Seismic Response Characteristic Of Fractured Medium

Fracture area is the main reservoir space and the important migration pathway of fractured oil and gas.Therefore,studying seismic response of the fractured medium can be meaningful to a better understanding of reservoirs.In this thesis,we extended this method to three dimensional condition,and showed that the method can be used at simulation of heterogeneous and anisotropic media.Most of the exiting modeling methods fail to avoid the diffraction on the tips of fracture due to the grid shape of finite difference,and FT method with integrated elastic parameters was regarded a good way to solve this problem.In the implementation of the programing,only the speed components need to be saved.Therefore,in addition to saving a lot of computing memory,integrating method can also provide higher S/N seismic signal by scattering suppression caused by fracture tips,compared to the conventional speed-stress FD method.In this thesis,we applied PML boundary condition to this method.The result showed that PML boundary condition has a better absorption effect than the original Sponge boundary condition.We also realized the simulation of seismic response of fractured media with pore pressure effect by extending BGK model,which is used to simulating the diffusion process of pore pressure in porous medium to three dimensional condition.By analyzing the effect of pore pressure on seismic wave propagation,we revealed the law of the attenuation of wave field with the increase of the pore pressure in fractured medium.This may provide a theoretical basis for prediction of abnormal high pore pressure and hydrocarbon migration monitering.