Velocity Model Construction and Time-to-Depth Conversion of a Vintage Seismic Reflection Profile for Improving the Constraints on a Subsurface Geological Model: An Example from the Sicily Channel (Central Mediterranean Sea)

Abstract

The well-known uncertainties in subsurface velocity field definition call for the integration of all the available data, including vintage seismic profiles, which, despite typically being in raster or paper format, often contain velocities derived from stacking and associated interval velocities. This study aims to build a velocity model for the time-to-depth conversion of an interpreted seismic reflection profile by using the interval velocity reported on a vintage, paper-format seismic profile and contribute to improving the subsurface geological model of the Sicily Channel, Central Mediterranean. Spline interpolation is used for velocity model building of the shallower part (3.5 sec TWT) of the seismic profile CS89-01, derived from the stacking velocities of 31 Common Depth Point (CDP) gathers. This was followed by the Gaussian convolution operator and a data exclusion filter to improve the accuracy of the velocity model. The time-to-depth-converted seismic reflection profile is a regional cross-section that covers almost the entire Sicily Channel, crossing part of the northern margin of the African Plate, from Tunisia to eastern Sicily. This study provides a new subsurface velocity field that can be applied, or taken into account, to most parts of the Sicily Channel when structural and stratigraphic interpretations are carried out at specific sites and where uncertainties in subsurface geological model exist (e.g., in the present study, the volcanic bodies in the Pantelleria Graben and Lampedusa High).