Asterix SERPENT visit report

Abstract

This report presents the results from the SERPENT project collaborative research with StatoilHydro at the
Asterix deep-water exploration oil well, drilled from the Transocean Leader in the Norwegian Sea. The
study was designed to investigate seabed disturbance resulting from the drilling activities at Asterix and the
effects of these activities on the benthic environment and megafaunal organisms.
The ROV Magnum 018, was used to take eight video transects of at least 100m in length which were used
to assess visually the extent of drill cuttings and to determine megafaunal densities. Also a series sediment
samples were collected using ROV operated push cores at 50, 80 and 100m from the well to determine
heavy metal concentrations, total organic matter and particle size distribution.
Comparison of these methods suggested disturbance was variable depending on heading but suggested
complete coverage of the seabed up to 60m from the well and partial coverage to 100m. Analysis of the
sediment showed elevated Barium concentration in surface sediments at all sample locations, decreasing
with distance and with depth sections. At the site closest to the well mean particle size increased in
comparison to the background sediment. These physical changes were associated with significant
reductions in megafaunal abundance and changes in the megafaunal community structure, with very few
animals observed in a 50m radius of the well. Small ophiuroids were extremely abundant at the site
reaching up to 20m-2. Similar to the megafauna, their numbers were reduced by the disturbance event and
density was significantly reduced within 80m of the well.
Details of a short documentary film made by StatoilHydro about the SERPENT collaboration on board the
Transocean Leader are also given here.

More information

Identifiers

Catalogue record

Export record