Numerical Simulation Of Seismic Wave In VTI Medium With Rugged Seafloor

In marine seismic exploration,the seismic exploration technology of Ocean Bottom Nodes(OBN)has gradually emerged in recent years.It adopts a unique layout method and can obtain rich information about longitudinal waves and converted shear waves.VTI medium rugged seafloor numerical simulation is a necessary method to study the propagation of OBN seismic wavefields in rugged seafloor environment.It provides an important tool for studying seismic wavefield lighting analysis,data processing and interpretation under complex seafloor geological conditions,which can provide a deeper understanding of each seismic wave.The wave propagation law has important theoretical and practical significance for the exploration and development of offshore oil and gas resources.In order to more accurately simulate the relationship between the travel time and energy changes of the rugged seafloor seismic waves under the OBN acquisition system,and to enhance people's understanding of the propagation of seismic waves in the actual seafloor media,the paper studies the hybrid mesh division method of the rugged seafloor and complex underground velocity interface model.This method can better simulate the seafloor and velocity interface,associate the geophone with the seafloor interface,and improve the situation that the multi-step incident and reflected waves in the zone must be symmetrical.The research of the thesis will improve the multi-stage calculation technology of land-based observation system to be applicable to the seafloor observation system,and realize the linear interpolation(LTI)ray tracing technology of multi-stage calculation seismic wave travel in the OBN observation system.The Thomsen anisotropy parameter is applied to the OBN observation system to study the group-phase relationship of complex media under the undulating seabed,and to realize the numerical simulation of the seismic wave field of the undulating complex seabed.Based on the traditional Zoeppritz equation of the Pwave incident solid-solid interface,we applied the Zoeppritz equation of S-wave incident solid-solid interface,solid-liquid interface,and P-wave incident solid-liquid interface,liquid-solid interface to the undulating seabed LTI ray tracing algorithm,to achieve energy distribution at the speed interface.The thesis applies the geometric diffusion law applicable to reflected and refracted waves to the LTI ray tracing algorithm to further simulate the energy attenuation.In this paper,the interlayer absorption attenuation simulation of different media is applied to the rugged seafloor ray tracing LTI algorithm to simulate the absorption attenuation of the seawater layer and different geological layers of the seabed,so as to realize dynamic ray tracing in the OBN observation system.The numerical calculation results of the theoretical model show that the algorithm in this paper is relatively reliable.Through the simulation of the first arrival wave,reflected wave,converted wave,and multiple wave of the 2D rugged seafloor VTI medium model,the stability and effectiveness of the algorithm are verified through analysis.The thesis innovatively developed the OBN dynamic ray tracing method based on LTI algorithm.Carrying out research on seismic wave travel time,ray path calculation and amplitude energy of the rugged submarine complex medium provides an effective method for the wave field identification of OBN seismic acquisition data and the study of seismic wave propagation laws.