Marchenko imaging based on self-adaptive traveltime updating

Abstract

Marchenko imaging obtains the subsurface reflectors using one-way Green’s functions, which are retrieved by solving the Marchenko equation. This method generates an image that is free of spurious artifacts due to internal multiples. The Marchenko imaging method is a target-oriented technique; thus, it can image a user specified area. In the traditional Marchenko method, an accurate velocity model is critical for estimating direct waves from imaging points to the surface. An error in the velocity model results in the inaccurate estimation of direct waves. In turn, this leads to errors in computation of one-way Green’s functions, which then affects the final Marchenko images. To solve this problem, in this paper, we propose a self-adaptive traveltime updating technique based on the principle of equal traveltime to improve the Marchenko imaging method. The proposed method calculates the time shift of direct waves caused by the error in the velocity model, and corrects the wrong direct wave according to the time shift and reconstructs the correct Green’s functions. The proposed method improves the results of imaging using an inaccurate velocity model. By comparing the results from traditional Marchenko and the new method using synthetic data experiments, we demonstrated that the adaptive traveltime updating Marchenko imaging method could restore the image of geological structures to their true positions.