Upgrading control systems at a UK gas storage site
04 September 2012
The Humbly Grove Oilfield and Gas Storage Facility near Lasham in Hampshire has to be in a state of readiness at all times to either import or export gas from or to the national grid. The company recently upgraded its control and monitoring systems to ensure improved reliability and availability, with the work undertaken by Cougar Automation, based locally at Waterlooville, using the latest version of Wonderware InTouch, provided by SolutionsPT.
Humbly Grove is a top tier COMAH site south of Basingstoke, Hampshire
Humbly Grove Energy Ltd is a wholly owned subsidiary of Petronas and operates in the Weald Basin, a major geological feature of southern England. Its operations are disposed across the region, with an oil production and gathering plant at Weston Common, satellite well sites, interconnecting pipelines for the transfer of gas, oil and water, an oil pipeline to a rail terminal at Holybourne and a gas pipeline to Barton Stacey for gas import and export.
The 285 million cubic metres-capacity underground gas storage facility at Humbly Grove was built as an extension to an existing on-shore oil production plant. The store operates by taking natural gas from the National Grid Gas Transmission System through a 27km long, 24-inch diameter pipeline to the Humbly Grove oilfield. The gas is then pumped for storage into depleted oil reservoirs.
The original oil production and gathering plant at Humbly Grove has been in operation for over 25 years, whilst the gas storage facility commenced operations in 2005. Gas storage operations at Humbly Grove take gas from the grid when demand is low and resupply to the grid when the market demand is greater, providing valuable additional capacity to the system. The gas is compressed into the underground reservoirs from which oil has been extracted, the reservoir occurring naturally and being surrounded by impervious strata. When the gas is required it is drawn from the reservoir, conditioned in various stages to remove H2S, heavier hydrocarbons, water and particulates, and then recompressed to feed into the national grid.
The original 2005 control and monitoring scheme was designed using Wonderware InTouch and Rockwell PLC with Pilz SIL3 equipment. Over the years, the system became increasingly unresponsive as it expanded, mainly owing to network loading and non-optimised architecture. Support was proving difficult and on one occasion a problem requiring urgent attention was brought to the attention of Cougar Automation, who arrived on site within two hours and remedied the problem. This local support was noted and when the new control room was being planned, Cougar was asked to undertake a complete systems review and recommend improvements.
The main problem with the architecture was that it had been extended and the data volume was overwhelming the control network infrastructure. To remedy this, the SCADA system was removed from the control network and a separate Ethernet system installed by adding Ethernet cards to the Rockwell controllers to improve SCADA system performance. This restored system responsiveness, but other work was needed to ensure reliable operation and to make the system more supportable. The need for availability and robustness was paramount -- there had in the past been reliability issues when switching from master to slave.
The Wonderware InTouch SCADA in use was Version 9 running on Windows XP, which required SolutionsPT-supplied DRAX (Dual Redundant Active X) to provide redundancy in this critical system by automating the changeover of tag servers. Although this had proven to be successful, it was an extra aspect that needed support.
Following the upgrade, a noticeable change is that the visualisation of the plant from the control room is now clear and intuitive
Upgrading to the latest InTouch version would mean that DRAX was no longer needed, as redundant operation is standard in InTouch and is enabled by a single mouse click. Transfers from master to slave are now not seen by operators as they are seamless and require little maintenance, and any work that is needed can be undertaken without causing downtime.
Kevin Baker, Project Manager, Cougar Automation, said: “The built-in redundancy function in the latest version of InTouch allowed us to readily configure resilience into the application”.
Higher performance upgrade
The InTouch update was an automatic process, with a report generated about areas that needed manual intervention. This proved minimal, and Cougar Automation made some refinements to the SCADA displays for better clarity and aesthetic appeal. At the same time, the operating system was upgraded to Windows 7.
A noticeable change is that the visualisation of the plant is now clear and intuitive. The Shift Superintendent at the plant said: “I can now rely on what is displayed and make the right decisions immediately.” This is important when a gas import or export operation is in progress, as decisions have to be made quickly and correctly with large volumes in balance:
the plant handles up to 8.5 million cubic metres of gas per day.
The hardware for the tag servers was supplied by Cougar Automation and procured from SolutionsPT’s hardware division, HardwarePT. These were two rack mounted units each running in RAID 1, further adding to the robustness of the whole system, and being pre-loaded with InTouch by HardwarePT. All the control room SCADA clients were changed to new machines with an array of flat screen displays.
The integrity of the site control system had to be validated following the upgrade, and Cougar Automation produced a ‘cause and effect’ testing system. The site has comprehensive emergency shutdown procedures that are executed from the control room using dedicated hardwired systems.
Humbly Grove Energy is a Top Tier Control of Major Accident Hazards (COMAH) site and works under the stringent regulations that apply to these sites. System security is an important aspect for such a strategic facility, and the complete control system runs in isolation from other IT systems.
Phill Allen, Humbly Grove Energy C&I Engineer, is pleased with the results of the upgrade.
Wonderware InTouch is the company’s preferred system, he says, as it provides a clear overview display and full insight into the facility’s operations, with detailed alarms and reports.
Cougar Automation has, when required, secure remote access to the system to assist in rapid problem diagnosis, and a 24:7 support contract is in place.
“Cougar Automation has provided peace of mind at many levels, most importantly because the system is so well supported”, says Allen. “They have provided us with a system that is much more resilient and responsive”.
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