NGWA (EF) Mud Rotary Drilling Exam
Practice Questions And Correct Answers
(Verified Answers) Plus Rationales 2026
Q&A | Instant Download Pdf
1. What is the primary purpose of drilling fluid (mud) in rotary drilling?
A. To cool the rig crew
B. To carry cuttings to the surface
C. To lubricate drill pipe threads
D. To increase formation pressure
Rationale: Drilling fluid primarily carries cuttings to the surface.
2. Which component in drilling mud provides viscosity and suspension?
A. Salt
B. Calcium carbonate
C. Bentonite
D. Barite
Rationale: Bentonite clay increases viscosity and suspension in mud.
,3. What is “barite” used for in drilling fluid?
A. To reduce viscosity
B. To clean the drill bit
C. To increase mud weight
D. To reduce fluid loss
Rationale: Barite is a weighting agent that increases mud density.
4. High pump pressure with low flow rate may indicate:
A. Bit is worn
B. High returns
C. Blocked bit nozzles
D. Normal conditions
Rationale: Blocked nozzles restrict flow, increasing pump pressure.
5. What does “pH” of drilling mud measure?
A. Density
B. Viscosity
C. Acidity/alkalinity
D. Solids content
Rationale: pH indicates the acidity or alkalinity of the mud.
,6. Which test measures drilling fluid’s ability to suspend solids?
A. pH test
B. Mud weight
C. Gel strength test
D. Sand content
Rationale: Gel strength reflects the mud’s ability to suspend solids.
7. What is the purpose of a shale shaker?
A. Increase mud density
B. Remove large cuttings
C. Add chemicals to mud
D. Measure fluid loss
Rationale: Shale shakers remove large cuttings from returning mud.
8. The unit “ppg” stands for:
A. Pounds per gallon
B. Parts per gallon
C. Pounds per gallon
D. Pressure per gauge
Rationale: Mud weight is measured in pounds per gallon.
, 9. Excessive fluid loss into the formation can cause:
A. Increased returns
B. Higher viscosity
C. Formation damage
D. Lower density
Rationale: Fluid loss can damage the formation by filtrate invasion.
10. Which ingredient helps control fluid loss?
A. Sand
B. Bentonite
C. Polymers
D. Barite
Rationale: Polymers reduce fluid loss through filtration control.
11. What does “ANNULAR SPACE” refer to?
A. Drill bit nozzles
B. Mud tanks
C. Space between casing and borehole
D. Weight on bit
Rationale: Annular space is between the casing and the drilled hole.
Practice Questions And Correct Answers
(Verified Answers) Plus Rationales 2026
Q&A | Instant Download Pdf
1. What is the primary purpose of drilling fluid (mud) in rotary drilling?
A. To cool the rig crew
B. To carry cuttings to the surface
C. To lubricate drill pipe threads
D. To increase formation pressure
Rationale: Drilling fluid primarily carries cuttings to the surface.
2. Which component in drilling mud provides viscosity and suspension?
A. Salt
B. Calcium carbonate
C. Bentonite
D. Barite
Rationale: Bentonite clay increases viscosity and suspension in mud.
,3. What is “barite” used for in drilling fluid?
A. To reduce viscosity
B. To clean the drill bit
C. To increase mud weight
D. To reduce fluid loss
Rationale: Barite is a weighting agent that increases mud density.
4. High pump pressure with low flow rate may indicate:
A. Bit is worn
B. High returns
C. Blocked bit nozzles
D. Normal conditions
Rationale: Blocked nozzles restrict flow, increasing pump pressure.
5. What does “pH” of drilling mud measure?
A. Density
B. Viscosity
C. Acidity/alkalinity
D. Solids content
Rationale: pH indicates the acidity or alkalinity of the mud.
,6. Which test measures drilling fluid’s ability to suspend solids?
A. pH test
B. Mud weight
C. Gel strength test
D. Sand content
Rationale: Gel strength reflects the mud’s ability to suspend solids.
7. What is the purpose of a shale shaker?
A. Increase mud density
B. Remove large cuttings
C. Add chemicals to mud
D. Measure fluid loss
Rationale: Shale shakers remove large cuttings from returning mud.
8. The unit “ppg” stands for:
A. Pounds per gallon
B. Parts per gallon
C. Pounds per gallon
D. Pressure per gauge
Rationale: Mud weight is measured in pounds per gallon.
, 9. Excessive fluid loss into the formation can cause:
A. Increased returns
B. Higher viscosity
C. Formation damage
D. Lower density
Rationale: Fluid loss can damage the formation by filtrate invasion.
10. Which ingredient helps control fluid loss?
A. Sand
B. Bentonite
C. Polymers
D. Barite
Rationale: Polymers reduce fluid loss through filtration control.
11. What does “ANNULAR SPACE” refer to?
A. Drill bit nozzles
B. Mud tanks
C. Space between casing and borehole
D. Weight on bit
Rationale: Annular space is between the casing and the drilled hole.
