All change on the rig

Maximising uptime whilst maintaining safety is paramount for offshore operators, a focus harshly re-sharpened in the wake of the recent catastrophic disaster in the Mexican Gulf. Downtime is expensive and key spares are becoming less readily available, with some parts now having to be specially made.

As the majority of the oil rigs in the North Sea pass their 30th birthday, safety and reliability continue to be the major challenges affecting operators. Improved drilling and extraction technologies, together with increased oil prices, have allowed companies to extend the life of the oilfields - and with it the planned operational life of their rigs.

An increase in reliability of just one percent can represent huge eight- or nine-figure annual savings for operators: if an oil rig produces 20,000 barrels a day at a margin of $70 per barrel, lost profits are $1.4 million for every day the rig is shut down for unscheduled repairs.

The global recession has affected Aberdeen, making reliability savings all the more important, notes Stephen Hill of AV Technology (AVT), a company specialising in condition-based maintenance (CBM) for the sector. However, he adds, rig operators are prepared to invest in new technologies - and expect them as part of overall service packages.

Important changes are taking place in the way offshore predictive maintenance is carried out,” added Hill, who recently joined AVT as offshore CBM general manager, based in Aberdeen, and has over 15 years’ experience in this sector.

“Traditional CBM has relied primarily on vibration analysis data,” according to the AVT expert. “But today clients want a more integrated approach, where data from different CBM disciplines is collectively used and integrated with their CMMS (computerised maintenance management system). They want to assess the overall ongoing condition of equipment in a more effective and controlled manner.”

An important application of CBM technology is in monitoring of reciprocating compressors - vital assets in the oil and gas industries, which require specialist ongoing analysis to monitor their complexities. Here, AVT has recently made a “significant investment” in four-channel 6320 portable data collection and analysis equipment from Windrock Inc. This is designed for use on reciprocating and rotating equipment - engines, compressors, pumps and fans - as well as structure and piping vibrations. The device, noted Hill, offers 16 times the resolution of any reciprocating machine analyser on the market.

Overall, Hill believes that while vibration analysis remains a key discipline, combined data from other key areas, including oil analysis, lubrication management, thermography and electrical particle discharge analysis, provides a far clearer picture of any potential reliability problems.

“When this CBM data is able to be viewed alongside process performance information - collected online or by hand - it becomes an extremely valuable insight into machine performance; important decisions become a lot easier to make,” Hill explained.