Contingent continuous circulation drilling system

摘要

A method for deploying a tubular string into a wellbore includes: injecting fluid through a top drive and flow sub into a top of the tubular string and lowering the tubular string into the wellbore. The flow sub: connects the tubular string top to a quill of the top drive, is in a top injection mode, and has a closed port and an open bore. The method further includes halting injection of the fluid through the top drive and lowering of the tubular string. The method further includes, while injection and lowering are halted: disconnecting the flow sub from the tubular string top; adding one or more tubular joints to the tubular string and connecting the flow sub to a top of the added joints. The method further includes resuming injection of the fluid through the top drive and lowering of the tubular string.