Thin-bed AVO effects

Tuning caused by closely spaced impedance boundaries affects seismic amplit udes. At zero-offset the shape of the composite reflected signal approaches the time-derivative of the original pulse as the layer thickness decreases . For layers thinner than half of the tuning thickness, the reflected ampli tude is modified by a factor equal to twice the time-thickness of the thin layer. Offset-dependent tuning can be approximated by the time differences between primary reflections. For high-velocity contrasts locally converted waves will also affect the total reflected seismic response. The contributi on from intrabed multiples can, in most cases, be ignored. Correction for o ffset-dependent tuning should be considered before conventional AVO analysi s.