A major part of the multiple energy in seismograms is caused by reflections from the free surface, which often contaminate the primary reflections that propagate from the subsurface as upgoing waves. Since such energy come down from the ocean surface and is contained in the downgoing wavefield, it can naturally be suppressed by attenuating the downgoing wavefield, provided the wavefield can successfully be separated into the upgoing and downgoing parts. Generally, wavefield separation is performed on multicomponent ocean-bottom seismic (OBS) data. However, as a simplification of this method, this decomposition also can be realized on dual-sensor OBS data. In this report, the wavefield separation techniques on multicomponent or dual-sensor data are discussed in detail and the algorithms for attenuating the downgoing wavefield are presented.
View full article as PDF (0.25 Mb)