Thin-skinned versus thick-skinned structural models for Apulian carbonate reservoirs: constraints from the Val D'Agri Fields

The Apulian Platform Carbonates form the reservoir unit in several major oil fields in the Val d'Agri area of southern Italy. Traps are formed by compressional fold structures developed in the hanging wall of major reverse faults. Published models for these structures emphasize a 'thin-skinned' tectonic style with a basal detachment located in Triassic evaporites. However, the generally poor quality of seismic data in the southern Apennines means that subsurface geometries are poorly constrained and seismic-structural interpretation becomes model-driven. The density of data associated with field development in the Val d'Agri area provides an opportunity to constrain structural models at a variety of scales. Good quality seismic data image the front of the Monte Alpi field and show involvement of the Base Apulian seismic reflection in compressional structures. Locally, well-defined fault plane reflectors image the moderate-steeply dipping, convex-up reverse faults that bound the structures. Integration of well, vertical seismic profiles and seismic data confirm the dominance within the reservoir of moderate-high angle reverse and normal faulting. Taken together these elements suggest that a thick-skinned structural model is most appropriate for the Val d'Agri Apulian structures, whilst the geometry of the main bounding faults suggests that they are inverted Permo-Triassic extensional faults