06857487 is referenced by 102 patents and cites 438 patents.

The present invention provides a method and apparatus for setting concentric casing strings within a wellbore in one run-in of a casing working string. In one aspect of the invention, the apparatus comprises a drilling system comprising concentric casing strings, with each casing string having a drill bit piece disposed at the lower end thereof. The drill bit pieces of adjacent casing strings are releasably connected to one another. In another aspect of the invention, a method is provided for setting concentric casing strings within a wellbore with the drilling system. In another aspect of the invention, the releasably connected drill bit pieces comprise a drill bit assembly.

Title
Drilling with concentric strings of casing
Application Number
10/331964
Publication Number
6857487 (B2)
Application Date
December 30, 2002
Publication Date
February 22, 2005
Inventor
David J Brunnert
Houston
TX, US
Gregory G Galloway
Conroe
TX, US
Agent
Moser Patterson & Sheridan L
Assignee
Weatherford Lamb
TX, US
IPC
E21B 047/01
E21B 007/20
E21B 007/20
E21B 010/32
E21B 010/60
E21B 007/20
E21B 019/00
E21B 010/66
E21B 043/10
E21B 007/06
E21B 019/16
E21B 019/16
E21B 019/16
E21B 019/16
E21B 023/00
E21B 004/18
E21B 033/14
E21B 007/06
E21B 007/18
E21B 007/06
E21B 007/20
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