Irrigated well-drilling tool - incorporates motor, pump and seal operating so that irrigation fluid sweeps contact zone between tool and earth in inverse circulation

摘要

A well-drilling appts. uses a tool with a central bore, capable of being rotated and irrigated by a drill fluid which flows from the periphery towards the centre of the tool. The appts. is suspended at the end of a tubular drilling column. It incorporates in combination a motor which can be supplied with energy, a pump, with its suction inlet connected to the bore of the tool, driven by the motor and a partial sealing device which creates a pressure drop in the flow of drill fluid before the irrigation of the tool. The irrigation fluid sweeps the contact zone between the drilling tool and the earth in a radial direction directed from the wall towards the centre of the drilled hole, i.e. in "inverse circulation".