| 摘要 |
The present invention provides a method and apparatus for setting concentr ic casing strings within a wellbore in one run-in of a casing working string. I n one aspect of the invention, the apparatus comprises a drilling system comprisin g 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.
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