Constant normal‐moveout (CNMO) correction: a technique and test results

Abstract

We introduce a processing technique which minimizes the ‘stretching effects’ of conventional NMO correction. Unlike conventional NMO, the technique implies constant normal moveout (CNMO) for a finite time interval of a seismic trace. The benefits of the proposed method include preservation of higher frequencies and reduction of spectral distortions at far offsets. The need for severe muting after the correction is reduced, allowing longer spreads for stack, velocity and AVO analysis. The proposed technique has been tested on model and real data. The method may improve the resolution of CMP stack and AVO attribute analysis. The only assumptions for this stretch‐free NMO correction are (i) all time samples of a digital reflected wavelet at a particular offset have the same normal moveout, and (ii) reflection records have an interference nature.

The importance of non-hyperbolic and stretch effects in far-offset P and PS NMO processing

“…An alternative method is to apply NMO directly without stretching the wavelet (Shatilo and Aminzadeh, 2000). This is called constant NMO (CNMO).…”

Improving resolution of NMO stack using shaping regularization

“…Multiple other algorithms have been proposed that aim to reduce NMO-stretching effects (Byun and Nelan, 1997;Hicks, 2001;Hilterman and Schuyver, 2003;Rupert and Chun, 1975;Perroud and Tygel, 2004;Masoomzadeh et al, 2010;Zhang et al, 2013;Kazemi and Siahkoohi, 2011). Shatilo and Aminzadeh (2000) proposed a constant NMO-correction strategy, which applies a constant NMO shift within a finite-time interval that is equal to the wavelet length of a trace. This approach eliminates wavelet stretch and preserves higher frequencies than the conventional method, resulting in a higher resolution stack.…”

A reversible transform for seismic data processing

“…Various authors have developed strategies for handling the effects of NMO stretch in practical seismic data processing (Miller, 1992;Perroud and Tygel, 2004;Shatilo and Aminzadeh, 2000). NMO stretch manifests the most at far offsets and early times, where the NMO correction is the most severe.…”