Burial history influence on the generation of some Italian oils
- AGIP SPA, San Donato Milanese (Italy)
Many Italian oils were sourced by Triassic source rock; evidence of this exists in the Po Plain. In the Adriatic Sea, and offshore southern Sicily. Bulk and geochemical characteristics of these oils are quite dissimilar: heavy oils as well as gasolines were discovered. Such differences are partly attributable to the organic matter type and to environmental conditions, but the role of the source rock's burial histories is fundamental in determining oil characteristics. The different burial histories in these two areas definitely account for these differences. In the Po Plain, the Raethian Argilliti di Riva di Solto Formation, source rock of condensates of the Malossa area, started to generate very early as a consequence of the noticeable Rhaetian-Liassic subsidence. The generation of oil continued for a long geological time, but probably hydrocarbons were lost for the lack of traps. Only condensates, generated by the further Pliocene-Quaternary burial, were accumulated in the Neogene traps. In the western part of the Po Plain, Gaggiano and Villafortuna oils (34 and 40{degree} API), sourced by the Ladinian Meride Formation, were generated only during the sizeable Neogene-Quaternary subsidence. The high heating rate in this case probably enhanced expulsion efficiency, allowing secondary migration toward shallower depths and, consequently, preventing hydrocarbons from secondary cracking. Offshore in southern Sicily (Gela field), the recent subsidence (Pliocene-Pleistocene) is responsible for Triassic source rock maturation. In this case the shallower depth reached by the source rock and, consequently, the lower temperatures at which maturity occurred are partly responsible for the generation of heavy oils, even if other factors such as early expulsion due to tectonics and organic matter type probably play a more important role.
- OSTI ID:
- 6666897
- Report Number(s):
- CONF-900605-; CODEN: AABUD
- Journal Information:
- AAPG Bulletin (American Association of Petroleum Geologists); (USA), Vol. 74:5; Conference: Annual convention and exposition of the American Association of Petroleum Geologists, San Francisco, CA (USA), 3-6 Jun 1990; ISSN 0149-1423
- Country of Publication:
- United States
- Language:
- English
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58 GEOSCIENCES
ITALY
PETROLEUM DEPOSITS
SOURCE ROCKS
GAS CONDENSATES
GEOCHEMISTRY
GEOLOGIC FORMATIONS
GEOLOGIC TRAPS
MATURATION
MIGRATION
QUATERNARY PERIOD
TRIASSIC PERIOD
CENOZOIC ERA
CHEMISTRY
CONDENSATES
EUROPE
FLUIDS
GEOLOGIC AGES
GEOLOGIC DEPOSITS
LIQUIDS
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580000 - Geosciences