Patent ID: 7849937

Claim:
A method for producing a cased string bore extending from a well shaft in the horizontal direction into a rock wall mass surrounding the well shaft, for the installation of a filter string, comprising the steps of: inserting a hydraulically driven drill motor having a drilling tool rotationally driven thereby into a starter drill pipe in such a way that the drilling tool protrudes from the leading end of the starter drill pipe; supporting the drill motor in the starter drill pipe by means of an engaging clamping device engaging the starter drill pipe so as to be fixed against rotation and axial displacement, and sealing the starter drill pipe after the drill motor with the aid of the clamping device; driving the starter drill pipe and subsequently further drill pipes into the rock mass surrounding the well shaft through an opening in the wall of the well shaft by using a drive means arranged in the well shaft while rotating the drilling tool by the drill motor; supplying pressurized water to the drilling tool via a flushing pipe penetrating the clamping device and conveying the drilled material, which is crushed by the drilling tool, toward the surface through a straight conveying channel penetrating the drill motor and the clamping device in a longitudinal direction and through a conveying pipe, which is connected to the conveying channel and extends through the drill pipes to the well shaft; on reaching the final length of the string bore retracting the drilling tool or the string of drill pipes and forming a free space between the drift face of the string bore, the drilling tool and the starter drill pipe; filling and sealing the free space by injection of an expanding filling compound through the conveying pipe and the conveying channel into the free space; and once the string of pipes has been successfully sealed on a drift face by setting of the expanded filling compound disengaging the clamping device and removing the clamping device, the drill motor and the drilling tool from the drill pipes.