Oil spills near oil rigs

An ERS-1 SAR image of 11 July 1994, around 61.25N 2.0E, 100km x 100km, off the Norwegian Coast with oil rigs clearly visible as bright points. The image was acquired by the Tromsoe Satellite station and analysed by NERSC, Bergen.

This scene taken over the North Sea comprises to the right of the image a part of the Norwegian sector with the oil rigs of Gullfaks A, B and C, as well as the rig Tordis, and the British sector to the left or west, with oil rigs aligned north-south, including from top to bottom: Snorre, Statfjord C, A and D and Brent D, C, and B.

According to meteorological maps there were southerly winds, around 2.5m/sec.
Most of the visible slicks (feature of dark oblong shape) can be connected with a platform.
By evaluating the history of the wind in the days before the data acquisition it must be concluded that the slicks are rather persistent and hence represent a certain quantity of pollutant. The material might well be traces of oil or drilling mud. There are slicks still linked to the rig, showing an on-going operation (the wake of Stafjord B and the one south of the Brent platforms in the British sector), or already detached and drifting as in the case of the pollution between Stafjord A and C.

It seems that all wakes are man-made and are not merely caused by wind shadow effects, lee-side of large off-shore structures. The knowledge of the wind records is not only essential to trace back the pollution to its originator, but also to assess the timely start and duration of a spill since this deepens widely from the wind-speed and direction. Any change in this respect will clearly earmark a spill, since this will be seen as a change in direction of a wake.

(after NERSC, Bergen, techn. report no.102)

ERS Data Utilization Section, ESA/ESRIN

Keywords: ESA European Space Agency - Agence spatiale europeenne, observation de la terre, earth observation, satellite remote sensing, teledetection, geophysique, altimetrie, radar, chimique atmospherique, geophysics, altimetry, radar, atmospheric chemistry