Another look at NMO stretch

Geophysics ◽  
1992 ◽  
Vol 57 (5) ◽  
pp. 749-751 ◽  
Author(s):  
Arthur E. Barnes
Keyword(s):  
Seismic Reflection ◽  
Qualitative Assessment ◽  
Seismic Reflection Data ◽  
Reflection Data ◽  
Amplitude Spectra ◽  
Nmo Correction ◽  
Zero Offset ◽  
Nmo Stretch ◽  
Dominant Frequencies

The normal moveout (NMO) correction is applied to seismic reflection data to transform traces recorded at non‐zero offset into traces that appear to have been recorded at zero offset; this introduces undesirable distortions called NMO stretch (Buchholtz, 1972). NMO stretch must be understood because it lengthens waveforms and thereby reduces resolution. Buchholtz (1972) gives a qualitative assessment of NMO stretch, Dunkin and Levin (1973) derive its effect on the amplitude spectra of narrow waveforms, while Yilmaz (1987, p. 160) considers its effect on dominant frequencies. These works are approximate and do not show how spectral distortions vary through time.

Automatic NMO correction in anisotropic media and non-hyperbolic NMO velocity field estimation

2016 ◽  
Vol 56 (2) ◽  
pp. 592
Author(s):  
Mohamed Sedek ◽  
Lutz Gross
Keyword(s):  
Velocity Field ◽  
Seismic Reflection ◽  
Fast Method ◽  
Gas Field ◽  
Seismic Reflection Data ◽  
Anisotropic Effect ◽  
Reflection Data ◽  
Nmo Correction ◽  
Zero Offset ◽  
The One

The authors propose a new method to automatically normal move-out correct pre-stack seismic reflection data that is sorted by CDP gathers, and to estimate the normal move-out (NMO) velocity (Vnmo) as a full common depth point (CDP) velocity field that instantaneously varies with offsets/azimuths. The method is based on doing a pre-defined number of NMO velocity iterations using linear vertical interpolation of different NMO velocities at each seismic trace individually. At each iteration the seismic trace is shifted and multiplied by the zero offset trace followed by the summation of the product. Then, after all the iterations are done, the one with the maximum summation value is chosen, which is assumed to be the most suitable NMO velocity trace that accurately flattens seismic reflection events. The other traces follow the same process, and a final velocity field is then extracted. Another new, simple and fast method is also introduced to estimate the anisotropic effect from the extracted NMO velocity field. The method runs by calculating the spatial variation of the estimated NMO velocities at each arrival time and offset/azimuth, therefore instantaneously estimating the anisotropic effect. Isotropic and anisotropic synthetic geological models were built based on a ray-tracing algorithm to test the method. A range of synthetic background noise was applied, starting from 10–30%. The method has also been tested on Hess’s model and coal seam gas field data CDP examples. An Alaskan pre-stack seismic CDP field example has also been used.

Labeling long‐period multiple reflections

Geophysics ◽  
1989 ◽  
Vol 54 (1) ◽  
pp. 122-126 ◽  
Author(s):  
R. J. J. Hardy ◽  
M. R. Warner ◽  
R. W. Hobbs
Keyword(s):  
Seismic Reflection ◽  
High Amplitude ◽  
Data Sets ◽  
Multiple Reflections ◽  
Multiple Series ◽  
Seismic Reflection Data ◽  
Long Period ◽  
Reflection Data ◽  
Zero Offset ◽  
Marine Seismic

The many techniques that have been developed to remove multiple reflections from seismic data all leave remnant energy which can cause ambiguity in interpretation. The removal methods are mostly based on periodicity (e.g., Sinton et al., 1978) or the moveout difference between primary and multiple events (e.g., Schneider et al., 1965). They work on synthetic and selected field data sets but are rather unsatisfactory when applied to high‐amplitude, long‐period multiples in marine seismic reflection data acquired in moderately deep (700 m to 3 km) water. Differential moveout is often better than periodicity at discriminating between types of events because, while a multiple series may look periodic to the eye, it is only exactly so on zero‐offset reflections from horizontal layers. The technique of seismic event labeling described below works by returning offset information from CDP gathers to a stacked section by color coding, thereby discriminating between seismic reflection events by differential normal moveout. Events appear as a superposition of colors; the direction of color fringes indicates whether an event has been overcorrected or undercorrected for its hyperbolic normal moveout.

Estimation of Q from surface seismic reflection data

Geophysics ◽  
1998 ◽  
Vol 63 (6) ◽  
pp. 2120-2128 ◽  
Author(s):  
Rahul Dasgupta ◽  
Roger A. Clark
Keyword(s):  
Attenuation Factor ◽  
Spectral Ratio ◽  
Ratio Method ◽  
Amplitude Analysis ◽  
Gas Reservoir ◽  
Seismic Reflection Data ◽  
Reflection Data ◽  
Anelastic Attenuation ◽  
Zero Offset ◽  
Nmo Stretch

Reliable estimates of the anelastic attenuation factor, Q, are desirable for improved resolution through inverse Q deconvolution and to facilitate amplitude analysis. Q is a useful petrophysical parameter itself, yet Q is rarely measured. Estimates must currently be made from borehole seismology. This paper presents a simple technique for determining Q from conventional surface seismic common midpoint (CMP) gathers. It is essentially the classic spectral ratio method applied on a trace‐by‐trace basis to a designatured and NMO stretch‐corrected CMP gather. The variation of apparent Q versus offset (QVO) is extrapolated to give a zero‐offset Q estimate. Studies on synthetics suggest that, for reasonable data quality (S/N ratios better than 3:1, shallow (<5°) dips, and stacking velocity accuracy <5%), source‐to‐reflector average Q is recoverable to within some 3% and Q for a specific interval (depending on its two‐way time thickness and depth) is recoverable to 15–20%. Three case studies are reported. First, Q versus offset and vertical seismic profiling (VSP) Q estimates for a southern North Sea line were in close agreement, validating the method. For Chalk, Mushelkalk‐Keuper, and Bunter‐Zechstein, Q was estimated as 130 ± 15, 47 ± 8, and 156 ± 18, respectively. Next, two alternative lithological interpretations of a structure seen in a frontier area were discriminated between when Q estimates of 680 to 820 were obtained (compared to some 130–170 in the overlying units), favoring a metamorphic/crystalline lithology rather than (prospective) sediments. This was later confirmed by drilling. Third, a profile of Q estimates along a 200-ms-thick interval, known to include a gas reservoir, showed a clear and systematic reduction in Q to a low of 50 ± 11, coincident with the maximum reservoir thickness, from some 90–105 outside the reservoir. Q for the reservoir interval itself was estimated at 17 ± 7.

On: “Pulse distortion in depth migration,” M. Tygel, J. Schleicher, and P. Hubral (October 1994 GEOPHYSICS, 59, p. 1561–1569).

Geophysics ◽  
1995 ◽  
Vol 60 (6) ◽  
pp. 1942-1944 ◽  
Author(s):  
Arthur E. Barnes
Keyword(s):  
Seismic Reflection ◽  
Prestack Depth Migration ◽  
Seismic Reflection Data ◽  
Depth Migration ◽  
Reflection Data ◽  
Time Migration ◽  
Pulse Distortion ◽  
Nmo Stretch ◽  
Frequency Shifting

Tygel et al. have written an excellent and rigorous discussion of pulse distortion in seismic reflection data caused by prestack depth migration. Such distortion is easily understood by recognizing that it is more or less the same effect as normal moveout (NMO) stretch combined with frequency shifting due to poststack time migration.

Modeling of zero-offset reflection profiles with asymptotic ray theory

1981 ◽  
Vol 18 (3) ◽  
pp. 551-560
Author(s):  
George A. McMechan
Keyword(s):  
Seismic Reflection ◽  
Constant Velocity ◽  
Seismic Refraction ◽  
Drill Core ◽  
Ray Theory ◽  
Low Velocity ◽  
Tectonic Structures ◽  
Seismic Reflection Data ◽  
Reflection Data ◽  
Zero Offset

Synthetic reflection profiles computed by asymptotic ray theory can be used in the interpretation of laterally varying tectonic structures. The algorithm is implemented for normally incident (zero-offset) rays in two-dimensional models that are specified in terms of constant velocity layers separated by piecewise cubic boundaries. Applications include modeling of profiles containing lenses, interbedded high- and low-velocity layers, and oceanic ridges. The method is practical and flexible in the sense that structural, lithologic, drill core, and seismic refraction constraints can be directly combined with the seismic reflection data.

The style of transverse faulting in the Dead Sea basin from seismic reflection data: The Amazyahu fault

2006 ◽  
Vol 55 (3) ◽  
pp. 129-139 ◽  
Author(s):  
Avihu Ginzburg ◽  
Moshe Reshef ◽  
Zvi Ben-Avraham ◽  
Uri Schattner
Keyword(s):  
Seismic Reflection ◽  
Dead Sea ◽  
Seismic Reflection Data ◽  
Reflection Data ◽  
Dead Sea Basin ◽  
The Dead

Archive of digital boomer seismic reflection data collected offshore east-central Florida during USGS cruise 00FGS01, July 14-22, 2000

Data Series ◽  
10.3133/ds496 ◽  
2009 ◽  
Author(s):  
Janice A. Subino ◽  
Shawn V. Dadisman ◽  
Dana S. Wiese ◽  
Karynna Calderon ◽  
Daniel C. Phelps
Keyword(s):  
Seismic Reflection ◽  
Seismic Reflection Data ◽  
East Central ◽  
Central Florida ◽  
Reflection Data
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