Four-parameter velocity analysis and its applications to Shengli Ken-71 multicomponenet seismic data

摘要

The Shengli Ken-71 area 3-D multicomponent seismic data were acquired by digital MEMS (micro-electro-mechanical system ) sensors over a mixed sand and shale sequence in the overburden. This gives rise to serious non-hyperbolic moveout effects in the converted-wave data due to both the asymmetry raypath and the anisotropic effects. Conventional velocity analysis based isotropic methods can no longer flatten the moveout. Here, we use a four-parameter theory to evaluate these effects and process the data. These four parameters include the PS converted wave stacking velocity (V_(C2)), the vertical velocity ratio (γ_0), the effective velocity ratio (γ_(eff)) and the anisotropy parameter (X). The method utilizes the moveout information at different offsets to estimate the different parameters, and ensures that the events are properly a-ligned for stacking. As a result, this four-parameter theory leads to an improvement in imaging quality and correlation between the P-waves and con-verted-waves.