Stacking apertures and estimation strategies for reflection and diffraction enhancement

Abstract

It is well known that the quality of stacking results (e.g., noise reduction, event enhancement, and continuity) can be greatly influenced not only by the traveltime operator chosen but also by the apertures used. We have considered two so-called diffraction-stack traveltimes, together with the corresponding apertures, designed to enhance reflections and diffractions, respectively. The first one is the common-reflection-surface (CRS) diffraction traveltime that is obtained from the general CRS traveltime upon the condition that the target reflector reduced to a point, which we refer to as the diffraction CRS (DCRS) traveltime. The second one is the double-square-root (DSR) traveltime, well established in time migration. We have observed that the DCRS and DSR traveltimes depend on fewer parameters (two in 2D and five in 3D) than the full CRS traveltime (three in 2D and eight in 3D). For the DCRS and DSR traveltimes, we have proposed specific apertures based on the projected Fresnel zone, which are able to produce high-quality stacked sections using less parameters to be estimated. The key factor in that approach lies in the choice of traveltime operators together with careful selection of stacking apertures. In particular, suitable choices of operators and apertures lead to stacking volumes in which reflections are enhanced (and the diffractions are attenuated) or the corresponding ones in which diffractions are enhanced (and reflections are attenuated). Synthetic and field data confirm the proposed approach has good potential for image-quality improvement.

Stretch‐free generalized normal moveout correction

“…Due to its approximated nature, it demands appropriate midpoints and offsets apertures, which in our case are based on Faccipieri et al . () for the real aforementioned data set. Figure illustrates a seismic event and the CRS stacking surface depending on midpoint and half offset limited by apertures in both directions.…”

“…The CRS approach assumes locally continuous reflectors, in the subsurface, which have their traveltime approximation given by a squared second-order Taylor polynomial. Due to its approximated nature, it demands appropriate midpoints and offsets apertures, which in our case are based on Faccipieri et al (2016) for the real aforementioned data set. Figure 12 illustrates a seismic event and the CRS stacking surface depending on midpoint and half offset limited by apertures in both directions.…”

“…Coimbra, Novaes and Schleicheret (2016b) derived an accurate traveltime equation capable of identifying the common reflection point contribution along half offsets and midpoints that can be used in a finite-offset case. 52 C 2018 European Association of Geoscientists & Engineers Faccipieri et al (2016) proposed estimation and stacking apertures to ensure reliable fitting of the CRS traveltime and minimize event smoothing. Sarkar, Baumel and Larner (2002) and Fomel (2009) proposed modified coherence measures that consider amplitude variations along reflection events.…”

“…Faccipieri et al . () proposed estimation and stacking apertures to ensure reliable fitting of the CRS traveltime and minimize event smoothing. Sarkar, Baumel and Larner () and Fomel () proposed modified coherence measures that consider amplitude variations along reflection events.…”

Common Reflection Surface using Particle Swarm Optimization on Graphical Processing Unit Devices

“…where x is the source-receiver offset of the trace, t 0 is the traveltime for zero offset. This equation uses only one parameter to stack, that is the stacking velocity v. On the other hand, the CRS-2D uses the following traveltime equation (Jäger et al, 2001;Faccipieri et al, 2016)…”