Drill Rig Operation and Production
What the exam tests
Making hole efficiently and safely: control application, drilling parameters, spoil handling, and response to changing ground. The exam rewards reading the rig and the returns, not simply pushing harder.
Core rules
- Match the tool to the formation: auger in cohesive soils, bucket in dense or hard layers, rotary with fluid or air in rock, and casing where collapse is possible.
- Control weight on bit and rotation. Too much crowd in clay can ball the bit; too little can polish the hole and slow penetration.
- Maintain circulation: watch returns, pressure, and spoil. Loss of returns can indicate hole instability or a blockage.
- Keep the mast plumb and avoid side loading. Stop rotation before pulling tools, and use the winch smoothly.
- Monitor torque, vibration, and rig movement. Back off when the rig signals that the hole is changing.
Worked example
A 120 ft hole is planned. The first 30 ft took 15 minutes at steady conditions. Penetration rate = 30 / 15 = 2 ft/min. At the same rate, the remaining 90 ft takes 45 minutes, for a 60-minute total. If returns slow and torque rises, the rate assumption is invalid-investigate before pressing on.
Traps
Chasing penetration rate by adding crowd; ignoring changes in spoil; pulling the auger without clearing it; using rotation to break out a stuck tool; leaving an open hole unbarricaded.