NGWA questions with verified answers
Explain percentage retention in designing a screen for a gravel well.
Ans✓✓✓ The proportion of gravel or formation particles that the
screen is designed to retain, ensuring proper filtration while allowing
water flow without clogging.
Explain various methods for setting casing using air rotary equipment.
Ans✓✓✓ Driving: Use a hammer or rig to drive the casing down.
Rotating: Rotate the casing into place using the drill rig.
Pushing: Use the rig's hydraulic system to push the casing down.
Explain why soft formations require low annular velocities. Ans✓✓✓
To prevent erosion, collapse, or destabilization of the borehole due to
excessive cuttings removal or formation washout.
How are air rotary rigs sized? Ans✓✓✓ Air compressor capacity
(CFM/PSI)
drilling depth capacity
mast height
How are screen lengths determined? Ans✓✓✓ By the thickness of the
water-bearing formation and the desired water yield.
Explain percentage retention in designing a screen for a gravel well.
Ans✓✓✓ The proportion of gravel or formation particles that the
screen is designed to retain, ensuring proper filtration while allowing
water flow without clogging.
Explain various methods for setting casing using air rotary equipment.
Ans✓✓✓ Driving: Use a hammer or rig to drive the casing down.
Rotating: Rotate the casing into place using the drill rig.
Pushing: Use the rig's hydraulic system to push the casing down.
Explain why soft formations require low annular velocities. Ans✓✓✓
To prevent erosion, collapse, or destabilization of the borehole due to
excessive cuttings removal or formation washout.
How are air rotary rigs sized? Ans✓✓✓ Air compressor capacity
(CFM/PSI)
drilling depth capacity
mast height
How are screen lengths determined? Ans✓✓✓ By the thickness of the
water-bearing formation and the desired water yield.
