04637479 is referenced by 104 patents and cites 16 patents.

In the representative embodiments of the present invention described herein, a new and improved directional drilling tool carrying a rotable drilling bit is dependently coupled to a rotatable drill string for excavating a borehole along one or more selected courses of excavation. Passage means on the directional drilling tool are communicated with the several fluid-discharge passages in the drill bit. A rotating flow obstructing member is arranged in the directional drilling tool for selectively communicating the drilling fluid with the bit passages as the drill bit is rotated. A selectively operable driver is arranged for rotating the flow-obstructing member at one rotational speed when it is desired to sequentially discharge drilling fluid into most, if not all, adjacent sectors of the borehole as the drill bit rotates so as to advance the drill bit along a generally linear course of excavation. Alternatively, by rotating the flow-obstructing member at a different rotational speed, drilling fluid is sequentially discharged from the bit passages into only a single peripheral sector of the borehole to divert the drill bit to another course of excavation. Various controls are disclosed for utilizing typical directional measurements to control the direction of excavation.

Title
Methods and apparatus for controlled directional drilling of boreholes
Application Number
6/740110
Publication Number
4637479
Application Date
May 31, 1985
Publication Date
January 20, 1987
Inventor
Lawrence J Leising
Rosenberg
TX, US
Assignee
Schlumberger Technology Corporation
NY, US
IPC
E21B 7/08
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