A number of serious well failures in recent years led to investigations of well-integrity issues. The Petroleum Safety Authority Norway (PSA) performed a pilot well-integrity survey based on supervisory audits and requested input from seven operating companies, 12 preselected offshore facilities, and 406 wells. The wells were a representative selection of production and injection wells with variation in both age and development categories.
The pilot project indicates that 18% of the wells in the survey have integrity failure, issues, or uncertainties, and 7% of these are shut in because of well-integrity issues. The selection of wells and the companies indicate that the statistics are representative.
The well incidents in the past and the results of the pilot well-integrity survey revealed that the industry needs to increase focus on barrier philosophy. Control of barrier status is an important health, safety, and environment (HSE) factor to avoid major incidents caused by unintentional leaks and well-control situations. Knowledge of well-integrity status at all times enables the companies to take the right actions in a proactive manner to prevent incidents.
The paper presents the results and the conclusions from the pilot survey. In addition, a number of technical well failures will be presented, identifying critical elements such as corrosion, leaks, and operational factors. In particular, the understanding of barrier regulations, standards, and implementation was found to be inadequate.
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NORSOK D-010: Well integrity in drilling and well operations, thirdedition. 2004. Stavanger: Norwegian Oil Industry Association (OLF)/Federationof Norwegian Manufacturing Industries (TBL).
Vignes, B., Andreassen, J., and Tonning, S.A. 2006. Well IntegrityChallenges on the Norwegian Shelf. Presented at the PSA's Well Safety Seminar,4 May 2006. Petroleum Safety Authority Norway (PSA).