22 September 2020

In this EAGE E-Lecture: "Seismic Attenuation: Friend or Foe", we assess the role of attenuation in marine near surface seismic reflection data sets and discuss whether it is a potentially useful property for quantitative characterisation of the subsurface. The basic theory of intrinsic attenuation is briefly outlined, introducing the seismic Quality factor (Q-factor) parameter. We show several methods that can be used to make estimates of the subsurface Q-factor from single-channel or short-offset seismic reflection data and how basic data quality can be improved by compensating for attenuation. Moreover, we look at how variations in Q-factor reflect changing ground conditions, demonstrating a strong link with sediment lithology and drained versus undrain soil mechanical behaviour. By combining Q-factor estimates with more standard geophysical parameters (P-wave velocity and/or impedance) we illustrate how fundamental ground conditions can be inferred using geophysical data alone. As such, we suggest that attenuation should be considered a useful quantitative parameter, alongside reflection amplitude, phase and frequency.

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