The harsh, corrosive environment found on offshore oil & gas platforms can lead to unplanned downtime and lost production when equipment fails. A Scandinavian Oil-Gas magazine article, Upgraded Online Protection and Prediction Systems Improve Machinery Health Monitoring, highlights how the Shell Draugen oil and gas platform in the North Sea has upgraded the protection and prediction systems to monitor and protect key platform equipment.
The objective was to improve maintenance efficiency and increased production by performing 40 percent of its offshore maintenance workload on Draugen with prediction based maintenance.
The article’s author, Shell’s Graham Baird, noted that:
Shell embraced both protection and machinery health management systems many years ago, but are now transitioning from an obsolete system to newer technology that will deliver improved performance benefits.
With the upgrade:
Shell is now able to integrate data from remote and standalone online machinery health monitoring systems directly into the Shell Smart Connect global asset monitoring system. By providing open global access, this has enabled Shell to efficiently review data, compare data from other platforms and determine best practice solutions to potential problems.
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The Shell Smart Connect system is used to provide an overall picture of the health of assets from sources globally – in a common manner to those that need it. Data from the prediction system was also required to be sent to a data historian, enabling tasks such as trending to be performed in the office domain. Shell’s vision is to make as much asset monitoring data available at the office level as possible, making it easily accessible to any authorised person in any location.
The machinery protection and prediction systems included AMS Machinery Manager, portable vibration analyzers to collect additional offline, route-based data on less critical devices, and over 250 sensors. It’s important to note that the protection and prediction systems are kept separate to meet the API 670 (Machinery Protection Systems, Fourth Edition) requirements, although the systems share the information coming from the sensors.
The monitoring solution monitors and protects:
…the power turbines, condensate pumps, crude oil booster and loading pumps, the booster and gas compressors, fire/sea water pump, water injection booster pump, PWRI (produced water reinjection) booster pump, and two tornado-driven water injection skids.
From analysis of the vibration data:
…potential problems are instantly identified and the system is able to pinpoint the exact cause. This could include shaft imbalance or misalignment, or bearing defects caused by wear.
One example of what the prediction system helped uncover was when the Shell team:
…had to install new seals on a gas compressor during a planned shutdown. Following the change, compressor stability was upset and we started to incur problems. The new monitoring system immediately identified an increase in vibration levels from the drive end of the compressor during start-up. Using the Emerson system it was possible to deduce that there was imbalance near the centre of the shaft, which needed to be addressed quickly.
Having the transient data available:
…reduced the number of starts and stops needed to pinpoint the exact point in the shaft to add weight. This significantly reduced the time the compressor was offline.
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Having this information [data from hot shutdowns] in advance saved an estimated 1.5 days of compressor downtime, amounting to around 60,000 barrels of oil.
He closes the article:
The integration of analysed vibration data from the machinery protection and prediction systems into the Shell Smart Connect system has enabled access to this information by experts located anywhere in the world. This is helping Shell to detect issues earlier and rectify them before production is interrupted.
The investment in the prediction and protection system upgrade has been already covered by the savings made by a more efficient maintenance programme and the reduced downtime needed to correct the compressor balancing issue.
