Difference between revisions of "Suppressing multiples by NMO differences"

From SEG Wiki
Jump to: navigation, search
(Also in this chapter: fixed page)
(add)
 
Line 14: Line 14:
 
  | isbn    = ISBN 9781560801153
 
  | isbn    = ISBN 9781560801153
 
}}
 
}}
== Problem ==
+
== Problem 6.11 ==
 
A primary and a multiple each arrive at 0.600 s at <math>x=0</math>; their stacking velocities are 1800 and 1500 m/s, respectively. Calculate the residual NMO (after NMO correction for the primary velocity) for offsets of 300 <math>n</math>, where <math>n=1, 2,...</math>. What is the shortest offset that will give good multiple suppression for a wavelet with a 50-ms dominant period?
 
A primary and a multiple each arrive at 0.600 s at <math>x=0</math>; their stacking velocities are 1800 and 1500 m/s, respectively. Calculate the residual NMO (after NMO correction for the primary velocity) for offsets of 300 <math>n</math>, where <math>n=1, 2,...</math>. What is the shortest offset that will give good multiple suppression for a wavelet with a 50-ms dominant period?
  

Latest revision as of 15:22, 8 November 2019

Problem 6.11

A primary and a multiple each arrive at 0.600 s at Failed to parse (MathML with SVG or PNG fallback (recommended for modern browsers and accessibility tools): Invalid response ("Math extension cannot connect to Restbase.") from server "https://en.wikipedia.org/api/rest_v1/":): {\displaystyle x=0} ; their stacking velocities are 1800 and 1500 m/s, respectively. Calculate the residual NMO (after NMO correction for the primary velocity) for offsets of 300 Failed to parse (MathML with SVG or PNG fallback (recommended for modern browsers and accessibility tools): Invalid response ("Math extension cannot connect to Restbase.") from server "https://en.wikipedia.org/api/rest_v1/":): {\displaystyle n} , where Failed to parse (MathML with SVG or PNG fallback (recommended for modern browsers and accessibility tools): Invalid response ("Math extension cannot connect to Restbase.") from server "https://en.wikipedia.org/api/rest_v1/":): {\displaystyle n=1, 2,...} . What is the shortest offset that will give good multiple suppression for a wavelet with a 50-ms dominant period?

Solution

The distance to the primary reflector is Failed to parse (MathML with SVG or PNG fallback (recommended for modern browsers and accessibility tools): Invalid response ("Math extension cannot connect to Restbase.") from server "https://en.wikipedia.org/api/rest_v1/":): {\displaystyle (0.600\times 1800)/2=540\ {\rm m}} and to the reflector responsible for the multiple, assuming it is simply a double bounce, is Failed to parse (MathML with SVG or PNG fallback (recommended for modern browsers and accessibility tools): Invalid response ("Math extension cannot connect to Restbase.") from server "https://en.wikipedia.org/api/rest_v1/":): {\displaystyle (0.600\times 1500)/4=225\ {\rm m}} . NMO is given by equation (4.1c), Failed to parse (MathML with SVG or PNG fallback (recommended for modern browsers and accessibility tools): Invalid response ("Math extension cannot connect to Restbase.") from server "https://en.wikipedia.org/api/rest_v1/":): {\displaystyle \Delta t_{\rm NMO} =x^{2} /2V^{2} t_{0}} . We obtain the following values for the moveouts:

Offset 300 m 600 m 900 m
Primary NMO 0.023 s 0.093 s 0.208 s
Multiple NMO 0.033 s 0.133 s 0.300 s
NMO Difference 0.010 s 0.040 s 0.092 s

Multiple suppression should be maximum when the NMO difference approximates half the wavelet period so that some of the traces are out-of-phase, which is achieved at offset Failed to parse (MathML with SVG or PNG fallback (recommended for modern browsers and accessibility tools): Invalid response ("Math extension cannot connect to Restbase.") from server "https://en.wikipedia.org/api/rest_v1/":): {\displaystyle x} where

Failed to parse (MathML with SVG or PNG fallback (recommended for modern browsers and accessibility tools): Invalid response ("Math extension cannot connect to Restbase.") from server "https://en.wikipedia.org/api/rest_v1/":): {\displaystyle \begin{align} x^{2} /1.200\times 1500^{2} -x^{2} /1.200\times \; 1800^{2}\; =0.050,\; x =660\ {\rm m}. \end{align} }

Continue reading

Previous section Next section
Differential moveout between primary and multiple Distinguishing horizontal/vertical discontinuities
Previous chapter Next chapter
Geometry of seismic waves Characteristics of seismic events

Table of Contents (book)

Also in this chapter

External links

find literature about
Suppressing multiples by NMO differences
SEG button search.png Datapages button.png GeoScienceWorld button.png OnePetro button.png Schlumberger button.png Google button.png AGI button.png