Time-frequency Domain Electromagnetic Sounding to Map Deep Targets in M Depression

This study discussed the application of time-frequency domain electromagnetic (TFEM) sounding technique to map and characterize the deep basement structure. It has enhanced our understanding of the deep basement structure of the Permian and Carboniferous formation in the M depression of the SH Basin in western China. The electrical structure from the 2 TFEM sounding inversion sections and residual gravity anomalies reflect the development of the east and west Carboniferous residues subsags within the M depression.

The M depression developed 2 Carboniferous residues subsags in the east and west direction. The TFEM inversion section shows a 1,000 m ∼ 1,500 m thick low resistivity layer on the top of the east subsag but not on the top of the west subsag, and this low resistivity layer is thicker in the east and south direction but thinner in the west and north side. Therefore, we believe the east subsag located on the east-south side of M depression is the major residual hydrocarbon generation subsag, and it extends to the northeast side. This study has also identified local volcanic rock bodies with hydrocarbon potential in the Carboniferous residual hydrocarbon generation subsag on the southeast side of the M depression.