Advanced Simulation of Wave Reflection: Theory and Applications for Subsurface Imaging

Zhao Zhao, University of Connecticut - Storrs

Open Access Open Access


This Ph. D. dissertation focuses on the numerical simulation of physical wave propagation in time domain focusing on the wave reflection simulation and their relationship with the inner structure imaging. First of all, this dissertation studies the wave phenomena from a systematic perspective.

Secondly, a series of wave propagation simulation methods are developed. These methods include the finite difference time domain method (FDTD), pseudospectral time domain (PSTD) method and multi-region (MR) method. The advantages and disadvantages of these methods are discussed. The novel efficient recursive integration perfectly matched layer is used as the absorbing boundary condition.

The third, a novel directional Kirchhoff integration is introduced and developed in this dissertation. The novel directional Kirchhoff integration makes the multi-region PSTD method into the directional multi-region PSTD method. A case study is shown to prove that the directional multi-region PSTD method is valid in the full waveform simulation while keeping all the computational efficiencies of the traditional multi-region PSTD method.

The fourth, a novel model subtraction method is introduced in detail. The purpose of the introduction of the model subtraction is to apply the directional multi-region PSTD method in some real reflection model simulation. A case study is illustrated to show that the model subtraction is the ideal method to apply the directional multi-region method into the simulation of a reflection model. Combined with the pre-stack Kirchhoff time migration and stack techniques, the model subtraction method with directional multi-region PSTD algorithm is proved to be able and efficient in the inner structure imaging studies.

The fifth part of this dissertation is the discussion of interferometry technique and its utilization into some geological fracture imaging. Interferometry technique transfers the wave field obtained by a transmission model into a virtual reflection wave field. It is especially useful in subsurface borehole radar survey because it is very easy to target the area of research interests. A 3D case study is provided to show that the interferometry method is efficient in fracture detection. Based on the synthetic model results, the simulation and migration results suggest some vital clue in subsurface fracture detection and characterization.