Theoretical analysis of the application of pseudo-noise signals in marine pulse electromagnetic prospecting

Abstract

Using numerical modeling of a useful signal based on  a characteristic geoelectric model of underwater permafrost and real recordings of a noise signal, we conducted a comparative analysis of noise suppression during transient sounding using a marine towed dipole-dipole array in accumulation modes with opposite-polar current pulses and pseudo-noise signals (PNS). For a series of current sequences in the form of PNS with different durations and numbers of pulses, as well as for a signal in the accumulation mode, with the superposition of an identical noise signal, transient sounding curves were obtained corresponding to the geoelectric model under consideration at a recording time of the order of 8–13 s per station. Based on the results of comparison of the obtained curves reconstructed from noisy synthetic data in the accumulatio n and PNS modes, it was established that in the PNS mode with pulses of duration 100 μs and 1 ms, the relative error in the PNS mode on average over the profile turns out to be significantly lower (up to 1.5 times) than a similar one error in the accumulation mode, and remains within an acceptable value (up to several percent) until later times.