Shear Waves in Streamer Data via Non-geometrical Conversions

In this paper we show that when an airgun source and a hydrophone streamer are situated in the vicinity of the water bottom, shear-related events are generated via the evanescent part of the P-wave in the water. The shear-related events are not only the often-used surface/Scholte waves but also body S-waves which can be reflected/refracted in the subsurface. The gain of this approach that neither source nor receiver is making any contact with the water bottom itself, making it possible to do shear-wave surveys on water in an efficient manner. We show that such shear-wave events are observed in real data, and can be reproduced by modelling. The results are further validated via real measurements in a borehole.