Drilling a wellbore

Rotary drilling is the most widely used in oil wells. This method employs cylindrical steel tubes (drill rods) coupled to a drum (rotary table) by which they are printed for rapid rotation. The tube string is connected, at its lower end, to a drill (drill bit) with cutting elements of various sizes, depending on the type of rock to be drilled, made of hardened steel or inlaid with diamonds.

The material milled by the drill bit is extracted by pressure circulation of water mixed with clay (drilling mud), which also helps to support the walls of the well, keeping it full of mud.

The use of cores allows a sample of the bottom material to be extracted during drilling, which automatically penetrates the drill rod and is recovered on the surface for analysis.