Two‐dimensional seismic imaging of the Valhall model from synthetic OBC data by frequency‐domain elastic full‐waveform inversion

Abstract

Quantitative imaging of the elastic properties of the subsurface is essential for reservoir characterization. We apply two‐dimensional frequency‐domain full‐waveform inversion (FWI) to image shallow‐water synthetic and models of the Valhall oil and gas field from 3‐C ocean‐bottom‐cable data. In soft‐seabed environment where a small amount of P‐to‐S mode conversion occurs at the sea bottom, the seismic wavefield is dominated by the P waves whereas the S waves have a weaker signature. We first show that acoustic FWI of elastic data provides accurate model in such environment. Elastic FWI, that is desired for reservoir characterization, is a more difficult task. Hierarchical processing of the different parameter classes and data components is required, in addition to low‐frequency data and robust multi‐scale algorithm, to converge toward acceptable models.