| 基于格林函数理论的波场预测和鬼波压制方法 |
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| 引用本文： | 李洪建,韩立国,巩向博,刘强,周岩.基于格林函数理论的波场预测和鬼波压制方法[J].地球物理学报,2016,59(3):1113-1124. |
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| 作者姓名： | 李洪建 韩立国 巩向博 刘强 周岩 |
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| 作者单位： | 1. 吉林大学地球探测科学与技术学院, 长春 130026;2. 国土资源部应用地球物理重点实验室, 长春 130026 |
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| 基金项目： | 国家高技术研究发展计划(863计划)重大项目课题(2014AA06A605)和国家自然科学基金项目(41374115)联合资助. |
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| 摘 要： | 作为一种特殊的噪声,鬼波对一次波的波形及频带宽度产生极大的影响,鬼波压制是提高海上地震资料分辨率及保真度的重要因素.以格林公式为基础,详细论述了基于格林函数理论的鬼波压制方法,在不需要地下介质信息的条件下,进行地震数据驱动鬼波压制,并根据"Double Dirichlet"(双狄利克雷)边界条件,预测压力波场和垂直速度波场.建立了基于格林函数理论鬼波压制的处理流程,数值模拟和实际资料处理结果表明,基于格林函数理论鬼波压制方法在很好地去除鬼波的同时极大地拓宽了地震资料的频带,尤其提升了低频端能量,有利于后续资料的处理解释.
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| 关 键 词： | 格林函数 鬼波压制 双狄利克雷 波场预测 |
| 收稿时间： | 2015-05-22 |
A wavefield prediction and ghost suppression method based on Green function theory |
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| LI Hong-Jian,HAN Li-Guo,GONG Xiang-Bo,LIU Qiang,ZHOU Yan.A wavefield prediction and ghost suppression method based on Green function theory[J].Chinese Journal of Geophysics,2016,59(3):1113-1124. |
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| Authors: | LI Hong-Jian HAN Li-Guo GONG Xiang-Bo LIU Qiang ZHOU Yan |
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| Institution: | 1. College of Geo-Exploration Science and Technology, Jilin University, Changchun 130026, China;2. Key Laboratory of Applied Geophysics, Ministry of Land and Resources, Changchun 130026, China |
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| Abstract: | Conventional acquisition in marine seismic exploration cannot remove ghost, a special noise, effectively, which has a great impact on waveforms and the bandwidth of primaries. Due to the incidence angle of the upgoing wavefield and the depth of streamer cable, interference between upgoing and downgoing wavefields creates nulls or notches in the recorded spectrum, which will lead to narrow band. So deghosting is one of the most important factors for enhancing resolution and higher fidelity in marine seismic exploration.To acquire broad-band data, we discuss a deghosting method based on Green function theory. We start from Green's formula and scattering theory, and firstly introduce a perturbation operator. The actual wave velocity can be treated as a perturbation of the background medium. We replace parameters of Green's formula with actual wavefield and Green function, then the upgoing wavefield can be calculated based on measured wavefield and its vertical derivative. However, the vertical derivative cannot be measured directly, so we adopt Huygens-Fresnel principle and integrate the energy of every virtual receiver. By using "Double Dirichlet" boundary conditions, the pressure and vertical velocity fields at any depth can be predicted.Three models are used to test our method. The first one is a simple three layer model, using 7 m depth streamer wavefield, we accurately estimate pressure and vertical velocity fields of 2 m. After deghosting, the ghost energy is removed, and simultaneously the signal-noise ratio is improved. Another example is actual dual-sensor data. Compared with original records, the resolution is improved with clearer events followed ghost suppressed. We supplement the notch energy and broaden the band effectively. Finally we apply the idea to actual towed streamer data. After wavefield prediction and deghosting, we improve the energy of low-frequency part.Based on Green's formula, a deghosting method based on Green theory is presented. Without the need of any subsurface information, it can successfully achieve data-driven ghost removal. By using "Double Dirichlet" boundary conditions, we can predict pressure and vertical velocity fields at any depth. In this paper, we establish a ghost suppression processing. The examples of a synthetic data and a marine data show that ghost can be well attenuated, simultaneously the band especially the low-frequency component is broadened, which is favorable for subsequent processing and interpretation. |
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| Keywords: | Green's function Deghosting Double Dirichlet Wavefield prediction |
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