DRILL BIT AND SYSTEM FOR DRILLING A BOREHOLE

摘要

A drill bit having a central longitudinal axis and comprising: - a pilot section (1) for drilling a pilot bore section of the borehole; - an under-reaming section (3) in a following position with respect to the pilot section (1); - a connecting shaft (4) extending between the pilot section (1) and the under-reaming section (3); - a stabilising section (2) located between the pilot section (1) and the under-reaming section (3), wherein the stabilising section (2) fits inside the pilot bore section and is capable of laterally stabilising the drill bit while allowing rotation of at least the pilot section (1).