Comparative Analysis of the Resolution of Marine Electromagnetic Technologies in the Time and Frequency Domains

A comparative analysis of marine controlled source electromagnetic technologies in the frequency (FD CSEM) and time (TD CSEM) domains for solving hydrocarbon exploration problems is presented. One of the important goals of the research is to develop requirements for measuring equipment in order to increase the level of anomalous signal from the target, improve the signal-to-magnetotelluric (MT) noise ratio, and also reduce the influence of geological interference. The analysis was carried out using 3D finite element modeling for geoelectrical models corresponding to real oil and gas fields. It is shown that TD CSEM method allows us to obtain a significantly larger relative response from the resistivity anomaly at a high absolute value of the anomalous signal in comparison with FD CSEM method. The signal-to-noise ratio in TD CSEM method is at least no worse than in FD CSEM method. It is also shown that both methods are sensitive to geological interference such as salt bodies and near-seabed heterogeneities, but their influence can be reliably excluded by using measurements at different time channels for TD CSEM method or frequencies for FD CSEM method.