Pipeline & Process
Pipeline De-Commissioning
Successful pigging programme enables pipeline disconnection from the platforms
19.5km of 16” pipeline from Murchison to Dunlin cleaned to less than 30 mg/l hydrocarbon in water content
Challenge
For the Murchison oil export line PL115 to be disconnected and decommissioned, it first had to be cleaned to a standard whereby the breaking of containment could be achieved without undue environmental impact. To this end, a progressive pigging/flushing campaign had to be devised, with the aim of cleaning the line down to below 30 mg/l oil in water content.
solution
A pigging programme to remove all wax and hydrocarbons from the line was actioned. As the line was not in production, the pipeline had to be pigged with chemically treated filtered seawater, via a temporary pumping and telemetry standard metering package provided by ourselves.
results
10 pig runs and 2 x pipeline flushes took place taking samples after every pig run to analyse the oil in water content. Upon completion of this activity, an oil in water content of below 5 ppm was achieved allowing the line to be disconnected and abandoned. Upon completion of other works, the Murchison Platform and jacket was removed.