粘弹性波动方程正演和偏移

理论和实际研究均表明大地介质属于非完全弹性介质,它是具有粘滞性的粘弹性体,地震波在大地中传播时,质点的震动能量转化为其他各种形式的能量,这种能量的转化使地震波在粘弹性介质中传播时,其高频成分很容易被吸收,振幅近似按指数规律衰减,波形和相位失真.作者从二维粘弹性波动方程出发,在频率波数域内导出了粘弹性波动方程的正演和偏移算法.根据设计的地质模型,分别对粘弹性介质和弹性介质中的点状绕射源进行正演模拟,模拟结果表明介质的粘滞性对地震波予以吸收和衰减;将粘滞性介质中点状绕射源的正演结果,分别用粘弹性波动方程偏移算法和弹性波动方程偏移算法进行偏移模拟,并予以对比分析,其结果进一步说明了对实际介质中地震波的吸收和衰减作用的处理效果,证明了所得算法的准确性和有效性.

Viscoelastic wave equation forward modeling and migration

The theoretical research and actual investigation show that actual media is not elastic media, but is viscoelastic media, and that the seismic wave was absorbed and weakened, its processing was affected. There were some research reports on seismic wave processing in the world, but none of the methods was based on frequency wavenumber domain . The method based on frequency wavenumber forward formula and migration arithmetic had characteristics of simpleness , celerity ,less dependence on stratum obliquity and good stabilization. According to the visco elastic wave equation, forward formula and migration arithmetic is put forward through F K method. In order to prove the validity of the method, a geology model was designed and made as input of forward formula of viscoelastic media and elastic media respectively. The results of forward modeling disclosed the attenuation and absorption of seismic wave in viscoelastic media. Migration was carried out on forward result of diffract point in viscoelastic by viscoelastic wave equation migration arithmetic and wave equation migration arithmetic respectively. The two results obtained were compared in this paper and showed the influence of absorption and attenuation of seismic wave on processing result, so the developed method is proved to be accurate and effective simultaneity.