What is a down-the-hole drilling method?

The video shows the down-the-hole drilling method for very hard soil or rock. A rotary drilling rig, type LB 20, working with down-the-hole hammer inside a casing. A flushing current conveys the loosened drill cuttings upwards and exits at the upper end of the casing.

How does a down-the-hole drill work?

In down-the-hole drilling a drill rod is fitted with a hammer at its lower end. The hammer, which is mounted on the drill bit, is activated through the addition of compressed air and driven into the ground – simultaneously rotating and impacting. A flushing current collects the loosened drill cuttings and conveys them upwards.

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 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.

How do you drill a rock with a DTH hammer?

This method is mainly applied for hard to very hard rock and/or for penetrating large boulders. 1. Setting the DTH hammer with drill rod and casing on the drilling point. 2. Rotary and percussive drilling of the drill string under compressed air supply. 3. After reaching the final depth, unlocking of the drill rod with DTH hammer and pilot bit.

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.