During operational pigging between Shell’s Gannet platform and Talisman’s Fulmar platform, a pig became stuck between 4 and 16km from the Gannet in a water depth of approximately 100m. A build-up of wax on the pipe wall was believed to have slowed the pig’s progress before halting it completely. Failure to dislodge the pig led to the kick-off of an extended series of multi-agency campaigns between Altus Intervention, Shell and Talisman. The campaigns were scheduled to complete an 18-month workscope with the aim of returning the pipeline to service.
Altus Intervention’s remit was to provide experienced personnel and innovative technologies to clean out the entire pipeline. This involved significant data gathering which informed the pressurisation and controlled depressurisation of the line before the entire pipeline was de-oiled. Altus Intervention supplied interconnecting temporary equipment and personnel to be utilised when the original pipeline was offline. A reinstatement leak test of the complete pipeline was to be performed and flows, pressures, fluid densities and sampling were to be effectively monitored before dewatering and gel breaking operations commenced.
Throughout the 18-month project, Altus Intervention successfully performed 15 major equipment mobilisations and supplied expertise and project support to both Shell and Talisman to return the Gannet Oil Export pipeline to service. The extended multi-agency project’s success was achieved on time with no incidents, lost time or non-conformance reports.