Kelly borehole drilling arrangement - involves telescopically nested pipes connected to drill head

摘要

The Kelly drill-pipe arrangement has a rotating drill-head (29) with a passage through it and a transmission piece that turns with the head. The drill head is coupled to a Kelly arrangement in which the drill pipes can be telescoped into one another with positive drive from one to the other. The outermost kelly pipe extends only below the drill head, and remains in rotary connection with the transmission piece. Several variants are claimed. USE/ADVANTAGE - This Kelly drill-pipe arrangement enables a drill head of relatively small dia. to be used for drilling deep boreholes without fitting additional pipes.