Patent Number: 7,131,505

Title: Drilling with concentric strings of casing

Abstract: 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.

Inventors: Galloway; Gregory G. (Conroe, TX), Brunnert; David J. (Houston, TX)

Assignee: Weatherford/Lamb, Inc.

International Classification: E21B 10/62 (20060101)

Expiration Date: 2019-11-07 0:00:00