The principal findings of this inquiry were presented on 11 February in a meeting at the PSA, which was also attended by the Norwegian Climate and Pollution Agency (Klif) and the Norwegian Petroleum Directorate (NPD).
Statoil launched the investigation after cuttings and chemicals injected into the Utsira formation on Veslefrikk were found to be leaking to the seabed.
At the meeting, the company also outlined the measures it has adopted both on the field and to monitor other cutting injectors it operates.
Statoil has reached no firm conclusion about how the injected cuttings and chemicals reached the surface, but two theories have been proposed.
One is that the materials escaped through fracturing of the strata above Utsira, while the other is that flows have bypassed the formation because the injection well was poorly cemented.
The well may have been leaking for years – possibly since it was taken into use in 1997 and until injection ceased when big seabed craters were found close to one leg of the Veslefrikk installation in November 2009.
According to the Statoil investigation, no routines were in place for monitoring either injection pressures or rates in the wells.
Nor had criteria been established for shutting down injection in the event of abnormal pressure or rates. And nobody was responsible for monitoring the wells and for ensuring that personnel had expertise/training.
The PSA will now review the report and determine further follow-up with Statoil on the basis of the findings which have been presented.
As a result, it has at present no further comments on or assessments of the specific incident on Veslefrikk.
Injection wells for cuttings have been found to be leaking on a number of occasions in recent years,including one on the Tordis field in May 2008.
Many similarities exist between these incidents on Tordis, Veslefrikk and other fields.
Most of the wells used to inject cuttings today were drilled from the early 1990s until 2008, and are based on the same design as the Tordis and Veslefrikk injectors.
They may therefore share the same weaknesses, and the PSA accordingly considers it necessary to take immediate steps to secure an overall view of the condition of such wells on the NCS.
It will therefore request information on the technical and operational condition of injection wells for cuttings from all operators with such facilities.
Operators will also be asked to report on the corrective measures they have taken or intend to adopt if weaknesses or uncertainties are revealed.
The PSA will also check that the well integrity project being pursued by the Norwegian Oil Industry Association (OLF) takes account of all wells – including cutting injectors.
In addition, the PSA is collaborating with the other government agencies concerned – Klif and the NPD – to coordinate other measures where these are required.