SEGJ Technical Conference

3D inversion of combined CSEM data of towed and ocean bottom receivers

Abstract Inversion of combined ocean bottom and towed receiver data of controlled-source electromagnetic (CSEM) surveys can map shallow and deep seafloor resistivity structures. Although two dimensional (2D) inversion has been used for the combined CSEM data, the 2D inversion has difficulty in incorporating the 3D distributed data and recovering the 3D resistivity structures below the seafloor. This study applies 3D inversion to the combined ocean bottom and towed receiver data of CSEM surveys. A synthetic test showed that the 3D inversion of the combined data could recover the shallow and deep seafloor resistivity structure close to the true structure. The inversion was applied to real CSEM data obtained in the Okinawa Trough. The resistivity model obtained from the combined data specified conductors, which might be related to sulfide deposits. The result using the synthetic and real data showed the effectiveness of the 3D inversion of the combined CSEM data to map shallow and deep seafloor resistivity structures.