Reverse-time Migration

This dissertation mainly studys forward modeling of two-dimension acoustic wave equation with high order finite difference and reverse time migration. Forward modeling of acoustic wave equation bases on wave theory, which can effectively keep the characters of kinematics and accurately express the seismic wave propagation law. This is benificial to simulate the seismic wave fields and becomes the basis of reverse time migration.Up to now,with the increasingly high demand for exploration accuracy, high-precision forward modeling and reverse-time migration, involving seismic data acquisition, processing and so on, has caused more and more attention, which aims to improve awareness of seismic wave propagation law under the complex structure and to solve the complex structural imaging, as well as to guarantee the oil and gas exploration and development.In the process of forward numerical simulation of acoustic, the key problem is the accuracy, stability of differential numerical solution, as well as boundary conditions, which directly affects the accuracy of numerical simulation. From a theoretical point, this thesis analyses what results in the errors of differential precision, and the condition of difference stability and boundary. And high order staggered grid finite difference method is applied to improve simulation accuracy. PML absorbing boundary conditions has good result in absorbing reflected wave field resulted from boundary, which is helpful to avoid wave field interference caused by boundary reflection. What’s more, criteria and temporal step meeting the stability should be chosen to avoid differential instability. High accuracy finite difference modeling can be achieved by the above methods. In the process of RTM, the imaging conditions and migration noise suppression is a key to RTM imaging. This thesis selects autocorrelation imaging condition to achieve a precise imaging of underground wave field,and in order to suppress low-frequency noise generated in the RTM, Laplace noising technology is chosed to improve the migration effect. This thesis has high accuracy,easy-identified waveform characteristics, stable calculation process algorithm and little or none boundary reflection etc.