A laboratory approach for the calibration of seismic data in the western part of the Swiss Molasse Basin: the case history of well Humilly-2 (France) in the Geneva area
- Journal Article
Rights / licenseCreative Commons Attribution 4.0 International
A collection of 81 plugs were obtained from the Humilly-2 borehole (France), that reached the Permo-Carboniferous sediments at a depth of 3051 m. Experimental measurements of physical parameters and mineralogical analysis were performed to explore the links between sedimentary facies and seismic characteristics and provide a key tool in the interpretation of seismic field data in terms of geological formations. The plugs, cylinders of 22.5 mm in diameter and ∼30 mm in length were collected parallel and perpendicular to the bedding in order to explore their anisotropy. Ultrasound wave propagation was measured at increasing confining pressure conditions up to 260 MPa, a pressure where all micro-fractures are considered closed. The derivatives of velocities with pressure were established, allowing the simulation of lithological transitions at in-situ conditions. At room conditions, measured grain densities (kg/m3) range from 2630 to 2948 and velocities vary from 4339 to 6771 and 2460 to 3975 m/s for P- and S-waves propagation modes, respectively. The largest seismic-reflections coefficients were calculated for the interface between the evaporitic facies of the Keuper (Lettenkohle) and the underlying Muschelkalk carbonates (Rc= 0.3). The effective porosity has the range of 0.23% to 16.65%, while the maximum fluid permeability (m2) is 9.1 ×10−16. A positive correlation between porosity and ultrasound velocity has been observed for P- and S-waves. The link between velocities and modal content of quartz, dolomite, calcite, and micas has been explored. This paper presents a unique set of seismic parameters potentially useful for the calibration of seismic data in the Geneva Molasse Basin. Show more
Journal / seriesSwiss Journal of Geosciences
Pages / Article No.
SubjectUltrasound seismic velocities; Geothermy; Borehole rock samples; Refectivity; Swiss Molasse
Organisational unit09494 - Saar, Martin O. / Saar, Martin O.
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Is part of: https://doi.org/10.3929/ethz-b-000445518
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