The application of high-resolution 3D seismic data to model the distribution of mechanical and hydrogeological properties of a potential host rock for the deep storage of radioactive waste in France

In the context of deep geological disposal of high level radioactive wastes, the French National Radioactive Waste Management Agency (Andra) has conducted an extensive characterization of the Callovo-Oxfordian argillaceous rock and surrounding formations in the Eastern Paris Basin. For such characterization, a detailed 3D geological model is needed. This paper shows the procedure used for building the 3D model with depth by combining time-to-depth conversion of seismic horizons, consistent seismic velocity model and elastic impedance in time. It also shows how the 3D model is used for mechanical and hydrogeological studies. The 3D field data example illustrates the potential of the proposed depth conversion procedure for estimating a density model with depth. The geological model shows good agreement with logging data obtained at a reference well, a closest borehole located in the vicinity of the 3D seismic area. Modeling of mechanical parameters such as shear modulus, young modulus, bulk modulus indicates weak variability of these parameters which confirm the homogeneity of the Callovo-Oxfordian clay. 3D modeling of a permeability index (Ik-Seis) computed from seismic attributes (instantaneous frequency, envelope, elastic impedance) and validated at the reference borehole shows promising potential for supporting hydrogeological simulation.