Model-based Attenuation for Scattered Dispersive Waves

Coherent noise in land seismic data primarily consists of source-generated surface-wave modes. This ground roll consists of surface-wave modes propagating directly from sources to receivers. Near surface heterogeneities and discontinuities 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 usually can address the tails and not the apices of the scattered events. Large source and receiver arrays can attenuate scattering, but only in exchange for compromise to signal fidelity and resolution. We present a model based technique for the scattering attenuation, based on the estimation of the surface-wave properties and on the prediction of the 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 cope with aliased surface waves.