Fast estimation of prestack common reflection surface parameters
A.U. Waldeland, T.A. Coimbra, J.H. Faccipieri, A.H. Schistad Solberg and L.J. Gelius
Journal name: Geophysical Prospecting
Issue: Vol 67, No 5, June 2019 pp. 1163 - 1183
Info: Article, PDF ( 22.09Mb )
We present a method for fast estimation of finite offset common reflection surface parameters. Firstly, the derivatives with respect to offset are derived from the velocity guide. Secondly, we apply structure tensors to extract the derivatives with respect to midpoint from stacked common offset sections. Finally, the mixed derivative is estimated using a one-parametric semblance search. The proposed method is com-pared to the global five-parametric semblance search and the pragmatic sequential two-parametric semblance search on one synthetic and one real data set. The experi-ments show that the proposed method is more robust against noise than the pragmatic search and have comparable robustness with the global search. The proposed method smoothes parameter estimates in a local window, and the window size is set to give the best trade-off between detail and robustness. Since the proposed method is dependent on a velocity guide, the quality of the other parameter estimates may be influenced by any inaccuracies in the guide. The main advantage of the proposed method is the computational efficiency. When compared with a gridded implementation of the semblance search, the proposed method is 10 and 400 times faster than the pragmatic and global search. Alternative search strategies significantly reduce the computational cost of the global search. However, since more than 99% of the computational cost of the proposed method comes from the semblance search to estimate the mixed derivative, it is expected that such techniques also reduce the computational cost for the proposed method.