Petrophysical variation in the Senonian chalk of the Paris Basin and their influence on static corrections

Uncertainties in static corrections for seismic reflection data in the Paris Basin are on the same scale as the target closures. The larger part of the static corrections is due to variations in the Tertiary strata, but a significant contribution also arises from velocity inconsistencies in the underlying Upper Cretaceous chalk. The problem of evaluating accurate static corrections requires a multidisciplinary approach involving three sources of information: data on outeropping formations in the northwestern quarter of the Paris Basin; data from wells (lithological descriptions and wireline logs), which are mainly located in the central part of the basin; and seismic sections.