1. Guangdong Provincial Key Laboratory of Geophysical High-Resolution Imaging Technology, Southern University of Science and Technology, Shenzhen, Guangdong 518055, China; 2. Department of Earth and Space Sciences, Southern University of Science and Technology, Shenzhen, Guangdong 518055, China; 3. Guangzhou Marine Geological Survey, Guangzhou, Guangdong 511458, China
Abstract：The marine controlled-source electromagnetic method (MCSEM) is an effective method to evaluate and accurately explore offshore oil gas traps. At present, the three-dimensional forward modeling of the accurate, efficient, and stable MCSEM data has made great progress. In terms of the accurate three-dimensional forward modeling of MCSEM, the electrical characterization of a three-dimensional grid is refined, and a grid element function based on porosity and rock physical properties is established through the classification characteristics of marine strata and rocks. The resistivity characterization of five types of media in the MCSEM circuit is given in this paper, such as the grid unit of the copper electrode, seawater layer, submarine sediment layer, oil and gas reservoir layer, and its cover layer. At the same time, the equivalent model of complex resistivity is fitted to the dispersion test data of the above five types of media, and the optimal characterization of the complex resistivity is further obtained. The modeling method considering the porosity of reservoir rocks and the characteristics of seawater stratification and sufficiently utilizing the known information can improve the accuracy of 3D simulation and provides an idea for the direct inversion of oil saturation in reservoirs. As a result, the method will inevitably promote the wider application of the MCSEM in the field of oil and gas exploration.
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