Experience from Operation, Inspection and Condition Monitoring of Offshore Pipeline Systems on the Norwegian Continental Shelf

摘要

The Norwegian Petroleum Directorate (NPD) possesses a computer database called CODAM (COrrosion and DAMage Database) in which incidents and damages on structures, risers and pipelines are registered. The reporting to the CODAM database is part of the requirements stated in regulations relating to loadbearing structures and regulations concerning pipeline systems. The regulations state that the different operators shall submit an annual summary report for each pipeline system and load carrying structure. The summary report provides the results from the inspection and condition monitoring of the different pipeline systems and structures. This paper will only cover incidents to pipelines and risers. Today, approximately 5400 km of gas pipelines, approx. 920 km of oil pipelines and approx. 580 km of pipeline with other media, like condensate, water or glycol, exist on the Norwegian Continental Shelf. The above mentioned lengths of pipelines include all kinds of different systems from large diameter export pipelines ending in Germany, United Kingdom, Norway, Belgium and France to small diameter pipelines and risers between subsea structures and offshore installations as well as in between different offshore installations. Approximately 2200 incidents and damages to these pipeline systems have been reported to CODAM. We divide the reporting incidents in three different categories; major, minor and insignificant. The intention with this paper is to provide an overview of different incidents and occurrences related to offshore pipeline systems on the Norwegian Continental Shelf, based on the infonnation available in CODAM. The types of incidents available are in general very different and include for instance causes of loss of containment, corrosion attacks (both internally and externally), free spans exceeding the design criteria, upheaval buckling, scratchmarks, dents, cracks, horizontal deflections etc. A description of the types of incidents and damages will be presented and some explanation will be provided Also different statistics will be presented. The paper describes incidents, which have occurred during the period 1975 -1996. All the statistics will be presented in an anonymous form.