Reelwell, A.s.

Tore Høgset

Harald Syse

Espen Alhaug

A method for operating a dual drill string disposed in a wellbore, the string having a shutoff valve for at least a fluid return drill string therein proximate a bottom end thereof includes pumping fluid into the fluid return string such that a pressure therein is substantially equal to a fluid pressure in the wellbore. Circulation of fluid in the wellbore is initiated by pumping fluid into a fluid supply string of the dual drill string such that the shutoff valve on the fluid return string opens to enable the fluid leaving the wellbore to enter the fluid return string.

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Stavanger, Norway

Tore Høgset