摘要
海底Scholte波沿着海底流—固界面传播,具有典型的频散特性。Scholte波的频散特性可以反演海底浅层的横波速度,是海底横波速度建模的有效手段。建立准确的Scholte波频散理论模型至关重要。根据真实海水—海底环境建立水平层状海水—海底弹性模型,并利用边界应力和位移连续性条件推导了该模型的Scholte波频散方程及位移方程。分析了海水深度和海底物性参数对Scholte波频散特性的影响,6层海水—海底模型实验结果表明:①无论是硬海底还是软海底,Scholte波都具有明显的频散特性,硬海底Scholte波能量主要集中在海水中,基阶能量最弱,2阶能量最强,随着海水深度增加,Scholte波频散特性减弱;软海底模型固体海底的Scholte波能量明显增强,此时海水深度对Scholte波频散特性影响很小。②相比于深海环境,浅海Scholte波能量更强,频散特征更明显,因此在浅海环境利用Scholte波反演海底浅层横波速度的精度和可信度更高。最后,基于东海某工区的实际海底弹性地质模型模拟海底多分量地震数据并从中提取频散曲线,与理论计算的频散曲线进行对比分析,二者的频散曲线吻合很好,验证了所提理论方法的正确性。
Scholte waves propagate along the seafloor fluid‑solid interface and exhibit typical dispersion characteristics.The dispersion properties of Scholte waves can be utilized for the inversion of the shear wave velocity of the shallow seabed,making it an effective tool for seabed shear wave velocity modeling.It is of critical importance to establish the theoretical model of Scholte wave dispersion.In this study,a horizontal layered model of seawater‑seabed elasticity is developed based on a real seawater‑seabed environment.The dispersion equation and displacement equation for Scholte waves in this model are derived using the continuity conditions of boundary stress and displacement.The influence of seawater depth and seabed property parameters on the dispersion characteristics of Scholte waves is analyzed.Experimental results using a 6‑layer seawater–seabed model show that:①Regardless of the seabed is hard or soft,Scholte waves exhibit distinct dispersion characteristics.In the case of a hard seabed,the energy of Scholte waves is mainly concentrated in the seawater,with the fundamental mode having the weakest energy and the second mode having the strongest energy.As the seawater depth increases,the dispersion characteristics of Scholte waves weaken.For the soft seabed model,the energy of Scholte waves on the solid seabed significantly increases,and the seawater depth has little effect on Scholte wave dispersion characteristics.②Compared with deep‑water environments,Scholte waves have stronger energy and more pronounced dispersion characteristics in shallow water.Therefore,utilizing Scholte waves for inverting the shallow seabed shear wave velocity in shallow water environments yields higher accuracy and reliability.Finally,based on an actual seabed elastic geological model of a working area in the East China Sea,multi‑component seismic data are simulated,and dispersion curves are extracted.A comparison analysis between the theoretically calculated dispersion curves and the extracted dispersion curve
作者
于鹏飞
陈隽琳
江佳萌
杨小慧
YU Pengfei;CHEN Junlin;JIANG Jiameng;YANG Xiaohui(College of Oceanography,Hohai University,Nanjing,Jiangsu 210024,China;Sinopec Geophysical Research Institute,Nanjing,Jiangsu 211103,China)
出处
《石油地球物理勘探》
EI
CSCD
北大核心
2024年第2期206-218,共13页
Oil Geophysical Prospecting
基金
国家自然科学基金项目“海面拖缆与海底OBN/OBS地震数据联合弹性波成像方法研究”(42074149)
江苏省自然基金项目“改进的声—弹耦合方程及其在OBS地震数据弹性波成像上的应用”(BK20201318)联合资助。
关键词
Scholte波
水平层状海底
频散特性
振幅深度分布
横波速度
Scholte wave
horizontal and layered seabed
dispersion characteristics
amplitude‑depth distribution
shear wave velocity
