Projet ANR-06-BLAN-0373 – DEG : Développements expérimentaux innovants et datation multi-méthodes des eaux souterraines et des glaces polaires
Programme : Programme blanc (BLANC) 2006
Année de financement : 2006
Coordinateur du projet : CENTRE NATIONAL DE LA RECHERCHE SCIENTIFIQUE - DELEGATION  AQUITAINE LIMOUSIN (CENTRE NATIONAL DE LA RECHERCHE SCIENTIFIQUE - DELEGATION  AQUITAINE LIMOUSIN)
Partenaires : Centre national de la recherche scientifique; Centre national de la recherche scientifique; Centre national de la recherche scientifique
Montant : 280000.0 euros
Date de début : 2006
Durée : 36 mois
Résumé : 1 Objectives and Background  This project's objective is to use different dating methods, some of which quite innovative, on groundwater or polar ice samples, to deal with major environmental problems like Global warming via CO2 geological storage, and decrypting glacial archives, or future MHAVL nuclear waste in case of disposal in deep geological formations.  In order to reduce CO2 emissions in the atmosphere, some very important studies are being carried to assess the possibility of injecting and then storing this gas into deep aquifers. To do that, some work has to be done to characterize the surrounding hydrogical systems, as in the long run these are going to have an impact on the confinement properties of the site; on the other hand, knowing them will contribute to the finalization of storage site CO2 monitoring protocols. These hydrological models are developed starting from the physical properties of the aquifer rocks to constrain the transportation process in the different geological formations concerned, and thus evaluate the speed of CO2 release into the atmosphere and the impact on the atmosphere-biosphere system. The studies that we propose, will be carried out in collaboration with the Paris IPG, on water samples taken from the old oil Weyburn site, in the NE part of the Williston basin, which stretches on the states of Saskatchewan, of North Dakota and of Manitoba in North America. Following to water and then CO2 injections, for oil extraction purposes, the Weyburn site is nowadays the object of an international research program carried out by the PTRC (Petroleum Technology Research Centre) based in Regina (Saskatchewan, Canada) in association with the Paris IPG. The water studied for dating purposes will be from deep aquifers of reservoir formations (Midale dolomites of Mississipian age) far from the injection site and from the middle and surface aquifers situated in the overlying mesozoic formations. In France, the use of deep geological layers is also envisaged for MHAVL nuclear waste disposal. Situated at the border between the Meuse and the Haute-Marne, the Bure site has been kept for the implantation by the Andra (National Agency for Radioactive waste management), of an underground research laboratory within the Callovo-oxfordian clay layer at a depth of 490 m. This laboratory will allow to carry out detailed in situ studies to assess the possible impact of storage on the clay material that constitutes the ultimate long term (106-108 years) natural confinement barrier. As with CO2, it is very important to characterize the hydrological environment of the site and, notably the weak aquifer levels present in the limestone formations of Oxfordian and Dogger ages framing the clay layer. Here too, the aim of the studies is to constrain the existing hydrogical models, by integrating the residency time of formation water, so as to evaluate possible transfers, in the long run, of radionuclides from the storage site, as water represents the major vector of restitution to the surface and to the biosphere of these radionuclides. Even though the objective of these studies is very different, amongst all the parameters considered, the determination of water residence time in the host formation, or in the formations overlying and underlying the host layer, is essential in both cases. Nowadays there exist few methods for dating water as old as that found in the geological formations of the sites selected for confinement applications. For this reason, within the framework of this project, we propose to use different dating methods, some of which innovative, which are suitable for ancient groundwaters, which is within a range of 50 000 years and 1 million years.  Furthermore, it is known today that polar ice has registered the climatic variations on the Earth over very long periods of time. Deciphering these archives is an essential step to better predict the future evolution of global climate and, in particular, the impact