Patent attributes
At least a portion of a subsea well is drilled casing-while-drilling techniques. A landing shoulder is formed within an outer string of a casing. The outer string of casing is secured to an outer wellhead housing above the landing shoulder and lowered into the wellbore. A casing hanger is attached to an inner string of casing and lowered through the outer string of casing into the wellbore. A drill bit at the at the lower end of the inner string of casing is rotated to deepen the well. The string of inner casing moves downward as the well is being deepened until landing the casing hanger on the load shoulder. A tieback member is attached to an inner wellhead housing and lowered into sealing engagement with the casing hanger. The inner wellhead housing lands in the outer wellhead housing.
