Borehole Drilling Method

reverse circulation drilling

alt label
RC more like this
notation 2.4 more like this
definition The drilling mechanism for reverse circulation (RC) drilling is a pneumatic reciprocating piston known as a "hammer" driving a tungsten-steel drill bit. Compressed air passes down to the drill bit along the annular space between an outer and inner drill rod to return to the surface carrying drill cuttings. This is the reverse of the air path employed in normal ‘open hole’ rotary percussion drilling (including RAB drilling). At the top of the hole, the air and drill cuttings are passed through a cyclone to collect the cuttings for sampling. The RC drilling technique prevents the upcoming sample from being contaminated with material from the wall of the hole above the sampling depth. RC drilling utilises much larger rigs and machinery and depths of up to 500 metres are routinely achieved. more like this
source more like this
broader percussion drilling
narrower reverse circulation drilling
in scheme boreholedrillingmethod
is primary topic of reverse circulation drilling