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Audit of well safety for temporarily abandoned wells

Audit: During the period from November 2007 to June 2008, the Petroleum Safety Authority Norway (PSA) conducted an audit of operating companies on the Norwegian shelf that have temporarily abandoned wells. The topic of the audit was well safety.


Background for the audit
An up-to-date overview of the number of temporarily abandoned wells on the Norwegian shelf was needed.  Activities aimed at gathering information have previously been implemented, and this year the activity was expanded to verify that the industry has an adequate overview of the technical condition, barriers and well integrity for all such wells.
 
In the fourth quarter of 2007, the operating companies were asked to submit information about well barriers, risk assessments and future plans.  The documentation received shows that several of the wells were temporarily abandoned in the 1980s and 1990s.

Based on the PSA's main priority linked to aging and lifetime extension, as well as our follow-up of well integrity in 2006-2008, a decision was made to secure clarifications from those operating companies that have temporarily abandoned wells more than eight years old.

The results from the audit will be evaluated with a view towards contributing to RNNP (Trends in risk levels on the Norwegian shelf), as well as a means of sharing experience with the authorities in other countries.

Purpose of the audit
The purpose of the audit was to verify that the companies have an overview of their temporarily abandoned wells on the Norwegian shelf.  This overview should include information about the technical status of the well, including barriers, integrity and risk assessments in accordance with regulatory requirements, as well as further plans for use or permanent plugging of the wells.

Result of the audit
The audit was conducted in two phases.

Phase 1 was data collection from all operators with temporarily abandoned wells.  The companies' responses indicate a total of 44 temporarily abandoned wells on the Norwegian shelf, which represents an increase since the previous overview compiled in 2005.  The companies only indicated concrete plans for using these wells in a few cases.

Phase 2 was carried out as an audit of the companies BP Norge AS, ConocoPhillips Skandinavia AS, Hess Norge AS, StatoilHydro ASA, Talisman Energy Norge AS and Total E&P Norge AS, all of which have temporarily abandoned wells that are older than eight years.  Most of the companies have prepared a status and overview of their temporarily abandoned wells, including risk assessments according to the regulatory requirements.

Normally, temporarily abandoned wells do not represent a major accident potential.  The results of the audit indicate little likelihood of corrosion of casing and equipment in the well under stagnated, closed conditions.

The PSA has recommended that the companies obtain information about experience gained from similar wells, including from other continental shelves.  There is a need for more information about these wells, with a view towards number, location and the risk they represent, both during the period when they are temporarily abandoned and in connection with further activity in the wells.

BP Norge AS
No regulatory nonconformities were identified, but we did note one item with potential for improvement.

ConocoPhillips Skandinavia AS
One nonconformity in relation to regulatory requirements was identified:

Hess Norge AS
One nonconformity in relation to regulatory requirements was identified.

StatoilHydro ASA
One nonconformity in relation to regulatory requirements was identified.

We also identified one item with potential for improvement:

Talisman Energy Norge AS
One nonconformity in relation to regulatory requirements was identified:

We also identified two items with potential for improvement:

Total E&P Norge AS 
No regulatory nonconformities were identified, nor did we note any items with potential for improvement.