NPD's 3D Seismic of Troms II Delayed, but Plans to Wrap as Planned

The NPD's acquisition of 3D seismic data in Troms II offshore northern Norway has been delayed by well over a week. The delay means that the 3D acquisition period will be somewhat shorter than originally planned. The acquisition period will be concluded as planned on July 31.

2D and 3D seismic

The main difference between 2D and 3D seismic is that 2D seismic is acquired using a single listening cable towed behind the seismic vessel, whereas 3D seismic is acquired using six parallel listening cables. The 3D vessel used by the NPD has six listening cables at 100-meter intervals, and the cables are 6 kilometers long. This means that the tow is 500 meters wide and 6 kilometers long.
The sound source used for 3D seismic is as strong as the one used for 2D seismic, and the intervals between each sound wave sent down to the subsurface are the same for 2D and 3D seismic, with new sound waves emitted every 25 meters.
Impact research

Concurrent with the 3D seismic, research will be carried out on the scare effect on fish. Fishing vessels have been hired to fish before and during the seismic activities. The research shall help us ascertain how far away from the sound source fish are frightened. Furthermore, measurements will be carried out of how the sound wave pressure travels through the water, in order to establish models for sound wave dispersion. The research project will be carried out by the Institute of Marine Research.

Company: Norwegian Petroleum Directorate more info
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