Research Of Seismic Wavefield Numerical Simulation In EDA Media

To reveal the wavefield characters of fracture reservoir, and in order to see the wavefield manifestation of EDA media, we make numerical simulations about EDA media in several aspects. By the results, we summarize some rules among seismic velocity, seismic records and fissure's parameters in EDA media.First, we make necessary analysis of Hudson theory and Thomsen theory. According to them, we make numerical simulations about compressional wave velocity and shear wave velocity in different type of fissure, the results are analyzed to find the relevant rules of velocities.By the analyzed results, the seismic wave velocity in EDA media relates fissure's parameters closely. When the fracture density is in certain range, the seismic wave velocity decreases with its increase, and changes periodically with the changes of azimuth angle or entrance angle. The change of seismic wave velocity in dry crack is stronger than which in crack contains fluid.Secondly, in simulations of seismic record, high difference method is used in order to solve elastic wave equations of fissure type, and we get the ideal shear wave splitting record, pre-stack single-shot record and post stack migration record.The ideal shear wave splitting record indicates the fracture density and fracture azimuth angel on the impact of shear wave splitting phenomenon. When the fracture density is above a certain value, the more the density is, the more shear wave splitting phenomenon will be. The intension of the fast, slow shear wave relates with the azimuth angle.Three component elastic seismic records indicate the relations between the azimuth angle and the energy of records. Through the wavefield snapshot, we can see the shear wave splitting phenomenon.We design two models in order to compare, to analyze the characters of seismic wavefiled under equivalent velocity theory based on seismic wave phase velocity theory which declares by Chirstoffel Equations.The pre-stack single-shot record, post stack record and post stack migration record in EDA media indicates the wavefiled characters of anisotropic media of fissure type. Because of the existence of media of fissure type, records got from elastic wave equations of fissure type are more complex than which from acoustic wave equations, but their geologic conformations are basically the same, which reveals the validity of equivalent theory.