Structural frame of the Paris Basin (France) based on the reprocessing and interpretation of regional seismic lines
Résumé
BRGM is France's leading public institution in the Earth Sciences field, where it plays the role of the national geological survey. For the last few years, it has developed a valorization activity of all the geological subsurface French data. The emphasis has been particularly put on the seismic data, which lead to the recent creation of a dedicated seismic pole. The team deals with the entire seismic post acquisition process line, from the data management to the geological interpretation, through the complete reprocessing of the collected seismic profiles. Several leading projects have been consecutively launched, such as the regional structural study of the Paris Basin presented in this paper. Another example taken in the Aquitaine Basin of SW France is given on the next poster. The regional structural study of the Paris Basin is based on the build-up, reprocessing and interpretation of 14 regional north-south and west-est seismic transects, representing a total of 2'516 km length. These transects were created on the basis of modern signal processing, harmonization and merge of approximately 240 seismic profiles; the profiles were recorded by petroleum operators between 1971 and 1995. Concerning the reprocessing, a special focus has been done on the static corrections of the upper Cretaceous (chalk) and Tertiary deposits. The lines cross the main oil fields of the Paris Basin, as well as high potential areas for oil exploration. As a result, the density of the regional transects, added to the regional wells database, lead to a comprehensive view of the 3D geometry of the Paris Basin, as well as a better understanding of the spatio-temporal relationships between the major faults and the sedimentary cycles. Both oil industry and academic institutions are interested by this type of regional seismic study. Oil companies have been undeniably interested by this modern, large-scale view of the Paris Basin. The study has indeed highlighted numerous potential exploration targets, which then triggered detailed investigations. The study also opens many possibilities for academic people working on the Paris Basin. The interpreted regional transects definitely give complementary information to the existing studies, which generally lack of seismic (and therefore structural) data. Many poorly known topics with structural implications may be then investigated: let's mention, among others, the relationships, inheritance and role of the Caledonian and Variscan structures during the basin evolution, or the complex tectono-sedimentary evolution of Liassic deposits. At the end, our aim is to build an up-to-date structural model of the Paris Basin, coupled with the larger scale geodynamic evolution of the West-European region.