Understanding seismic thin-bed responses using frequency decomposition and RGB blending

1 ffA, Northpoint, Suite E3, Exploration Drive, Aberdeen, AB23 8HZ, UK. 2 Norwegian Energy Company ASA, Verksgata 1a, 4003 Stavanger, Norway. * Corresponding author, E-mail: [email protected] Abstract RGB colour blending is a powerful technique of co-visualization of different band-limited magnitude volumes created by frequency decomposition. The aims of this study were to investigate the impact of changes in geometry and acoustic impedance on what we observe in a blend of frequency magnitude volumes, and to examine how sensitive different methods of frequency decomposition are to these variations. We present a comparison of frequency decomposition methods applied to the Hermod Member submarine fan system, a well understood fan system from the Northern North Sea, and to simple synthetic models. Observations made from RGB imaging are compared to equivalent results from synthetic models created using well measurements and systematic variations in reservoir parameters. We show that thickness variations between events are the dominant factor controlling RGB colour response and that subtle lithological changes, presented as differences in acoustic impedance, are a second order effect. Furthermore, when the source frequency and decomposition bands of a synthetic wedge model are matched to a real dataset, we can relate colour values directly to thicknesses. In doing so we extend the classical tuning wedge for use as a calibration tool for frequency decomposition colour blends. Understanding seismic thin-bed responses using frequency decomposition and RGB blending