Application of the redundant‐lifting scheme for ground‐roll attenuation in near‐surface characterization using full‐waveform inversion on P‐wave seismic data

Abstract

ABSTRACTSeismic modelling of the shallow subsurface (within the first few metres) is often challenging when the data are dominated by ground‐roll and devoid of reflection. We showed that, even when transmission is the only available phase for analysis, fine‐scale and interpretable P‐wave velocity (VP) and attenuation (QP−1) models can still be prepared using full‐waveform inversion, with data being preconditioned for ground‐roll. To prove this idea, we suppressed the ground‐roll in two different ways before full‐waveform inversion modelling: first, through a bottom mute; second, through a novel wavelet transform‐based method known as the redundant‐lifting scheme. The applicability of full‐waveform inversion is tested through imaging two buried targets. These include a pair of utility water pipes with known diameters of 0.8 m and burial depths of 1.5 m, respectively. The second target is the poorly documented backfill, which was the former location of the pipe(s). The data for full‐waveform inversion are acquired along a 2D profile using a static array of 24, 40 Hz vertical component geophones and a buried point source. The results show that (a) the redundant‐lifting scheme better suppresses the ground roll, which in turn provides better images of the targets in full‐waveform inversion; and (b) the VP and QP−1 models from full‐waveform inversion of redundant‐lifting scheme data could detect the two targets adequately.