Revisited Hydrocarbon Prospectivity in the Adriatic Basin

Riva, Alberto ¹; Di Cuia, Raffaele ¹; Marian, Mara ¹
(1)G.E.Plan Consulting, Ferrara, Italy.

The Adriatic basin is an elongated area that lies between the eastern cost of Italy and the coasts of Slovenia, Croatia, Montenegro and Albania. This offshore basin is more than 820 km long and 80 km to 220 km wide and is bounded to both sides by thrust belts, to the west by the Apennine thrust belt and its foreland and to the east by the Dinarides thrust-belt.

The Adriatic basin has been explored for hydrocarbons since the late 50’s with a major period of high drilling activities between 1968-1972 and an increasing drilling activity from 1978 to 1992.

The two main proved plays are represented by the biogenic gas in the Pliocene-Pleistocene sequence and by the oil and gas in the Cretaceous to Miocene carbonates.

The Pliocene-Pleistocene play type is characterized by a sequence with the presence of clastic turbidites deposited mainly along the long axis of the Plio-Pleistocene foredeep of Northern and Central Apennines. The reservoir is made of the sandy part of the turbiditic sequence while the finer portion and the background basinal deposition represent a very effective seal. The source rock is within the same turbiditic sequence and could generate biogenic gas because of the characteristics of temperature and subsidence of the basin. The traps are represented by the external structures of the Apennine thrust belt or by differential compaction over Mesozoic structures.

The Cretaceous to Miocene play type is mainly characterized by heavy to light oils generated by lower Cretaceous intra-platform sequences deposited in anoxic conditions or by upper Triassic carbonate/evaporitic sequences with high organic content. The reservoir is represented by the Upper Cretaceous fractured carbonates (low matrix properties) or by the Eocene and Upper Cretaceous karstified limestone underneath the main Miocene unconformity. The seal is represented by the fine-grained clastic sequence belonging to the lower part of the Pliocene sequence. The hydrocarbon accumulations are mainly trapped in horst-type structures or partially inverted blocks.

A recent revision of the existing available data has highlighted the presence of a new partially proved deep play sourced by hydrocarbons generated in the Middle Triassic limestone sequence with mixed sabkha and anhydrite facies. If confirmed this new play may open new exploration opportunities related to structural highs at Triassic levels in the eastern part of the basin.

AAPG Search and Discovery Article #90135©2011 AAPG International Conference and Exhibition, Milan, Italy, 23-26 October 2011.