Abstract

The wavefield created by a seismic source propagates in all three dimensions. Marine seismic towed streamer acquisition geometries are long and thin and consequently record only a small part of the 3D reflected wavefield, in effect measuring a small azimuth range of the full 3D wavefield. In areas where the geology is simple and homogeneous this limited surface geometry can still provide consistent illumination of the target reservoirs. However in areas where the geology is complex (due to high dip, complex structure, faulted over-burden and lateral velocity and facies changes), the ray paths are bent and scattered in the overburden and inconsistently measured with the relatively narrow surface spread. In extreme cases large zones of the target horizon can be completely unilluminated by the towed streamer dataset.