Core-Based Facies Analysis of the Cretaceous/Oligocene Boundary - Offshore Central Adriatic Sea, Italy

Brandano, Marco ²; Campagnoni, Veronica ¹; Lipparini, Lorenzo ¹; Pignatti, Johannes ²; Mannetta, Domenico ³
(1)E&P, Medoilgas Italia S.p.A., Rome, Italy. (2) Scienze della Terra, Sapienza Università di Roma, Rome, Italy. (3) Petrolab Italia s.a.s., Rome, Italy.

Facies and biostratigraphy analyses of the Cretaceous and Oligo-Miocene succession of Apulian Carbonate Platform, were carried out in a sector of the Central Adriatic Sea offshore the Abruzzo region (Italy).

This study is a result of the collaboration between La Sapienza University of Rome and the Medoilgas Italia S.p.A., and it is part of a more extended technical effort aimed to understand and define in detail the Ombrina Mare oil field.

The presented work is intended to summarize and share some of the results obtained, specifically on the Core based Facies Analysis, which represents one of the main elements for the understanding of the stratigraphic evolution of the area across the Cretaceous/Oligocene boundary.

Characters, stratigraphic position and depositional environment of each main recognized facies will be presented in sixteen “plates”.

The main input data for the study here presented is represented by thin sections from well Ombrina Mare 2 cores and cuttings. Moreover, a detailed critical review of available data (composite logs, core description, technical reports etc.), on several wells in the nearby area was carried out.

The description of the compositional characters of the investigated section is based on microfacies analysis under transmitted light microscopy, core description and observations on polished core slab. Modal composition of thin sections was analysed by point counting (up to 300 points), and point count results were analyzed statistically by a Hierarchical Cluster using the SPSS 13.0 for Windows program.

For biostratigraphic analysis, all thin sections from the cores and all suitable thin sections from cuttings were photographed, described and microfossils were classified.

Results & Conclusions

A total of eight sedimentary facies have been recognized and interpreted:

-4 facies in the Cretaceous interval [Breccia, laminated bindstone, fenestral mudstone, peloidal/ooidal grainstone];

-3 facies in the Oligocene interval [red algal debris/Larger Benthic Foraminifers (LBF) grainstone, LBF packstone, red algal nodule/LBF floatstone to packstone].

-1 facies in the Miocene interval [wackestone to packstone with planktonic foraminifera].

The Cretaceous facies may be referred to a flat-topped platfom, characterized by open lagoonal, sand shoals, restricted lagoon and tidal flat depositional environments.

The Oligo-Miocene facies association is referable to a middle to outer carbonate ramp environment.

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