Joint 3D electromagnetic and seismic shallow subsurface velocity modeling

The well QT1 obtained industrial gas flow in the Carboniferous-Permian carbonate rock formations, highlighting the significant exploration potential of thrust imbricate structures in this region. However, The study area is characterized by complex surface lithology and structure, where rapid lateral velocity variations are observed in shallow layers, velocity modeling is challenged by significant difficulties, and shallow-to-deep migration imaging is complicated by inherent technical limitations, making the integration of seismic and non-seismic methods critical for collaborative investigation. By conducting 3D audio-frequency electromagnetic exploration, the distribution of shallow special lithologic bodies is delineated, and an innovative electromagnetic-seismic joint shallow velocity modeling method is developed, providing critical constraints for seismic velocity modeling. Results from processed field data demonstrate that 3D high-frequency electromagnetic exploration can play an important complementary role in shallow lithology modeling in the complex piedmont belts.