45 
Figures 36 and 37 show, vice versa, that Middle East crudes generally contain higher amounts 
of Tm and norhopane (C29) than North Sea crudes. This might be connected with a higher 
maturity of these oils. Especially Arabian crude oils are characterized by a C29/hopane ratio 
greater than 1. The lower values of 0.7 to 1 are contributed by Iranian - and Emirate crudes, 
whereas the lowest values of the Middle East crudes belong to two Syrian light crude oils, 
thus originating from oil fields which are not directly connected with the main Gulf-area (i.e. 
the Arabian-Iranian Basin). 
Oils from the Niger Delta (Nigeria) are characterized by the presence of Oleanane in 
relatively high concentrations. Oleanane is a triterpenoid which presumably originates from 
terrestrial plants (Figure 38). 
Fig. 38: Hopanes of 4 Nigerian crude oils (Forcados, Oso, Odudu, Bonny Light), showing 
relatively high concentrations of Oleanane (peak left of hopane at 46.6 minutes). 
Oleanane seems to be highly specific for Nigerian crude oils. But, in addition, this 
characteristic feature is accompanied by relatively high concentrations of pristane in these oils 
(Figure 39). The source of pristane is presumably phytol, which is derived from the side chain 
of chlorophyll. The high concentrations of pristane thus additionally point to land plant 
sources.