OSLO, Norway -- Norway’s Petroleum Safety Authority Norway (PSA) has asked all Norwegian continental shelf operators to report on the safety status of wells used for injecting drill cuttings. This follows a report by Statoil on a leak at Veslefrikk in the North Sea.
Statoil conducted an investigation after discovering that cuttings and chemicals injected into the Utsira formation on Veslefrikk were leaking to the seabed. The company has no confirmation about how the injected cuttings and chemicals reached the surface, but has two theories.
1. The materials may have escaped through fracturing of the strata above Utsira, or alternatively, flows may have bypassed the formation because the injection well was inadequately cemented.
2. The well may have leaked for for some time. It entered service in 1997 and injection ceased this past November when seabed craters were found close to one leg of the Veslefrikk platform.
The PSA plans to review the report and to decide with Statoil on follow-up actions. It points out there have been numerous other incidents of cuttings leaking from injection wells on the Norwegian shelf in recent year, including one at Tordis in 2008.
Most wells used to inject cuttings today, PSA points out, were drilled from the early 1990s until 2008, and are based on the same design as the Tordis and Veslefrikk injectors. Accordingly, PSA plans immediate steps to draw up an overall view of the condition of such wells on the NCS.
This will need operators with these types of facilities to supply information on the technical and operational condition of injection wells for cuttings. They will have to report on the corrective measures they have undertaken or intend to adopt should weaknesses come to light.
PSA also will check that the Norwegian Oil Industry Association (OLF) well integrity project takes into account all wells, including cutting injectors.