For 299 days, the company’s remotely-operated SmartPlug pressure isolation tool remained in the Origin pipeline network offshore Australia. The purpose was to create a double-block isolation against gas pressure to depressurise a key section of the pipeline.
This was necessary in order that heavy lifting operations could be safely carried out to install a new 600 t accommodation module as part of the Yolla Mid Life Enhancement (MLE) Project. In addition, an emergency shutdown valve (ESDV) was replaced.
The isolation period was extended from 6-10 months due to adverse weather conditions that delayed the MLE heavy lifting operations. “By safely isolating the Yolla A Platform from hydrocarbons, Origin was able to successfully install the extensive living quarters, secure in the knowledge that the work was being completed under safe working conditions,” said TDW Regional Business Development Manager Rolf Gunnar Lie.
The MLE project is situated on a section of a 356 mm gas export pipeline that extends from the Yolla A Platform in the Bass Strait between Australia and Tasmania, to the Lang Lang Gas Processing Plant 70 km south of Melbourne, Australia.
TDW isolated the line by pigging a 356 mm SmartPlug tool with nitrogen through the topside piping, and then down the riser for approximately 300 m into the subsea pipeline to the set location, where a subsea communication skid had been installed.
The SmartPlug tool, which has a built-in pinger system and is controlled remotely via extremely low frequency (ELF) signals, was then set horizontally at the seabed in the line where it would remain until all work was completed.
To ensure that the SmartPlug tool was accurately tracked along the pigging route and that pipeline pressure was monitored, TDW used its remotely-operated SmartTrack tracking and monitoring system. By using the SmartTrack system to remotely set the SmartPlug tool in dormant mode, TDW was also able to extend the battery life of the tool so that it could remain in the line, creating an effective isolation.
Throughout the ESDV replacement operation, and the more complicated MLE project module installations, TDW regularly monitored the pressure and temperature in the line to make certain that the isolation was being effectively maintained. Following the scheduled shutdown and completion of this phase of the MLE project, TDW unset the SmartPlug tool and pigged it back to the launcher using gas pressure from the pipeline.
TDW Offshore Services provides tetherless, through-wall remote-controlled pipeline pressure isolation services. Click here for more information.
