Drilling narrow fit for circulation for directional drilling by means of a drive motor located in the drilled hole.

摘要

1,212,915. Boring earth. ROLLS-ROYCE Ltd. 17 Jan., 1969 [19 Jan., 1968], No. 2915/68. Heading E1F. A drill collar or collars 4d mounted in a drill string used for drilling curved holes is/are sufficiently flexible to prevent the collars 4 mounted in the string above it/them from exerting a bending moment on the device 4c, 6 which produces the deviation of the hole, but is/are capable of transmitting axial loads from collars 4 to the device 4c, 6. As described the deviation is produced by the weight of collar 4c creating a bending moment which is transmitted through bent sub 6 to the drilling bit 8. The bit is rotated by turbo drill 5. The positions of ram 7, which may be of the type described in Specification 755207 and which loads the bit, and of non-magnetic survey collar 4b may be interchanged.