Determining sea surface elevation to reduce effect of sea surface ghost reflections

摘要

Method for reducing the effect of rough sea surface ghost reflections in marine seismic surveys involves determining the sea surface elevation above the seismic source(s) and/or receiver(s) which may comprise streamers or ocean bottom cables. Sea surface waves occupy a frequency band of 0.03 Hz to 1 Hz and the wave height near the source of receiver location can be calculated by recording water pressure variation at that location within this low frequency band. The pressure data may be recorded by dedicated sensors or advantageously the data can obtained directly from the seismic receivers, preferably, seismic hydrophones or geophones that output their raw signals prior to conventional high-pass filtering. The sea elevation is calculated from the measured hydrostatic pressure and preferably includes corrections for effects due to rough sea waves and the depth of the sensors. The 2-D sea-surface may be reconstructed using the resultant data allowing the sea surface reflection response to the determined.