| 摘要 |
A method of casing drilling a portion of an offshore well includes running a casing string with a drill bit assembly attached to it into a previously drilled portion of the well. Before the drill bit assembly reaches bottom, the operator attaches drill pipe to the casing string and lowers the casing string on the drill pipe. When the drill bit is at bottom, an upper end of the casing string should be below the blowout preventer. The operator then performs casing drilling by rotating the drill pipe. When at a desired depth for the casing string, the operator pulls the drill pipe from the well and lifts the casing string up until its upper end is at the rig floor. The operator then runs the casing string back into the well but using casing in this instance. The operator then cements the casing string.
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