Study of the Present and Fossil Cold Seeps in the Northern Apennines (Italy) to Define the Total Petroleum System

A geochemical study on fluids from selected spontaneous seepages and drilled wells was carried out together with geologic investigation and deep cross-sections reconstruction, to examine the Petroleum System in the western Northern Apennines foothills. The foredeep deformation of the Northern Apennines foothills is mainly late Miocene to Pliocene in age. The comparison of the fluids from the wells and the mud volcanoes evidences different generation and migration steps, depending on burial conditions and deformation time.The achieved results suggest the occurrence of a common source rock deeper than the Tertiary reservoirs,which progressively entered in the oil window.A regional example of Methane Derived Authigenic Carbonates in shallow water setting is represented by the chimneys field exposed along the Enza riverbanks in the Lower Pleistocene deposits of the NorthernApennines. Within the Enza succession, methane leakage still occurs, showing δ13C isotopic values of about -70‰, indicating a biogenic origin; methane generated within the Plio-Pleistocene mudstones occurring in the subsurface of the Po plain. The improvement of the study on these fluid seepages gives further information to unravel the different fluids involved in MDAC formation and the fluid flow history,thus enhancing the understanding of the hydrocarbon potential in the foredeep.