Methodology Utilizing Continuous Source and Receiver Wavefields - Signal to Noise Ratio Considerations

The peak sound pressure levels (SPL) and the sound exposure levels (SEL) are significantly reduced with the seismic methodology based on the emission and recording of continuous source and receiver wavefields. The peak sound pressure levels are reduced because the emitted energy is spread out in time approaching the properties of white noise, in contrast to conventional marine sources where the emitted wavefield is approaching the properties of a spike. The energy levels emitted by marine seismic sources and its impact on the signal to noise ratio has been discussed in a number of papers. The ability to achieve comparable penetration in depth with the continuous wavefield method despite of significantly reduced peak SPL and SEL levels compared to the conventional marine seismic method is related to several aspects such as attenuation of shot generated noise, improved spatial sampling of source positions, and improved ability to attenuate noise with long continuous records. In this paper we will discuss the phase spectrum of the wavefield emitted by a source, and its influence on the signal to noise ratio after deconvolving the emitted wavefield from the received wavefield.