Numerical Simulation Of Seismic Wave And Analysis Of Wave Field’s Character Of Dual-Phase Medium

The hydrocarbon reservoir is actually a two-phase medium combined with solid and fluid. Thus the study of seismic wave based on multi-phase media is of great significance in theory and practice for the exploration of complex hydrocarbon reservoir. Seismic simulation is treated as an effective method for the research of underground medium. Finite element, finite difference and pseudo spectral methods are often used. And special emphasis is laid on finite difference method here. The paper focuses on the problem of numerical simulation of seismic wave and analyses the character of wave field.It applies the high rank of finite difference method for the realization of the numerical simulation of vertical wave equation of Biot dual-phase medium. This paper uses PML to deal with the artificial boundaries, and analyses wave field character by wave field snapshot. The simulation result indicated:high-order finite-difference operator has high simulation precision; the PMLcondition eliminates the boundary reflection well.Then, the relationship of physical property parameters and attenuation is discussed by researching the attenuation of seismic waves in Biot model. The results indicated: In the routine frequency scale of seismic exploration,frequency dispersion is not clear.It is discovered by phase velocity and inverse quality factor of 4 kinds of wave computed by numeric simulation of computer and changing rule of seismic wave velocity and attenuation along with propagation direction in polar coordinate that there is different performance of anisotropic feature in 4 kinds of wave and the anisotropic feature of attenuation showing stronger than that of phase velocity. The paper analyzed the influence of different parameters such as porosity, viscosity coefficient, permeability on phase velocity and attenuation of 4 kinds of wave in vertical direction and full-propagating azimuth region, which discovered that the influence also has anisotropic feature. Meanwhile, the paper also analyzed the characters that the wavefield changes with frequency in different parameter conditions and gained a series of meaningful conclusions.It ratiocinates AVO equation based on Biot model and obtains several types of AVO equations of the dual-phase medium including several types of interfaces. Finally, based on Biot-AVO and the Zoeppritz equation respectively, this paper analyses the relationship between the reflect coefficient and transmission coefficient and the incident angle of fast and slow vertical wave and horizontal wave. The results indicated:In general,Zoeppritz curves are similar to dual-phase curves, but there are still some differences.This paper analyses the characteristics of dual-phase medium seismic wave in transmission, the speed and attenuation, it also probes into the properties of incident and reflect angle. This research, based on dual-phase medium, is of great significance to the seismic survey of oil field.