Finite-difference numerical modeling with variable mechanisms for viscoacoustic wave equation
CAIRuiqian1,2, SUN Chengyu1,2, WU Dunshi3, LI Shizhong1,2
1. School of Geosciences, China University of Petroleum(East China), Qingdao, Shandong 266580, China; 2. Laboratory for Marine Mineral Resources, Qingdao National Laboratory for Marine Science and Technology, Qingdao, Shandong 266071, China; 3. Northwest Branch, Research Institute of Petro-leum Exploration & Development, PetroChina, Lanzhou, Gansu 730020, China
Abstract:Subsurface media are generally not elastic but viscoelastic, and the viscoelasticity is normally depicted by a dimensionless quantity, i.e., quality factor Q.Within the frequency band of seismic exploration, Q is widely considered frequency-independent, which can be properly characterized by the generalized standard linear solid (GSLS) mo-del.Thus, the GSLS model has become the mainstream while viscoelastic seismic wave modeling.However, when GSLS model has been chosen, the current modeling schemes commonly adopt a fixed number of relaxation mechanisms, which leads to a shortcoming, not being able to integrate the computational efficiency and precision.In this paper, we propose a finite difference viscoelastic seismic-wave modeling scheme with variable mechanisms based on GSLS model.More precisely, we use different number of mechanisms to approximate the Q in different areas of earth model, thereby integrating both computational efficiency and precision.We compare our results with the analytical solution, and analyze the relation between the precision and the number of mechanisms, and Q and the tra-veling distance to determine the appropriate applicable range of different mechanisms.We also compare the precision and efficiency of variable mechanisms with those of a fixed number of mechanisms, and analyze the applicability of the proposed method.The results indicate some merits of the proposed scheme:wider applicability, higher computational precision, and more efficient simulation.
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