自适应虚同相轴方法压制地震层间多次波

摘要

Seismic inter-bed multiples is a key factor to the quality of velocity analysis and the accuracy of seismic imaging.Compared with primaries,these multiples usually have similar NMO corrections,stacking velocity and traveltime,which is a challenge to distinguish,estimate and attenuate these sign als.The traditional virtual events method is based on the principle of pure physics and the accuracy of its prediction model can hardly facilitate inter-bed multiples estimation,which is also the main reason for the over-dependence on the adaptive matching algorithm.This paper proposed a new adaptive way of constructing virtual events based on rigorous theory deduction.Compared with the traditional virtual events method,the adaptive virtual events method can significantly improve the ability of suppressing inter-bed multiples and reduce the dependence of norm matching filter.This paper presents the deduction of the new theory and its application to 1D and 2D cases to show its advantage over the traditional method.Examples of the PLUTO model and land field data from western China prove that this new adaptive virtual events method is capable of suppressing inter-bed multiples,recovering and highlighting line-ups of reservoirs,and enhancing the resolution of seismic imaging.%地震数据中发育的层间多次波是影响速度分析和偏移成像的精度和可靠性的关键.通常情况下,层间多次波的动校正量、叠加速度和频率与一次波并无明显差异,从而对识别、预测和压制多次波带来了极大挑战.传统虚同相轴方法基于物理图像和定性公式,其预测的层间多次波振幅和相位精度难以满足实际需求,造成了其对匹配算法的过度依赖.本文针对传统虚同相轴方法的理论缺陷和计算精度问题,通过理论推导得到了新的自适应虚同相轴方法.相比于传统方法,自适应虚同相轴方法能够显著提高压制多次波能力,同时减少对匹配算法的依赖.本文给出了自适应虚同相轴方法的推导过程,并运用一维和二维模型算例验证了方法相较于传统虚同相轴方法的多次波预测精度优势.通过在PLUTO模型和实际陆地地震数据上的应用实例,证明了本文新研究的自适应虚同相轴方法对去除层间多次波,恢复并突出目标储层同相轴,提高地震成像分辨率的显著作用.