基于波动方程的薄互层正演模拟方法

The forward modeling method of thin interbeding based on wave equation

在薄互层正演模拟研究中,传统的褶积模型无法模拟地层中复杂的波场传播现象,导致在实际研究中存在一定的局限性.本文针对这一问题,提出了基于波动方程的薄互层正演模拟方法.该方法首先建立薄互层地质模型,并根据研究的需要转化成薄层和隔层地质模型.然后在频率-波数域通过相移算子完成地震波场的正向延拓,经各级地层界面反射后,反向延拓到地面,形成地面反射波场.对地面波场进行反傅立叶变换将其变换到时间域,形成正演模拟后的反射地震记录.不同厚度薄层、薄互层和隔层正演模拟结果表明:基于波动方程薄互层正演模拟方法可充分体现地震波传播过程中的动力学特性,可以完成任意厚度地层的精确模拟.

Conventional convolution model can not simulate the complex wave field propagation phenomena in strata therefore there are some limitations in the studies of thin interbeding forward modeling.Aimed at this problem,a forward modeling of thin interbeding based on wave equation is presented.The geological model of thin interbeding is firstly established and this model can convert into the thin layer and barrier bed model according to the request of research.Then the phase-shift operator is used to complete the seismic wave field downward extrapolation in frequency-wavenumber domain.The seismic wave field after interface reflection of the different levels of strata is extrapolated upward to the ground and form the ground reflection wave field.This wave field is transformed to time domain seismic record by using the inverse Fourier transform.The forward modeling result of thin layers,thin interbeding and barrier bed with different thicknesses show that the forward modeling method of thin interbeding based on wave equation can fully reflect the dynamic characteristics of seismic wave propagation and complete accurately simulation of any thickness thin layer.