TDW Offshore Services (TDW), a leading supplier of pipeline services and equipment, has successfully completed a subsea pipeline pressure isolation operation in the Gulf of Mexico. Carried out at a depth of 370 ft (113 m) against 870 psig, this isolation enabled the safe and effective tie-in of a piggable wye to the Mississippi Canyon Gas Pipeline, a 30-inch natural gas line running between the West Delta 143 platform – a hub facility for deepwater oil and gas production – and the Venice Gas Plant in Louisiana.
The isolation project utilized two remote-controlled 30-inch SmartPlug® dual module pressure isolation tools to isolate 45 miles of pipeline.
“The SmartPlug® isolation tool is certified to ‘Safety Class High’ in accordance with OS-F101 for Submarine Pipeline Systems and is uniquely suited for use in connection with diving operations,” says Bjørn-Olav Gilje, project manager for TDW.
Each tool was composed of two plug modules and two pigging modules. One of the tools provided double block isolation on the high pressure side of the tie-in location. The first module on the second tool provided a hydraulic locked barrier of the high pressure side for the divers installing the wye. The second module on the second tool was used to perform a leak test to verify integrity of the new wye after installation.
Following launch, TDW technicians aboard dive support vessel Norman Commander used the remotely-operated SmartTrack™ tracking and pressure monitoring system to continuously monitor the locations of the SmartPlug® tools as they traveled to their subsea set destinations. The SmartTrack™ system uses two-way, through-wall, electromagnetic communication between a transponder and a receiver to track tool progress. Once the tools were set, the isolation period was approximately two and a half weeks.
“TDW worked with the client and their contractors over several months to ensure that associated risks were evaluated and mitigated,” Gilje adds. “This thorough up-front planning resulted in a successful tie-in operation for our client. Working together achieved a result that we are proud to have been part of.”
Press Release, September 24, 2012