Spectral Density Logging Tool Measurement Principle Electrical Engineering
Questions and Answers
- 1.
Select all of the following applications of the SDLT.
- A.
Determine the volume of shale
- B.
Measure formation permeability
- C.
Identification of gas bearing formations
- D.
Estimation of formation true resistivity
- E.
Estimation of hydrocarbon density
- F.
Determine formation porosity
- G.
Determine lithology
Correct Answer(s)
A. Determine the volume of shale
C. Identification of gas bearing formations
E. Estimation of hydrocarbon density
F. Determine formation porosity
G. Determine lithologyExplanation
The SDLT (Spectral Density Logging Tool) can be used to determine the volume of shale by analyzing the spectral gamma ray response. It can also help in the identification of gas bearing formations by detecting the presence of gas through gamma ray and neutron measurements. The tool can estimate hydrocarbon density by measuring the bulk density of the formation. It can determine formation porosity by analyzing the neutron and density measurements. Additionally, the SDLT can determine lithology by analyzing the spectral gamma ray response and comparing it to known lithology signatures.Rate this question:
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- 2.
Select all of the following that apply to scintillation detectors.
- A.
Crystal is composed of sodium chloride NaCl
- B.
Scintillation crystal coupled to a photo multiplier tube
- C.
Gamma rays interact with the scintillation crystal
- D.
Electrons pass through high voltage fields to produce several secondary electrons
- E.
Electrons are ejected from the photo multiplier tube
Correct Answer(s)
B. Scintillation crystal coupled to a photo multiplier tube
C. Gamma rays interact with the scintillation crystal
D. Electrons pass through high voltage fields to produce several secondary electronsExplanation
Scintillation detectors are composed of a scintillation crystal coupled to a photo multiplier tube. These detectors work by detecting gamma rays that interact with the scintillation crystal. When gamma rays interact with the crystal, electrons are produced and pass through high voltage fields, creating several secondary electrons. These secondary electrons are then ejected from the photo multiplier tube.Rate this question:
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- 3.
Lithology can be determined from
- A.
Photoelectric factor
- B.
Tortuosity factor
- C.
Cementation exponent
- D.
Saturation exponent
Correct Answer
A. Photoelectric factorExplanation
The lithology can be determined from the photoelectric factor. The photoelectric factor is a measure of the rock's ability to absorb or emit gamma rays when exposed to radiation. Different lithologies have different photoelectric factors due to variations in their mineral composition and density. By analyzing the photoelectric factor, geologists can identify the lithology of a rock formation.Rate this question:
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- 4.
The SDLT cannot acquire accurate data in
- A.
Cased Hole
- B.
Freshwater-based mud
- C.
Saltwater-based mud
- D.
Air-drilled holes
Correct Answer
A. Cased HoleExplanation
The SDLT (Shallow Depth Logging Tool) is unable to acquire accurate data in cased holes. Cased holes are wells that have been lined with casing to provide stability and prevent collapse. The casing obstructs the direct contact between the tool and the formation, making it difficult for the SDLT to accurately measure the properties of the rock or fluid in the formation. Therefore, the SDLT is not suitable for acquiring accurate data in cased holes.Rate this question:
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- 5.
The SDLT employs a 1.5 Curie chemical source of ________ to emit a continuous stream of gamma rays
- A.
Cesium-137
- B.
Americium/Beryllium
- C.
Cobalt 60
- D.
Thorium
Correct Answer
A. Cesium-137Explanation
The correct answer is Cesium-137. Cesium-137 is a radioactive isotope that emits gamma rays. It is commonly used in industrial and medical applications, including in the construction of the Self-Contained Directional Locator Tool (SDLT). The SDLT utilizes a 1.5 Curie chemical source of Cesium-137 to emit a continuous stream of gamma rays, which can be detected and used for various purposes such as locating underground pipes or determining the density of materials.Rate this question:
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- 6.
Which of the following statements is true?
- A.
Energy loss in gamma rays can be related to physical characteristics of the formation
- B.
Gamma rays interacting with electrons in formation gain energy
Correct Answer
A. Energy loss in gamma rays can be related to physical characteristics of the formationExplanation
Gamma rays can lose energy as they interact with the physical characteristics of the formation, such as the density and composition of the rocks. This energy loss can occur through various processes, including Compton scattering and photoelectric absorption. As the gamma rays interact with the electrons in the formation, they can transfer energy to the electrons, causing the gamma rays to lose energy. Therefore, the statement "Energy loss in gamma rays can be related to physical characteristics of the formation" is true.Rate this question:
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- 7.
Gamma rays may be absorbed by an electron when their energy level reaches
- A.
100 keV
- B.
1000 keV
- C.
10,000 keV
Correct Answer
A. 100 keVExplanation
Gamma rays may be absorbed by an electron when their energy level reaches 100 keV. This is because the energy of the gamma ray needs to match or exceed the binding energy of the electron in order for the absorption to occur. At energy levels below 100 keV, the gamma ray does not have enough energy to overcome the binding energy of the electron and therefore cannot be absorbed.Rate this question:
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- 8.
The binding energy of inner shell electrons is greater than outer shell electrons and increases proportionally to the atomic number of the nucleus.
- A.
True
- B.
False
Correct Answer
A. TrueExplanation
The statement is true because the binding energy of inner shell electrons is indeed greater than that of outer shell electrons. This is because inner shell electrons are closer to the nucleus and experience a stronger attraction, resulting in a higher binding energy. Additionally, the binding energy increases proportionally to the atomic number of the nucleus, as a higher atomic number means more protons in the nucleus and a stronger attraction for the electrons.Rate this question:
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- 9.
The energy loss experienced by a gamma ray in a collision with an outer shell electron is dependent on the rock's molecular composition.
- A.
True
- B.
False
Correct Answer
A. TrueExplanation
The energy loss experienced by a gamma ray in a collision with an outer shell electron is dependent on the rock's molecular composition. This is because different elements and compounds have different atomic structures and electron configurations, which affect the probability of interaction between gamma rays and electrons. Therefore, the molecular composition of the rock determines the energy loss experienced by the gamma ray during collision.Rate this question:
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- 10.
What happens when a low energy (<100 keV) gamma ray interacts with the inner shell electron?
- A.
The electron absorbs the gamma ray and is ejected from its shell
- B.
The electron is displaced to an outer shell
- C.
The electron remains in an unchanged state
Correct Answer
A. The electron absorbs the gamma ray and is ejected from its shellExplanation
When a low energy gamma ray interacts with the inner shell electron, it transfers its energy to the electron. This energy is sufficient to overcome the binding energy of the electron, causing it to be ejected from its shell. Therefore, the correct answer is that the electron absorbs the gamma ray and is ejected from its shell.Rate this question:
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- 11.
Which of the following best describes Compton scattering?
- A.
Higher energy (>100 keV) gamma rays collide with an outer shell electron and transfers some of its energy to that electron.
- B.
Higher energy (>100 keV) gamma rays collide with an inner shell electron causing the electron to move to an outer shell
- C.
Low energy (
- D.
Low energy (
Correct Answer
A. Higher energy (>100 keV) gamma rays collide with an outer shell electron and transfers some of its energy to that electron.Explanation
Compton scattering occurs when higher energy gamma rays collide with an outer shell electron and transfer some of their energy to that electron. This process results in a change in the direction and wavelength of the gamma ray, while the electron is ejected from its original position with increased energy. This phenomenon is an important interaction between gamma rays and matter, providing evidence for the particle-like nature of photons and supporting the concept of wave-particle duality.Rate this question:
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- 12.
Energy levels of greater than ________ are used to obtain a formation's bulk density.
- A.
100 keV
- B.
1 MeV
- C.
1000 keV
- D.
10,000 keV
Correct Answer
A. 100 keVExplanation
The energy levels of greater than 100 keV are used to obtain a formation's bulk density. This suggests that in order to accurately measure the bulk density of a formation, a minimum energy level of 100 keV is required. Energy levels below this threshold may not provide sufficient penetration or resolution to accurately measure the density of the formation.Rate this question:
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- 13.
When a low energy gamma ray collides with the inner shell electron and transfers its entire energy to that electron, which of the following occurs?
- A.
Photoelectric absorbsion
- B.
Compton scattering
- C.
Scintillation
Correct Answer
A. Photoelectric absorbsionExplanation
When a low energy gamma ray collides with the inner shell electron and transfers its entire energy to that electron, photoelectric absorption occurs. In this process, the electron is ejected from its orbit, creating a vacancy. Another electron from a higher energy level fills this vacancy, releasing energy in the form of characteristic x-rays or Auger electrons. This phenomenon is commonly observed in materials with high atomic numbers.Rate this question:
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- 14.
How many detectors does the SDLT employ?
- A.
2
- B.
1
- C.
3
- D.
4
Correct Answer
A. 2Explanation
The SDLT employs 2 detectors.Rate this question:
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- 15.
Bulk density and photoelectric factor measurements are processed using windows W1 through W4.
- A.
True
- B.
False
Correct Answer
A. TrueExplanation
The given statement is true. Bulk density and photoelectric factor measurements are processed using windows W1 through W4. This means that these measurements are analyzed and calculated using specific software or tools that are labeled as W1, W2, W3, and W4. These windows may have different functions or algorithms to process the data and provide accurate results for bulk density and photoelectric factor measurements. Therefore, the statement is correct.Rate this question:
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- 16.
Which of the following curves represents corrections applied to bulk density for lithology?
- A.
CORM curve
- B.
CORP curve
- C.
RHOB curve
Correct Answer
A. CORM curveExplanation
The CORM curve represents corrections applied to bulk density for lithology.Rate this question:
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- 17.
Which of the following curves represents corrections applied to bulk density caused by stand-off?
- A.
CORM curve
- B.
CORP curve
- C.
RHOB curve
Correct Answer
B. CORP curveExplanation
The CORP curve represents corrections applied to bulk density caused by stand-off.Rate this question:
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- 18.
What correction is applied to the bulk density measurement for a washout?
- A.
Positive
- B.
Negative
- C.
No change
Correct Answer
A. PositiveExplanation
When a washout occurs, it refers to the loss of material from the sample during the measurement process. This loss can result in a decrease in the bulk density measurement. To correct for this, a positive correction is applied to account for the lost material and adjust the bulk density measurement upward. This ensures that the measurement accurately reflects the density of the remaining material in the sample.Rate this question:
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- 19.
What correction is applied to the bulk density measurement for barite mudcake?
- A.
Positive
- B.
Negative
- C.
No Change
Correct Answer
B. NegativeExplanation
The correction applied to the bulk density measurement for barite mudcake is negative. This means that the measured bulk density of the mudcake is adjusted downwards to account for any excess weight or density caused by the presence of barite particles. This correction is necessary to obtain an accurate measurement of the actual density of the mudcake without the influence of the barite.Rate this question:
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- 20.
Stand-off refers to
- A.
Any physical separation between a detector and formation
- B.
Distance between source and short-spaced detector
- C.
Physical distance between the short-spaced and long-spaced detector
- D.
Distance traveled by gamma rays from the source to the point at which it is absorbed
Correct Answer
A. Any physical separation between a detector and formationExplanation
Stand-off refers to any physical separation between a detector and formation. This means that there is a distance or gap between the detector and the formation being measured. This physical separation can affect the accuracy and reliability of the measurements taken by the detector, as it introduces potential sources of error or interference. Therefore, stand-off is an important factor to consider when analyzing and interpreting data collected by detectors in various applications.Rate this question:
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- 21.
The SDLT can acquire accurate data in
- A.
Cased Hole
- B.
Freshwater-based mud
- C.
Saltwater-based mud
- D.
Air-drilled holes
Correct Answer(s)
B. Freshwater-based mud
C. Saltwater-based mud
D. Air-drilled holesExplanation
The SDLT (Sonic Data Logging Tool) is capable of acquiring accurate data in cased hole, freshwater-based mud, saltwater-based mud, and air-drilled holes. This implies that the tool is versatile and can be used in different drilling environments. It can effectively measure and analyze sonic data in these specific conditions, providing valuable information for well evaluation and reservoir characterization.Rate this question:
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- 22.
The Spectral Density Logging Tool (SDLT) is designed to measure the electron density and gamma ray absorption properties of a formation.
- A.
True
- B.
False
Correct Answer
A. TrueExplanation
The Spectral Density Logging Tool (SDLT) is specifically created to measure the electron density and gamma ray absorption properties of a formation. This tool enables the evaluation of the formation's composition and characteristics by analyzing the electron density and gamma ray absorption. Therefore, the statement "True" accurately reflects the purpose and function of the SDLT.Rate this question:
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- 23.
Gamma rays emitted from the cesium-137 source have an initial energy of _____ KeV.
- A.
662
- B.
62
- C.
6,662
Correct Answer
A. 662Explanation
Gamma rays emitted from the cesium-137 source have an initial energy of 662 KeV.Rate this question:
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- 24.
At higher energy levels (>100 KeV), gamma rays interact with ____ shell electrons of atoms.
- A.
Outer
- B.
Inner
Correct Answer
A. OuterExplanation
At higher energy levels (>100 KeV), gamma rays interact with outer shell electrons of atoms. This is because gamma rays are high-energy photons that can penetrate through the inner shells of atoms without interacting significantly. However, when they encounter the outer shell electrons, they can cause ionization or excitation of these electrons, leading to various atomic processes such as the emission of characteristic X-rays or the production of electron-positron pairs.Rate this question:
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- 25.
At lower energy levels (<100 KeV), gamma rays interact with ____ shell electrons of atoms.
- A.
Outer
- B.
Inner
Correct Answer
B. InnerExplanation
At lower energy levels (Rate this question:
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- 26.
Interactions with outer shell electrons are ___________.
- A.
Lithology-independent
- B.
Lithology-dependent
- C.
Porosity-independent
- D.
Porosity-dependent
Correct Answer
A. Lithology-independentExplanation
Interactions with outer shell electrons are independent of the lithology. This means that the type of rock or mineral composition does not affect how the outer shell electrons interact with other substances or elements. The behavior of these electrons remains consistent regardless of the lithology, making their interactions lithology-independent.Rate this question:
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- 27.
Interactions with inner shell electrons are ___________.
- A.
Lithology-independent
- B.
Lithology-dependent
- C.
Porosity-independent
- D.
Porosity-dependent
Correct Answer
B. Lithology-dependentExplanation
Interactions with inner shell electrons depend on the lithology, or the type of rock or mineral present. Different lithologies have different arrangements of electrons in their inner shells, which affects how they interact with other particles or radiation. Therefore, the interactions with inner shell electrons are lithology-dependent.Rate this question:
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- 28.
The SDLT employs ___ scintillation detectors to measure the amount and energy level of scattered gamma rays.
- A.
1
- B.
2
- C.
3
- D.
4
Correct Answer
B. 2Explanation
The correct answer is 2 because the question states that the SDLT employs scintillation detectors to measure scattered gamma rays. The word "scintillation" implies the use of scintillation detectors, which are devices that can detect and measure gamma rays. Therefore, it is logical to assume that the SDLT employs more than one scintillation detector, hence the answer is 2.Rate this question:
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- 29.
Measured gamma rays are sorted according to their energy levels into ____ different ranges or windows.
- A.
4
- B.
2
- C.
6
- D.
8
Correct Answer
D. 8Explanation
Gamma rays are high-energy electromagnetic waves emitted during radioactive decay or nuclear reactions. They can have a wide range of energy levels. To effectively analyze and interpret gamma ray data, scientists sort them into different energy ranges or windows. The more energy ranges they use, the more detailed and precise their analysis can be. Therefore, having 8 different ranges or windows would provide a more comprehensive understanding of the gamma ray data compared to having fewer ranges.Rate this question:
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- 30.
Which windows are used to compensate for shifts in the energy spectra that are caused by temperature variations downhole?
- A.
W1-W4
- B.
W2-W5
- C.
W4-W8
- D.
W5-W8
Correct Answer
D. W5-W8Explanation
Windows W5-W8 are used to compensate for shifts in the energy spectra that are caused by temperature variations downhole.Rate this question:
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- 31.
Once electron density (ρe) is derived from the count rates, it must be corrected for borehole diameter and mud weight.
- A.
True
- B.
False
Correct Answer
A. TrueExplanation
The statement is true because when deriving electron density from count rates, it is necessary to correct for borehole diameter and mud weight. Borehole diameter affects the amount of mud in the hole, which in turn affects the measurement of electron density. Similarly, mud weight, which is the density of the drilling mud, can also influence the measurement. Therefore, to obtain accurate electron density values, corrections for these factors must be applied.Rate this question:
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- 32.
Which of the following are gamma ray absorbers?
- A.
Iron
- B.
Barite
- C.
Bentonite
- D.
Hydrogen
Correct Answer(s)
A. Iron
B. BariteExplanation
Iron and Barite are both gamma ray absorbers. Iron is a commonly used material for shielding against gamma rays due to its high density and atomic number. It effectively absorbs and attenuates the gamma radiation. Barite, a mineral composed of barium sulfate, is also known for its ability to absorb gamma rays. It is often used in the oil and gas industry as a weighting agent in drilling fluids to provide radiation shielding. Bentonite and Hydrogen, on the other hand, are not known for their gamma ray absorption properties.Rate this question:
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