What is a down-the-hole drill?

A down-the-hole drill, usually called DTH by most professionals, is basically a jackhammer screwed on the bottom of a drill string. The fast hammer action breaks hard rock into small cuttings and dust that are evacuated by a fluid (air, water or drilling mud). The DTH hammer is one of the fastest ways to drill hard rock.

What is down-the-hole (DTH) drilling?

Down-the-hole (DTH) drilling has made it easier for contractors to drill wells faster and more efficiently, and to transition from dirt boring to rock boring just by adding a compressor and hammer to the drill bit.

How to drill a hole with a drill bit?

Specific operation method: whenever drilling begins, the operator must swing the drilling tools gradually to the bottom of the hole. When the frequency down the hole reaches 700~900 times/min and the pressure of the drilling tool on the drill bit reaches about 3kN, it can be the best impact speed.

How long did it take to drill a 12,000 ft hole?

The original estimate for completion of a 12,000-foot hole was 30 days using the conventional rotary technique, which was reduced to 13 days using the DTH method. Before DTH was used, drillers would typically case the vertical portion of the well and convert to rotary drilling to drill at a tangent.

How was a hole drilled?

This system could not guarantee a finished hole size and only pure vertical holes could be drilled as the system basically relied on gravity. Debris from the hole was baled out using a baling tube with a clack valve, which was periodically dropped on a winch to capture the slurry, which was then brought to the top of the hole to be discharged.

How does DTH drilling work?

With DTH drilling, contractors can change the drill that they were using for the current directional bore to a rock drill when they encounter rock by connecting the drill with a compressor and a steerable hammer. Well drilling also needed changes to be made to rotary drilling when the well needed to take a turn.