当前位置: X-MOL 学术Geophysics › 论文详情
Our official English website, www.x-mol.net, welcomes your feedback! (Note: you will need to create a separate account there.)
Seismic diffraction separation in the near surface: Detection of high-contrast voids in unconsolidated soils
Geophysics ( IF 3.3 ) Pub Date : 2021-03-11 , DOI: 10.1190/geo2020-0366.1
Parsa Bakhtiari Rad 1 , Craig J. Hickey 1
Affiliation  

Seismic diffractions carry the signature of near-surface high-contrast anomalies and need to be extracted from the data to complement the reflection processing and other geophysical techniques. Because diffractions are often masked by reflections, surface waves, and noise, careful diffraction separation is required as a first step for diffraction imaging. A multiparameter time-imaging method is used to separate near-surface diffractions. The implemented scheme makes use of the wavefront attributes that are reliable fully data-derived processing parameters. To mitigate the effect of strong noise and wavefield interference in near-surface data, our workflow incorporates two wavefront-based parameters, dip angle and coherence, as additional constraints. The output of the diffraction separation is a time trace-based stacked section that provides the basis for further analysis and applications such as time migration. To evaluate the performance of the proposed wavefront-based workflow, it is applied to two challenging field data sets that were collected over small culverts in very near-surface soft soil environments. The results of the proposed constrained workflow and the existing unconstrained approach are presented and compared. The proposed workflow demonstrates superiority over the existing method by attenuating more reflection and noise, leading to improved diffraction separation. The abundance of unmasked diffractions reveals that the very near surface is highly scattering. Time migration is carried out to enhance anomaly detection by focusing the isolated diffractions. Although strong diffractivity is observed at the approximate location of the targets, there are other diffracting zones observed in the final sections that might bring uncertainties for interpretation.

中文翻译:

近地表的地震衍射分离:未固结土壤中高对比度孔隙的检测

地震衍射带有近地表高对比度异常的特征,需要从数据中提取出来以补充反射处理和其他地球物理技术。因为衍射经常被反射,表面波和噪声掩盖,所以作为衍射成像的第一步,需要仔细的衍射分离。多参数时间成像方法用于分离近表面衍射。实施方案利用了波前属性,这些属性是可靠的,完全由数据得出的处理参数。为了减轻强噪声和近场数据中的波场干扰的影响,我们的工作流程将两个基于波前的参数(倾角和相干性)纳入了其他约束条件。衍射分离的输出是基于时间轨迹的堆叠部分,为进一步分析和应用(例如时间迁移)提供了基础。为了评估所提出的基于波前的工作流程的性能,将其应用于两个极具挑战性的现场数据集,这些数据集是在非常近地表的软土环境中的小涵洞上收集的。提出并比较了所提出的约束工作流程和现有的无约束方法的结果。拟议的工作流程通过衰减更多的反射和噪声,证明了优于现有方法的优势,从而改善了衍射分离。大量未掩盖的衍射表明,非常近的表面是高度散射的。通过聚焦分离的衍射来进行时间迁移以增强异常检测。
更新日期:2021-03-12
down
wechat
bug