NGWA Cable Tool Drilling Exam (A/B)
Questions and Correct Answers (Verified
Answers) Plus Rationales
Question 1: What is the primary function of the walking beam on a cable tool
drilling rig?
A. To rotate the drill string continuously
B. To provide the up-and-down reciprocating motion that lifts and drops the drill
tools
C. To spool and unspool the sand line during bailing operations
D. To power the mud pump for circulating drilling fluid
CORRECT ANSWER: B. To provide the up-and-down reciprocating motion that
lifts and drops the drill tools
Rationale: The walking beam is a critical mechanical component that converts rotary
motion from the engine into the vertical oscillating stroke required for percussion
drilling. This motion raises the tools on the upstroke and allows them to free-fall on
the downstroke, delivering the impact energy that fractures the formation.
Question 2: In cable tool drilling, what is the purpose of the “jar” in the tool
string?
A. To measure the depth of the borehole continuously
B. To provide a delayed impact that helps free stuck tools by delivering a sharp
upward or downward blow
C. To circulate drilling fluid past the bit face
D. To stabilize the casing during driving operations
CORRECT ANSWER: B. To provide a delayed impact that helps free stuck tools
by delivering a sharp upward or downward blow
Rationale: Jars are specialized links placed in the tool string that allow a controlled
amount of free travel. When the tools become stuck, the sudden engagement of the
jar creates a sharp percussion force that can jar the tools loose without damaging
the cable or other components.
Question 3: Which of the following best describes the action of a cable-tool bit
during drilling?
A. Continuous rotation with fluid circulation to cut the formation
Page 1 of 65
,B. Intermittent impact and crushing action produced by the free fall of the tools
C. High-speed abrasion using diamond-impregnated surfaces
D. Hydraulic jetting that erodes the formation with high-pressure fluid
CORRECT ANSWER: B. Intermittent impact and crushing action produced by
the free fall of the tools
Rationale: Cable-tool drilling relies on percussion. The bit is repeatedly lifted and
allowed to drop, crushing and fracturing the rock. The resulting cuttings are mixed
with water in the borehole and removed by bailing.
Question 4: What is the primary purpose of the sand line on a cable tool rig?
A. To suspend the main drill tools during the drilling stroke
B. To raise and lower the bailer for removing cuttings and fluid from the hole
C. To drive casing into the ground with successive blows
D. To measure the exact length of the drill cable
CORRECT ANSWER: B. To raise and lower the bailer for removing cuttings and
fluid from the hole
Rationale: The sand line is a separate lighter cable dedicated to operating the bailer.
After a period of drilling, the main tools are pulled, and the bailer is run on the sand
line to clean the borehole of cuttings and slurry.
Question 5: When driving casing with a cable tool rig, what device is
commonly used to protect the top of the casing from damage?
A. A rotary table
B. A drive head or drive shoe fitted over the casing top
C. A kelly bushing
D. A blowout preventer stack
CORRECT ANSWER: B. A drive head or drive shoe fitted over the casing top
Rationale: A drive head (or drive clamp) is placed on the upper end of the casing so
that the weight of the tools or a separate drive weight can be applied without
mushrooming or splitting the casing top. A drive shoe is welded or threaded to the
bottom of the casing to protect the leading edge as it is driven.
Question 6: What is the function of the bull wheel on a traditional cable tool
drilling machine?
A. To store and control the main drilling cable that supports the tool string
B. To circulate drilling mud through the system
C. To rotate the turntable that turns the drill pipe
D. To power the generator for lighting
CORRECT ANSWER: A. To store and control the main drilling cable that
supports the tool string
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,Rationale: The bull wheel is the large diameter drum that holds the main drilling
line. It is used to raise and lower the entire tool string and to control the amount of
line fed out as the hole deepens.
Question 7: In cable tool drilling, why is a small amount of water usually
maintained in the borehole?
A. To cool a high-speed rotating bit
B. To create a slurry that suspends cuttings and cushions the impact of the tools
C. To generate hydraulic pressure for jetting the formation
D. To lubricate the rotary table bearings
CORRECT ANSWER: B. To create a slurry that suspends cuttings and cushions
the impact of the tools
Rationale: Water mixes with the crushed rock to form a slurry that keeps cuttings
from packing tightly around the bit. The fluid also provides a cushion that helps
transmit impact energy efficiently and reduces tool wear.
Question 8: What is the most common method of removing cuttings from a
cable-tool borehole?
A. Continuous mud circulation through a drill pipe
B. Air-lift pumping
C. Bailing with a dart-valve or flat-bottom bailer
D. Reverse-circulation with dual-wall pipe
CORRECT ANSWER: C. Bailing with a dart-valve or flat-bottom bailer
Rationale: After drilling a short interval, the tools are pulled and a bailer is lowered
on the sand line. The bailer fills with slurry and cuttings; when lifted, a valve at the
bottom closes to retain the material, which is then dumped at the surface.
Question 9: Which component of the cable-tool string is primarily responsible
for delivering the percussive force to the formation?
A. The drill collar
B. The drill bit (spudding or drilling bit)
C. The swivel
D. The kelly
CORRECT ANSWER: B. The drill bit (spudding or drilling bit)
Rationale: The heavy bit at the bottom of the string absorbs the kinetic energy of
the free-falling tools and transfers that energy into the rock as a crushing impact.
Different bit designs (chisel, cross, star, etc.) are selected according to formation
hardness.
Question 10: What is the purpose of “spudding” in the early stages of cable-
tool drilling?
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, A. To rotate the casing while driving it
B. To start the borehole with short, controlled strokes and to establish vertical
alignment
C. To install the surface conductor pipe under high pressure
D. To perform a formation-pressure integrity test
CORRECT ANSWER: B. To start the borehole with short, controlled strokes and
to establish vertical alignment
Rationale: Spudding refers to the initial drilling phase in which the tools are
operated with short strokes and careful attention to plumbness. Once a stable,
vertical hole is established, longer, more efficient strokes can be used.
Question 11: Which of the following is a primary advantage of cable-tool
drilling compared with rotary methods in certain formations?
A. Higher penetration rates in soft unconsolidated sediments
B. Ability to drill with minimal fluid and excellent formation sampling
C. Continuous cuttings removal without stopping to bail
D. Suitability for very deep, high-pressure oil and gas wells
CORRECT ANSWER: B. Ability to drill with minimal fluid and excellent
formation sampling
Rationale: Cable-tool drilling uses very little water, produces relatively undisturbed
cuttings, and allows the driller to examine formation material recovered in the
bailer. This makes it especially useful for water-well work where water quality and
accurate lithologic logs are important.
Question 12: What is the function of the temper screw on a cable-tool rig?
A. To adjust the stroke length of the walking beam
B. To feed the drilling cable gradually as the hole deepens so that the tools remain
at the proper working depth
C. To tighten the casing joints during driving
D. To control the speed of the bull wheel
CORRECT ANSWER: B. To feed the drilling cable gradually as the hole deepens
so that the tools remain at the proper working depth
Rationale: The temper screw is a threaded device that allows the driller to pay out
small increments of cable while the tools continue to work. This maintains the
correct relationship between the tools and the bottom of the hole without having to
stop and reset the cable clamps.
Question 13: In cable-tool operations, what is a “sinker bar” used for?
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Questions and Correct Answers (Verified
Answers) Plus Rationales
Question 1: What is the primary function of the walking beam on a cable tool
drilling rig?
A. To rotate the drill string continuously
B. To provide the up-and-down reciprocating motion that lifts and drops the drill
tools
C. To spool and unspool the sand line during bailing operations
D. To power the mud pump for circulating drilling fluid
CORRECT ANSWER: B. To provide the up-and-down reciprocating motion that
lifts and drops the drill tools
Rationale: The walking beam is a critical mechanical component that converts rotary
motion from the engine into the vertical oscillating stroke required for percussion
drilling. This motion raises the tools on the upstroke and allows them to free-fall on
the downstroke, delivering the impact energy that fractures the formation.
Question 2: In cable tool drilling, what is the purpose of the “jar” in the tool
string?
A. To measure the depth of the borehole continuously
B. To provide a delayed impact that helps free stuck tools by delivering a sharp
upward or downward blow
C. To circulate drilling fluid past the bit face
D. To stabilize the casing during driving operations
CORRECT ANSWER: B. To provide a delayed impact that helps free stuck tools
by delivering a sharp upward or downward blow
Rationale: Jars are specialized links placed in the tool string that allow a controlled
amount of free travel. When the tools become stuck, the sudden engagement of the
jar creates a sharp percussion force that can jar the tools loose without damaging
the cable or other components.
Question 3: Which of the following best describes the action of a cable-tool bit
during drilling?
A. Continuous rotation with fluid circulation to cut the formation
Page 1 of 65
,B. Intermittent impact and crushing action produced by the free fall of the tools
C. High-speed abrasion using diamond-impregnated surfaces
D. Hydraulic jetting that erodes the formation with high-pressure fluid
CORRECT ANSWER: B. Intermittent impact and crushing action produced by
the free fall of the tools
Rationale: Cable-tool drilling relies on percussion. The bit is repeatedly lifted and
allowed to drop, crushing and fracturing the rock. The resulting cuttings are mixed
with water in the borehole and removed by bailing.
Question 4: What is the primary purpose of the sand line on a cable tool rig?
A. To suspend the main drill tools during the drilling stroke
B. To raise and lower the bailer for removing cuttings and fluid from the hole
C. To drive casing into the ground with successive blows
D. To measure the exact length of the drill cable
CORRECT ANSWER: B. To raise and lower the bailer for removing cuttings and
fluid from the hole
Rationale: The sand line is a separate lighter cable dedicated to operating the bailer.
After a period of drilling, the main tools are pulled, and the bailer is run on the sand
line to clean the borehole of cuttings and slurry.
Question 5: When driving casing with a cable tool rig, what device is
commonly used to protect the top of the casing from damage?
A. A rotary table
B. A drive head or drive shoe fitted over the casing top
C. A kelly bushing
D. A blowout preventer stack
CORRECT ANSWER: B. A drive head or drive shoe fitted over the casing top
Rationale: A drive head (or drive clamp) is placed on the upper end of the casing so
that the weight of the tools or a separate drive weight can be applied without
mushrooming or splitting the casing top. A drive shoe is welded or threaded to the
bottom of the casing to protect the leading edge as it is driven.
Question 6: What is the function of the bull wheel on a traditional cable tool
drilling machine?
A. To store and control the main drilling cable that supports the tool string
B. To circulate drilling mud through the system
C. To rotate the turntable that turns the drill pipe
D. To power the generator for lighting
CORRECT ANSWER: A. To store and control the main drilling cable that
supports the tool string
Page 2 of 65
,Rationale: The bull wheel is the large diameter drum that holds the main drilling
line. It is used to raise and lower the entire tool string and to control the amount of
line fed out as the hole deepens.
Question 7: In cable tool drilling, why is a small amount of water usually
maintained in the borehole?
A. To cool a high-speed rotating bit
B. To create a slurry that suspends cuttings and cushions the impact of the tools
C. To generate hydraulic pressure for jetting the formation
D. To lubricate the rotary table bearings
CORRECT ANSWER: B. To create a slurry that suspends cuttings and cushions
the impact of the tools
Rationale: Water mixes with the crushed rock to form a slurry that keeps cuttings
from packing tightly around the bit. The fluid also provides a cushion that helps
transmit impact energy efficiently and reduces tool wear.
Question 8: What is the most common method of removing cuttings from a
cable-tool borehole?
A. Continuous mud circulation through a drill pipe
B. Air-lift pumping
C. Bailing with a dart-valve or flat-bottom bailer
D. Reverse-circulation with dual-wall pipe
CORRECT ANSWER: C. Bailing with a dart-valve or flat-bottom bailer
Rationale: After drilling a short interval, the tools are pulled and a bailer is lowered
on the sand line. The bailer fills with slurry and cuttings; when lifted, a valve at the
bottom closes to retain the material, which is then dumped at the surface.
Question 9: Which component of the cable-tool string is primarily responsible
for delivering the percussive force to the formation?
A. The drill collar
B. The drill bit (spudding or drilling bit)
C. The swivel
D. The kelly
CORRECT ANSWER: B. The drill bit (spudding or drilling bit)
Rationale: The heavy bit at the bottom of the string absorbs the kinetic energy of
the free-falling tools and transfers that energy into the rock as a crushing impact.
Different bit designs (chisel, cross, star, etc.) are selected according to formation
hardness.
Question 10: What is the purpose of “spudding” in the early stages of cable-
tool drilling?
Page 3 of 65
, A. To rotate the casing while driving it
B. To start the borehole with short, controlled strokes and to establish vertical
alignment
C. To install the surface conductor pipe under high pressure
D. To perform a formation-pressure integrity test
CORRECT ANSWER: B. To start the borehole with short, controlled strokes and
to establish vertical alignment
Rationale: Spudding refers to the initial drilling phase in which the tools are
operated with short strokes and careful attention to plumbness. Once a stable,
vertical hole is established, longer, more efficient strokes can be used.
Question 11: Which of the following is a primary advantage of cable-tool
drilling compared with rotary methods in certain formations?
A. Higher penetration rates in soft unconsolidated sediments
B. Ability to drill with minimal fluid and excellent formation sampling
C. Continuous cuttings removal without stopping to bail
D. Suitability for very deep, high-pressure oil and gas wells
CORRECT ANSWER: B. Ability to drill with minimal fluid and excellent
formation sampling
Rationale: Cable-tool drilling uses very little water, produces relatively undisturbed
cuttings, and allows the driller to examine formation material recovered in the
bailer. This makes it especially useful for water-well work where water quality and
accurate lithologic logs are important.
Question 12: What is the function of the temper screw on a cable-tool rig?
A. To adjust the stroke length of the walking beam
B. To feed the drilling cable gradually as the hole deepens so that the tools remain
at the proper working depth
C. To tighten the casing joints during driving
D. To control the speed of the bull wheel
CORRECT ANSWER: B. To feed the drilling cable gradually as the hole deepens
so that the tools remain at the proper working depth
Rationale: The temper screw is a threaded device that allows the driller to pay out
small increments of cable while the tools continue to work. This maintains the
correct relationship between the tools and the bottom of the hole without having to
stop and reset the cable clamps.
Question 13: In cable-tool operations, what is a “sinker bar” used for?
Page 4 of 65
