一种基于能量密度空间聚类算法的面波频散曲线自动拾取方法

    A method for automatically picking surface wave dispersion curves based on the energy density-based spatial clustering of applications with noise algorithm

    • 摘要: 面波分析方法目前已广泛应用于许多不同领域,用于表征近地表的横波速度结构。面波频散信息的提取是面波分析方法的重要环节之一,传统的频散曲线拾取方法主要是通过手动拾取,或人为划定频散能量区域半自动拾取。对于油气勘探中地震数据量大的特点,人工处理方法无法达到实际生产要求。为此,本文采用一种基于无监督机器学习方法来自动拾取多阶频散曲线。首先,利用能量阈值滤波去除一部分频散谱中的背景噪声点。然后通过基于能量密度的噪声应用空间聚类(E-DBSCAN)算法将其区分为不同的面波模式。最后搜索不同面波模式区域中的峰值,并通过卡尔曼滤波进行平滑处理来消除噪声的影响,获得多模式频散曲线。该方法考虑了频散能量值,具有较高的可靠性。数值实验表明,自动拾取的频散曲线能与理论频散曲线准确地匹配。同时,方法对比及实际数据测试进一步证实了方法的可靠性。

       

      Abstract: Surface wave analysis, used to characterize near-surface shear-wave velocity structures, has been widely applied to various distinct fields. Extracting surface wave dispersion information serves as a significant step in surface wave analysis. Conventional methods for picking dispersion curves primarily include manual picking and semi-automatic picking in manually delineated dispersion energy zones. Given the large volume of seismic data used in oil and gas exploration, manual processing methods struggle to satisfy the requirements of practical production. Therefore, this study proposes a method for automatically picking multi-mode surface-wave dispersion curves based on an unsupervised machine learning approach. First, some background noise points in a dispersion spectrum are removed using energy threshold filtering. Second, different surface wave modes in the dispersion spectrum are determined using the energy density-based spatial clustering of applications with noise (E-DBSCAN) algorithm. Third, energy peaks in zones corresponding to different surface wave modes are searched, followed by noise elimination through Kalman filtering and smoothing. As a result, multi-mode dispersion curves are obtained. The proposed method incorporates dispersion energy values, offering high reliability. Numerical experiments demonstrate that the automatically picked dispersion curves accurately match the theoretical dispersion curves. Meanwhile, method comparison and field data tests further confirm the reliability of the proposed method.

       

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