NGWA (EF) MUD ROTARY DRILLING VERIFIED EXAM SOLUTIONS -
COMPREHENSIVE QUESTIONS AND ANSWERS - CURRENT VERSION
(2026/2027)
1. Q: What is the primary purpose of drilling fluid in mud rotary drilling?
ANSWER To remove cuttings from the borehole, cool and lubricate the bit,
stabilize the borehole walls, and control formation pressures.
2. Q: What are the three main components of a mud rotary drilling
system? ANSWER The rotary system (rotary table, drill pipe, bit), the
circulating system (pump, hoses, swivel), and the hoisting system (mast,
drawworks, cable).
3. Q: What is the function of the swivel in a rotary drilling rig? ANSWER
To allow rotation of the drill string while maintaining a sealed connection for
drilling fluid circulation.
4. Q: What is the purpose of the kelly in rotary drilling? ANSWER To
transmit rotary motion from the rotary table to the drill string while allowing
vertical movement.
5. Q: What is a typical shape of a kelly? ANSWER Square or hexagonal
cross-section to engage with the rotary table bushings.
6. Q: What is the function of drill collars? ANSWER To provide weight on
bit (WOB) and keep the drill string in tension above the collars.
7. Q: Why are drill collars made with thick walls? ANSWER To provide
maximum weight per unit length while maintaining strength and rigidity.
8. Q: What is the purpose of stabilizers in a drill string? ANSWER To
keep the hole straight, reduce drill pipe wear, and prevent dogleg severity.
9. Q: What is the desanding equipment used in mud rotary drilling?
ANSWER Shale shakers, desanders (hydrocyclones), desilters, and mud
cleaners.
,10. Q: What is the function of a shale shaker? ANSWER To remove large
cuttings and solids from the drilling fluid as it returns from the borehole.
11. Q: What size particles do desanders typically remove? ANSWER
Particles between 45-74 microns.
12. Q: What size particles do desilters typically remove? ANSWER
Particles between 15-45 microns.
13. Q: What is a mud cleaner? ANSWER A combination unit that includes
hydrocyclones mounted over a fine-mesh shale shaker.
14. Q: What is the purpose of the mud pits? ANSWER To hold and
condition drilling fluid, allow settling of solids, and provide suction for the mud
pumps.
15. Q: What is the typical configuration of mud pits? ANSWER Multiple
compartments including suction pit, settling pit, and mixing pit.
16. Q: What is the function of a mud hopper? ANSWER To mix dry
additives into the drilling fluid using a venturi effect.
17. Q: What type of pump is most commonly used for circulating drilling
mud? ANSWER Positive displacement pumps, typically duplex or triplex
reciprocating pumps.
18. Q: What is the advantage of a triplex pump over a duplex pump?
ANSWER Smoother flow with less pulsation and typically higher pressure
capability.
19. Q: What is the purpose of a pulsation dampener? ANSWER To reduce
pressure fluctuations in the discharge line from reciprocating pumps.
20. Q: What is a rotary table? ANSWER A mechanically driven turntable
that provides rotational force to the drill string.
21. Q: What is a top-head drive system? ANSWER A motorized system
suspended from the hook that rotates the drill string, eliminating the need for a
kelly.
22. Q: What are the advantages of a top-head drive? ANSWER Faster
tripping, ability to rotate while tripping, safer operations, and better hole
cleaning.
, 23. Q: What is the function of the drawworks? ANSWER To raise and
lower the drill string using wire rope and a hoisting drum.
24. Q: What is the purpose of the crown block? ANSWER To support the
traveling block and provide mechanical advantage for hoisting.
25. Q: What is a derrick or mast? ANSWER The vertical structure that
supports the crown block and allows vertical movement of the drill string.
26. Q: What is the difference between a derrick and a mast? ANSWER A
derrick is assembled piece by piece on location; a mast is a portable unit raised
as a single structure.
27. Q: What is the purpose of the deadline anchor? ANSWER To secure
the stationary end of the hoisting line on the drilling rig.
28. Q: What safety device prevents the traveling block from hitting the
crown block? ANSWER A crown-o-matic or similar over-hoist prevention
device.
29. Q: What is a drilling jar? ANSWER A tool that delivers impact blows to
help free stuck pipe.
30. Q: What are the two types of drilling jars? ANSWER Hydraulic jars
and mechanical jars.
31. Q: What is a bit sub? ANSWER A short connector placed between the bit
and drill collars to protect collar threads.
32. Q: What is the purpose of a float valve or sub? ANSWER To prevent
backflow of drilling fluid and formation fluids into the drill string.
33. Q: What is the function of drill pipe protectors? ANSWER To reduce
wear on drill pipe from contact with the borehole wall.
34. Q: What is a kelly saver sub? ANSWER A short, replaceable sub
between the kelly and drill pipe to protect kelly threads.
35. Q: What are elevator links? ANSWER Connecting devices between the
elevators and the traveling block or hook.
36. Q: What is the purpose of slips? ANSWER To grip and support the drill
string in the rotary table when making connections.
COMPREHENSIVE QUESTIONS AND ANSWERS - CURRENT VERSION
(2026/2027)
1. Q: What is the primary purpose of drilling fluid in mud rotary drilling?
ANSWER To remove cuttings from the borehole, cool and lubricate the bit,
stabilize the borehole walls, and control formation pressures.
2. Q: What are the three main components of a mud rotary drilling
system? ANSWER The rotary system (rotary table, drill pipe, bit), the
circulating system (pump, hoses, swivel), and the hoisting system (mast,
drawworks, cable).
3. Q: What is the function of the swivel in a rotary drilling rig? ANSWER
To allow rotation of the drill string while maintaining a sealed connection for
drilling fluid circulation.
4. Q: What is the purpose of the kelly in rotary drilling? ANSWER To
transmit rotary motion from the rotary table to the drill string while allowing
vertical movement.
5. Q: What is a typical shape of a kelly? ANSWER Square or hexagonal
cross-section to engage with the rotary table bushings.
6. Q: What is the function of drill collars? ANSWER To provide weight on
bit (WOB) and keep the drill string in tension above the collars.
7. Q: Why are drill collars made with thick walls? ANSWER To provide
maximum weight per unit length while maintaining strength and rigidity.
8. Q: What is the purpose of stabilizers in a drill string? ANSWER To
keep the hole straight, reduce drill pipe wear, and prevent dogleg severity.
9. Q: What is the desanding equipment used in mud rotary drilling?
ANSWER Shale shakers, desanders (hydrocyclones), desilters, and mud
cleaners.
,10. Q: What is the function of a shale shaker? ANSWER To remove large
cuttings and solids from the drilling fluid as it returns from the borehole.
11. Q: What size particles do desanders typically remove? ANSWER
Particles between 45-74 microns.
12. Q: What size particles do desilters typically remove? ANSWER
Particles between 15-45 microns.
13. Q: What is a mud cleaner? ANSWER A combination unit that includes
hydrocyclones mounted over a fine-mesh shale shaker.
14. Q: What is the purpose of the mud pits? ANSWER To hold and
condition drilling fluid, allow settling of solids, and provide suction for the mud
pumps.
15. Q: What is the typical configuration of mud pits? ANSWER Multiple
compartments including suction pit, settling pit, and mixing pit.
16. Q: What is the function of a mud hopper? ANSWER To mix dry
additives into the drilling fluid using a venturi effect.
17. Q: What type of pump is most commonly used for circulating drilling
mud? ANSWER Positive displacement pumps, typically duplex or triplex
reciprocating pumps.
18. Q: What is the advantage of a triplex pump over a duplex pump?
ANSWER Smoother flow with less pulsation and typically higher pressure
capability.
19. Q: What is the purpose of a pulsation dampener? ANSWER To reduce
pressure fluctuations in the discharge line from reciprocating pumps.
20. Q: What is a rotary table? ANSWER A mechanically driven turntable
that provides rotational force to the drill string.
21. Q: What is a top-head drive system? ANSWER A motorized system
suspended from the hook that rotates the drill string, eliminating the need for a
kelly.
22. Q: What are the advantages of a top-head drive? ANSWER Faster
tripping, ability to rotate while tripping, safer operations, and better hole
cleaning.
, 23. Q: What is the function of the drawworks? ANSWER To raise and
lower the drill string using wire rope and a hoisting drum.
24. Q: What is the purpose of the crown block? ANSWER To support the
traveling block and provide mechanical advantage for hoisting.
25. Q: What is a derrick or mast? ANSWER The vertical structure that
supports the crown block and allows vertical movement of the drill string.
26. Q: What is the difference between a derrick and a mast? ANSWER A
derrick is assembled piece by piece on location; a mast is a portable unit raised
as a single structure.
27. Q: What is the purpose of the deadline anchor? ANSWER To secure
the stationary end of the hoisting line on the drilling rig.
28. Q: What safety device prevents the traveling block from hitting the
crown block? ANSWER A crown-o-matic or similar over-hoist prevention
device.
29. Q: What is a drilling jar? ANSWER A tool that delivers impact blows to
help free stuck pipe.
30. Q: What are the two types of drilling jars? ANSWER Hydraulic jars
and mechanical jars.
31. Q: What is a bit sub? ANSWER A short connector placed between the bit
and drill collars to protect collar threads.
32. Q: What is the purpose of a float valve or sub? ANSWER To prevent
backflow of drilling fluid and formation fluids into the drill string.
33. Q: What is the function of drill pipe protectors? ANSWER To reduce
wear on drill pipe from contact with the borehole wall.
34. Q: What is a kelly saver sub? ANSWER A short, replaceable sub
between the kelly and drill pipe to protect kelly threads.
35. Q: What are elevator links? ANSWER Connecting devices between the
elevators and the traveling block or hook.
36. Q: What is the purpose of slips? ANSWER To grip and support the drill
string in the rotary table when making connections.
