a - march abgelenktes kernbohr or bohrsystem

摘要

An assembly for sidetracked drilling in a wall of a borehole previously drilled or cored in a formation includes a guide element and an expansible device fixed to the front end of the guide element operable to be selectively expanded by an actuation means. A sidetracking channel is formed in the guide element in alignment with an internal space, upstream of the expansible device in the direction of advance. A longitudinal cavity is formed in the guide element parallel to the longitudinal axis and arranged to allow passage from the internal space to the actuation means of the expansible device. Within the internal space of the guide element, an external tube of the core barrel includes a core bit fixed to the front end of the external tube and arranged to slide, after having been released, in the internal space and in the sidetracking channel and then progress to the formation.