Exploring nonlinearity and nonuniqueness in surface-wave inversion for near-surface velocity estimation

With the rapid increase in prospecting for unconventional oil and gas, a large part of which remains on land, the demand for land seismic data processing has increased substantially and is expected to further increase in the future. It is known that land seismic data are often of much poorer quality than marine seismic data. This is to a large extent caused by the presence of unconsolidated rock in the near surface with often complex velocity structure, which is absent in many marine settings. Such near-surface variations cause the wavefield to scatter or even lose its coherence as it propagates. This makes it difficult to accurately image the deeper-lying targets in land seismic data.