NDTnet 1998 Aug, Vol.3 No.8

Abstract

Ekofisk is located in the southern part of the North Sea and is among the largest oil gas fields offshore. It was discovered in 1968 and first oil was produced in 1971. The original operating license awarded to the Phillips Norway Group was slated to end in 2011. Due to enhanced recovery factor it will now take longer to deplete the fields than first supposed and the license has now been extended to 2028. For this reason Ekofisk installations are needed for a longer time than was planned when they were designed and engineered.

The area comprises no less than eight oil and gas fields where PPCoN is the operator. The fields are interconnected with the Ekofisk Complex by oil and gas pipelines. The Complex also serves as a transport node for a number of other oil and gas fields operated by other companies.

Ekofisk production had to be shut-down twice during January-February this year (1997) due to a leak and an incipient leak in the process train at Ekofisk Tank (2/4-T). These two incidents were in places deemed to have moderate probability of local corrosion damage. Samples of the flowline content and scale on the internal pipewall faces were taken and analyzed. Also part of the damaged flowline was taken ashore for damage assessment. It was decided early on to work on the hypothesis that the damage could be due to Microbiologically Influenced Corrosion, MIC. And in fact the subsequent analysis work proved that MIC was the culprit.

This is a damage mechanism that has only once been verified before in a process plant on an Ekofisk installation. The damage was detected as the result of the standard inspection program. Due to the fact that only one case of MIC had been recorded it was deemed unnecessary to implement a special inspection program for MIC damage before the events of January. Since then, it has been necessary to establish such a program, and an intensive inspection program is being implemented to determine the extent of damage throughout the entire process plant at the Ekofisk Complex.

The report further describes the work done and continuing to determine how MIC can be precluded or reduced in future, and how the MIC status in the process trains can be monitored in future

Abstract Source:
Book of Abstracts, 7th European Conference on Non-Destructive Testing, 26-29 May 1998, ISBN: 87-986898-0-00

Full-Text Source:
Proceedings of the 7th European Conference on Non-Destructive Testing, 26-29 May 1998, ISBN:

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