• anomalous events
• horizontal components
• precursor events
• VSP

In this work, I describe the VSP methodology and the processing of a near offset VSP data acquired in southern Tuscany, in the Travale geothermal field. VSP acquisitions are very important in complex areas, as they permit to validate surface seismic interpretation in the subsurface around the well.
The real data shows anomalous events in the horizontal components characterized by similar amplitude with those of the vertical component, usually the only ones present in near-offset data. An advanced elaboration is then carried out in order to understand these strong amplitude events. It results they are pure S waves, probably originated as a mode conversion close to the source position, at the surface.
The conventional processing is performed both for the vertical component and for the horizontal component of maximum energy. The same processing sequence is applied to deconvolved data: the deconvolution operator, directly derived from the signature traces, is applied to the traces in an early pre-stack stage.
I analyse also other anomalous events, that anticipates in time the direct arrivals on the horizontal components. They are explained by the interaction of the waves with the casing of the well.
The work compares then the results obtained by conventional and non conventional processing, with an enphasis to the output of the horizontal component processing. VSP results are then integrated into the 3D surface seismic of the geothermal area.