197 7. Integrated seismic study We have demonstrated the advantages of geo-statistical processing both to quantify the quality of the seismic amplitude (SQI) and to perform depth conversion (Bayesian Kriging). The Q factor of geological formations can be obtained from VSP data. We made use of the fact that attenuation introduces dissipative dispersion, which can be measured from the frequency-dependent phase velocity of the VSP down-going wave. The methodology has been extended from well data to surface seismic data. For this purpose, a high-resolution velocity model is required. It is obtained by the elastic inversion of the seismic data and by conversion of acoustic impedance Ip into velocity Vp. The procedure can be used to build a geo-model in depth defined by mechanical and hydrogeological parameters: velocities (Vp, Vs), density, Q factor, porosity, specific surface and index of permeability (Mari and Yven, 2014). The seismic procedure was extended to calculate a seismic pseudo gamma ray (GR-Seis). A highly porous layer was detected at the top of the Dogger, and lateral variation in shale content can be seen in the Callovo Oxfordian. Acknowledgements Many thanks to Andra for granting permission to use the datasets. References Andra (2005) Dossier 2005 Argile – Synthèse : Evaluation de la faisabilité du stockage géologique en formation argileuse – décembre 2005. Andra (2009) Stockage réversible profond - Proposition d’une zone d’intérêt pour la reconnaissance approfondie et de scénarios d’implantation en surface – C RP ADP 09-0035. Andra (2016) Dossier Option de Sûreté – Partie Exploitation (DOS-EXPL) - CG-TE-D-NTE-AMOA-SR1-0000-15-0060. André G., Hibsch C., Beaudoin B., Carpentier C., Fourcade S., Cathelineau M., Elion P., 2004. Oxfordian sedimentary dykes: Tectonic and diagenetic implications for the eastern Paris Basin, Bull. Soc. Geol. Fr, 175, 6, 595-605. Benjumea B., Lopez A.I., Mari J.L., Garcia-Lobon J.L., 2019, Petrophysical characterization of carbonates (SE of Spain) through full sonic data, Journal of Applied Geophysics, 160, 1-14, https://doi.org/10;1016/J.appgeo.2018.10.024. Bourges M, Mari J.L., Jeannée N., 2012, A practical review of geostatistical processing applied to geophysical data: methods and applications, Geophysical Prospecting, 60, 400-412, DOI: 10.1111/j.1365-2478.2011.00992.x
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