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

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.