06213226 is referenced by 161 patents and cites 44 patents.

The drilling assembly includes an eccentric adjustable diameter blade stabilizer having a housing with a fixed stabilizer blade and a pair of adjustable stabilizer blades. The adjustable stabilizer blades are housed within openings in the stabilizer housing and have inclined surfaces which engage ramps on the housing for camming the blades radially upon their movement axially. The adjustable blades are operatively connected to an extender piston on one end for extending the blades and a return spring at the other end for contracting the blades. The eccentric stabilizer also includes one or more flow tubes through which drilling fluids pass that apply a differential pressure across the stabilizer housing to actuate the extender pistons to move the adjustable stabilizer blades axially upstream to their extended position. The eccentric stabilizer is mounted on a bi-center bit which has an eccentric reamer section and a pilot bit. In the contracted position, the areas of contact between the eccentric stabilizer and the borehole form a contact axis which is coincident with the pass through axis of the bi-center bit as the drilling assembly passes through the existing cased borehole. In the extended position, the extended adjustable stabilizer blades shift the contact axis such that the areas of contact between the eccentric stabilizer and the borehole form a contact axis which is coincident with the axis of the pilot bit so that the eccentric stabilizer stabilizes the pilot bit in the desired direction of drilling as the eccentric reamer section reams the new borehole.

Title
Directional drilling assembly and method
Application Number
8/984846
Publication Number
6213226 (B1)
Application Date
December 4, 1997
Publication Date
April 10, 2001
Inventor
Albert C Odell
Kingwood
TX, US
David E Rios Aleman
Houston
TX, US
Jay M Eppink
Spring
TX, US
Agent
Conley Rose & Tayon P C
US
Assignee
Halliburton Energy Services
TX, US
IPC
E21B 7/06
View Original Source