Synthetic seismic reflection modelling in the supercritical geothermal system of the Larderello field (Italy).

Synthetic seismic reflection modelling is a useful tool for geothermal exploration as it represents a remarkable support to calibrate geological-geophysical interpretations and model reconstructions, and to explore future seismic reflection acquisition and processing scenarios in geothermal prospecting. The aim of this work is to test the synthetic seismic reflection modelling along a seismic line (CROP-18A) crossing the historical site of Larderello geothermal field which, with its numerous wells and data, represents a valuable site to calibrate advanced exploration techniques in a potential supercritical geothermal system. The CROP-18A, as many others in the study area, is characterized by a discontinuous but locally very bright seismic marker, named K-horizon, which has been associated to various geological processes, among which to the presence of fluids at supercritical condition. The main effort of this work is oriented to test and verify the potentiality of synthetic seismic reflection modelling to the comprehension of the nature of the K-horizon. Two geophysical models are used to test the seismic response of the K-horizon, which is associated to 1) a lithological discontinuity, or 2) a "Physically Perturbed Layer", represented by a randomized velocity distribution in a thin layer. Despite the reliable calibration implied by the use of a lithological discontinuity, the seismic modelling clearly shows that the "Physical Perturbed Layer" explains better the reflectivity features associated to the K-horizon.