南黄海崂山隆起浅水多次波压制及成像分析

SHALLOW WATER MULTIPLES DEPRESSION AND IMAGING ANALYSIS ON THE LAOSHAN UPLIFT OF THE SOUTH YELLOW SEA BASIN

南黄海崂山隆起的中、新生代碎屑岩与下伏的古生代碳酸盐岩地层分界面是一个强反射界面,对地震波向下传播具有强烈的屏蔽作用,加之海上多次波比较发育,使得深部地震反射能量弱、成像困难。在浅水区,由于缺少近偏移距的海底反射信号,利用常规SRME(Surface related multiple elimination)方法不能有效地衰减海底相关多次波,Taup域预测反褶积压制多次波会破坏与海底多次波周期相近的一次有效反射信号,特别在硬海底多次波的振幅能量比海底反射还更强,这种情况下预测反褶积不能完全压制多次波。采用DWD+SRME组合法来衰减海底相关多次波,其中DWD(deterministic water-layer demultiple)方法用来衰减与海底相关的短周期多次波,SRME方法压制自由表面相关的长周期多次波,另外运用高精度Radon变换去除层间多次波,使多次波得到了良好的压制,深部有效反射信号逐步得以体现。通过以上处理效果揭示了崂山隆起为一个平缓的背斜构造,背斜上发育多个逆冲断裂,崂山隆起是在加里东期形成雏形,印支期隆起形成,燕山期为主要发展阶段。

The boundary between the Ceno-Mesozoic clastic deposits and the underlying Palaeozoic carbonate is a strong reflection interface on the Laoshan Uplift of the South Yellow Sea Basin. It acts as a strong shield to prevent the seismic waves from propagation downward, in addition to the multiples in the sea. As the results, deep seismic reflections are usually weak and difficult to image. Furthermore, there is lack of nearly offset reflected signals from seabed in shalloow water, the seabed related multiples can not be depressed effectively by conventional SRME （Surface Related Multiple Elimination） method. The Taup do- main predictive deconvolution method always destroy valid reflected signals if the wave cycle is similar to the seabed multiple, particularly if the seabed is hard. The amplitude of the seabed multiple wave energy is stronger than the seabed reflection. In this case, the method of predictive deconvolution can not be used to depress seabed related multiples entirely. In this paper, seabed related multiples wave depression is performed by using the DWD ＋ SRME combination method. DWD （Deterministic Water-layer Demultiple） method is used for attenuating short period seabed related multiples, and the SRME method is used for suppressing long period free surface related multiples. In addition, the method of Radon transform is also used for remove inter-layer multiples, so the multiples are depressed effectively, and thus deep reflection signals appear gradually. Trough the above mentioned seismic processing it is revealed that the Laoshan Uplift is a gentle anticline structure, and there are multiple thrust faults cutting through it. The Laoshan Uplift was embryonic in the Caledonian stage, formed in the Indosinian period and matured in the Yanshan period.