Seismic Data Processing (May 16)
QUIZ for QAB 4083: Seismic Data Processing (May 2016 Semester)
Instruction to the students:
1. There are 10 multiple choice questions, 10 fill in the box questions and 1 essay question. Answer ALL the questions.
2. Time given for this quiz is 30 minutes.
3. No time extension will be allowed.
Good luck!
Questions and Answers
- 1.
Given shot record in (a), propose the necessary step(s) required to obtain a good shot record as in (b).
- 2.
Why is it useful to transform the seismic data from time domain to frequency domain,before processing and analysing them?
- A.
Time series data is complicated because it is unclear when certain events occur.
- B.
It will easier to analyse the seismic data through amplitude and phase in frequency domain.
- C.
Frequency data has smaller data space size, thus can accommodate more information.
- D.
Final seismic data use for interpretation is in frequency domain.
Correct Answer
B. It will easier to analyse the seismic data through amplitude and phase in frequency domain.Explanation
Fourier transform is from time domain to frequency domain. All the process and analysis were conducted in frequency domain.Rate this question:
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- 3.
Which of the statements below best describe the objective of seismic data processing?
- A.
To manipulate the acquired data into an image that can be used to infer the subsurface geologic structure.
- B.
To render the most accurate possible graphic representation of specific portion of the Earth’s subsurface geologic model.
- C.
Analysing recorded data to create a subsurface image and estimate the distribution of properties.
- D.
Alteration of seismic data to suppress noise, enhance signal and migrate seismic events to the appropriate location in space.
Correct Answer
D. Alteration of seismic data to suppress noise, enhance signal and migrate seismic events to the appropriate location in space.Explanation
Other answer options also correct, but not best represent the seismic data processing.Rate this question:
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- 4.
How is acquiring seismic data at sea different from acquiring seismic data on the land?
- A.
Seismic data acquired at sea is much wetter than it is on land.
- B.
During seismic acquisition at sea, the source and recording instruments are continuously moving.
- C.
Seismic data acquisition at sea affected by salt water, making the process a bit complicated.
- D.
There is no requirement for any type of static corrections for seismic data acquisition at sea.
Correct Answer
B. During seismic acquisition at sea, the source and recording instruments are continuously moving.Explanation
In marine data acquisition, the boat is moving continuously, towing the air gun and streamers at the same time.Rate this question:
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- 5.
What properties determine how long it takes a seismic wave to travel through a material?
- A.
Density and seismic velocity.
- B.
Subsurface Impedance and seismic velocity.
- C.
Density and mineral content.
- D.
Reflectivity coefficient.
Correct Answer
A. Density and seismic velocity.Explanation
The properties that determine how long it takes a seismic wave to travel through a material are density and seismic velocity. Density refers to the mass per unit volume of the material, while seismic velocity is the speed at which the wave travels through the material. These two properties are directly related to each other, as materials with higher density tend to have higher seismic velocities. Therefore, the correct answer is density and seismic velocity.Rate this question:
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- 6.
Which statements follow best describe the Fourier Transform?
- A.
An algorithm function that turns frequency data into sinusoidal waves.
- B.
A transform used in engineering for complex number arithmetic.
- C.
Mathematical tool that shows us how to deconstruct the waveform into its sinusoidal components.
- D.
An algorithm used to convert time domain data to Fourier domain.
Correct Answer
D. An algorithm used to convert time domain data to Fourier domain.Explanation
The Fourier Transform is a mathematical tool that allows us to analyze a waveform by decomposing it into its individual sinusoidal components. It is used to convert time domain data, such as a waveform in the time domain, into the frequency domain, where we can see the different frequencies present in the signal. This transformation is achieved through an algorithm, making the statement "An algorithm used to convert time domain data to Fourier domain" the best description of the Fourier Transform among the given options.Rate this question:
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- 7.
Cross correlation operations are almost similar to convolution. Which of the operations that cross correlation does not take part in convolution?
- A.
Summation
- B.
Shifting
- C.
Multiplication
- D.
Folding
Correct Answer
D. FoldingExplanation
Cross correlation operations involve shifting and multiplication, which are also part of convolution. However, folding is not a part of cross correlation. Folding refers to flipping the signal horizontally, which is not done in cross correlation. Instead, cross correlation calculates the similarity between two signals by sliding one signal over the other and calculating the sum of the element-wise products. Therefore, folding is the operation that cross correlation does not take part in convolution.Rate this question:
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- 8.
What kind of analysis that is NOT in pre-processing takes place?
- A.
Velocity analysis.
- B.
Signal recovery analysis.
- C.
Attribute analysis.
- D.
Amplitude gaining analysis
Correct Answer
C. Attribute analysis.Explanation
Attributes analysis will be conducted in post-stack processing.Rate this question:
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- 9.
Trace editing process need to be done in order to remove:I. Dead geophone signal.II. Seismograph amplifier failure.III. Cultural noise.IV. Refracted wave and direct wave.
- A.
I, II and III
- B.
I, II and IV
- C.
I, III and IV
- D.
II, III and IV
Correct Answer
A. I, II and IIIExplanation
Refracted and direct wave can be remove by FK Filtering process.Rate this question:
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- 10.
Following statements are the reason why we do pre-stack filtering, EXCEPT:
- A.
Avoid aliasing effects
- B.
Identify harmonic signal in the data
- C.
Highlight signals of certain frequencies
- D.
Removal of bad trace segments
Correct Answer
B. Identify harmonic signal in the dataExplanation
Harmonic signal can be identify using Fourier series.Rate this question:
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- 11.
Which processes that involve in restoring the amplitude energy?
- A.
Automatic Gain Control and muting
- B.
Gain and trace editing
- C.
Gain and trace balancing
- D.
Programmable Gain Control and filtering
Correct Answer
C. Gain and trace balancingExplanation
Gain and trace balancing is the correct answer because it refers to the processes that involve restoring the amplitude energy. Gain balancing refers to adjusting the gain or amplification of a signal to ensure that it is at the desired level. Trace balancing, on the other hand, involves adjusting the amplitude of individual traces within a signal to achieve a balanced overall waveform. Both of these processes are essential in restoring the amplitude energy of a signal.Rate this question:
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- 12.
Identify the correct processing step for the data enhancement purpose as follow:To place shot/receiver separations in trace headers.
Correct Answer
Geometry calculationExplanation
The correct processing step for the data enhancement purpose of placing shot/receiver separations in trace headers is geometry calculation. This step involves calculating the distances between the shot and receiver locations and storing this information in the trace headers. This helps in accurately positioning the seismic data and enables further analysis and interpretation of the data.Rate this question:
- 13.
Identify the correct processing step for the data enhancement purpose as follow:To remove refraction signal and differentiate from reflections.
Correct Answer
Mute, FK FitlerExplanation
The correct processing step for the data enhancement purpose of removing refraction signal and differentiating it from reflections is Mute, FK Filter. Muting involves suppressing or zeroing out specific time intervals in the seismic data where the refraction signal is expected to occur. This helps in isolating the reflections and enhancing their clarity. FK (Frequency-Wavenumber) filtering is then applied to further separate the desired reflections from the remaining noise and unwanted signals.Rate this question:
- 14.
Identify the correct processing step for the data enhancement purpose as follow:To find which frequencies are strongest and allow separation into signal and noise.
Correct Answer
Ampltiude spectrumExplanation
The correct processing step for data enhancement in this case is the amplitude spectrum. The amplitude spectrum helps to identify the strongest frequencies in the data, allowing for the separation of signal and noise. By analyzing the amplitude spectrum, one can determine which frequencies contribute the most to the overall signal and distinguish them from the unwanted noise.Rate this question:
- 15.
Identify the correct processing step for the data enhancement purpose as follow:To convert the broad wavelet into a spike, and improve resolution.
Correct Answer
Spiking DeconvolutionExplanation
Spiking Deconvolution is the correct processing step for the data enhancement purpose described. This technique is used to convert a broad wavelet into a spike, which helps to improve resolution. Deconvolution is a mathematical operation that removes the effects of convolution from a signal, and in this case, it is used to enhance the data by sharpening the wavelet and increasing the resolution. Spiking Deconvolution specifically focuses on transforming a broad wavelet into a spike, which can be beneficial in various applications such as seismic data processing.Rate this question:
- 16.
Identify the correct processing step for the data enhancement purpose as follow:To increase the amplitude temporarily during display session.
Correct Answer
Automatic gain controlExplanation
Automatic gain control is the correct processing step for enhancing data by temporarily increasing the amplitude during a display session. This technique automatically adjusts the gain of a signal to maintain a consistent output level, regardless of variations in input signal strength. By increasing the amplitude, the data can be displayed more prominently and effectively, allowing for better visualization and analysis.Rate this question:
- 17.
Identify the correct processing step for the data enhancement purpose as follow:To prevent artifact appear on data after FK filtering process.
Correct Answer
Anti alias filterExplanation
To prevent artifacts from appearing on the data after the FK filtering process, an anti-alias filter is used. This filter helps to remove or reduce high-frequency components in the data that can cause aliasing, which is the distortion or artifacts that occur when the sampling rate is too low to accurately capture the original signal. By applying an anti-alias filter before the FK filtering process, these artifacts can be minimized or eliminated, resulting in enhanced data quality.Rate this question:
- 18.
Identify the correct processing step for the data enhancement purpose as follow:To increase the amplitude due to wave propagation effect.
Correct Answer
Spherical divergence correctionExplanation
Spherical divergence correction is the correct processing step for enhancing data by increasing the amplitude due to wave propagation effects. This technique is used to compensate for the decrease in amplitude that occurs as waves propagate through space. By applying spherical divergence correction, the amplitude of the waves can be increased, resulting in enhanced data quality.Rate this question:
- 19.
What is the standard tape format during the acquisition?
Correct Answer
SEGD, SEG2Explanation
The standard tape format during the acquisition is SEGD and SEG2. These formats are commonly used in the field of geophysical exploration for storing and transmitting seismic data. SEGD is an acronym for Society of Exploration Geophysicists Data Exchange Format, which is a standard format for storing seismic data on magnetic tapes. SEG2, on the other hand, refers to the SEG-Y Revision 2 format, which is a widely used industry standard for storing seismic data in digital form. Both formats are essential for efficient data exchange and analysis in the field of geophysics.Rate this question:
- 20.
Identify the correct processing step for the data enhancement purpose as follow:To remove a singe noisy trace / dead trace.
Correct Answer
Trace editingExplanation
Trace editing is the correct processing step for the purpose of removing a single noisy trace or dead trace. This step involves manually reviewing and modifying the seismic data to eliminate any unwanted or irrelevant traces that may interfere with the interpretation or analysis of the data. By removing the noisy or dead trace, the overall quality and accuracy of the data can be enhanced, allowing for better analysis and interpretation of the seismic information.Rate this question:
- 21.
Identify the correct processing step for the data enhancement purpose as follow:To remove water bottom multiple without velocity analysis.
Correct Answer
Predictive deconvolutionExplanation
Predictive deconvolution is the correct processing step for removing water bottom multiples without velocity analysis. Predictive deconvolution is a technique used in seismic data processing to suppress or remove multiples, which are unwanted reflections that occur due to the presence of multiple layers of rock or fluid in the subsurface. This technique uses a predictive filter to estimate and subtract the multiples from the seismic data, thus enhancing the primary reflections of interest. In this case, predictive deconvolution is specifically used to remove water bottom multiples without the need for velocity analysis.Rate this question:
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