TEXAS WATER WELL DRILLER LICENSE EXAM COMPLETE QUESTIONS
AND CORRECT ANSWERS FOR TOP PERFORMANCE
1. Q: What is the primary purpose of drilling mud in rotary drilling?
ANSWER To cool the drill bit, remove cuttings from the borehole,
stabilize the wellbore walls, and prevent formation fluids from entering
the well.
2. Q: What is the typical rotation speed range for a rotary drill bit?
ANSWER Between 50 to 150 RPM depending on formation type and bit
size.
3. Q: What is the main advantage of cable tool drilling over rotary
drilling? ANSWER Better for drilling in unconsolidated formations,
simpler equipment, and easier to identify water-bearing zones.
4. Q: What size hole is typically required for a 6-inch diameter well
casing? ANSWER Typically 8 to 10 inches to allow proper cement
placement and casing installation.
5. Q: What is the purpose of a drill collar in rotary drilling? ANSWER
To provide weight on the bit and keep the drill string in tension above the
collars.
6. Q: What type of bit is best for drilling through hard rock
formations? ANSWER Tricone roller bits or diamond bits are most
effective for hard rock.
7. Q: What is the function of a bailer in cable tool drilling? ANSWER
To remove water and cuttings from the bottom of the borehole.
8. Q: What is the recommended circulation rate for drilling mud?
ANSWER Sufficient to carry cuttings to the surface, typically 50-100
gallons per minute depending on hole size.
9. Q: What causes a drill bit to "chatter"? ANSWER Excessive bit
weight, improper rotation speed, or worn bearings.
,10.Q: What is the purpose of using a centralizer on well casing?
ANSWER To keep the casing centered in the borehole for proper cement
placement around the entire casing.
11.Q: What is the minimum wall thickness required for steel well
casing? ANSWER Varies by diameter and application, but typically
follows ASTM standards (e.g., Schedule 40 or 80).
12.Q: What is a drive shoe used for? ANSWER Attached to the bottom of
casing to protect the casing edge and facilitate driving or setting the
casing.
13.Q: What is the purpose of reaming a borehole? ANSWER To enlarge
or smooth the borehole, remove obstructions, or straighten crooked holes.
14.Q: What type of drilling method is best for shallow wells in soft
formations? ANSWER Auger drilling or cable tool drilling.
15.Q: What is the function of a kelly in rotary drilling? ANSWER To
transmit rotational motion from the rotary table to the drill string.
16.Q: What causes drill pipe to twist off? ANSWER Excessive torque,
fatigue, corrosion, or improper connection makeup.
17.Q: What is the purpose of a swivel in rotary drilling? ANSWER To
allow the drill string to rotate while maintaining a stationary connection
to the mud hose.
18.Q: What is bentonite clay used for in well drilling? ANSWER As a
drilling mud additive to increase viscosity, seal porous formations, and
stabilize the borehole.
19.Q: What is the recommended cement slurry density for well
construction? ANSWER Typically 15-16 pounds per gallon, but varies
based on formation and casing specifications.
20.Q: What causes lost circulation during drilling? ANSWER Drilling
into fractured rock, cavernous formations, or porous zones that absorb
drilling fluid.
21.Q: What is a tremie pipe used for? ANSWER To place cement or
grout at the bottom of a well, allowing it to rise from the bottom up.
22.Q: What is the purpose of conducting a plumbness test? ANSWER
To ensure the well is drilled vertically and within acceptable deviation
limits.
, 23.Q: What is the typical life expectancy of a properly constructed
water well? ANSWER 20-50 years or more with proper maintenance
and favorable conditions.
24.Q: What is a gravel pack used for? ANSWER To prevent fine sand
from entering the well while allowing water flow, placed around the well
screen.
25.Q: What size gravel is typically used for gravel packing? ANSWER
Based on grain size analysis of formation, typically 2-4 times larger than
formation particles.
26.Q: What is the purpose of developing a well? ANSWER To remove
fine materials from around the well screen, improve formation
permeability, and increase well yield.
27.Q: What is surging in well development? ANSWER Moving water up
and down in the well to loosen fine materials and improve flow into the
well.
28.Q: What is the minimum distance a well should be from a septic
tank? ANSWER At least 50 feet in Texas, though 100 feet or more is
recommended.
29.Q: What is the purpose of a pitless adapter? ANSWER To provide a
sanitary, below-ground connection for the discharge pipe while
maintaining well seal.
30.Q: What is the difference between static water level and pumping
water level? ANSWER Static is the level when not pumping; pumping
level is the lowered level during pump operation.
31.Q: What is drawdown in a water well? ANSWER The difference
between static water level and pumping water level.
32.Q: What causes excessive drawdown in a well? ANSWER Inadequate
well development, screen plugging, insufficient aquifer yield, or
oversized pump.
33.Q: What is specific capacity of a well? ANSWER The yield (GPM)
divided by drawdown (feet), indicating well efficiency.
34.Q: What is an artesian well? ANSWER A well where water rises
above the top of the aquifer due to hydrostatic pressure.
AND CORRECT ANSWERS FOR TOP PERFORMANCE
1. Q: What is the primary purpose of drilling mud in rotary drilling?
ANSWER To cool the drill bit, remove cuttings from the borehole,
stabilize the wellbore walls, and prevent formation fluids from entering
the well.
2. Q: What is the typical rotation speed range for a rotary drill bit?
ANSWER Between 50 to 150 RPM depending on formation type and bit
size.
3. Q: What is the main advantage of cable tool drilling over rotary
drilling? ANSWER Better for drilling in unconsolidated formations,
simpler equipment, and easier to identify water-bearing zones.
4. Q: What size hole is typically required for a 6-inch diameter well
casing? ANSWER Typically 8 to 10 inches to allow proper cement
placement and casing installation.
5. Q: What is the purpose of a drill collar in rotary drilling? ANSWER
To provide weight on the bit and keep the drill string in tension above the
collars.
6. Q: What type of bit is best for drilling through hard rock
formations? ANSWER Tricone roller bits or diamond bits are most
effective for hard rock.
7. Q: What is the function of a bailer in cable tool drilling? ANSWER
To remove water and cuttings from the bottom of the borehole.
8. Q: What is the recommended circulation rate for drilling mud?
ANSWER Sufficient to carry cuttings to the surface, typically 50-100
gallons per minute depending on hole size.
9. Q: What causes a drill bit to "chatter"? ANSWER Excessive bit
weight, improper rotation speed, or worn bearings.
,10.Q: What is the purpose of using a centralizer on well casing?
ANSWER To keep the casing centered in the borehole for proper cement
placement around the entire casing.
11.Q: What is the minimum wall thickness required for steel well
casing? ANSWER Varies by diameter and application, but typically
follows ASTM standards (e.g., Schedule 40 or 80).
12.Q: What is a drive shoe used for? ANSWER Attached to the bottom of
casing to protect the casing edge and facilitate driving or setting the
casing.
13.Q: What is the purpose of reaming a borehole? ANSWER To enlarge
or smooth the borehole, remove obstructions, or straighten crooked holes.
14.Q: What type of drilling method is best for shallow wells in soft
formations? ANSWER Auger drilling or cable tool drilling.
15.Q: What is the function of a kelly in rotary drilling? ANSWER To
transmit rotational motion from the rotary table to the drill string.
16.Q: What causes drill pipe to twist off? ANSWER Excessive torque,
fatigue, corrosion, or improper connection makeup.
17.Q: What is the purpose of a swivel in rotary drilling? ANSWER To
allow the drill string to rotate while maintaining a stationary connection
to the mud hose.
18.Q: What is bentonite clay used for in well drilling? ANSWER As a
drilling mud additive to increase viscosity, seal porous formations, and
stabilize the borehole.
19.Q: What is the recommended cement slurry density for well
construction? ANSWER Typically 15-16 pounds per gallon, but varies
based on formation and casing specifications.
20.Q: What causes lost circulation during drilling? ANSWER Drilling
into fractured rock, cavernous formations, or porous zones that absorb
drilling fluid.
21.Q: What is a tremie pipe used for? ANSWER To place cement or
grout at the bottom of a well, allowing it to rise from the bottom up.
22.Q: What is the purpose of conducting a plumbness test? ANSWER
To ensure the well is drilled vertically and within acceptable deviation
limits.
, 23.Q: What is the typical life expectancy of a properly constructed
water well? ANSWER 20-50 years or more with proper maintenance
and favorable conditions.
24.Q: What is a gravel pack used for? ANSWER To prevent fine sand
from entering the well while allowing water flow, placed around the well
screen.
25.Q: What size gravel is typically used for gravel packing? ANSWER
Based on grain size analysis of formation, typically 2-4 times larger than
formation particles.
26.Q: What is the purpose of developing a well? ANSWER To remove
fine materials from around the well screen, improve formation
permeability, and increase well yield.
27.Q: What is surging in well development? ANSWER Moving water up
and down in the well to loosen fine materials and improve flow into the
well.
28.Q: What is the minimum distance a well should be from a septic
tank? ANSWER At least 50 feet in Texas, though 100 feet or more is
recommended.
29.Q: What is the purpose of a pitless adapter? ANSWER To provide a
sanitary, below-ground connection for the discharge pipe while
maintaining well seal.
30.Q: What is the difference between static water level and pumping
water level? ANSWER Static is the level when not pumping; pumping
level is the lowered level during pump operation.
31.Q: What is drawdown in a water well? ANSWER The difference
between static water level and pumping water level.
32.Q: What causes excessive drawdown in a well? ANSWER Inadequate
well development, screen plugging, insufficient aquifer yield, or
oversized pump.
33.Q: What is specific capacity of a well? ANSWER The yield (GPM)
divided by drawdown (feet), indicating well efficiency.
34.Q: What is an artesian well? ANSWER A well where water rises
above the top of the aquifer due to hydrostatic pressure.
