41 
If a tanker having transported Oseberg crude oil in this scenario is found, the frequency of 
transports of this oil type plays the dominant role. A strong connection between the oil spill 
and a tanker may possibly be achieved by coupling the drift of the oil with the course of the 
ship. But since the oil does not contain a “fingerprint” of the ship, it might hardly be possible 
to exclude a second tanker by chemical analysis, if a second tanker would have been under 
suspicion, too. 
These two quite different scenarios show that chemical analysis might play quite different 
roles in tracing back the sources of oil pollution. But, accordingly, different parameters may 
have a quite different meaning in Oil Spill Identification. Whereas the 25-norhopane, for 
example, turns out to be of greatest importance, when an oil spill in the Oseberg area has to be 
associated with a single platform in the vicinity, this compound might play only a very minor 
role when crude oil residues from tanker loadings have to be identified. An example is given 
in Figure 33 where Oseberg C crude is compared with an Arabian heavy crude oil. 
Fig. 33: Overlay of the hopanes of Oseberg C - and Arabian heavy crude oil (below), 
subtracted mass-chromatograms (above). 25-norhopane indicated.