基于各向异性介质理论的煤系地震数据高分辨处理方法与应用

A high-resolution method for processing coal measures seismic data based on anisotropic medium theories and its application

  • 摘要: 【目的】随着深部资源勘探开发的重要性不断提高,对高精度地震勘探提出了新要求。针对具有强各向异性的含煤地层,传统基于各向同性的资料处理方法不再适用。【方法】提出一种基于水平横向各向同性介质(Transverse Isotropy Medium with Vertical Symmetry Axis,VTI)和方位各向异性介质(Transverse Isotropy with Horizontal Axis of Symmetry,HTI)联合处理的地震数据处理方法。首先,针对含煤地层沉积特征,分析VTI介质特点,采用高阶动校正处理,可以有效消除各向异性在大偏移距数据中引起的同相轴弯曲,保证共反射点远近道能达到同相,提高数据叠加成像质量。其次,针对构造裂隙发育特征,立足于HTI介质的方位各向异性分析,采用OVT域处理方法,通过建立方位各向异性参数场去除不同方位角差异对数据的影响。联合应用上述2种处理方法,通过制定合理的处理流程,优选关键参数,搭建一套实用的、适合目标地层的各向异性处理校正方法,解决含煤地层在复杂条件下的速度分析、叠加等问题,从而提高煤系地震数据的分辨率和解释精度。【结果和结论】实际应用结果表明,新方法获得的地震数据主频更高、频带更宽,在小构造特征识别和古地理环境刻画方面更具优势,为精细地质解释提供了有力支撑。同时也强调了对含煤地层进行各向异性处理的必要性,推动各向异性处理技术的在宽方位地震勘探中的应用。

     

    Abstract: Objective The increasing importance of the exploration and exploitation of deep resources poses new requirements for high-precision seismic exploration. Given that conventional isotropy-based data processing methods are no longer applicable to the coal-bearing strata with strong anisotropy. Methods This study proposed a method for processing seismic data based on theories of both transverse isotropy medium with a vertical symmetry axis (VTI) media and transverse isotropy with a horizontal axis of symmetry (HTI) media. First, to characterize the depositional characteristics of coal-bearing strata, this study analyzed the features of VTI media, revealing that high-order dynamic correction can effectively eliminate anisotropy-induced event bending in large-offset seismic data, thus ensuring that the common reflection points in both far and near channels can be in-phase and improving the data stacking and imaging quality. Second, targeting the characteristics of tectonic fissures, this study relied on the azimuthal anisotropy analysis of HTI media. Specifically, using Offset-Vector Tiles (OVT) domain processing, the influence of varying azimuthal differences on data was removed by establishing the parameter fields of azimuthal anisotropy. Using both methods, this study developed a practical processing and correction method suitable for target strata with anisotropy by establishing a rational process and choosing optimal key parameters. This method can achieve effective velocity analysis and data stacking of coal-bearing strata under complex conditions, thus improving the resolution and interpretation accuracy of coal measures seismic data. Results and Conclusions The application results indicate that the new method can obtain seismic data with higher dominant frequency and a wider frequency band and is more advantageous in identifying the features of small structures and characterizing paleogeographic environments, thereby providing strong support for the fine-scale geological interpretation. This study highlighted the necessity of the processing of anisotropy for coal-bearing strata, potentially promoting the applications of anisotropy processing techniques in wide-azimuth seismic explorations.

     

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