04605077 is referenced by 156 patents and cites 14 patents.

Methods and apparatus for facilitating the drilling of a well with a top drive unit having a motor which is connected to the upper end of the drill string and moves upwardly and downwardly therewith. The methods and apparatus of the invention enable the drill string to be pulled upwardly off of the bottom of the well each time an additional length of drill pipe is added to the string, with the connection between that added length and the upper end of the string being made at an elevated location spaced above the rig floor. In one form of the invention, an elevated platform is provided on which a person may move to a location near the raised upper end of the string for assisting in making the connection, with that platform preferably being mounted to swing between a retracted position in which it remains during the drilling operation and an active position in which it projects to a point near the top of the string during the connecting process. In another form of the invention, the back-up tool for preventing rotation of the upper end of the string may be controlled remotely and be removable relative to the string between an active position in which it can grip the elevated upper end of the string and a retracted position in which it remains during drilling.

Title
Top drive drilling systems
Application Number
6/677988
Publication Number
4605077
Application Date
December 4, 1984
Publication Date
August 12, 1986
Inventor
George I Boyadjieff
Anaheim
CA, US
Agent
William P Green
Assignee
Varco International
CA, US
IPC
E21B 19/16
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