Publication Date:
2015-04-01
Description:
The Pleistocene Saturnia travertine (central Italy) represents a possible analog of the pre-salt continental carbonate reservoirs discovered in the Santos and other basins in the South Atlantic margin of Brazil. Two subhorizontal travertine tabular bodies, several tens of meters thick and extending over an area of 15 km2 (5.8 mi2), have been studied in two quarries. Facies variations and associated petrophysical properties were reconstructed applying a multidisciplinary approach. The Saturnia travertine, formed from a warm water spring, is composed of various stacked carbonate banks, separated by subaerial erosive phases and paleosols. The lacustrine tabular bodies, terraces, and sills are made of crystalline crust, shrub, pisoid, paper-thin raft, coated bubble, reed, and lithoclast-breccia facies. The δ13C (from +4‰ to +8‰) supports an interpreted CO2 volcanic mantle source, whereas, the δ18O (from −9‰ to −5‰) is in agreement with warm meteoric waters. The 87Sr∕86Sr ratio isotopic signature indicates a carbonate from dissolution of deep-seated carbonates. The facies reservoir properties were studied via porosity and permeability analysis of plugs, three-dimensional x-ray computer tomography, as well as image analysis on microscale under thin section and macroscale on large rock slabs to define various porosity indices. A strong heterogeneity of the petrophysical properties and variable connectivity were observed (porosity from 4% to 30% and permeability up to hundreds of md), but no compartmentalization of the carbonate bodies is present.
Print ISSN:
0149-1423
Electronic ISSN:
1943-2674
Topics:
Geosciences
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