Imprints of Earth Transmission on Seismic Reflections

Broadband seismic acquisition and advances in amplitude preserving processing have driven the industry toward pre-stack reflection amplitudes that are proportional to the earth’s subsurface reflectivity; resulting in improved drilling success rates and increased production. The amplitude and phase of a reflection is a function of spreading loss, inelastic attenuation, interbed multiples and transmission loss interacting with the spatial distribution of elastic (Vp, Vs, anisotropy and density) and inelastic (Qp, Qs) earth properties. Effective Qp (absorption plus scattering) for near-surface layers is on the order of 5-10 (Mangriotis, et al., 2013) and typically increases with depth to 50-130 for water saturated sediments. Vertical and wide-angle scattering can reduce amplitudes by factors of 2 to 3. Taken together these effects can alter absolute amplitudes by factors of 50 and relative event amplitudes vs. offset by factors of 0.3 to 3.