基于拟声波一阶应力-速度方程的TI介质叠前逆时偏移

TI medium reverse time migration based on quasi acoustic first-order velocitystress equation

随着计算机硬件技术发展和对野外数据高分辨率勘探需求的增加,叠前逆时偏移技术逐渐的运用到实际生产中;又鉴于实际地层中各向异性的普遍存在性,故实现各向异性介质的叠前逆时偏移成像很有必要.文中从各向异性介质中弹性波的基本理论出发,导出各向异性介质中的拟声波一阶速度-应力方程,并基于此方程提出一套稳健的叠前逆时偏移策略.对逆冲模型的数值模拟表明在旋转角变化的TTI介质(具有倾斜对称轴的横向各向同性介质)中该拟声波方程稳定性要好于基于频散关系推导出的拟声波方程;VTI_HESS模型的逆时偏移结果表明较常规声波方程,新导出的拟声波方程成像更清晰,深处保幅效果更加明显.

With the development of computer computing rate and hardware level,especially the GPU parallel computing technology is introduced,prestack reverse time migration gradually used up to the field of seismic data. In view of the universal existence of anisotropy in the actual formation,considering anisotropy in the reverse time migration imaging is very necessary. In this paper,we will derive quasi acoustic first-order velocity-stress equation based on the basic theory of elastic wave in anisotropic medium,and According to this equation,put forward a set of robust prestack reverse time migration strategy. Numerical simulation of the thrust model shows that this new quasi acoustic wave equation in wave field extrapolation is more stability than the quasi acoustic wave equation which derived from dispersion relation in the TTI medium with the varying rotation. The HESS model of reverse time migration imaging showed that compared with the conventional acoustic wave equation, quasi acoustic wave equation imaging more clearly,the effect of amplitude preserving in depths is more obvious.