Elastic wave forward modeling and wave-field separation of irregular free-surface based on the layered mapping method
Qu Yingming1, Huang Jianping1, Li Zhenchun1, Li Qingyang1, Li Runze2, Wang Yunchao3
1. School of Geosciences, China University of Petroleum(East China), Qingdao, Shandong 266580, China;
2. Gas Development Department, Qinghai Oilfield Company, PetroChina, Golmud, Qinghai 816000, China;
3. Korla Branch, GRI, BGP Inc., CNPC, Korla, Xinjiang 841001, China
Abstract：Conventional finite difference method has some difficulties to deal with irregular free-surface. Conventional mapping method can overcome the disadvantage by transforming irregular surface to horizontal surface. But at the same time, the interface below the surface will be destroyed, resulting in inaccurate wave propagation and false reflection. Thus we improve the conventional mapping method and propose an elastic wave forward modeling and wave-field separation of irregular free-surface based on layered mapping method. After realizing the algorithm, several typical irregular free surface models are tested with the seismic forward modeling. The results suggest that:A. The layered mapping method can transform both the irregular surface and interface to horizontal surface and interface. Compared with conventional rectangular grids and conventional mapping method, the layered mapping method has a better adaptability for dual-complex structure; B. Forward modeling comparison tests prove that the layered mapping method has higher simulation accuracy and a better ability of suppressing dispersion; C. The wave-field separation of irregular free-surface based on layered mapping method can accurately separate P- and S-wave, which can provide a key approach for the irregular free-surface elastic imaging.
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