3D Gaussian Beam Forward Modelling Based on Projected Fresnel Zone for Irregular Topography

For seismic exploration of irregular topography areas, it is important to develop a 3D forward modelling method which is fast, accurate and highly adaptable for complex geological conditions. A method of 3D Gaussian beam forward modelling for irregular topography based on projected Fresnel zones is developed in this paper. By introducing the idea of projected Fresnel zone into Gaussian beam forward modelling, we gave a new choice of initial parameter in dynamic ray tracing of the Gaussian beam method, which improves the accuracy of travel time and amplitude extrapolation near the central ray, especially for deep reflections. In addition, we applied our method to irregular topographic models and obtained good numerical modelling results, which shows that: (1) the seismogram synthesized by our method has a better dynamic property than that synthesized with conventional methods, and(2) our method has good adaptability to 3D complex topography models. Keywords3D Irregular Topography; Projected Fresnel Zone; Gaussian Beam; Forward Modelling