TDW Offshore Services (TDW) has completed the longest ever pipeline isolation operation in company history for Origin Energy Limited (Origin). 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 depressurize 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-ton accommodation module as part of the Yolla Mid Life Enhancement (MLE) project. In addition, an emergency shutdown valve (ESDV) was replaced.

Due to adverse weather conditions that delayed the MLE heavy lifting operations, the isolation period was extended from six months to 10 months. “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 Rolf Gunnar Lie, Regional Business Development Manager – Asia Pacific for TDW.

Isolation tool remotely pigged 300 meters into subsea line The MLE project is situated on a section of a 14-inch 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 14-inch SmartPlug tool with nitrogen through the topside piping, and then down the riser for approximately 984 feet (300 meters) 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.

Tags: TDW Offshore Services