Research On Forward Modeling Of VTI Medium Wave Equation And Analysis Of Wave Field Characteristics

The wave equation forward modeling can simulate the full wave field information.The realization process is using computer to obtain the numerical solution of wave equation by means of numerical method.Because there is no approximate treatment of wave equation,the wave equation forward modeling has the highest veracity than any other simulation method,in the same medium approximation.But the computational cost is huge.In recent years,with the rapid development of computer technique,the advantage of wave equation forward modeling is gradually reflected.The forward modeling of wave equation is based on the theory of wave propagation.It is necessary to abstract the complex underground media first,The media hypothesis determines the approximate degree of the forward simulation and the real data acquisition.and the traditional wave equation modeling is based on the abstract of the earth medium as the complete elasticity and isotropic.With the improvement of observation technology and observation precision,The development of medium theory and the increase of exploration difficulty(especially for shale gas reservoirs with strong anisotropic media).isotropic hypothesis has not been sufficient to explain the wave field characteristics of seismic data and can not accurately image.In today's exploration environment,it is very important to use anisotropic theory to guide exploration.It is very important to study the propagation law and characteristics of seismic wave in underground medium by using the theory of anisotropy.Based on the research of many scholars,this paper conducts an in-depth study on the TI media,which widely existed in the underground,and realizes the numerical simulation of the elastic wave and quasi-p wave of the VTI medium.The specific research contents are as follows:1)the causes of seismic anisotropys are systematically analyzed,and the propagation equation of elastic wave and quasi-longitudinal wave in VTI medium is deduced in detail.2)Further study of the finite difference numerical simulation method of time domain,and analyzed the problems of dispersion,boundary and stability during numerical simulation.3)analyzed the wave field characteristics of elastic wave and quasi-p wave in VTI medium,and a new method is proposed for the artificial shear wave interference of the pseudo-acoustic wave equation.4)The SEG Hess model was used to test the numerical simulation method,the effects of different assumptions on the imaging effects were compared.