The Reverse Circulation Drilling system (RCD), also known as air-lift system, compresses air which is then injected into the drill pipe below water level just above the drill bit. This reduces the density of the internal water column and starts the circulation. The mixture of water, air and cuttings is then flushed out through the drill pipe into setting tanks.
It is an efficient, safe and environmentally friendly solution and ideal for:
1) Large dia (more than 800mm)
2) Depth (more than 50m)
3) Hard rock (75Mpa ~ 250Mpa)
4) Bore piling in marine conditions