Certified Drilling Operator Licensing
Exam With Actual Questions & Verified
Answers, Plus Explained
Rationales/Expert Verified For
Guaranteed 100% Pass 2026/Latest
Update/Instant Download Pdf
1. What is the primary purpose of a blowout preventer (BOP)?
A. To increase drilling speed
B. To prevent uncontrolled release of formation fluids
C. To measure drilling depth
D. To control mud viscosity
B. To prevent uncontrolled release of formation fluids
Rationale: BOPs are critical safety devices designed to seal the
wellbore and prevent blowouts.
2. Which component connects the drill string to the drill bit?
A. Kelly
B. Drill collar
C. Swivel
D. Drill bit sub
D. Drill bit sub
Rationale: The drill bit sub connects the drill bit to the lower end
of the drill string, allowing rotation and weight transfer.
3. What is the function of drilling mud?
A. Only cool the drill bit
, B. Lubricate the drill string and remove cuttings
C. Cement the well casing
D. Seal formation fractures
B. Lubricate the drill string and remove cuttings
Rationale: Drilling mud serves multiple purposes including
cooling the bit, transporting cuttings, and balancing formation
pressure.
4. What is meant by “trip” in drilling operations?
A. Adding a new section of drill pipe
B. Pulling the drill string out of the wellbore
C. Changing the mud type
D. Measuring formation porosity
B. Pulling the drill string out of the wellbore
Rationale: A trip refers to removing or running the drill string
into the well for maintenance, bit replacement, or other
operations.
5. Which drilling method is typically used for directional wells?
A. Rotary drilling
B. Cable tool drilling
C. Top drive drilling
D. Horizontal drilling
D. Horizontal drilling
Rationale: Horizontal drilling allows directional control to reach
targets not directly beneath the rig.
6. What is the primary risk of underbalanced drilling?
A. Slow drilling rate
B. Wellbore collapse
C. Formation fluid influx
D. Mud loss
, C. Formation fluid influx
Rationale: Underbalanced drilling has a lower hydrostatic
pressure than formation pressure, increasing the risk of influx or
kicks.
7. Which instrument measures wellbore pressure in real time?
A. Dynamometer
B. Manometer
C. Pressure transducer
D. Flow meter
C. Pressure transducer
Rationale: Pressure transducers are used for real-time
monitoring of wellbore pressures during drilling operations.
8. What is the purpose of casing in a well?
A. Increase drilling speed
B. Support the wellbore and prevent collapse
C. Measure formation porosity
D. Lubricate the drill string
B. Support the wellbore and prevent collapse
Rationale: Casing stabilizes the well, isolates formations, and
provides a conduit for production or injection.
9. What is “mud weight” a measure of?
A. Drilling fluid viscosity
B. Density of the drilling fluid
C. Flow rate of mud
D. Pump pressure
B. Density of the drilling fluid
Rationale: Mud weight is the density of the drilling fluid,
typically measured in pounds per gallon or kilograms per cubic
meter.
Exam With Actual Questions & Verified
Answers, Plus Explained
Rationales/Expert Verified For
Guaranteed 100% Pass 2026/Latest
Update/Instant Download Pdf
1. What is the primary purpose of a blowout preventer (BOP)?
A. To increase drilling speed
B. To prevent uncontrolled release of formation fluids
C. To measure drilling depth
D. To control mud viscosity
B. To prevent uncontrolled release of formation fluids
Rationale: BOPs are critical safety devices designed to seal the
wellbore and prevent blowouts.
2. Which component connects the drill string to the drill bit?
A. Kelly
B. Drill collar
C. Swivel
D. Drill bit sub
D. Drill bit sub
Rationale: The drill bit sub connects the drill bit to the lower end
of the drill string, allowing rotation and weight transfer.
3. What is the function of drilling mud?
A. Only cool the drill bit
, B. Lubricate the drill string and remove cuttings
C. Cement the well casing
D. Seal formation fractures
B. Lubricate the drill string and remove cuttings
Rationale: Drilling mud serves multiple purposes including
cooling the bit, transporting cuttings, and balancing formation
pressure.
4. What is meant by “trip” in drilling operations?
A. Adding a new section of drill pipe
B. Pulling the drill string out of the wellbore
C. Changing the mud type
D. Measuring formation porosity
B. Pulling the drill string out of the wellbore
Rationale: A trip refers to removing or running the drill string
into the well for maintenance, bit replacement, or other
operations.
5. Which drilling method is typically used for directional wells?
A. Rotary drilling
B. Cable tool drilling
C. Top drive drilling
D. Horizontal drilling
D. Horizontal drilling
Rationale: Horizontal drilling allows directional control to reach
targets not directly beneath the rig.
6. What is the primary risk of underbalanced drilling?
A. Slow drilling rate
B. Wellbore collapse
C. Formation fluid influx
D. Mud loss
, C. Formation fluid influx
Rationale: Underbalanced drilling has a lower hydrostatic
pressure than formation pressure, increasing the risk of influx or
kicks.
7. Which instrument measures wellbore pressure in real time?
A. Dynamometer
B. Manometer
C. Pressure transducer
D. Flow meter
C. Pressure transducer
Rationale: Pressure transducers are used for real-time
monitoring of wellbore pressures during drilling operations.
8. What is the purpose of casing in a well?
A. Increase drilling speed
B. Support the wellbore and prevent collapse
C. Measure formation porosity
D. Lubricate the drill string
B. Support the wellbore and prevent collapse
Rationale: Casing stabilizes the well, isolates formations, and
provides a conduit for production or injection.
9. What is “mud weight” a measure of?
A. Drilling fluid viscosity
B. Density of the drilling fluid
C. Flow rate of mud
D. Pump pressure
B. Density of the drilling fluid
Rationale: Mud weight is the density of the drilling fluid,
typically measured in pounds per gallon or kilograms per cubic
meter.
