Environmental monitoring report. Morvin 2009–2010

Abstract

From the Summary: “This report presents results from environmental monitoring during discharge of mud and drill cuttings during top hole drilling of four wells at the Morvin field in 2009 and 2010 (Block 6506/11 and production license 134b/c).

An observation platform equipped with acoustical and optical technology was developed that together with traditional environmental monitoring could be used to evaluate the effects of release of mud and drill cuttings on the environment in general and on corals in particular.

The sediment core samples reveal that one sample close to discharge point is contaminated with THC. There are also elevated levels of Barium in the downstream direction as expected. No other metal contamination was found.

The sediment trap upstream of the discharge point contained barium levels that were an order of magnitude lower than at the other sediment trap sites, although concentrations of Ba at this location were still considerably above the local background levels, so some minor contamination of that location is possible. The two downstream traps collected drill cuttings

Lipid class and fatty acid analyses of corals that had been exposed to drill cuttings and of corals that had not been exposed showed no significant differences between the two. Hence, the exposed corals did not have decreased amount of storage lipids compared corals from the unexposed control area and this suggest that there is no differences in the feeding rate between the two.

Image analyses revealed no significant behavioural differences between corals that were exposed to drill cuttings and unexposed corals. Detailed analyses of the time series from the exposed coral reef revealed that changes in current direction and speed were the main reasons for changes in coral polyp behaviour.

In conclusion, the mud and drill cuttings did reach the coral reefs in the downstream direction. However, our analyses do not reveal any immediate damage to the corals. It is recommended that the coral reefs are revisited at a later stage to reveal long-term effects of the discharge of mud and drill cuttings.”