Numerical Simulation Of Two-Dimensional High-Order Elastic Wave And Reverse Time Migration Imaging

As one of the basic contents of seismic exploration,the numerical simulation of seismic wave forward modeling plays an extremely important role in studying the propagation law of seismic waves in underground media.At present,the numerical simulation of seismic waves has been widely used in every stage of seismic exploration.It is more important to use the numerical simulation method which is simple,efficient and accurate.With the development of seismic exploration,the target of exploration turned to geological anomalies with small scales,such as karst caves,pores and faults.These geological anomalies are more complex and closer to actual geological problems.In the study of these complex geological problems,the numerical simulation method is required to be higher.The study of migration imaging technology has always been an important issue in seismic exploration.As the imaging object becomes more complex,the imaging difficulty increases.The migration imaging method based on ray theory and one-way wave equation also shows some shortcomings.The inverse time migration based on the two-way wave equation completely follows the wave equation,and can carry out the migration imaging for all the wave propagation paths,which is the most accurate migration imaging method at present.In this paper,the first order velocity stress equation of isotropic medium is derived on the basis of summarizing the previous research results.The staggered grid high-order finite difference method is used to simulate the seismic waves of different models,and the wave field snapshots and seismic records of each model are obtained,which verifies the effectiveness of the numerical simulation method.By analyzing the wave field snapshot and seismic record of each model,the waveforms of different geological anomalies are studied to explain the characteristics of the wave field.On the basis of numerical simulation,the reflected wave field of the reflection interface is removed,the scattered wave field information is retained and the scattered wave is analyzed.Based on the numerical simulation of seismic wave forward modeling,the prestack inverse time migration method is implemented.The imaging condition of inverse time migration which is widely used at present is introduced.The cross-correlation imaging condition is used to conduct inverse time migration imaging for each model in seismic wave forward modeling.The whole wave field and the scattered wave field were imaged by inverse time migration imaging method,and the imaging results were compared.By analyzing the results of inverse time migration imaging,it can be obtained that the imaging results of pre-stack inverse time migration imaging on circular scatterer model,rectangular scatterer model,sag model,fault model and fracture model are satisfactory,which proves that the imaging method is true and reliable.However,the inverse time migration imaging results of the scattered wave field are clearer and better for the diffraction points.