Influence of direction on velocity analyses
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| Series | Geophysical References Series |
|---|---|
| Title | Problems in Exploration Seismology and their Solutions |
| Author | Lloyd P. Geldart and Robert E. Sheriff |
| Chapter | 5 |
| Pages | 141 - 180 |
| DOI | http://dx.doi.org/10.1190/1.9781560801733 |
| ISBN | ISBN 9781560801153 |
| Store | SEG Online Store |
Contents
Problem 5.20
Given orthogonal dip and strike seismic lines, will velocity analyses at line intersections yield the same values?
Background
Reflecting points on a CMP gather in the dip direction are located updip by distances which increase with offset [see equation (4.11e)] so that a CMP stack smears the data. A DMO correction (Sheriff and Geldart, 1995, section 9.10.2) remedies this.
Solution
A line in the strike direction should yield reliable velocity values, but depths will be slant distances perpendicular to the bed, and reflecting points will be located updip. A commonmidpoint gather in the dip direction will not involve common reflecting points, and measurements will yield erroneous values unless DMO corrections have been made. The velocity analyses will probably yield somewhat different values.
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|---|---|
| Velocity versus depth from sonobuoy data | Effect of time picks, NMO stretch, and datum choice on stacking velocity |
| Previous chapter | Next chapter |
| Geometry of seismic waves | Characteristics of seismic events |
Also in this chapter
- Maximum porosity versus depth
- Relation between lithology and seismic velocities
- Porosities, velocities, and densities of rocks
- Velocities in limestone and sandstone
- Dependence of velocity-depth curves on geology
- Effect of burial history on velocity
- Determining lithology from well-velocity surveys
- Reflectivity versus water saturation
- Effect of overpressure
- Effects of weathered layer (LVL) and permafrost
- Horizontal component of head waves
- Stacking velocity versus rms and average velocities
- Quick-look velocity analysis and effects of errors
- Well-velocity survey
- Interval velocities
- Finding velocity
- Effect of timing errors on stacking velocity, depth, and dip
- Estimating lithology from stacking velocity
- Velocity versus depth from sonobuoy data
- Influence of direction on velocity analyses
- Effect of time picks, NMO stretch, and datum choice on stacking velocity
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