共接收点倾斜叠加波动方程偏移

WAVE EQUATION MIGRATION AFTER COMMON RECEIVING POINT SLANT STACKS

共接收点倾斜叠加波动方程偏移,本质上是一种叠前偏移方法.每给定一个斜率P,对经过叠前(动校正前)常规处理的地震记录中的各共接收点道集,沿直线t=τ+px进行倾斜叠加,就形成一个共接收点倾斜叠加剖面.对之进行波动方程偏移,该偏移剖面将代表地下真实构造.对一系列的p,我们可以得到一系列这样的偏移剖面.对它们作共接收点叠加,偏移叠加剖面的信噪比将超过水平叠加剖面.本文导出了在均匀、水平层状及非均匀介质条件下的共接收点倾斜叠加波动方程偏移算法.

Wave equation migration after common receiving point slant stacks (WEMCRPSS) is essentially a prestack migration method. Common receiving point gathers are formed before NMO correction. The traces in each gather are stacked slantly into one trace along the line t = τ + px. These traces stacked are combined according to receiving points to form a common receiving point slant stack(CRPSS) section. We can migrate the CRPSS section with wave equation and obtain image of the earth structure. A series of migrated CRPSS sections corresponding to different P values can be gotten. The sections migrated are stacked into one section according to receiving points. The primary reflections migrated to their reflecting points can be stacked in phase. But multiples are not stacked in phase and are weakened comparatively because there are moveouts changing with slope p for the multiples migrated with wrong velocities. Random noises and other disturbances are also suppressed. The S/N of the section stacked after migrations will be greater than CMP stack section especially in the areas where CMP stacks are not the exact common reflecting point stacks- The migration methods of CRPSS sections are deduced for horizontal layer, homogeneous, and inhomogeneous media.