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.

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.

METHOD USING ELLIPSES TO INTERPRET SEISMIC REFLECTION DATA

Geophysics ◽  
1964 ◽  
Vol 29 (6) ◽  
pp. 926-934
Author(s):  
Gary S. Gassaway
Keyword(s):  
Seismic Reflection ◽  
Seismic Velocity ◽  
Vertical Section ◽  
Reflection Point ◽  
Seismic Reflection Data ◽  
Reflection Data ◽  
The One ◽  
Time Of Travel ◽  
Reflecting Surfaces ◽  
Reflecting Surface

The properties of an ellipse can be used to interpret seismic reflection data by using the positions in a vertical section of a shot and a geophone as the foci of an ellipse. With the shot and geophone as the foci, the total time of travel of a reflected seismic wave serves as the constant necessary to define the ellipse. The reflecting surface then is tangent to this ellipse. Therefore, if many ellipses are plotted, the reflecting surfaces may be found by drawing smooth curves that are tangent in common to closely intersecting families of arcs. This basic principle is extended to the interpretation of complex structures that are not perpendicular to the line of traverse and to areas where the seismic velocity changes with depth by the following steps: The shots and geophones are plotted on a graph where the units along both the ordinate and the abscissa are virtual seismic traveltimes. These positions of the shots and geophones are then used as the foci of the ellipses as above. The reflecting surfaces are then drawn tangent to the dark bands of closely intersecting elliptical arcs. From this graph the one‐way time from a shot to a point of reflection, and from the point of reflection to a geophone may be scaled off; this is done by drawing the elliptical radii from the shot and geophone to the point of tangency between the ellipse and reflecting surface. The lengths of these radii are the one‐way times at the time scale of the graph. With the attitude of the wavefront as it returned to the surface at a geophone determined by a spread of three parallel geophone lines, and the one‐way time from the reflection point, one has the necessary and sufficient data to find the point of reflection in space coordinates for the assumed velocity function. Using the ray paths from the shot and geophone to this reflection point, the dip and strike of the reflecting surface at this point are found. This process is then repeated for every shot‐geophone combination for each reflecting surface.

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.

CASE HISTORY OF WILD GOOSE GAS FIELD, BUTTE COUNTY, CALIFORNIA

Geophysics ◽  
1954 ◽  
Vol 19 (3) ◽  
pp. 509-516 ◽  
Author(s):  
Wallace L. Matjasic
Keyword(s):  
Cross Sections ◽  
Seismic Reflection ◽  
Upper Cretaceous ◽  
Gas Field ◽  
Contour Map ◽  
Seismic Reflection Data ◽  
Reflection Data ◽  
History Of ◽  
Further Development ◽  
Wild Goose

The discovery well of the Wild Goose gas field was drilled and completed in 1951 on a structure located by a reflection seismograph survey conducted in 1950. An additional seismograph survey was made subsequent to discovery to define the structure better for further development. The illustrations include two seismic cross sections, a contour map based on the original seismic reflection data, an aeromagnetic map, a structure contour map, and an electric log of the discovery well. The producing sands are in an interval between the Forbes shale of Upper Cretaceous age and the overlying Capay shale of Eocene age.

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
Sign in / Sign up

Export Citation Format

Share Document