GNGTS 2018 - 37° Convegno Nazionale

GNGTS 2018 S essione 1.1 111 After loading the SEG-Y files labelled as NOR01 (migrated), NOR02 (stack & migrated) into OpendTect software (http://dgbes.com/) , we tested several seismic attributes, and the most relevant are listed below: - “ Energy ” (E): ratio between the sum of the squared sample values within a specified time window and the number of samples in the gate (Forte et al. , 2012, Ercoli et al. , 2015). The Energy is a measure of the reflectivity, useful to emphasize low or irregular amplitude reflections (acoustic rock properties), and to enhance lateral variations in seismic events. - “ Energy gradient ” (EG): the first derivative of the Energy with respect to time (or depth). It is very effective to better display, with a relative low level of subjectivity, detailed 2D/3D semi-automatic mapping of horizons and lateral discontinuities like channels or faults. - “ Pseudo-Relief ” (PR): the “Energy” attribute is first computed in a short time window, then it is followed by a phase rotation of -90° degrees though a Hilbert transform. Such an attribute is very commonly used in 2D seismic interpretation by the interpreters: the seismic section appears as “topography-like” image, allowing an easier detection of faults. Fig. 2 - Attribute analysis on NOR1 (Norcia Basin, Nb). a) standard amplitude line; b) Energy-Gradient (EG) displaying the top Basement s.l. (blu arrows) and the enhanced signature of faults (red arrows).