Model-based attenuation for scattered dispersive waves
C. Strobbia, A. Zarkhidze, F. Ibrahim and R. May
Journal name: Geophysical Prospecting
Issue: Vol 62, No 5, September 2014 pp. 1143 - 1161
Info: Article, PDF ( 5.38Mb )
Coherent noise in land seismic data primarily consists in source-generated surfacewave modes. The component that is traditionally considered most relevant is the so-called ground roll, consisting in surface-wave modes propagating directly from sources to receivers. In many geological situations, near–surface heterogeneities and discontinuities, as well as topography irregularities, diffract the surface waves and generate secondary events, which can heavily contaminate records. The diffracted and converted surface waves are often called scattered noise and can be a severe problem particularly in areas with shallow or outcropping hard lithological formations. Conventional noise attenuation techniques are not effective with scattering: they can usually address the tails but not the apices of the scattered events. Large source and receiver arrays can attenuate scattering but only in exchange for a compromise to signal fidelity and resolution. We present a model–based technique for the scattering attenuation, based on the estimation of surface-wave properties and on the prediction of surface waves with a complex path involving diffractions. The properties are estimated first, to produce surface–consistent volumes of the propagation properties. Then, for all gathers to filter, we integrate the contributions of all possible diffractors, building a scattering model. The estimated scattered wavefield is then subtracted from the data. The method can work in different domains and copes with aliased surface waves. The benefits of the method are demonstrated with synthetic and real data.