Low-frequency SNR improvement of refracted waves by cascaded correlation and convolution

Low-frequency SNR improvement of refracted waves by cascaded correlation and convolution

Velds, C.B.

Campman, X.H. (mentor)
Draganov, D. (mentor)
Wapenaar, C.P.A. (mentor)

Civil Engineering and Geosciences

Geoscience & Engineering

Applied Geophysics and Petrophysics

2014-08-21

Seismic interferometry is the process where new impulse responses, i.e. Green’s functions, are retrieved between two points by cross-correlation, convolution or deconvolution of wavefield responses. Seismic interferometry is also referred to as Green’s function retrieval. Newly retrieved Green’s function might contain spurious events that arise due to strict requirements for Green’s function representation for seismic interferometry that are not met in practice. Methods exist for the suppression of spurious events; however, it is shown in various studies that spurious events can be very useful. The virtual refraction is a well-known coherent spurious event that arises when refracted waves are correlated. This event can upon stacking be strongly enhanced with sources located post-critically in the stationary-phase region, which complies with typical 2D exploration source and receiver geometries. This event contains information of the velocity and depth of layers that cause waves to be guided along an interface (refraction). Source-receiver interferometry additionally to cross-correlation adds convolution to retrieve a Green’s function between a source and receiver, hereby turning a virtual refraction into a refraction with the same traveltime characteristics as the original refracted wave. This work explains how source-receiver interferometry can be applied to refracted waves. Synthetic seismic data and controlled-source field data shot in the desert in Oman are used to apply source-receiver refraction interferometry. Results show how signal-to-noise ratio for random noise as well as coherent noise refracted waves is improved in long-offset data.

active-source seismic-interferometry
Green's function retrieval

http://resolver.tudelft.nl/uuid:ac1c5b04-6562-423f-94b5-c7364b6afb35

Student theses

master thesis

(c) 2014 Velds, C.B.