断层阴影区地震优势信号提取新技术及其在西湖TT区的应用

    A new technique for seismic dominant signal extraction in fault shadow zone and its application in TT Block, Xihu Sag, East China Sea

    • 摘要: 在复杂断块地区,地震成像受断层的影响,断层下盘同相轴出现“上拉”、“下拉”或者同相轴错断的现象,极大地影响了断层圈闭构造高点的确定以及圈闭幅度的准确判断。开展针对复杂断层的高精度速度建模和高精度成像技术被认为是解决断层阴影区成像的主要处理技术解决方案。立足于地震采集信号自身的属性信息,充分挖掘地震信号的潜力,提出广角反射的折射线性去噪技术、中低频有效信号提取技术和优势信号精细速度建模技术,在西湖TT区目标评价中取得了良好的效果,明显减低了断层阴影对目标构造形态的影响,提高了构造圈闭定位的准确性。应用结果表明:通过准确的PSDM速度模型结合断层阴影区优势信号的提取,获得更聚焦的反射能量,断层阴影区弱振幅区得到消除,有效改善了断裂阴影区的成像效果。

       

      Abstract: In complex fault block areas, seismic imaging is affected by faults, resulting in the phenomenon of "pull up", "pull down", or displacement of same phase axis in the footwall of the fault, which greatly affects the determination of the structural highs of fault traps and the accurate judgment of trap amplitude. High-precision velocity modeling and high-precision imaging for complex faults were considered the main processing technological solutions for imaging the shadow zones of faults. Based on the attributes of the seismic acquisition signal, we fully explored the potential of seismic signal and proposed techniques for refractive linear denoising for wide angle reflection, the medium- and low-frequency effective signal extraction, and the dominant signal fine velocity modeling, which have achieved good outcome in the target evaluation for the TT area of Xihu Sag in East China Sea, significantly reduced the influence of fault shadow on the target structural morphology and improved the accuracy of fault trap locating. The application results show that by combining accurate PSDM (pre-stack depth migration) velocity model and the extraction of dominant signal of fault shadow zone, more focused reflection energy could be obtained, the weak amplitude zone of the fault shadow zone was eliminated, and the imaging effect of the fault shadow zone was effectively improved.

       

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