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1 DESI/GERM, AGIP S.p.A., San Donato Milanese (Milano), Italy
2 SGEL/GEOL, AGIP S.p.A., San Donato Milanese (Milano), Italy
The Fossa Bradanica is located in Southern Italy, East of the Apennine mountain chain. It has undergone a complex geotectonic evolution: from platform (Mesozoic carbonates) to unstable foreland (Eocene-Miocene) and finally to foredeep of the Apennine thrust belt (Plio-Pleistocene). Petroleum exploration targets in this province are represented by: (a) Gas and oil in carbonates of the pre-Pliocene substratum. In this domain traps are only structural; (b) Gas and subordinately oil in Plio-Pleistocene sands, where structural, stratigraphic and combination traps can be found. The oils produced range in gravity from 3° to 45° API, with prevailing values of 1520° API. Two families of oils have been recognized: oils generated by a shaly source deposited in oxygenated waters and oils derived from a carbonate source deposited in a euxinic environment. Most of the oils are classified as non-mature or marginally mature oils. Gas is mostly dry: 79% of the gas discovered in Fossa Bradanica being of biogenic, 6% of thermogenic and 15% of mixed origin. Many fields have high CO2 concentrations (50 to 90% in the carbonates). The CO2 content decreases, moving upwards in the stratigraphic column.