NGWA (EF) MUD ROTARY DRILLING NEW EXAM QUESTIONS AND CORRECT ANSWERS FOR TOP PERFORMANCE

1. The primary purpose of drilling fluid in mud rotary drilling is to:
A. Increase drilling speed only
B. Cool the drill bit and remove cuttings
C. Seal the borehole permanently
D. Prevent corrosion of casing
ANSWER : B
Explanation: Drilling fluid cools and lubricates the bit while carrying cuttings
to the surface.


2. Which component circulates drilling mud down the drill string?
A. Mud pit
B. Swivel
C. Mud pump
D. Shale shaker
ANSWER : C
Explanation: The mud pump provides the pressure needed to circulate drilling
fluid through the system.


3. What is the main function of bentonite in drilling mud?
A. Increase corrosion
B. Add weight only
C. Provide viscosity and filtration control
D. Harden the borehole wall
ANSWER : C
Explanation: Bentonite improves viscosity and helps form a filter cake on
borehole walls.

,4. Excessive mud weight can cause:
A. Faster penetration
B. Lost circulation
C. Cleaner cuttings
D. Lower pump pressure
ANSWER : B
Explanation: High mud weight increases formation pressure, which may
fracture formations and cause fluid loss.


5. Which soil formation is best suited for mud rotary drilling?
A. Solid granite
B. Frozen soil
C. Unconsolidated sands and clays
D. Steel-reinforced ground
ANSWER : C
Explanation: Mud rotary is ideal for unconsolidated formations where borehole
stability is needed.


6. What device removes large cuttings from drilling fluid?
A. Mud pump
B. Desander
C. Shale shaker
D. Swivel
ANSWER : C
Explanation: A shale shaker screens out large solids from returning drilling
fluid.


7. The annulus is defined as the space between:
A. Drill bit and pump
B. Borehole wall and drill pipe
C. Mud pit and pump
D. Casing and grout

,ANSWER : B
Explanation: The annulus allows drilling fluid to carry cuttings upward.


8. Which drilling fluid property measures resistance to flow?
A. Density
B. pH
C. Viscosity
D. Filtration
ANSWER : C
Explanation: Viscosity determines how well the fluid can suspend and
transport cuttings.


9. What happens if drilling mud viscosity is too low?
A. Bit wear increases
B. Cuttings may settle
C. Borehole becomes over-pressurized
D. Pump pressure increases
ANSWER : B
Explanation: Low viscosity reduces the mud’s ability to lift cuttings to the
surface.


10. Which tool connects the drill string to the rotary table?
A. Kelly
B. Swivel
C. Bit
D. Stabilizer
ANSWER : A
Explanation: The Kelly transmits rotary motion from the table to the drill
string.


11. The main purpose of a drill bit is to:
A. Stabilize the borehole
B. Circulate mud

, C. Cut or grind formations
D. Measure depth
ANSWER : C
Explanation: Drill bits break down formation material to advance the borehole.


12. What is “lost circulation”?
A. Excessive mud flow
B. Loss of drilling fluid into formations
C. Pump failure
D. Surface spill
ANSWER : B
Explanation: Lost circulation occurs when mud escapes into fractures or
porous zones.


13. Which additive helps control lost circulation?
A. Bentonite
B. Soda ash
C. Lost circulation material (LCM)
D. Chlorine
ANSWER : C
Explanation: LCM seals fractures and voids to reduce fluid loss.


14. What does mud density primarily control?
A. pH level
B. Formation pressure balance
C. Drill speed
D. Casing size
ANSWER : B
Explanation: Proper mud weight prevents formation collapse or fluid influx.


15. A sudden drop in mud return volume may indicate: