Angle domain converted wave Gaussian beam migration in VTI media

作者:Li ZhenChun; Liu Qiang*; Han WenGong; Zhang Min; Wang TianQi; Xiao JianEn; Wu JunHong
来源:Acta Geophysica Sinica, 2018, 61(4): 1471-1481.
DOI:10.6038/cjg2018K0455

摘要

As targets are highly variable complex reservoirs, the difficulty of hydrocarbon exploration has been gradually increasing. Taking into account the wavefield information of both primary and shear waves, images with high resolution could be obtained by using the migration method of converted waves, which can help lithology identification, reservoir prediction and reservoir characterization. However, by far only the information of the primary wavefield is widely utilized in migration, which results in many drawbacks of the primary migration method especially when the prospecting area is complex. On the basis of the anisotropic acoustic ray tracing algorithm, we derive the equations and develop a ray tracing algorithm of converted waves for an anisotropic medium. Furthermore, we summarize the imaging formula of converted waves in the angle domain for this medium. Using this algorithm, we propose a Gaussian beam migration imaging method of converted waves in the angle domain for anisotropic VTI media. Numerical experiments on fault-block and complex structural models have verified its accuracy and efficiency. Besides, the proposed method is not only more efficient compared with the anisotropic Gaussian beam migration imaging method put forward, but also more accurate in comparison with the isotropic Gaussian beam migration imaging method. Moreover, the result of angle domain common imaging gathers could also provide useful information for migration velocity analysis.

全文