Different Drilling Methods

The reverse circulation drilling process is being used successfully in areas where rocks are deeply weathered, as in many tropical locales, or when drilling in glacial overburden. In this method, a tri-cone bit and dual-tube drill pipe are employed.

Drilling fluid or air, or a combination of the two, is pumped down between the dual tubing and returned up the inner tube, bringing cuttings from the bit to surface.

Sonic drilling, in which a sonic vibration device pushes the drill rod into the ground, can be used for soil investigation.

Sometimes explorers don’t need a core sample, as when an open hole allows instruments to be lowered. A standard rotary drill equipped with necessary compressors and drill pipe is all that is needed for this type of drilling.

Where applicable, cost reduction is significant together with greatly improved productivity. However, this method is not as reliable as collecting the full core by diamond drilling.