Drilling rigs are at the foundation of every mining operation, tunnel, water well, and major construction project. Used to penetrate the Earth’s surface, there are various drilling rigs available to suit any specific environmental need.
Most drill rigs and associated equipment are portable, to some degree. They may be one man operations or require an entire crew with heavy equipment to manage. Some drilling rigs can be utilized in multiple applications through the ability to change drilling heads, which bore holes from 4 inches to 24 inches in diameter.
A drilling rig is classified by several attributes.
- Power sources may be mechanical, electrical, hydraulic, or pneumatic.
- Height, measured by the number of pipe lengths that can stand in the derrick when changing bits, is referred to as single-, double-, triple- or quadri- stand.
- Drilling methods include push drilling, where no rotation occurs, rotary table drilling, top drive rotation, sonic, and percussive.
- Derrick position may be vertical or at a 45-degree slant.
The type of drill rig required for a specific job will be based on the reason for drilling, the type of subsurface being drilled, and the scope of the operation at hand, from deep earth core samples to massive bridge pilings.
- Augers employ a helical screw with a bladed bit to drill into sub-surface soils. The debris “rides the flights” out of the hole as the auger drills deeper. The stem may be solid or hollow to allow concrete grout to be pumped into the hole, creating a cast piling that will support heavy loads in weak soil.
- Percussion Rotary Air Blast (RAB) drilling is primarily used for mineral exploration. Also known as down-the-hole drilling, this method employs a pneumatic hammer with tungsten “teeth” that chew away the rock surface as the debris is blown up and out through the excess space surrounding the rod.
- Air Core drilling is very similar to RAB drilling, but is used in softer soils and, because it has a central evacuation tube to move debris out of the hole, more accurate soil samplings may be taken.
- Cable tool drill rigs are used to drill water wells in bedrock aquifers. A cable raises, turns, and drops a hammer, pulverizing the soil in the hole. The debris is then mucked out by a “bailer”, a bucket with a trapdoor bottom, that scoops out the overburden. The hammer is then re-employed and the process repeats.
- Direct push drilling is similar to cable tool drilling except the hammer does not rotate. It is used for drilling into in very soft soils.
The hallmarks of a good drilling company, as well as a good drill rig are reliability, versatility, and affordability. Your supplier should be able to provide all tools, equipment, service, and instruction to ensure your best success.