ABSTRACT Seismic velocity is an attractive parameter for geohazard interpretation, pore pressure analysis, play and prospect evaluations, and other geological studies, but ordinary seismic processing velocities often do not have a good enough resolution. We adapt a dynamic time warping algorithm to estimate geologically reasonable high‐resolution velocities from average‐quality seismic data that can be used for geohazard analysis based on 3D seismic data. To predict free gas and/or excess pore water pressure in thin shallow layers, we use velocity inversion. It is a method for simultaneous inversion of velocity data to geological attributes. It runs in the depth domain, uses a background velocity model for balancing of input velocities to wells and a normal compaction trend model to simultaneously estimate lithology, pore pressure and net apparent erosion attributes, while porosity is calculated from a sandstone–porosity relationship. The overall workflow is applied for geohazard analysis at two marine sites. The first example is a deep‐water one from the Norwegian Sea, where thin and possibly overpressured or gas‐filled layers are identified in the Pleistocene section. The second example is in a region with limestone‐dominated lithology, where thin overpressured shales can cause severe drilling problems. In both examples, the thicknesses of the layers prone to geohazards are estimated to be about half of the wavelength. Dedicated high‐resolution velocity estimations, such as those obtained through the proposed workflow with dynamic time warping, applied to standard 3D seismic data and followed by dedicated velocity inversion routines, are, therefore, a necessity for proper geohazard assessment.

中文翻译：

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高分辨率地震速度场估计技术及其在地质灾害、岩性和孔隙度预测中的应用

摘要 地震速度是地质灾害解释、孔隙压力分析、远景区评价和其他地质研究的一个有吸引力的参数，但普通的地震处理速度通常没有足够好的分辨率。我们采用动态时间扭曲算法从可用于基于 3D 地震数据的地质灾害分析的平均质量地震数据中估计地质合理的高分辨率速度。为了预测薄薄层中的游离气体和/或超孔隙水压力，我们使用速度反演。它是一种将速度数据同时反演为地质属性的方法。它在深度域中运行，使用背景速度模型来平衡井的输入速度和正常压实趋势模型来同时估计岩性，孔隙压力和净表观侵蚀属性，而孔隙度是根据砂岩-孔隙度关系计算的。整个工作流程应用于两个海洋站点的地质灾害分析。第一个例子是来自挪威海的深水层，在更新世剖面中发现了薄且可能超压或充满气体的层。第二个例子是在一个以石灰岩为主的岩性地区，那里薄的超压页岩会导致严重的钻井问题。在这两个例子中，容易发生地质灾害的层的厚度估计约为波长的一半。专用的高分辨率速度估计，例如通过建议的具有动态时间扭曲的工作流程获得的，应用于标准 3D 地震数据，然后是专用的速度反演程序，因此，