NGWA FINAL PAPER 2025 QUESTIONS AND ANSWERS
RATED A+
✔✔What purpose does a Kelly saver sub serve? - ✔✔A Kelly saver sub protects the
Kelly from excessive wear by absorbing the torque and stress during drilling operations.
✔✔What type of lubrication system is used for DHH drilling? - ✔✔a mist or oil injection
lubrication system to reduce wear and cool the hammer mechanism.
✔✔Explain these terms: misting. dusting. - ✔✔Misting: Injecting water or fluid into the
air stream to control dust and cool the bit.
Dusting: Drilling without sufficient fluid, resulting in excessive dust and potential bit
overheating.
✔✔What is a surfactant? When is it needed? - ✔✔Reduces surface tension; needed to
create foam in drilling fluids for effective cuttings removal.
✔✔Explain the difference between high and low pressure air rotaries. - ✔✔High-
pressure air rotary: Faster drilling, better cuttings removal, used in hard formations.
Low-pressure air rotary: Slower drilling, more controlled, used in softer or unstable
formations.
✔✔Explain the difference between high and low volume air rotaries. - ✔✔High-volume
air rotary: Moves more air, better for deep holes or large cuttings removal.
Low-volume air rotary: Moves less air, suited for shallow holes or smaller cuttings.
✔✔How much pressure of air does it take to life 100 ft of water? Explain. - ✔✔It takes
43.5 psi to lift 100 feet of water because water pressure increases by about 0.435 psi
per foot of depth. Therefore, 100 feet × 0.435 psi/ft = 43.5 psi.
✔✔What are some advantages and/or disadvantages of the top head and table drive
system? - ✔✔Top head drive:
Advantages: Direct torque, better control, less drill string wear.
Disadvantages: More expensive, complex maintenance.
Table drive:
Advantages: Simpler, lower cost.
Disadvantages: Less control, higher drill string wear.
✔✔Why is it important to keep the bit in gauge? - ✔✔ensures proper hole diameter,
prevents well collapse, and maintains drilling efficiency.
, ✔✔How is the DHH drill bit sharpened? - ✔✔by grinding the worn or rounded edges of
the bit's cutting surfaces, usually with specialized grinding tools.
✔✔How could a crooked hole be corrected using air rotary? - ✔✔using stabilizers,
reducing weight on the bit, and adjusting the drilling angle.
✔✔Explain various methods for setting casing using air rotary equipment. - ✔✔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.
✔✔What could cause lost circulation in air rotary drilling? - ✔✔Fractured formations,
porous zones, or high-pressure air forcing fluids into surrounding formations.
✔✔How are air rotary rigs sized? - ✔✔air compressor capacity (CFM/PSI)
drilling depth capacity
mast height.
✔✔If up hole velocities decrease, what could be the probable cause? - ✔✔Reduced air
pressure
blockage in the air stream
increased hole diameter.
✔✔What can be added to water to aid in drilling with mud rotary? - ✔✔Bentonite,
polymers, and surfactants to improve viscosity, stabilization, and cuttings removal.
✔✔In using mud rotary in unconsolidated formations, what is the relationship of speed
in RPMs and feeds? - ✔✔In mud rotary drilling for unconsolidated formations, higher
RPMs require lower feeds to avoid collapsing the borehole, while lower RPMs can
tolerate higher feeds for better penetration.
✔✔What materials could be used to properly grout a mud rotary well? - ✔✔Bentonite,
cement, or a bentonite-cement mix.
✔✔How does weight (density) of the drilling fluid affect the down hole conditions during
drilling? - ✔✔controls downhole pressure, stabilizes the borehole, prevents formation
collapse, and helps control fluid loss or blowouts.
✔✔How is mud weight controlled? What factors enter into the viscosity of mud? -
✔✔Mud weight is controlled by adding materials like barite or bentonite
Viscosity factors: Type of additives, fluid composition, and solids content.
RATED A+
✔✔What purpose does a Kelly saver sub serve? - ✔✔A Kelly saver sub protects the
Kelly from excessive wear by absorbing the torque and stress during drilling operations.
✔✔What type of lubrication system is used for DHH drilling? - ✔✔a mist or oil injection
lubrication system to reduce wear and cool the hammer mechanism.
✔✔Explain these terms: misting. dusting. - ✔✔Misting: Injecting water or fluid into the
air stream to control dust and cool the bit.
Dusting: Drilling without sufficient fluid, resulting in excessive dust and potential bit
overheating.
✔✔What is a surfactant? When is it needed? - ✔✔Reduces surface tension; needed to
create foam in drilling fluids for effective cuttings removal.
✔✔Explain the difference between high and low pressure air rotaries. - ✔✔High-
pressure air rotary: Faster drilling, better cuttings removal, used in hard formations.
Low-pressure air rotary: Slower drilling, more controlled, used in softer or unstable
formations.
✔✔Explain the difference between high and low volume air rotaries. - ✔✔High-volume
air rotary: Moves more air, better for deep holes or large cuttings removal.
Low-volume air rotary: Moves less air, suited for shallow holes or smaller cuttings.
✔✔How much pressure of air does it take to life 100 ft of water? Explain. - ✔✔It takes
43.5 psi to lift 100 feet of water because water pressure increases by about 0.435 psi
per foot of depth. Therefore, 100 feet × 0.435 psi/ft = 43.5 psi.
✔✔What are some advantages and/or disadvantages of the top head and table drive
system? - ✔✔Top head drive:
Advantages: Direct torque, better control, less drill string wear.
Disadvantages: More expensive, complex maintenance.
Table drive:
Advantages: Simpler, lower cost.
Disadvantages: Less control, higher drill string wear.
✔✔Why is it important to keep the bit in gauge? - ✔✔ensures proper hole diameter,
prevents well collapse, and maintains drilling efficiency.
, ✔✔How is the DHH drill bit sharpened? - ✔✔by grinding the worn or rounded edges of
the bit's cutting surfaces, usually with specialized grinding tools.
✔✔How could a crooked hole be corrected using air rotary? - ✔✔using stabilizers,
reducing weight on the bit, and adjusting the drilling angle.
✔✔Explain various methods for setting casing using air rotary equipment. - ✔✔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.
✔✔What could cause lost circulation in air rotary drilling? - ✔✔Fractured formations,
porous zones, or high-pressure air forcing fluids into surrounding formations.
✔✔How are air rotary rigs sized? - ✔✔air compressor capacity (CFM/PSI)
drilling depth capacity
mast height.
✔✔If up hole velocities decrease, what could be the probable cause? - ✔✔Reduced air
pressure
blockage in the air stream
increased hole diameter.
✔✔What can be added to water to aid in drilling with mud rotary? - ✔✔Bentonite,
polymers, and surfactants to improve viscosity, stabilization, and cuttings removal.
✔✔In using mud rotary in unconsolidated formations, what is the relationship of speed
in RPMs and feeds? - ✔✔In mud rotary drilling for unconsolidated formations, higher
RPMs require lower feeds to avoid collapsing the borehole, while lower RPMs can
tolerate higher feeds for better penetration.
✔✔What materials could be used to properly grout a mud rotary well? - ✔✔Bentonite,
cement, or a bentonite-cement mix.
✔✔How does weight (density) of the drilling fluid affect the down hole conditions during
drilling? - ✔✔controls downhole pressure, stabilizes the borehole, prevents formation
collapse, and helps control fluid loss or blowouts.
✔✔How is mud weight controlled? What factors enter into the viscosity of mud? -
✔✔Mud weight is controlled by adding materials like barite or bentonite
Viscosity factors: Type of additives, fluid composition, and solids content.
