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近年来,基于Lowrank近似的qP波正演模拟受到广泛关注。通常的Lowrank近似两步法波场外推虽然也能消除伪横波干扰,但是两步法依赖一个实值的相位函数,且在大时间步长不适用。基于Lowrank近似的qP波一步法波场外推方法具有处理复值相位函数的能力,对相位函数进行改进,加入速度梯度项,并成功应用于TTI介质qP波正演模拟。通过试验可知:基于Lowrank近似的一步法波场延拓具有传统两步法的优点,无伪横波干扰,在大时间步长波传播时比两步法更加稳定;各向异性情况下,一步法波场外推适用于任意倾角情况下,波场模拟结果清晰准确,没有发生不稳定。
In recent years, based on Lowrank approximation of qP wave forward simulation has received widespread attention. The usual Lowrank two-step wavefield extrapolation can also eliminate the pseudo-shear wave interference, but the two-step method relies on a real-valued phase function and does not apply in large time steps. The qP wave based on Lowrank approximation method has the ability of dealing with complex-valued phase function, improves the phase function and adds the velocity gradient term, and has been successfully applied to the qP wave forward modeling of TTI media. It can be seen from the experiment that the one-step wavefield continuation based on Lowrank approximation has the advantages of the traditional two-step method without pseudo-transverse wave interference and is more stable than the two-step method in large-time-wave propagation; in the case of anisotropy, Field extrapolation applied to any inclination case, the wave field simulation results are clear and accurate, there is no instability.