Simulation And Characteristic Analysis Of Random Media Wavefield Forward Modeling

When conducting seismic exploration in complex geological formations,the subsurface medium is always heterogeneous.In these heterogeneous mediums,the irregular distribution of the medium leads to disturbances in the underground elastic parameters.These small disturbances have a significant impact on seismic waves when exploring the target body.This makes traditional reflection wave exploration challenging and difficult to address the effects of small-scale underground heterogeneity on seismic waves in practical work.To address these issues,this study focuses on the actual fluvial deposit formations with gravel development.It summarizes and investigates the applications and developments of random medium and seismic scattering wave theory.The study utilizes forward modeling methods to investigate the scattering waves in the random medium of fluvial deposit areas.Furthermore,based on common scattering point gathers,the imaging techniques for scattering waves in random mediums are systematically studied.The main contents are as follows:The study first investigates random media and scattering wave theory.It introduces the basic concepts of random media theory and random media models,providing a detailed description of the establishment of random media models.Furthermore,it explores the relationship between different autocorrelation functions in random media and the establishment of random media models.The basic concepts of seismic scattering waves and their classifications are also preliminarily examined.Through forward modeling simulations of single-layer random media theoretical models,the parameters and basic characteristics of random media models are studied,providing guidance for the establishment of actual gravel fan deposit models.This study characterizes the gravel fan area using different autocorrelation functions and parameters.By comparing the simulated records with actual records,it demonstrates that random media can better characterize gravel fan deposits compared to homogeneous media.To better investigate the wavefield characteristics in random media models,six different-scale random media models are established to study the scattering waves generated by different small-scale heterogeneities under the same background.Seismic records and wavefield snapshots are obtained through forward modeling simulations,and the influence of scattering waves in random media models on seismic records and wavefields is examined.Considering the limitations of conventional reflection wave imaging in gravel fan areas,this study explores scattering wave imaging techniques based on common-scattering point gathers.Moreover,actual seismic data from gravel fan areas are imaged,confirming the effectiveness of the technique in imaging scattering waves in random media models.This approach also addresses the challenges posed by complex geological structures and numerous small-scale heterogeneities in practical production,providing assistance for seismic exploration research in gravel fan areas.