06092610 is referenced by 236 patents and cites 101 patents.

An actively controlled rotary steerable drilling system for directional drilling of wells having a tool collar rotated by a drill string during well drilling. A bit shaft has an upper portion within the tool collar and a lower end extending from the collar and supporting a drill bit. The bit shaft is omni-directionally pivotally supported intermediate its upper and lower ends by a universal joint within the collar and is rotatably driven by the collar. To achieve controlled steering of the rotating drill bit, orientation of the bit shaft relative to the tool collar is sensed and the bit shaft is maintained geostationary and selectively axially inclined relative to the tool collar during drill string rotation by rotating it about the universal joint by an offsetting mandrel that is rotated counter to collar rotation and at the same frequency of rotation. An electric motor provides rotation to the offsetting mandrel with respect to the tool collar and is servo-controlled by signal input from position sensing elements such as magnetometers, gyroscopic sensors, and accelerometers which provide real time position signals to the motor control. In addition, when necessary, a brake is used to maintain the offsetting mandrel and the bit shaft axis geostationary. Alternatively, a turbine is connected to the offsetting mandrel to provide rotation to the offsetting mandrel with respect to the tool collar and a brake is used to servo-control the turbine by signal input from position sensors.

Title
Actively controlled rotary steerable system and method for drilling wells
Application Number
9/19468
Publication Number
6092610
Application Date
February 5, 1998
Publication Date
July 25, 2000
Inventor
Spyro J Kotsonis
Houston
TX, US
Dimitrios K Pirovolou
Houston
TX, US
Attilio C Pisoni
Sugar Land
TX, US
Alexandre G E Kosmala
Houston
TX, US
Agent
Steven L Christian
Wayne I Kanak
James L Jackson
Assignee
Schlumberger Technology Corporation
TX, US
IPC
E21B 7/04
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