Deep drilling tool drive assembly of tubular form - in which a residual core can grow within a core pipe which extends through the pipe

摘要

Drive assembly for a deep drilling tool is of tubular form so that, when using an annular drill bit (1), a residual core (2) can grow within a core pipe (3) which extends through the drive. Pref. the core pipe is replaceable by a plugging tube which closes the core pipe channel to permit full-section drilling. A harmonic drive transmission or a planetary transmission is pref. used as the torque transmission. The drive is pref. a turbine operated by drilling mud circulation. USE/ADVANTAGE - Used esp. in rotary core drilling using a downhole drive, e.g. for the German Continental Deep Drilling Programme. The design combines the advantages of the progressive core drilling technique with those of a downhole drill bit drive, while allowing directional drilling and even plugging of the core pipe channel for full-section drilling.