海洋可控源电磁法三维模拟电性模型研究

海洋可控源电磁法(MCSEM)是实现海洋油气圈闭评价和精确勘探的有效手段。目前，关于准确、高效、稳定的MCSEM数据三维正演模拟研究已取得长足进步。文中针对MCSEM正演的三维精确建模，从海洋地层岩石分类特征出发，细化三维网格电性表征，建立基于孔隙度和岩石物性特征的网格单元函数，给出了海洋可控源电磁回路中包括铜棒电极的网格单元和海水层、海底沉积层、油气储层及其盖层等五种类型介质的电阻率表征，同时通过对上述五类介质的频散测试数据进行复电阻率等效模型拟合，进一步获得其复电阻率最优表征。考虑储层岩石孔隙度及海水分层特征、充分利用已知信息的建模方法能够提高三维模拟精度，为直接反演储层含油饱和度提供了一种思路，这必将推动MCSEM在油气勘探领域更广泛的应用。

Study on the geo-electrical models for three-dimensional simulation of marine controlled-source electromagnetic fields

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.