Revised Processing and Interpretation of Reflection Seismic Data in the Travale Geothermal Field (Italy)

Abstract

Despite difficult conditions, such as rough topography and complex geological structures, reflection seismic is now recognized as a successful method in the detailed exploration of deep geothermal steam reservoirs of Tuscany (central Italy).
In the present work, a unified approach is adopted for both data re-processing and interpretation.
The aim of seismic re-processing is to provide a common signature for lines recorded in the last decades at different times and with different procedures. During re-processing, emphasis is put on detailed velocity analysis and trace amplitude consistency. Consequently it is now possible to sharpen the seismic image at greater depths and to identify interesting seismic lineaments that can be related to deep exploration targets.
The interpretation of seismic data is supported by non-seismic information, such as: surface geology, well-logs, core descriptions, temperature profiles. This data is jointly visualized on workstation and attributes of interest (typically seismic amplitudes and well logs) are extracted and highlighted.
This unified approach reduces uncertainties in interpretation and gives confidence in describing the structure of the area, consisting of extensional faults affecting a deep, prominent reflector of regional importance (K Horizon). This K Horizon shows high-amplitude reflectivity, suggesting gas/steam accumulations. Similarly, high amplitudes also characterize a shallower and discontinuous reflector (H Horizon). These two main seismic features seem to be related to each other, since locally, they are vertically connected by the above mentioned fault system.
As a result, reflection seismic enhances the comprehension in the area of study and provides the structural framework contributing to build-up the overall geothermal reservoir model.