Marco Mantovani

3D Velocity Model Building via Simultaneous Joint Inversion of 2D Seismic and 3D Gravity Datasets

In 2D seismic surveying the geology is often under-sampled in space. The geologic structures change in space more rapidly than what the grid sampling can capture. In modeling, tomography is used to infer perturbations in the ray trajectory and time, in order to update the velocity of the time reflections. To obtain a reliable solution, it is essential to provide the inverse solver with the most uniform information distribution in terms of areal coverage, offset and azimuth of propagation. The SJI methodology enables building a single 3D velocity model inferred by the simultaneous use of multiple 2D seismic lines of varying orientations and of a 3D non-seismic (potential field or EM) measurement. 2D seismic lines are gridded in a single 3D volume and inverted jointly with either 3D gravity or 3D EM data. While these 3D non-seismic measurements operate on their own properties for minimizing their own data misfit, the similarity criterion regularizes the 3D structure to the velocity property operated by the seismic data. This enables an advanced imaging for the 2D seismic lines. In particular, the estimation of a correct 3D tilt angle from the model enables the application of tilted-transverse isotropic (TTI) ray-tracing technology for tomography and migration.

Feasibility study for long offset seismic acquisition in a thrust‐belt

A new approach is used to define the optimal parameters for long offset acquisition in a thrust belt. The feasibility study makes use of ray-tracing, tomography, FD acoustic modelling and PSDM to determine the maximum offsets that could be used for imaging purposes and for velocity model building. The optimal acquisition parameters are then sought in terms of source spacing, maximum offset and actual coverage in the offset range that would provide the best imaging potential for the target.

Seismic long offsets for imaging below complex overburden

The feasibility of using seismic long offsets for imaging targets located below complex overburden is investigated by using synthetic modeling procedures based on a real geologic model of the central Apennines, Italy. Illumination through ray tracing, acoustic modeling and depth imaging through PSDM are the techniques used. The results indicate that extended offsets up to two times the depth of the target can be successfully used for imaging without introduction of artifacts and that the imaging results are substantially better than those obtained with a conventional seismic layout.