Table-driven 3-D angle-domain imaging approach for Kirchhoff prestack time migration
表驱三维角度域Kirchhoff叠前时间偏移成像方法

To overcome some of the shortages of widely-used Kirchhoff presatck time migration technique and to provide more powerful supports for amplitude versus incidence-angle and azimuth (AVA/AVAZ) analysis, we present a 3-D angle-domain imaging approach for prestack time migration based on the ray theory. Numerical tables of one-way traveltime and propagation angle for the reflection waves are first established by improved ray-tracing algorithm in the laterally homogeneous media. After the two-way traveltimes, weighted factors, azimuth and incidence angles at the reflectors are estimated, 3-D structural images and angle-domain common-image gathers are obtained through superposition of the impulse responses in the process of prestack time migration. Unlike the conventional approach, the implementation in this paper has taken ray-bending effect and 3-D propagation property of seismic waves in the real media into account. So it helps to extract variations of amplitude and moveout versus azimuth and incidence-angle more accurately. Synthetic and real data examples demonstrate the advantage and practicability of this technique.