Abstract

In marine seismic acquisition, the typical time interval between two adjacent shots is about 10s. This interval is considered sufficient to avoid the signal from one shot interfering with the signal from the next shot. However, when we are looking for very weak signals or weak changes in a given signal (time-lapse seismic), the influence of the shot-generated noise can be of importance. In the present work, shot records with a recording time of 30s are used to analyze the influence of the shot-generated noise from the previous shot. Simple decay models are used to match the observed rms decay curves. These calibrated models are used to estimate variations in signal-to-noise ratio versus shot time interval and source strength. For instance, if the source strength is doubled and the time interval between two shots is increased from 10to15s, an improvement in the signal-to-shot-generated noise from the previous shot of 4dB is expected. Especially for time-lapse seismic using permanently installed receivers, this way of increasing the S/N might be useful.

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