南方典型煤田小断层地震属性定量判别研究

Quantitative discrimination of seismic attributes of small faults in southern typical coalfield

  • 摘要: 断层是诱发矿井安全事故的重要因素,对落差5 m以内小断层的识别是一大难点。选取南方典型煤田——贵州省六盘水煤田作为研究区,对煤田地层进行详细调查和现场踏勘,设计地震物理模型,采用特有速度比1∶1.74,实现地震物理模型对埋深800 m、1 000 m和1 200 m,落差5 m、3 m和1 m小断层的构建和分析。应用地震波动力学方法提取多种地震属性对小断层进行分析,获得振幅包络、振幅一阶导数、振幅二阶导数等7种地震属性对小断层特征响应的敏感程度,据此建立地震属性与落差之间的相关关系。研究表明,当煤层小断层落差5 m以内时,不仅与传统上的振幅属性存在线性关系,还与相位、频率有关的地震属性成线性关系,其中振幅包络和振幅虚部的相关性较高,瞬时频率、振幅一阶导数、余弦瞬时相位、振幅二阶导数和振幅包络相关性较低。

     

    Abstract: Faults are an important factor inducing mine safety accidents, and it poses difficulties on the identification of faults within 5 m of drop.Taking the Liupanshui coalfield of Guizhou province as the study area, this paper investigated the coalfield strata and carried out an on-site survey.It proposed a seismic physical model and used the unique velocity ratio of 1∶1.74 to realize the construction and analysis of small faults with a burial depth of 800 m, 1 000 m and 1 200 m and a drop of 5 m, 3 m and 1 m.This paper extracted a variety of seismic properties by seismic dynamics method to analyze small faults, and obtained the sensitivity of seven seismic properties to the characteristic response of small faults, including amplitude envelope, amplitude first derivative, and amplitude second derivative, and the correlation between seismic properties and drop was established accordingly.The results show that when the small fault drop of the coal seam is less than or equal to 5 m, there is a linear relationship with the traditional amplitude attributes, and a linear relationship with the seismic properties related to phase and frequency.There is high correlation between the amplitude envelope and the amplitude imaginary part, and low correlation between the instantaneous frequency, the amplitude first derivative, the cosine instantaneous phase, the amplitude second derivative and the amplitude envelope.

     

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