A simulation study to verify the effects of air waves in Sea Bed Logging for shallow water

Detection of hydrocarbons (HC) by a Controlled Source Electromagnetic (CSEM), based on resistivity contrast, makes electromagnetic (EM) waves convincing method for HC detection in deep water exploration. However, HC survey done in shallow water is difficult due to a phenomenon called “air wave effect”. The waves that are produced by EM transmitter interact with air-sea interface to generate air waves that diffuse from the sea surface to the receivers. These air waves dominate the measured EM data such that the presence of the HC may not be detected. This work is a verification of the effect of air waves in shallow water environment. Data with hydrocarbon at 500m depth and data without hydrocarbon were simulated using CST EM Studio for this study for sea water depths from 1000m to 100m. Results have shown that the presence of hydrocarbon in shallow water is shielded by air waves.