NGWA page 1
What precautions must be used when sand seams are encountered in air rotary drilling
in unconsolidated formation? - Answer1.Reduced Air pressure
2. Use of Foam or Polymers
3. Monitor Cuttings
4. Casing Advancement
5. Slow Drilling Rate
How are samples obtained in air rotary drilling in unconsolidated formations? - answer
Continuous Sampling of Cuttings:
Split-spoon Sampling
Drilling Fluids/Polymers
Hole cleaning and penetration rates will vary with air rotary. What factors affect cleaning
and penetration? - answerAir Pressure and Volume
Formation Type
Bit type and Condition
Drilling Fluid/Injection
Drill Pipe Size and Depth
Cutting Size and Volume
Why is information concerning the geology important in proper grouting and
unconsolidated formations? - answerPermeability of the Formation
Stability of the Formation
Formation Pressure
Groundwater Flow
Formation Composition
When would you gravel pack a well? - answerWhen the formation is unconsolidated, to
prevent sand or fine material from entering the well, and to enhance water flow by
stabilizing the borehole
What formations are best to use a soft tri-cone bit? - answerclay, sand, or shale.
What functions must a drill pipe perform to drill unconsolidated formations? -
answerTransmit torque
Circulating Drilling fluid/air
Support drill string weight
Maintain borehole integrity
When would you use heavy drill collars? - answerto add weight on the bit, stabilize the
drill string, and prevent buckling in deep or hard formations.
What precautions must be used when sand seams are encountered in air rotary drilling
in unconsolidated formation? - Answer1.Reduced Air pressure
2. Use of Foam or Polymers
3. Monitor Cuttings
4. Casing Advancement
5. Slow Drilling Rate
How are samples obtained in air rotary drilling in unconsolidated formations? - answer
Continuous Sampling of Cuttings:
Split-spoon Sampling
Drilling Fluids/Polymers
Hole cleaning and penetration rates will vary with air rotary. What factors affect cleaning
and penetration? - answerAir Pressure and Volume
Formation Type
Bit type and Condition
Drilling Fluid/Injection
Drill Pipe Size and Depth
Cutting Size and Volume
Why is information concerning the geology important in proper grouting and
unconsolidated formations? - answerPermeability of the Formation
Stability of the Formation
Formation Pressure
Groundwater Flow
Formation Composition
When would you gravel pack a well? - answerWhen the formation is unconsolidated, to
prevent sand or fine material from entering the well, and to enhance water flow by
stabilizing the borehole
What formations are best to use a soft tri-cone bit? - answerclay, sand, or shale.
What functions must a drill pipe perform to drill unconsolidated formations? -
answerTransmit torque
Circulating Drilling fluid/air
Support drill string weight
Maintain borehole integrity
When would you use heavy drill collars? - answerto add weight on the bit, stabilize the
drill string, and prevent buckling in deep or hard formations.
