基于自适应变步长波场延拓的可控层分阶层间多次波模拟  

Modeling inter-layer multiples based on adaptive step-length-varying wavefield extrapolation

作　　者：匡伟康 胡天跃[1] 段文胜[2] 李劲松[3] 李艳东[3] KUANG WeiKang;HU TianYue;DUAN WenSheng;LI JinSong;LI YanDong(School of Earth and Space Science,Peking University,Beijing 100871,China;Tarim Oilfield Company,PetroChina,Korla Xinjiang 841000,China;Research Institute of Petroleum Exploration&Development,PetroChina,Beijing 100083,China)

机构地区：[1]北京大学地球与空间科学学院,北京100871 [2]中国石油塔里木油田公司,新疆库尔勒841000 [3]中国石油勘探开发研究院,北京100083

出　　处：《地球物理学报》2020年第5期2043-2055,共13页Chinese Journal of Geophysics

基　　金：国家重点研发计划(2018YFA0702503);国家自然科学基金(41674122);国家科技重大专项(2016ZX05004003)联合资助.

摘　　要：地下低速夹层的存在导致地震数据中包含较强能量的层间多次波,有效识别和预测深部储层上覆地层产生的层间多次波是提高深部储层解释精度的重要环节,而准确模拟层间多次波是辅助识别地震数据中层间多次波的一种非常有效的方法.本文提出了一种基于自适应变步长波场延拓的可控地层分阶层间多次波模拟方法,该方法基于自适应变步长波场延拓,以递归循环的方式实现分阶层间多次波的模拟.通过对模型添加双重层位约束,可以模拟指定地层产生的各阶层间多次波.利用二维反周期延拓方法压制波场延拓的边界反射优于传统方法,例如吸收边界法.提出自适应变步长波场延拓技术,大大提升了波场模拟的效率.理论和数值例子表明,本文方法模拟的一次波和各阶层间多次波与常用的有限差分方法模拟结果具有很好的一致性,且克服了有限差分方法无法分阶模拟波场的不足,显著提升了层间多次波识别的效率.Seismic data may contain some strong internal multiples resulted from low-velocity layers above the target reservoir.Identification and prediction of such internal multiples in seismic data are important procedures to achieve reliable interpretation.Internal multiples modeling is an effective way to distinguish the internal multiples in seismic data.We propose a method to simulate internal multiples of given layers based on adaptive step-length-varying wavefield extrapolation.Each order of internal multiple is simulated by the recursive loops.With the given layer constraints,internal multiples of varied orders can be simulated.A 2D antiperiodic extension method is implemented to suppress the boundary reflections,which is better than traditional ways,such as the absorbing boundary condition.A novel method of adaptive step-length-varying wavefield extrapolation is proposed to make the simulation more efficiently.Theoretical study and numerical examples show that the results of this method are consistent with the traditional finite difference method.Furthermore,this method can simulate internal multiples of different orders in given layers thus remarkably enhancing the efficiency of multiples identification,which the finite difference method cannot realize.

关 键 词：自适应变步长波场延拓 可控层 分阶层间多次波 波场模拟 

分 类 号：P631[天文地球—地质矿产勘探]