| Location: | Haklang, Norway |
| Position: | 670248.314 N 070331.860 E |
| Depth: | 1250 m |
| Water Temperature: | -1ºC |
| Rig: | Transocean Leader |
| Dates: | 23 September – 9 October 2008 14 – 19 October 2008 |
| Industry Partners | |
| Gas & Oil Company | Statoil |
| ROV Operator: | Oceaneering |
| Rig operator: | Transocean |
| SERPENT Representative: | Dr. Andrew Gates |
This mission was the latest SERPENT visit to the Transocean Leader. Since the project’s inception in 2002 we have made 5 visits to the rig. The Transocean Leader is a semi submersible drilling rig capable of operating in harsh environments.
Mission Plan
- Previous SERPENT work has shown the importance of the extent of drill cuttings on the abundance and distribution of benthic organisms around drilling operations. (see the graph below).
- Drilling disturbance can be assessed visually, using video transects and by measurement of the Barium concentration in the sediment around the well.
- The collection of push cores using ROVs is a time consuming task, especially in deep water so earlier missions have only collected limited samples.
- The results from the previous work on the smaller number of samples warranted a much more detailed study of the extent of chemical indicators of drill spoil and the relationship with visual observations of fauna and disturbance.
- The Haklang missions were devoted to collecting this information.
- Plans were made to take a video survey alongside a detailed coring programme with replicate samples collected at increasing distance from the centre of the disturbance.
- On return to the laboratory the samples will be analysed for a the chemicals in the sediment, including heavy metals and total organic carbon. This information will be compared with the detailed ecological information from the video survey.
Graph showing the cumulative frequency of the sea-urchin Echinus acutus observations with increasing distance along a post-drilling video transect at a previous North Sea study site. The graph also shows the concentration of Barium in the sediment (g per kg) at four locations along the transect. This works shows low animal abundance where barium concentration is high.
Sample Collection
The core samples and video transects taken at Haklang are represented in the diagram below. Sediment samples were collected from 6 sites at increasing distance from the BOP with replication at each site. The video transects were taken at nine headings radiating from the BOP.
Diagram showing the location of video transects and push core samples taken during the Haklang mission. The central black dot is the main drilling site.
The push cores were collected using the precise manipulation capabilities of the mechanical manipulator arms.
Eco Highlights
Visit the SERPENT archive for more Haklang images/video.
The fauna at Haklang was very similar to that at Midnattsol and some of the other Norwegian deep water sites SERPENT has worked at. For this reason more time was spent on sample collection than image and video collection. For a comprehensive gallery of images of animals from the Norwegian deep-sea have a look at the Norway Gallery
The most abundant species to be observed at Haklang was a type of cerianthid anemone. These are burrowing organisms so they were able to move up through the sediment, even in areas which had been heavily impacted by drill cuttings.
A cerianthid anemone and a pycnogonid, or sea spider, on the drill cuttings close to the well at Haklang
Other notable observations were the cirrate octopus that are often seen on SERPENT visits to this area and the rays which seem ubiquitous in the deep waters off Norway.
Cirrate octopod.
Rays are one of the most common fish found in the deep waters off Norway.
