Page 153 - Geology and Geochemistry of Oil and Gas

ORGANIC MATTER INSOLUBLE IN ORGANIC SOLVENTS: KEROGEN 123

Fig. 7.3. Vitrinite reflectance R a of the Jurassic sediments vs. depth (modified after Ammosov et al.,
1987).

Fig. 7.4. Present-day temperature of the Jurassic sediments vs. depth (modified after Ammosov et al.,
1987).
Despite all the above, so far the vitrinite thermometry is the major technique for
the determination of paleotemperatures and lithogenetic stages of sedimentary rocks.
Some scientists studied the possibility of oil generation from coal and its com-
ponents. Saxby and Shibaoka (1986) studied extracts from volatile components of
coals and concluded that there is a possibility, in certain geochemical environment,
of the oil generation from coal. Its preservation, however, is possible only if oil is
expelled prior to the beginning of gas generation. These authors stated that exinite is
the maceral most prone to the oil generation. It can generate oil 10 times greater than
vitrinite and 100 times greater than inertinite (fusinite). They also believed that all