NGWA - STUDY GUIDE - AIR ROTARY COMPREHENSIVE AIR ROTARY DRILLING ACTUAL QUESTIONS & VERIFIED ANSWERS

NGWA - STUDY GUIDE -
AIR ROTARY
COMPREHENSIVE AIR
ROTARY DRILLING




Section 1: Drilling Principles
1. What is the primary purpose of using air in air rotary drilling?
Answer:
To remove cuttings from the borehole and cool the drill bit.


2. What is a key advantage of air rotary drilling over mud rotary drilling?
Answer:

, Faster drilling rates and cleaner boreholes in consolidated formations.


3. What types of formations are best suited for air rotary drilling?
Answer:
Hard, consolidated rock formations like limestone, granite, and sandstone.


4. What is "up-hole velocity," and why is it important?
Answer:
The speed at which air moves up the borehole. It must be sufficient to lift cuttings to
the surface.


5. What is the typical up-hole velocity needed to carry cuttings effectively?
Answer:
Generally 3,000–5,000 feet per minute (fpm).


Section 2: Air Systems
6. What is the function of a compressor in air rotary drilling?
Answer:
To supply high-pressure air to lift cuttings and cool the bit.


7. What type of compressor is commonly used in air rotary drilling?
Answer:
Rotary screw compressors.


8. What is the purpose of an air-oil separator?
Answer:
To remove oil from compressed air before it enters the drill string.


9. What happens if oil is not adequately removed from compressed air?
Answer:
It may contaminate the formation or cause environmental issues.