ESTUDYR
NGWA - STUDY GUIDE - AIR ROTARY COMPREHENSIVE
AIR ROTARY DRILLING QUESTIONS & ANSWERS
1. What is the first precaution when encountering sand seams in air rotary drilling?
A. Increase air pressure
B. Reduce air pressure ✅
C. Stop drilling immediately
D. Change bit type
Answer: B – Reducing air pressure prevents excessive erosion of the sand formation.
Rationale: High air pressure can destabilize loose sand, leading to borehole collapse.
2. Which additive helps stabilize sand seams in air rotary drilling?
A. Bentonite
B. Foam or polymers ✅
C. Diesel fuel
D. Silica gel
Answer: B – Foam/polymers bind sand particles, improving hole stability.
Rationale: These additives reduce friction and prevent cuttings from sticking.
3. How are cuttings samples obtained in air rotary drilling?
A. Only at the end of drilling
B. Continuous sampling of cuttings ✅
C. Using a bailer
D. Core barrel extraction
Answer: B – Airflow carries cuttings to the surface for real-time analysis.
Rationale: Continuous sampling allows for accurate formation logging.
4. What is the best method for sampling in unconsolidated formations?
,ESTUDYR
A. Split-spoon sampling ✅
B. Diamond coring
C. Junk basket
D. Sonic drilling
Answer: A – Split-spoon samplers provide undisturbed samples for analysis.
Rationale: They preserve formation structure better than cuttings alone.
5. Which factor does NOT affect hole cleaning in air rotary drilling?
A. Air pressure
B. Formation type
C. Drill pipe color ✅
D. Bit condition
Answer: C – Pipe color has no impact on cuttings removal.
Rationale: Air volume, formation hardness, and bit wear are critical factors.
6. Why is geology critical for proper grouting in unconsolidated formations?
A. Determines grout setting time
B. Affects permeability and stability ✅
C. Controls drill rig selection
D. Influences bit rotation speed
Answer: B – Porous or unstable formations require tailored grout mixes.
Rationale: High-permeability zones may need low-viscosity grouts to prevent voids.
7. When is gravel packing necessary?
A. In solid bedrock
B. Only for deep wells
C. In unconsolidated formations ✅
D. When using cable tools
Answer: C – Gravel packs stabilize loose formations and improve flow.
Rationale: Prevents sand intrusion while allowing water passage.
,ESTUDYR
8. A soft tri-cone bit is best suited for:
A. Granite
B. Clay, sand, or shale ✅
C. Quartzite
D. Basalt
Answer: B – Wider teeth prevent balling in soft formations.
Rationale: Harder formations require tungsten carbide inserts.
9. What is NOT a function of drill pipe in unconsolidated formations?
A. Transmit torque
B. Circulate air/fluid
C. Generate electricity ✅
D. Support drill string weight
Answer: C – Drill pipes don’t produce power; they transmit mechanical force.
Rationale: Their primary role is structural support and fluid circulation.
10. Heavy drill collars are used to:
A. Decorate the rig
B. Add weight on bit and prevent buckling ✅
C. Reduce drilling speed
D. Filter cuttings
Answer: B – Extra weight improves penetration in hard/deep formations.
Rationale: Prevents drill string whip and maintains verticality.
11. Chip catchers help in formation logging by:
A. Storing extra drill bits
B. Preventing sample loss ✅
C. Cooling the drill string
D. Measuring air pressure
, ESTUDYR
Answer: B – Ensures representative cuttings for accurate analysis.
Rationale: Critical for real-time formation evaluation.
12. Bit design varies based on:
A. Rig color
B. Formation hardness ✅
C. Operator preference
D. Time of day
Answer: B – Soft formations use wide teeth; hard formations use compact, durable bits.
Rationale: Geology dictates bit selection for optimal performance.
13. Heavy steel casing is best used in:
A. Air rotary for unstable formations ✅
B. Cable tool in bedrock
C. Sonic drilling in clay
D. Auger drilling in sand
Answer: A – Provides stability in collapsing or unconsolidated zones.
Rationale: Prevents borehole washout during air drilling.
14. Daily air compressor checks must include:
A. Oil level and filters ✅
B. Paint condition
C. Tire pressure
D. Horn functionality
Answer: A – Ensures consistent air supply and prevents mechanical failure.
Rationale: Neglecting maintenance risks compressor failure mid-operation.
15. What indicates poor hole cleaning in air rotary drilling?
NGWA - STUDY GUIDE - AIR ROTARY COMPREHENSIVE
AIR ROTARY DRILLING QUESTIONS & ANSWERS
1. What is the first precaution when encountering sand seams in air rotary drilling?
A. Increase air pressure
B. Reduce air pressure ✅
C. Stop drilling immediately
D. Change bit type
Answer: B – Reducing air pressure prevents excessive erosion of the sand formation.
Rationale: High air pressure can destabilize loose sand, leading to borehole collapse.
2. Which additive helps stabilize sand seams in air rotary drilling?
A. Bentonite
B. Foam or polymers ✅
C. Diesel fuel
D. Silica gel
Answer: B – Foam/polymers bind sand particles, improving hole stability.
Rationale: These additives reduce friction and prevent cuttings from sticking.
3. How are cuttings samples obtained in air rotary drilling?
A. Only at the end of drilling
B. Continuous sampling of cuttings ✅
C. Using a bailer
D. Core barrel extraction
Answer: B – Airflow carries cuttings to the surface for real-time analysis.
Rationale: Continuous sampling allows for accurate formation logging.
4. What is the best method for sampling in unconsolidated formations?
,ESTUDYR
A. Split-spoon sampling ✅
B. Diamond coring
C. Junk basket
D. Sonic drilling
Answer: A – Split-spoon samplers provide undisturbed samples for analysis.
Rationale: They preserve formation structure better than cuttings alone.
5. Which factor does NOT affect hole cleaning in air rotary drilling?
A. Air pressure
B. Formation type
C. Drill pipe color ✅
D. Bit condition
Answer: C – Pipe color has no impact on cuttings removal.
Rationale: Air volume, formation hardness, and bit wear are critical factors.
6. Why is geology critical for proper grouting in unconsolidated formations?
A. Determines grout setting time
B. Affects permeability and stability ✅
C. Controls drill rig selection
D. Influences bit rotation speed
Answer: B – Porous or unstable formations require tailored grout mixes.
Rationale: High-permeability zones may need low-viscosity grouts to prevent voids.
7. When is gravel packing necessary?
A. In solid bedrock
B. Only for deep wells
C. In unconsolidated formations ✅
D. When using cable tools
Answer: C – Gravel packs stabilize loose formations and improve flow.
Rationale: Prevents sand intrusion while allowing water passage.
,ESTUDYR
8. A soft tri-cone bit is best suited for:
A. Granite
B. Clay, sand, or shale ✅
C. Quartzite
D. Basalt
Answer: B – Wider teeth prevent balling in soft formations.
Rationale: Harder formations require tungsten carbide inserts.
9. What is NOT a function of drill pipe in unconsolidated formations?
A. Transmit torque
B. Circulate air/fluid
C. Generate electricity ✅
D. Support drill string weight
Answer: C – Drill pipes don’t produce power; they transmit mechanical force.
Rationale: Their primary role is structural support and fluid circulation.
10. Heavy drill collars are used to:
A. Decorate the rig
B. Add weight on bit and prevent buckling ✅
C. Reduce drilling speed
D. Filter cuttings
Answer: B – Extra weight improves penetration in hard/deep formations.
Rationale: Prevents drill string whip and maintains verticality.
11. Chip catchers help in formation logging by:
A. Storing extra drill bits
B. Preventing sample loss ✅
C. Cooling the drill string
D. Measuring air pressure
, ESTUDYR
Answer: B – Ensures representative cuttings for accurate analysis.
Rationale: Critical for real-time formation evaluation.
12. Bit design varies based on:
A. Rig color
B. Formation hardness ✅
C. Operator preference
D. Time of day
Answer: B – Soft formations use wide teeth; hard formations use compact, durable bits.
Rationale: Geology dictates bit selection for optimal performance.
13. Heavy steel casing is best used in:
A. Air rotary for unstable formations ✅
B. Cable tool in bedrock
C. Sonic drilling in clay
D. Auger drilling in sand
Answer: A – Provides stability in collapsing or unconsolidated zones.
Rationale: Prevents borehole washout during air drilling.
14. Daily air compressor checks must include:
A. Oil level and filters ✅
B. Paint condition
C. Tire pressure
D. Horn functionality
Answer: A – Ensures consistent air supply and prevents mechanical failure.
Rationale: Neglecting maintenance risks compressor failure mid-operation.
15. What indicates poor hole cleaning in air rotary drilling?
