Patent ID: 9004195
Filing Date: 2015-04-14
Classification: E21B

Abstract:
1. A method of forming a wellbore, comprising: providing a drill string having an outer string that includes a plurality of axially-spaced apart landing locations and an inner string configured to attach to the outer string at each of the plurality of landing locations; attaching the inner string to a first landing location of the outer string, and forming the wellbore with the inner string of a first size and enlarging a first portion of the wellbore of the first size to a second size that is at least as large as the outer string; detaching the inner string from the first landing location; attaching the inner string at a second landing location of the outer string; and enlarging a second portion of the wellbore of the first size to at least the size of the outer string with the inner string attached at the second landing location.