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Improving the plane‑wave destruction method by parameterizing the local slope for VSP wavefield separation

Guo Yinling, Peng Suping, Du Wenfeng, Li Dong, Li Chuangjian

Acta Geophysica

2023

Vol. 71, no. 4

1659--1673

High-precision seismic exploration has attracted a great deal of attention. Vertical seismic profiles have the advantages of high exploration accuracy and ideal imaging effects, making them an effective tool for mine exploration. The separation of upgoing and downgoing waves is a vital step in vertical seismic profile processing. However, wavefield separation processing in the frequency–wavenumber domain often leads to aliasing in the time–distance domain. In addition, it is likely to result in incomplete wavefield separation in the sparse domain because of inaccurate threshold selection. As an effective time–distance domain wavefield separation method, the plane-wave destruction method can effectively avoid these problems. However, the traditional local slope estimation in plane-wave destruction is data-driven, making it difficult to distinguish linear upgoing and downgoing waves. Therefore, the velocity-based local slope parameterization method is proposed to construct a plane-wave destruction filter that can be used to separate the vertical seismic profile wavefield. Synthetic and field data show that the proposed separating strategy has higher separation accuracy than traditional methods when separating the upgoing and downgoing waves of vertical seismic profile data.

Influence of seismic diffraction for high-resolution imaging: applications in offshore Malaysia

Bashir Y., Ghosh D. P., Sum C. W.

Acta Geophysica

2018

Vol. 66, no. 3

305--316

Small-scale geological discontinuities are not easy to detect and image in seismic data, as these features represent themselves as diffracted rather than reflected waves. However, the combined reflected and diffracted image contains full wave information and is of great value to an interpreter, for instance enabling the identification of faults, fractures, and surfaces in built-up carbonate. Although diffraction imaging has a resolution below the typical seismic wavelength, if the wavelength is much smaller than the width of the discontinuity then interference effects can be ignored, as they would not play a role in generating the seismic diffractions. In this paper, by means of synthetic examples and real data, the potential of diffraction separation for high-resolution seismic imaging is revealed and choosing the best method for preserving diffraction are discussed. We illustrate the accuracy of separating diffractions using the plane-wave destruction (PWD) and dip frequency filtering (DFF) techniques on data from the Sarawak Basin, a carbonate field. PWD is able to preserve the diffraction more intelligently than DFF, which is proven in the results by the model and real data. The final results illustrate the effectiveness of diffraction separation and possible imaging for high-resolution seismic data of small but significant geological features.