Patent ID: 7320373

Claim:
An assembly for sidetracked drilling, in a wall of a borehole previously drilled in a formation comprising: a guide element; an expansible device fixed to the front end of the guide element operable to be selectively expanded by an actuation means; a sidetracking channel formed in the guide element in alignment with an internal space, upstream of the expansible device in the direction of advance; a longitudinal cavity 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; in the internal space of the guide element, an external tube of a core barrel including a core bit fixed to the front end of the external tube; the core bit arranged operable to slide, after having been released, in the internal space and in the sidetracking channel and then progress to the formation; the external tube of the core barrel configured to direct drilling fluid to actuate the expansible device.