Improving the Accuracy of 3-D Modeling Electromagnetic Fields in Marine Electrical Prospecting Problems

The paper is devoted to a new approach to modeling 3-D electromagnetic fields in marine electrical prospecting problems for the development of requirements for equipment and data processing during its testing and carrying out offshore hydrocarbon exploration. The proposed approach is based on a two-stage primary-secondary field approach. On the one hand, it ensures the maximum closeness of the primary field to the total field, which makes it possible to use coarse finite element meshes and thereby reduce computational costs. On the other hand, this approach takes into account bathymetry and curved surfaces of the geological layers as adequately as possible. Computational experiments show high accuracy of the obtained numerical solutions. The calculation error is less than 5% of the target response, and it is actually lower than the noise level of the modern measuring equipment and noise caused by vibrations of the measuring cable. It is shown that when conducting a profile survey, the sea depth must be known at a distance of at least 2000 m from the survey line.