Double-walled pipe for drilling wells in geological structures

摘要

Wells are drilled using a double-walled drill pipe, each section of which comprises an outer pipe (1) and a concentric inner pipe, placed using a threaded ring (9) which has passages (10) through it and an outer thread. The ring is fixed to the inner pipe and has a screwed connection to the outer pipe through a cylindrical part (8) of the thread. While the outer pipe is being screwed on, a pressure-tight joint is made with a preceding and following pipe through spigot (5) and socket (4) connections formed at the pipe ends. Preferably, the threaded ring has a slot (12) over a narrow portion of its circumference, so that a clamping action is produced when the screw connection is tightened.