【摘要】 在海洋地震勘探中,由于海底面具有较强的波阻抗差,当海底面以下存在高速反射层或散射体时,在海底与高速层(体)间会发育较强的海底相关层间多次波。由于这种相关层间多次波无特定的识别特征而难以去除,增加了地震资料处理的难度。为此,本文提出了基于地震干涉理论的海底相关层间多次波衰减方法和实现流程。首先介绍了基于互易理论的地震干涉法原理,阐述了其在非均匀介质中的近似条件和表达式;在此基础上提出了通过海底一次反射记录和海底以下构造的反射记录来构建海底相关层间多次波。该方法克服了基于共聚焦点(CFP)延拓方法对速度场的依赖性与逆散射级数(ISS)法计算效率低的缺点,是一种数据驱动型层间多次波衰减方法。Sigsbee2B模型测试及实际资料处理结果表明,海底相关层间多次波得到了较好的预测,叠前深度偏移结果中的偏移假象得到了明显压制,证明了文中方法的有效性。更多还原

【Abstract】 In marine seismic exploration,due to strong impedance difference at the sea bottom,serious peg-leg multiples are generated between sea bottom and high velocity layers or scatters just under the bottom.This kind of peg-leg multiples is very difficult to remove because they have no specific characteristics.Based on seismic interferometry,we propose in this paper an approach for sea bottom related peg-leg multiple removal.First,we introduce the principle of seismic interferometry based on reciprocity theory,and illustrate its approximate conditions and expression in inhomogeneous media.Then we construct bottom-related peg-leg multiples with sea bottom primary reflections and under-bottom reflections.This data-driven multiple removal approach overcomes velocity dependent as common focus point(CFP)has,and has higher computation efficiency than inverse scattering series(ISS).Both Sigsbee2 Bmodel test and real data example show that the proposed approach can better remove bottom-related peg-leg multiples.Furthermore,prestack depth migration artifacts disappear after bottom peg-leg multiple removal by this approach.更多还原