Angle domain common-image gather calculation based on wave equation prestack depth migration
Zhang Guangzhi1, Chang Dekuan2, Wang Yihui3, Yin Xingyao1, Chen Huaizhen1, Li Hailiang2
1. School of Geosciences, China University of Petroleum (East China), Qingdao, Shandong 266580, China;
2. Northwest Branch, Research Institute of Petroleum Exploration and Development, PetroChina, Lanzhou, Gansu 730020, China;
3. Geophysical Exploration Research Institute, Huabei Oilfield Company, PetroChina, Renqiu, Hebei 062552, China
Abstract:Angle-domain common image gathers (ADCIGs) extracted by the conventional conversion method and the straight-ray PSTM method cannot meet the requirements of both AVA analysis and inversion in geologically complicated areas. In this paper we put forward an amplitude-preserved wave equation prestack depth migration based on common offset gathers to extract ADCIGs. First, we process seismic datasets with prestack depth migration to obtain offset domain common image gathers. Then in the frequency-wavenumber domain, angle domain common image gathers are extracted with fast interpolation from offset domain common image gathers. Finally we analyze ADCIGs information and AVA properties calculated by both the direct transform method and the straight-ray line PSTM method. Both numerical experiments and real data tests show that ADCIGs obtained by the proposed approach have larger angle range and better amplitude, and are more suitable for AVA analysis and inversion.
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