moteur de fond

CONT: When a downhole motor is used, it is attached to the lower end of the drill string; then the bit is attached to the bottom end of the downhole motor. The drilling motor rotates the bit, rather than the bit being rotated by the drill pipe string.
CONT: There are two types of turbodrill or down-hole mud motor: the turbine, of which there are about six successful types, and the Dynadrill, a Moyno pump operating in reverse, consisting of a spiral shaft contained within a rubber sleeve. ... The down-hole turbine is basically similar to a gas turbine having a multi-stage stator and rotor.