GNGTS 2013 - Atti del 32° Convegno Nazionale

Conclusion. The conventional NMO correction cannot deal with long-offset recordings and may causes serious problem when it is applied to interfering events and data with amplitude and phase variations with offset. Not only is the NMOPC effective in avoiding stretching distortions caused by the NMO corrections, but it is also able to maintain much of the amplitude and phase features of the reflected wavelets. This can turn out useful in many situations such as when employing undershooting techniques or when useful reflections occur at large source- receiver offsets. Moreover, the NMOPC corrected CMPs can be employed for AVO and PVO analysis. The efficacy of our method is demonstrated by either the synthetic example and the real data application. The NMOPC is rather flexible and can adapt to different data. In fact the estimation window dimension and overlaps can be varied according to specific needs and targets. The same applies to the number of iterations controlled by the NMO percentage. The main purpose of the NMOPC is not to replace the traditional NMO correction, but to provide information in such cases when the over-stretch distortions cannot be avoided unless by the application of a muting function. Acknowledgements. We gratefully acknowledge the support of Landmark/Halliburton for the use of their Promax/ Landmark seismic software. References Buchholtz H.; 1972: A note on signal distorsion due to dynamic (nmo) correction. Geophysical Prospecting, 20 , no. 2, pp. 395-402. Cerveny V.; 1985: Ray synthetic seismograms for complex two-dimensional and three-dimensional structures. Journal of Geophysics, 58 , pp. 2-26. Colombo D.; 2005: Benefits of wide-offset seismic for commercial exploration targets and implications for data analysis. The Leading Edge, 24 , no. 4, pp. 352-363. Fig. 3 – a) Stacked section of a subset of the data described in Rocchi et al. (2007) employing all the recorded traces. b) Stacked section obtained using the undershooting test data after correction with the traditional NMO algorithm. c) Stacked section obtained using the NMOPC routine applied on the undershooting test data. 21 GNGTS 2013 S essione 3.1