40 
What a difference, in case Oseberg crude oil would be involved in a mystery oil spill in the 
southern North Sea! 
In a first step, it has to be found out here that the oil type “crude oil” is actually involved (Para 
2.1 to 2.5). The crude oil type “Oseberg” then may be identified by means of the crude oil 
database. Here, stored values of crude oil parameters are compared with the corresponding 
values of the unknown crude oil sample. Statistical calculations are performed in order to find 
out “best matches” with the spill sample. Even without the characteristic 25-norhopane in this 
case already the five parameters of the hopane-series given in Table 2 are sufficient, not only 
to indicate the general area where this oil originated (i.e. between the Shetland Islands and 
Norway) but also to find out the correct crude oil type (“Oseberg”, Table 1) among the 260 
crude oils of the database. 
Crude oil 
Sampling date 
Correlation Coefficient 
Oseberg 
01.07.1993 
0.9997 
Oseberg 
14.02.2002 
0.9988 
Oseberg 
19.01.2002 
0.9974 
Stati] ord 
01.07.1993 
0.9971 
Gullfacs 
01.07.1993 
0.9969 
Oseberg C (Sintef) 
07.05.2001 
0.9951 
Stati] ord 
07.01.2002 
0.9950 
Gullfacs 
22.12.2001 
0.9931 
Tab. 1: “Best matches” of crude oils, when Oseberg C crude oil (spill No 2, sample taken by 
Sintef) is correlated by using the five parameters given in Table 2 (database: 260 
crude oils from all over the world). 
Parameter Spill sample Best match (Tab. 1) % Difference 
Ts/Hopane 
0.160 
0.155 
3 
Tm/Hopane 
0.121 
0.120 
1 
28-Bisnorh./Hopane 
0.230 
0.230 
0 
Norhopane/Hopane 
0.394 
0.401 
2 
C31 S/Hopane 
0.347 
0.355 
2 
Tab. 2: Parameters used, single values and percentage difference of the spill sample versus the 
“best match” (samples given in Table 1).