Reflection-point smear for dipping reflectors

Problems in Exploration Seismology and their Solutions

Series	Geophysical References Series
Title	Problems in Exploration Seismology and their Solutions
Author	Lloyd P. Geldart and Robert E. Sheriff
Chapter	8
Pages	253 - 294
DOI	http://dx.doi.org/10.1190/1.9781560801733
ISBN	ISBN 9781560801153
Store	SEG Online Store

Problem

Assume a reflector 2000 m beneath the midpoint and a dip of $20^{\circ }$ with constant over-burden velocity. How much does the reflecting point move between members of the common-midpoint set for offsets of 0, 500, 1000, 1500, and 2000 m?

Background

Equation (4.11e) gives the shift in the reflecting point $\Delta L$ in terms of the dip $\xi$, slant depth $h_{c}$, and offset 2s:

${\begin{aligned}\Delta L=(s^{2}/2h_{c}){\rm {\;sin\;}}2\xi .\end{aligned}}$

(8.2a)

Solution

Because $\sin 2\xi =\sin 40^{\circ }=0.64$, equation (8.2a) becomes

${\begin{aligned}\Delta L=0.16\times 10^{-3}s^{2}{\mbox{m}}.\end{aligned}}$

Thus, we get the following values of $\Delta L$ for the various offsets:

${\begin{aligned}{\hbox{Offset}}(2s)&\rightarrow &0&500&1000&1500&2000m,\\{\hbox{Shift}}(\Delta L)&\rightarrow &0&40&160&360&640m.\end{aligned}}$

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Table of Contents (book)

Also in this chapter

• Effect of too many groups connected to the cable
• Reflection-point smear for dipping reflectors
• Stacking charts
• Attenuation of air waves
• Maximum array length for given apparent velocity
• Response of a linear array
• Directivities of linear arrays and linear sources
• Tapered arrays
• Directivity of marine arrays
• Response of a triangular array
• Noise tests
• Selecting optimum field methods
• Optimizing field layouts
• Determining vibroseis parameters
• Selecting survey parameters
• Effect of signal/noise ratio on event picking
• Interpreting uphole surveys
• Weathering and elevation (near-surface) corrections
• Determining static corrections from first breaks
• Determining reflector location
• Blondeau weathering corrections

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