基于矢量波场逆时偏移的保幅角道集提取方法（英文）

发布时间：2018-10-05 19:17

【摘要】：将偏移后的炮域偏移距道集转换为角度域共成像道集(ADCIGs)可为偏移速度分析(MVA)和叠前反演提供输入道集,并且ADCIGs是理论上没有假象的叠前反演道集,也是目前公认的精度最高的叠前反演道集。本文研究了基于矢量波场逆时偏移的弹性波保幅ADCIGs的提取方法,以保幅弹性波逆时偏移方程为基础,其核心是求取不同震源位置的纵、横波场在地下各成像点的入射角,对于转换波勘探,二者共享一个入射角,即震源纵波入射角。根据几何关系,震源纵波波场的传播角、构造的局部地层倾角之差为震源纵波入射角,震源纵波波场的传播角利用解耦后纵波场的极化向量得到,构造的局部地层倾角利用偏移叠加剖面的复波数得到。对纵、横波的共炮点偏移道集按入射角重新排列即可得到各自的ADCIGs。文中利用水平层状介质模型、倾斜层状介质模型、Marmousi-Ⅱ弹性波部分模型和实测资料验证了算法的有效性,计算结果表明,本文方法计算的纵、横波角度具有较高的精度,提取的角道集具有较好的振幅保真性,能够为MVA和叠前反演提供可靠的输入道集。
[Abstract]:Converting offset gathers in offset domain into angle domain common imaging gathers (ADCIGs) can provide input gathers for migration velocity analysis (MVA) and prestack inversion, and ADCIGs is a theoretical prestack inversion gathers without false image. It is also recognized as the highest accuracy of prestack inversion gathers. In this paper, the extraction method of elastic wave conformal ADCIGs based on vector wave field inverse time migration is studied. Based on the amplitude preserving elastic wave inverse time migration equation, the core of the method is to obtain the incident angles of the longitudinal and transverse wave fields at various imaging points under the ground. For converted wave exploration, they share an incident angle, that is, the source longitudinal wave incident angle. According to the geometrical relation, the propagation angle of the source longitudinal wave field, the difference of the local stratigraphic dip angle of the structure is the source longitudinal wave incident angle, and the propagation angle of the source longitudinal wave field is obtained by using the polarization vector of the decoupled longitudinal wave field. The local stratigraphic dip angle of the structure is obtained by using the complex wave number of the migration stack section. The common shot offset gathers of longitudinal and shear waves can be rearranged according to the incident angle to obtain their respective ADCIGs.. In this paper, the effectiveness of the algorithm is verified by using the horizontal layered medium model, the inclined layered media model and the measured data. The results show that the longitudinal and shear wave angles calculated by this method have high accuracy. The extracted corner gathers have good amplitude fidelity and can provide reliable input gathers for MVA and prestack inversion.
【作者单位】：青岛海洋地质研究所;海洋国家实验室海洋矿产资源评价与探测技术功能实验室;中国海洋大学海底科学与探测技术教育部重点实验室;
【基金】：supported by Financially Supported by Qingdao National Laboratory for Marine Science and Technology(No.QNLM2016ORP0206) National Science and Technology Major Project(No.2016ZX05027-002) China Postdoctoral Science Foundation(No.2017M612219) National Key R&D Plan(Nos.2017YFC0306706 and 2017YFC0307400) Financially Supported by Qingdao National Laboratory for Marine Science and Technology(No.QNLM201708) Natural Science Foundation of Shandong Province(No.ZR2016DB10) National Natural Science Foundation of China(Nos.41674118,41504109,and 41506084) Key Laboratory of Submarine Geosciences Foundation of SOA(No.KLSG1603) Qingdao Municipal Applied Research Projects(No.2016238)
【分类号】：P631.4

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