Intelligent Pigging : Policy, Recent Experience and Needs of a Petroleum Operator

Abstract On-line inspection of pipelines using intelligent pigs constitutes a major aspect of corrosion control programs. The policy established by a petroleum operator is presented. It defines when base-line and early inspection surveys are considered necessary. The paper discusses the pros and cons of intelligent pigging operations and gives guidelines for deciding when to run in-service inspections to assess the condition of a pipeline and to verify the efficiency of corrosion control measures on a long term basis. It highlights factors like the estimated maximum corrosion rate, the positive change of actual corrosion allowance with time and the detection limits by the selected intelligent pigs. In the second part, a recent experience concerning the base-line survey of the Lille-Frigg 10" wet gas production pipeline in the North Sea using an ultrasonic pig is presented. The inlet of this pipeline is situated at a subsea manifold. The third part of the paper discusses aspects of intelligent pigging where difficulties are found and where improvements or new technological developments are needed.