| 摘要 |
Methods and related equipment for drilling a wellbore in subterranean formations whereby a drill bit is attached to one end of a first conduit string, such as a casing string which is not usually used for drilling, and advancing the first conduit string and the drill bit into the subterranean formation to extend an existing wellbore, cleanout the wellbore or create a new lateral wellbore. This advancement is stopped and steps are taken to create a longitudinal opening through the drill bit. Thereafter, a second conduit string is advanced through the opening in the drill bit and into the subterranean formation to further extend, cleanout or create the lateral wellbore.
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