Elastic-wave numerical simulation and reverse time migration in pseudo-depth domain
ZOU Qiang1, HUANG Jianping1, LI Qingyang2, YONG Peng1, XIN Tianliang1
1. Geophysics Department, School of Geosciences, China University of Petroleum(East China), Qingdao, Shandong 266580, China; 2. Geophysical Exploration Research Institute, Si-nopec Zhongyuan Oilfield Company, Puyang, Henan 457001, China
Abstract：Wave field extrapolation using finite-difference method is usually accomplished in the Cartesian coordinate system.Oversampling may occur locally when subsurface velocity varies greatly; this will increase the workload of computation.To address this issue,we fulfill finite-difference numerical si-mulation in pseudo-depth domain.In accordance with the chain rule of coordinate conversion,we formulate the mapping relation between the Cartesian coordinate system and pseudo-depth domain as well as consequent elastic wave equation (PDD-EWE) in pseudo-domain.Memory consumption may be significantly reduced for wave field extrapolation in pseudo-depth domain,provided that the accuracy is guaranteed.A variable difference operator is adopted,and its length varies with velocity.The model tests show that for the similar accuracy,elastic-wave forward modeling and imaging with a variable difference operator in pseudo-depth domain is better than conventional finite-difference method in depth domain in view of less memory consumption and higher computational efficiency.
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