Acoustic wave numerical simulation in pseudo-depth domain
Li Qingyang1, Huang Jianping1, Li Zhenchun1, Li Na2, Qu Yingming1, Su Yun2
1. School of Geoscience, China University of Petroleum (East China), Qingdao, Shandong 266580, China;
2. Geophysical Exploration Research Institute, Zhongyuan Oilfield Branch Co., SINOPEC, Puyang, Henan 457001, China
Abstract：Surface seismic exploration usually meets challenges like low-velocity bodies, surface topography, steep structures, fractures and so on. Seismic wavefield simulation with conventional Cartesian finite difference forward modeling method in these areas often needs very small grid spacing to ensure the accuracy and stability. So it leads local oversampling problem. To overcome this problem, we introduce the idea of pseudo-depth to the forward modeling. Using the gradient and divergence formula in curvilinear coordinates, we derive the first-order velocity-stress equation in pseudo-depth domain and implement the pseudo-depth domain seismic modeling algorithm. Meanwhile, considering uneven horizontal sampling, we introduce adaptive variable-length spatial operators to calculate the horizontal spatial derivatives and propose seismic forward modeling method with adaptive variable-length spatial operators in the pseudo-depth domain. Finally, by extending the forward operator to reverse time migration, we implement pseudo-depth domain reverse time migration with adaptive variable-length spatial operators. Model test results show that our pseudo-depth domain method with adaptive variable-length spatial operators can reduce about 25% of computer time consuming and nearly 30% of the storage without influencing the accuracy of the results.
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