Analysis of Induction-polarization Response Characteristics of Marine Controlled-source Electromagnetic Multiphase Composite Medium

The complex composition and structure of the submarine reservoir and its secondary pyrite, which are multiphase composite media, can provoke the induced polarization (IP) effect, resulting in the change of the marine controlled-source electromagnetic (CSEM) induction-polarization response, which directly affects geological interpretation results. In this paper, the generalized effective-medium theory of induced polarization (GEMTIP) model is introduced to study the influence of composition, structure and geometric characteristics of submarine reservoirs and secondary pyrite on the 3D marine CSEM induction-polarization response. We first construct the 3D finite-difference frequency-domain (FDFD) electromagnetic field governing equation based on the GEMTIP model, apply the emission source on the non-uniform grid, and solve the linear equations by using the difference coefficient matrix. Then we perform forward calculation on a typical 1D reservoir model to verify the correctness and effectiveness of the proposed algorithm. Finally, we design the reservoir and secondary pyrite models, and analyze the influence laws of IP parameters and polarization layer geometry parameters on the 3D marine CSEM induction-polarization response. These studies are of great value for understanding the relationship between submarine multiphase composite medium and electromagnetic wavepropagation.