Method for obtaining a volumetric image of a geological structure present in the subsoil, the method comprising the phases of: - generating a plurality of seismic waves by means of a plurality of seismic sources; - acquiring a plurality of signals or traces, obtained by processing the seismic waves reflected by the geological structure, for creating a seismic record or shot gather for the same activation position of each seismic source; - migrating, through a numerical processing, the shot gathers for creating respective partial volumetric images of the geological structure, characterized in that the phase of migrating the shot gathers is obtained through the following phases: - grouping the seismic sources into a plurality of groups (G N) of N seismic sources each, wherein the N seismic sources of a generic group (G k) have a reciprocal distance such as to be contained in a circumference having a diameter (d k) lower than a predefined maximum distance (d max); - grouping the groups (G N) of seismic sources into super-groups of N groups (G N) each, wherein each super-group is composed by N 2 seismic sources and wherein the reciprocal distance (d i,k) between the barycentres of two distinct groups (G i,G k) of seismic sources belonging to the same super-group is greater than a predefined minimum distance (d min); - effecting N migrations for each super-group, wherein for each migration a composite N order shot gather is migrated, obtained by selecting a seismic source from each group (G N), thus obtaining the migration of N 2 seismic sources with N distinct migrations; - summing the single partial volumetric images thus obtained for attaining the overall volumetric image (I i) of the geological structure. - generating a plurality of seismic waves by means of a plurality of seismic sources; - acquiring a plurality of signals or traces, obtained by processing the seismic waves reflected by the geological structure, for creating a seismic record or shot gather for the same activation position of each seismic source; - migrating, through a numerical processing, the shot gathers for creating respective partial volumetric images of the geological structure, - grouping the seismic sources into a plurality of groups (G N) of N seismic sources each, wherein the N seismic sources of a generic group (G k) have a reciprocal distance such as to be contained in a circumference having a diameter (d k) lower than a predefined maximum distance (d max); - grouping the groups (G N) of seismic sources into super-groups of N groups (G N) each, wherein each super-group is composed by N 2 seismic sources and wherein the reciprocal distance (d i,k) between the barycentres of two distinct groups (G i,G k) of seismic sources belonging to the same super-group is greater than a predefined minimum distance (d min); - effecting N migrations for each super-group, wherein for each migration a composite N order shot gather is migrated, obtained by selecting a seismic source from each group (G N), thus obtaining the migration of N 2 seismic sources with N distinct migrations; - summing the single partial volumetric images thus obtained for attaining the overall volumetric image (I i) of the geological structure.