复杂地表地震资料叠前深度偏移成像

分析了复杂地表地区复杂地震波场的形成原因,探讨了基于高角度时空域单程波动方程适用于起伏地表之下构造成像的逆时叠前深度偏移方法。从声波方程有限差分法合成起伏地表上的炮集记录知,当激发点位于低速层中,共炮点道集中低速层表面和高速层表面接收到的信号强度相差较大:低速层表面的信号很强,而高速层表面的信号很弱,低速层中产生了较强的槽波。将该逆时叠前深度偏移方法应用于起伏地表地震波场的偏移处理。虽然在偏移成像前既没有压制与低速层有关的槽波,又没有压制随机噪声,但偏移剖面上界面清晰、位置正确,断层面也得到了很好的聚焦。

Prestack Depth Migration for Geological Structures with Complicated Surface

We analyzes the cause of formation of complicated wave field on rugged surface,and proposes a reverse-time prestack depth migration method based on a time-space domain one-way wave equation with high dip angle for imaging subsurface geological structures below the rugged surface.From synthetic shot gathers of a complicated structure with rugged surface simulated by solving acoustic wave equations using the finite-difference method,it is known that if the shot is in the low velocity layer,the energy received on the low velocity layer is much stronger than that received on the high velocity layer,and a strong guided wave is created in the low velocity layer.The proposed prestack migration method is applied to the synthetic shot gathers.Although neither the guided wave related to the low velocity media,nor the random noise is suppressed before migration,the interfaces are clear and their positions are correct,and the planes of fault are well focused too.