Serious stretch appears in shallow long offsset signals after NMO correction. In this article we study the generation mechanism of NMO stretch, demonstrate that the conventional travel time equation cannot accurately ...Serious stretch appears in shallow long offsset signals after NMO correction. In this article we study the generation mechanism of NMO stretch, demonstrate that the conventional travel time equation cannot accurately describe the travel time of the samples within the same reflection wavelet. As a result, conventional NMO inversion based on the travel time of the wavelet＇s central point occurs with errors. In this article, a travel time equation for the samples within the same wavelet is reconstructed through our theoretical derivation （the shifted first arrival point travel time equation）, a new NMO inversion method based on the wavelet＇s first arrival point is proposed. While dealing with synthetic data, the semblance coefficient algorithm equation is modified so that wavelet first arrival points can be extracted. After that, NMO inversion based on the new velocity analysis is adopted on shot offset records. The precision of the results is significantly improved compared with the traditional method. Finally, the block move NMO correction based on the first arrival points travel times is adopted on long offset records and non-stretched results are achieved, which verify the proposed new equation.展开更多
For strata with complex structure and faulting, the conventional horizontal stack method can not provide a high quality image and the conventional DMO technique has low computational efficiency and practicability. Thi...For strata with complex structure and faulting, the conventional horizontal stack method can not provide a high quality image and the conventional DMO technique has low computational efficiency and practicability. This＇article studies a logarithm stretching DMO method in the time domain to accelerate the computational speed as well as improve the image quality. It also covers the processing of physical model and real data using the logarithm stretching DMO algorithms. The logarithm stretching DMO method can produce reflections from faults and implements the in-phase stack of dipping layers and complicated structures better than the conventional horizontal stack method. So this method has better application to thrust-nappe areas.展开更多
基金sponsored by the National Natural Science Foundation of China (No. 41074075)
文摘Serious stretch appears in shallow long offsset signals after NMO correction. In this article we study the generation mechanism of NMO stretch, demonstrate that the conventional travel time equation cannot accurately describe the travel time of the samples within the same reflection wavelet. As a result, conventional NMO inversion based on the travel time of the wavelet＇s central point occurs with errors. In this article, a travel time equation for the samples within the same wavelet is reconstructed through our theoretical derivation （the shifted first arrival point travel time equation）, a new NMO inversion method based on the wavelet＇s first arrival point is proposed. While dealing with synthetic data, the semblance coefficient algorithm equation is modified so that wavelet first arrival points can be extracted. After that, NMO inversion based on the new velocity analysis is adopted on shot offset records. The precision of the results is significantly improved compared with the traditional method. Finally, the block move NMO correction based on the first arrival points travel times is adopted on long offset records and non-stretched results are achieved, which verify the proposed new equation.
基金This research is sponsored by National 973 Foundation (No. 2001CB209105)
文摘For strata with complex structure and faulting, the conventional horizontal stack method can not provide a high quality image and the conventional DMO technique has low computational efficiency and practicability. This＇article studies a logarithm stretching DMO method in the time domain to accelerate the computational speed as well as improve the image quality. It also covers the processing of physical model and real data using the logarithm stretching DMO algorithms. The logarithm stretching DMO method can produce reflections from faults and implements the in-phase stack of dipping layers and complicated structures better than the conventional horizontal stack method. So this method has better application to thrust-nappe areas.
