manage their system.
To see more about intelligent gas management solutions see: https://www.parasyn.com.au/solutions/