Separation of diffracted waves via SVD filter
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ORIGINAL PAPER
Separation of diffracted waves via SVD filter Hong‑Yan Shen1,2 · Qin Li1 · Yue‑Ying Yan1 · Xin‑Xin Li1,2 · Jing Zhao1,2 Received: 7 January 2020 © The Author(s) 2020
Abstract Diffracted seismic waves may be used to help identify and track geologically heterogeneous bodies or zones. However, the energy of diffracted waves is weaker than that of reflections. Therefore, the extraction of diffracted waves is the basis for the effective utilization of diffracted waves. Based on the difference in travel times between diffracted and reflected waves, we developed a method for separating the diffracted waves via singular value decomposition filters and presented an effective processing flowchart for diffracted wave separation and imaging. The research results show that the horizontally coherent difference between the reflected and diffracted waves can be further improved using normal move-out (NMO) correction. Then, a band-rank or high-rank approximation is used to suppress the reflected waves with better transverse coherence. Following, separation of reflected and diffracted waves is achieved after the filtered data are transformed into the original data domain by inverse NMO. Synthetic and field examples show that our proposed method has the advantages of fewer constraints, fast processing speed and complete extraction of diffracted waves. And the diffracted wave imaging results can effectively improve the identification accuracy of geological heterogeneous bodies or zones. Keywords Geological heterogeneity · Reflected waves · Diffracted waves · SVD filter · Seismic wave field separation · Migration imaging
1 Introduction Accurate identification of faults, thin-outs, karsts, lens bodies, collapse columns, fracture zones and other heterogeneous regions is one of the important, though difficult, goals of seismic data processing and interpretation (Yilmaz 2001; Khaidukov et al. 2004). Reflected waves are a reflection of the interface morphology of the subterranean strata, which is mainly characterized by lateral continuity. However, the interface of geological heterogeneous bodies is rough or there is no horizontal continuous interface at all. When the downing wave fields meet the geological heterogeneity, it will cause the seismic energy to diverge to the surroundings. Therefore, the seismic response characteristics
Edited by Jie Hao * Hong‑Yan Shen [email protected] 1
School of Earth Sciences and Engineering, Xi’an Shiyou University, Xi’an 710065, Shaanxi, China
Key Laboratory of Shaanxi Province for Oil and Gas Accumulation Geology, Xi’an 710065, Shaanxi, China
2
of geological heterogeneous bodies (such as breakpoints, pinch-outs, karsts and collapse columns) often appear as diffracted waves (Bansal and Imhof 2005; Fomel et al. 2007; Decker et al. 2015). The diffracted waves are seismic responses caused by uneven geological bodies in the strata, which carry high-resolution, potentially even super-highresolution, geological information (Neidell 1997; Khaidukov et al. 2004; Rad et al. 20
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