10 February 2020

QI workflows assume that seismic amplitudes are only linked to contrasts in rock properties, and that other wave propagation effects such as illumination, absorption, etc. have been addressed during seismic data processing and imaging. This assumption is often not met. The consequence is that 1D wavelets can’t adequately relate seismic amplitudes to reflectivity contrasts, and conventional time-domain inversion approaches inevitably struggle to accurately estimate the elastic rock properties. The effects of irregular illumination can be modelled by Point Spread Functions (PSFs), and removed from the seismic image with an inversion directly in the depth domain (Fletcher et at., 2012). This technique, called Depth Domain Inversion (DDI), improves imaging and inversion results by correcting for the effects of irregular illumination caused by the geological structure and overburden velocity variations. A North Sea case study is presented where DDI is enhances amplitude fidelity and resolution beneath cemented sand injectites.

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