Estimation of Induction Noise in a Towed EM Streamer

Towed-streamer receivers are in use for efficient acquisition of controlled source electromagnetic (CSEM) data. We investigate the contribution to the noise made by voltages induced, according to Faraday’s law of induction, in the telluric cables moving in the Earth’s magnetic field. We consider the Earth’s magnetic field to be spatially-invariant over the length of the receiver cable, and consider it to be either constant, or time variant. If the cable is straight behind the vessel, following the ship’s track, there is no induced voltage. If there are cross-currents and if the Earth’s magnetic field is time variant, there can be induced voltages which increase which the feathering angle, the length of the electric dipole receiver, and the magnitude of the rate of change of the magnetic field. Using a maximum feathering angle of 10° and the dipole length of 1100 m, the estimated noise is about two orders of magnitude less than the measured noise. We conclude that this is not the main source of noise. There must be some other mechanism causing the dominant component of the noise.