50-24 Operation
D20x22 Series II Navigator HDD
D
RILL
R
ODS
- A
DD
Refer to “Drill Rods - Add to Drill String,”
W
HILE
D
RILLING
Gauges - Monitor
Monitor gauges during drilling operation to ensure a good pilot bore. Watching the
gauges will help establish a baseline for rotation and thrust/pullback pressures.
Generally, the operator should try to keep rotation and thrust/pullback pressures as
low as possible throughout the bore.
Thrust/Pullback Pressure/Force (1)--
Thrust/pullback pressure can be affected by
product size and weight, bore path lubrication, soil conditions, and bends in the bore.
If the pullback gauge hits the maximum pressure, maximum pullback force is being
exerted, and the bore will be unable to continue.
Rotation Pressure/Torque (2)
--Rotation pressure will naturally rise as the bore progresses due to friction on
the increasing length of the drill string. But if rotation pressure rises substantially, even when not attempting to
make forward progress, it could be a sign that soil is taking on water and swelling around the drill string. If this
happens, it may be necessary to reevaluate the drilling fluid additives, increase flows, and redrill the pilot bore.
Drilling Fluid Pressure (3)--
The drilling fluid pressure gauge is best used as an indicator that flow is
occurring. Pressure can vary based on flow rates and nozzle sizes used in the tooling. A maximum indication on
the drilling fluid pressure gauge could be an indicator that flow has become restricted. Gauge reads hydraulic oil
pressure, not water pressure. Pressure of 2350 psi (162 bar) is equal to 750 psi (52 bar) drilling fluid pressure.
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3
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