HOUSTON– TDW Offshore Services L.L.C. has successfully completed a pipeline pressure isolation operation in the Gulf of Mexico for a major operator. The operation made it possible for the operator to safely replace a faulty shut down valve located above the riser on a platform situated off the coast of Louisiana.
TDW performed a “double-block” isolation against the gas pressure in the designated riser using two SmartPlug isolation plug modules linked together. Working from the platform, TDW launched the SmartPlug modules, using the SmartTrack system to monitor pressure and track them. The modules were pigged in for 80 ft (24 m) - traveling under a flow rate of 30 to 40 gal/min at approximately 131 bar (1,900 psi) - until reaching their destination near the top of the riser.
TDW set the downstream SmartPlug module and bled the topside pressure to approximately half of the riser pressure. With data communicated by the SmartTrack system confirming the integrity of the downstream seal, TDW technicians set the upstream SmartPlug module and monitored the pressure between modules until they were confident that the module was holding pressure. The SDV could be safely replaced.
The SmartPlug modules remained in the riser for 12 days while the operator replaced the SDV. Throughout this period, TDW took hourly pressure readings of the isolated section using SmartTrack “through pipe wall” communications technology, which relies on extremely low frequency electromagnetic waves to transmit isolation integrity data to a transceiver, which in turn relays it to a control center.
TDW assessed the data until the SDV was installed. Utilizing the double-block isolation, the crew performed a leak test on the repaired section. After confirming the integrity of the newly installed valve, pipeline pressure was equalized and the SmartPlug modules un-set and retrieved, allowing normal production to resume.