Before starting to drill with any particular rig,
thoroughly read and understand the manufacturers
manual for the machine. Make sure the drilling table, or
platform, is clean, dry as possible, and free of loose
objects. Doing so will help prevent personal injury and
loss of tools down the drill hole. For safety, ensure that
the sheave guards remain in place over moving gears
and chain drives while the rig is operating. Drillers learn
from experience why a well is dug in a certain way and
can visualize conditions at the bottom of the hole. No
set rules have been established to follow for adjusting
speeds of rotation and bit pressures.
In general, you proceed to set up the rig as follows:
Move the rig into position on the selected site. Use the
hydraulic outriggers to level the rig and take the weight
of the rig off the axles. Next, raise the mast and lock it
in place. Now check to see that the rig is slightly higher
in the rear to allow for settling during the drilling
For kelly-drive rotary drilling you continue by
doing the following:
1. Run the kelly through the turntable and thread
the pilot bit to the kelly.
2. Place the turntable transmission in the proper
gear for the soil formation being drilled.
3. Engage the turntable clutch and release the kelly
brake slowly to lower the bit into the ground.
4. Engage the mud pump and lower the kelly after
the bit has spudded into a depth of 6 to 12 inches.
5. Proceed to drill to the depth of the kelly. Raise
the drill bit 6 to 10 inches, circulate to bring all cuttings
to the surface, than shut off the mud pump and stop the
6. Next, raise the kelly until the pilot bit reaches the
surface. Remove the pilot bit and lift the kelly clear of
7. Move the turntable from its position over the
hole. Raise, then lower, a surface casing into the hole,
using the hoisting drum. The surfacing casing keeps the
well from caving-in from the surface.
8. Once again, position the turntable over the hole.
9. Next raise, then lower, a length of drill pipe into
the hole through the turntable, using the hoisting line.
The slips will hold the drill pipe in place in the turntable.
10. Follow up by lowering the kelly and attaching it
to the drill pipe. To keep these parts from seizing, apply
dope on the kelly coupling.
11. Using the kelly drum, raise the kelly and
attached drill pipe just enough to enable the slips to be
12. Lower the kelly and drill pipe so the kelly
bushing nut slips into the turntable.
13. Engage the turntable and start the mud pump. In
doing so, you lower the kelly to drill again.
14. The slips hold the drill pipe in place until the
breakout thongs are attached to the kelly. Rotate the
turntable slowly until the kelly is unscrewed from the
15. Raise the kelly far enough so another length of
drill pipe can be added to the pipe remaining in the hole.
Reconnect the kelly and lower into the turntable.
16. Start drilling again until you reach the end of the
Keep repeating this procedure until you have drilled
to the desired depth. You are now ready to complete the
drilling operation. Proceed to remove the drill pipe by
pulling it out with the hoisting line. Finally, lower the
casing with the screen to the desired depth.
If you must change bits before the desired depth is
reached, disconnect the kelly and attach the hoisting line
to the drill pipe. Pull the drill pipe a length at a time,
placing the bottom ends on a board to help keep them
Top-Head Drive Rotary Well Drilling Rig
The top-head drive rotary well drilling rig is a
special top-head drive ISO/airtransportable water
well-drilling rig (ITWD) (fig. 9-12) that the
development and production effort was conducted or
controlled by NAVFAC towards providing the NCF
with the capability for rapid water well drilling in a
variety of environments.
The self-propelled ITWD design has a lightweight
derrick a telescoping mast, and a top-head rotary drive
actuated by hydraulic cylinders able to accommodate
20-foot-long sections of drill pipe and well casings.
When the derrick is lowered for transport, the entire rig
weighs 23,000 pounds and is capable of fitting inside a
standard cargo container without disassembly and is air
transportable on board a C-130 aircraft. The ITWD is
capable of rotary drilling 12 1/4-inch holes to
1,250-foot depths and down-hole-drilling (DHD)
hammer (percussion) drilling, 6-inch holes to
1,500-foot depths. The ITWD will travel at a top speed