Petroleum to Source Rock Correlations

The Devonian oils in reservoirs D,-Tj of the Illizi Basin are characterised by a 5 C with a rather narrow spread of -28.10 to -29.85% and their pristane/phytane ratio of 

5 is the highest in the succession studied (Tables 5.2,5.3,5.4). This appears to be re-latedto an increase in the proportion of kerogen of terrestrial origin in the total amount of organic matter in the source rock. The isoprenoid content here is also low, as it is in the oils of Cambro-Ordovician reservoirs. 

Field Well Depth (m) Age Pristane/ phytane ratio Oil (0) or bituminoid (B) 

The isotopic composition of the bulk carbon in the oils is sufficiently uniform and varies only within a narrow range of -28 to -30%o (Table 5.6). On the whole, the oils are isotopically light which is typical of petroleum genetically related to marine source rocks. For the purpose of a correlation the isotopic composition of bituminoids from Silurian and Devonian shales of a very high hydrocarbon potential has been investigated (Tables 5.5,5.6). 

For the correlation of oils and source rocks we have used the carbon isotope composition of oils and bituminoids within probable source rocks as a diagenetic feature 

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