p.p1 {margin: 0.0px 0.0px 0.0px 0.0px; font: 13.9px Calibri} Both VSP and checkshot survey are one type of borehole seismic acquisition but the main difference(s) between VSP and checkshot survey is(are) .......... p.p1 {margin: 0.0px 0.0px 0.0px 0.0px; font: 13.9px Calibri}

only the first directly arriving signals sensed by the downhole geophone in a checkshot survey whereas VSP takes account of both reflected and direct arrival signals.

VSP survey takes into account of upgoing energy whereas checkshot survey takes into account of the downgoing energy.

only checkshot survey calibrates with the sonic log in order to correct for any erroneous velocity.

a check shot velocity survey measures a much larger cylindrical volume of rock compared to VSP survey.

p.p1 {margin: 0.0px 0.0px 0.0px 0.0px; font: 13.9px Calibri} Tuning effect is a phenomenon of _______ or _______ interference of waves resulting from events closer than _______ of the dominant wavelength. p.p1 {margin: 0.0px 0.0px 0.0px 0.0px; font: 13.9px Calibri}

constructive, destructive, one-quarter

constructive, positive, one-third

constructive, positive, one-quarter

constructive, destructive, one-third

p.p1 {margin: 0.0px 0.0px 0.0px 0.0px; font: 13.9px Calibri} Bright spot is a seismic amplitude anomaly that may indicate the presense of hydrocarbons. What is(are) the cause(s) of a bright spot? You may pick more than one answer.

Changes in acoustic impedance, e.g. shale overlies on a gas sand

Changes in signal-to-noise ratio in the data

Define the main difference between RMS velocity and stacking velocity.

RMS velocity is that of a wave that travels through subsurface layers of different interval velocity along a specific raypath whereas stacking velocity is velocity calculated from velocity analysis based on normal-moveout measurements.

RMS velocity is that of a wave that travels through subsurface layers of similar interval velocity along a specific raypath whereas stacking velocity is velocity calculated from velocity analysis based on normal-moveout measurements.

RMS velocity is that of a wave that travels through subsurface layers of different interval velocity along a specific raypath whereas stacking velocity is velocity calculated from varying constant models based on normal-moveout measurements.

When can both RMS and stacking velocity become comparable and equal?

The stacking velocity and the root-mean-square velocity approach equality when source-receiver offset approaches zero and layers are horizontal and isotropic.

The stacking velocity and the root-mean-square velocity approach equality when the layers are horizontal and isotropic.

The stacking velocity and the root-mean-square velocity approach equality when the velocities in the subsurface layers are varying horizontally only (not vertically).

The stacking velocity and the root-mean-square velocity approach equality when the velocities in the subsurface layers are varying vertically only (not horizontally).

Geophysics 101

10 Questions | By Dnphd29 | Updated: Jan 25, 2013 | Attempts: 738

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1.

p.p1 {margin: 0.0px 0.0px 0.0px 0.0px; font: 12.0px Calibri} p.p1 {margin: 0.0px 0.0px 0.0px 0.0px; font: 13.9px Calibri} Spectral decomposition is a useful tool in decomposing the seismic signal into its constituent velocities as seismic section is a composition of different bands of seismic velocities. Thus, this tool helps the observer to appreciate the subtle details beyond conventional seismic data. p.p1 {margin: 0.0px 0.0px 0.0px 0.0px; font: 13.9px Calibri} p.p1 {margin: 0.0px 0.0px 0.0px 0.0px; font: 13.9px Calibri}
- A.
  
  True
- B.
  
  False
Correct Answer
B. False

Explanation
Spectral decomposition is a techinque that can extract the range of frequencies constituting a seismic section since a seismic section consists of different bands of frequencies.

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1
0
2.

p.p1 {margin: 0.0px 0.0px 0.0px 0.0px; font: 13.9px Calibri} Both VSP and checkshot survey are one type of borehole seismic acquisition but the main difference(s) between VSP and checkshot survey is(are) .......... p.p1 {margin: 0.0px 0.0px 0.0px 0.0px; font: 13.9px Calibri}
- A.
  
  VSP survey takes into account of upgoing energy whereas checkshot survey takes into account of the downgoing energy.
- B.
  
  Only checkshot survey calibrates with the sonic log in order to correct for any erroneous velocity.
- C.
  
  A check shot velocity survey measures a much larger cylindrical volume of rock compared to VSP survey.
- D.
  
  Only the first directly arriving signals sensed by the downhole geophone in a checkshot survey whereas VSP takes account of both reflected and direct arrival signals.
Correct Answer
D. Only the first directly arriving signals sensed by the downhole geophone in a checkshot survey whereas VSP takes account of both reflected and direct arrival signals.
3.

p.p1 {margin: 0.0px 0.0px 0.0px 0.0px; font: 12.0px Calibri} p.p1 {margin: 0.0px 0.0px 0.0px 0.0px; font: 13.9px Calibri} Bayes’s theorem is used for the modification process to integrated direct geophysical evidence with indirect geological risking.
- A.
  
  True
- B.
  
  False
Correct Answer
A. True

Explanation
Bayes's theorem is a theorem that gives a-posteria probability in terms of a-priori probability and this theorem is used in estimating POS for geophysical risking

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4.

p.p1 {margin: 0.0px 0.0px 0.0px 0.0px; font: 13.9px Calibri} Tuning effect is a phenomenon of _______ or _______ interference of waves resulting from events closer than _______ of the dominant wavelength. p.p1 {margin: 0.0px 0.0px 0.0px 0.0px; font: 13.9px Calibri}
- A.
  
  Constructive, positive, one-third
- B.
  
  Constructive, positive, one-quarter
- C.
  
  Constructive, destructive, one-third
- D.
  
  Constructive, destructive, one-quarter
Correct Answer
D. Constructive, destructive, one-quarter
5.

p.p1 {margin: 0.0px 0.0px 0.0px 0.0px; font: 13.9px Calibri} Bright spot is a seismic amplitude anomaly that may indicate the presense of hydrocarbons. What is(are) the cause(s) of a bright spot? You may pick more than one answer.
- A.
  
  Changes in signal-to-noise ratio in the data
- B.
  
  Changes in acoustic impedance, e.g. shale overlies on a gas sand
- C.
  
  Changes in tuning effect
- D.
  
  Changes in lithology
Correct Answer(s)
B. Changes in acoustic impedance, e.g. shale overlies on a gas sand
C. Changes in tuning effect
D. Changes in lithology
6.

Define the main difference between RMS velocity and stacking velocity.
- A.
  
  RMS velocity is that of a wave that travels through subsurface layers of similar interval velocity along a specific raypath whereas stacking velocity is velocity calculated from velocity analysis based on normal-moveout measurements.
- B.
  
  RMS velocity is that of a wave that travels through subsurface layers of different interval velocity along a specific raypath whereas stacking velocity is velocity calculated from velocity analysis based on normal-moveout measurements.
- C.
  
  RMS velocity is that of a wave that travels through subsurface layers of different interval velocity along a specific raypath whereas stacking velocity is velocity calculated from varying constant models based on normal-moveout measurements.
Correct Answer
B. RMS velocity is that of a wave that travels through subsurface layers of different interval velocity along a specific raypath whereas stacking velocity is velocity calculated from velocity analysis based on normal-moveout measurements.
7.

When can both RMS and stacking velocity become comparable and equal?
- A.
  
  The stacking velocity and the root-mean-square velocity approach equality when the layers are horizontal and isotropic.
- B.
  
  The stacking velocity and the root-mean-square velocity approach equality when source-receiver offset approaches zero and layers are horizontal and isotropic.
- C.
  
  The stacking velocity and the root-mean-square velocity approach equality when the velocities in the subsurface layers are varying horizontally only (not vertically).
- D.
  
  The stacking velocity and the root-mean-square velocity approach equality when the velocities in the subsurface layers are varying vertically only (not horizontally).
Correct Answer
B. The stacking velocity and the root-mean-square velocity approach equality when source-receiver offset approaches zero and layers are horizontal and isotropic.
8.

What is the equation used to determine the interval velocity within a series of flat and parallel layers?
- A.
  
  Humble Formula
- B.
  
  Dix Formula
- C.
  
  Zoeppritz Equation
Correct Answer
B. Dix Formula

Explanation
Humble formula involves a particular relation between the formation factor (F) and porosity (phi) proposed by the Humble Oil Company.

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9.

How and what are the ways to examine the quality of seismic data? You may tick more than one answer.
- A.
  
  Well-to-seismic tie
- B.
  
  Attribute extraction
- C.
  
  Volume scanning
- D.
  
  Gathers analysis
Correct Answer(s)
A. Well-to-seismic tie
C. Volume scanning
D. Gathers analysis
10.

What can deteriorate the quality of well-to-seismic tie? You may tick more than one answer.
- A.
  
  Invasion effects
- B.
  
  Poor seismic data quality
- C.
  
  Erroneous sonic logs
- D.
  
  The acoustic impedances of sands and shales are quite similar
Correct Answer(s)
A. Invasion effects
B. Poor seismic data quality
C. Erroneous sonic logs
D. The acoustic impedances of sands and shales are quite similar

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Current Version
Jan 25, 2013

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May 11, 2011

Quiz Created by
Dnphd29

Geophysics 101

p.p1 {margin: 0.0px 0.0px 0.0px 0.0px; font: 13.9px Calibri} Both VSP and checkshot survey are one type of borehole seismic acquisition but the main difference(s) between VSP and checkshot survey is(are) .......... p.p1 {margin: 0.0px 0.0px 0.0px 0.0px; font: 13.9px Calibri}

p.p1 {margin: 0.0px 0.0px 0.0px 0.0px; font: 12.0px Calibri} p.p1 {margin: 0.0px 0.0px 0.0px 0.0px; font: 13.9px Calibri} Bayes’s theorem is used for the modification process to integrated direct geophysical evidence with indirect geological risking.

p.p1 {margin: 0.0px 0.0px 0.0px 0.0px; font: 13.9px Calibri} Tuning effect is a phenomenon of _______ or _______ interference of waves resulting from events closer than _______ of the dominant wavelength. p.p1 {margin: 0.0px 0.0px 0.0px 0.0px; font: 13.9px Calibri}

p.p1 {margin: 0.0px 0.0px 0.0px 0.0px; font: 13.9px Calibri} Bright spot is a seismic amplitude anomaly that may indicate the presense of hydrocarbons. What is(are) the cause(s) of a bright spot? You may pick more than one answer.

Define the main difference between RMS velocity and stacking velocity.

When can both RMS and stacking velocity become comparable and equal?

What is the equation used to determine the interval velocity within a series of flat and parallel layers?

How and what are the ways to examine the quality of seismic data? You may tick more than one answer.

What can deteriorate the quality of well-to-seismic tie? You may tick more than one answer.

p.p1 {margin: 0.0px 0.0px 0.0px 0.0px; font: 13.9px Calibri} Tuning effect is a phenomenon of ___ or _ interference of waves resulting from events closer than _____ of the dominant wavelength. p.p1 {margin: 0.0px 0.0px 0.0px 0.0px; font: 13.9px Calibri}