NGWA -GENERAL DRILLING EXAM |
COMPLETE STUDY GUIDE 2026 | VERIFIED
ANSWERS | 100% CORRECT | GRADED A+|
PASS GUARANTEED /RECENT VERSION
How is the DHH drill bit sharpened? - ANSWER 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? - ANSWER using
stabilizers, reducing weight on the bit, and adjusting the drilling angle.
Explain various methods for setting casing using air rotary equipment. -
ANSWER 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? - ANSWER Fractured
formations, porous zones, or high-pressure air forcing fluids into surrounding
formations.
How are air rotary rigs sized? - ANSWER air compressor capacity (CFM/PSI)
drilling depth capacity
,mast height.
If the up-hole velocities decrease, what could be the probable cause? -
ANSWER Reduced air pressure
blockage in the air stream
increased hole diameter.
What can be added to water to aid in drilling with mud rotary? -
ANSWER Bentonite, polymers, and surfactants to improve viscosity,
stabilization, and cuttings removal.
In using mud rotary in unconsolidated formations, what is the relationship
between speed in RPMs and feed? - ANSWER 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? -
ANSWER Bentonite, cement, or a bentonite-cement mix.
How does the weight (density) of the drilling fluid affect the downhole conditions
during drilling? - ANSWER 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? -
ANSWER Mud weight is controlled by adding materials like barite or bentonite
Viscosity factors: Type of additives, fluid composition, and solids content.
, What causes cavitations in the pumping drilling method? -
ANSWER Cavitation is caused by low fluid levels, high pump speed, air
entrainment, or improper pump suction, leading to vapor bubbles that collapse and
damage equipment.
Explain why soft formations require low annular velocities. - ANSWER to
prevent erosion, collapse, or destabilization of the borehole due to excessive
cuttings removal or formation washout.
What can cause lost circulation in mud rotary drilling? - ANSWER Fractured
formations, porous zones, or over-pressurized drilling fluids forcing fluid into the
formation.
What are the most common types of mud pumps? - ANSWER Duplex, triplex,
and centrifugal pumps.
Polyphosphates are used for what purpose? - ANSWER used to prevent mineral
scaling and to disperse clays in drilling fluids
Explain percentage retention in designing a screen for a gravel well. -
ANSWER the proportion of gravel or formation particles that the screen is
designed to retain, ensuring proper filtration while allowing water flow without
clogging.
How are screen lengths determined? - ANSWER by the thickness of the water-
bearing formation and the desired water yield.
, What information should you have available when determining well screen design
- ANSWER Formation particle size, water flow rate, well depth, and aquifer
characteristics.
Could specific capacity be determined in sizing a well screen? - ANSWER Yes,
specific capacity (water yield per unit of drawdown) helps determine the
appropriate screen size to optimize flow and minimize drawdown.
What materials and methods for placement of the materials are used in gravel-
packed wells? - ANSWER Materials: Gravel, typically well-sorted and clean.
Methods: Gravity placement, tremie pipe, or reverse circulation to place gravel
uniformly around the well screen.
Explain the difference between natural and artificial gravel-packed wells. -
ANSWER Natural gravel pack: Utilizes the existing formation materials for
filtration around the well screen.
Artificial gravel pack: Involves adding specially selected gravel around the well
screen to enhance filtration and stability.
What information can be obtained from electric logging the well? -
ANSWER Electric logging provides information on formation resistivity,
porosity, water quality, and the location of water-bearing zones.
COMPLETE STUDY GUIDE 2026 | VERIFIED
ANSWERS | 100% CORRECT | GRADED A+|
PASS GUARANTEED /RECENT VERSION
How is the DHH drill bit sharpened? - ANSWER 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? - ANSWER using
stabilizers, reducing weight on the bit, and adjusting the drilling angle.
Explain various methods for setting casing using air rotary equipment. -
ANSWER 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? - ANSWER Fractured
formations, porous zones, or high-pressure air forcing fluids into surrounding
formations.
How are air rotary rigs sized? - ANSWER air compressor capacity (CFM/PSI)
drilling depth capacity
,mast height.
If the up-hole velocities decrease, what could be the probable cause? -
ANSWER Reduced air pressure
blockage in the air stream
increased hole diameter.
What can be added to water to aid in drilling with mud rotary? -
ANSWER Bentonite, polymers, and surfactants to improve viscosity,
stabilization, and cuttings removal.
In using mud rotary in unconsolidated formations, what is the relationship
between speed in RPMs and feed? - ANSWER 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? -
ANSWER Bentonite, cement, or a bentonite-cement mix.
How does the weight (density) of the drilling fluid affect the downhole conditions
during drilling? - ANSWER 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? -
ANSWER Mud weight is controlled by adding materials like barite or bentonite
Viscosity factors: Type of additives, fluid composition, and solids content.
, What causes cavitations in the pumping drilling method? -
ANSWER Cavitation is caused by low fluid levels, high pump speed, air
entrainment, or improper pump suction, leading to vapor bubbles that collapse and
damage equipment.
Explain why soft formations require low annular velocities. - ANSWER to
prevent erosion, collapse, or destabilization of the borehole due to excessive
cuttings removal or formation washout.
What can cause lost circulation in mud rotary drilling? - ANSWER Fractured
formations, porous zones, or over-pressurized drilling fluids forcing fluid into the
formation.
What are the most common types of mud pumps? - ANSWER Duplex, triplex,
and centrifugal pumps.
Polyphosphates are used for what purpose? - ANSWER used to prevent mineral
scaling and to disperse clays in drilling fluids
Explain percentage retention in designing a screen for a gravel well. -
ANSWER the proportion of gravel or formation particles that the screen is
designed to retain, ensuring proper filtration while allowing water flow without
clogging.
How are screen lengths determined? - ANSWER by the thickness of the water-
bearing formation and the desired water yield.
, What information should you have available when determining well screen design
- ANSWER Formation particle size, water flow rate, well depth, and aquifer
characteristics.
Could specific capacity be determined in sizing a well screen? - ANSWER Yes,
specific capacity (water yield per unit of drawdown) helps determine the
appropriate screen size to optimize flow and minimize drawdown.
What materials and methods for placement of the materials are used in gravel-
packed wells? - ANSWER Materials: Gravel, typically well-sorted and clean.
Methods: Gravity placement, tremie pipe, or reverse circulation to place gravel
uniformly around the well screen.
Explain the difference between natural and artificial gravel-packed wells. -
ANSWER Natural gravel pack: Utilizes the existing formation materials for
filtration around the well screen.
Artificial gravel pack: Involves adding specially selected gravel around the well
screen to enhance filtration and stability.
What information can be obtained from electric logging the well? -
ANSWER Electric logging provides information on formation resistivity,
porosity, water quality, and the location of water-bearing zones.
