Patent ID: 6988553

Claim:
A method of drilling and completing a subsea production well with a casing installed in the wellbore and a wellhead housing having wellhead housing bore installed on the upper end of the casing, the method comprising: lowering a spool of a tree into connection with an upper end the wellhead housing, the spool having a spool bore along substantially its axial length greater than the wellhead housing bore below the spool; installing a BOP at the upper end of the spool, the BOP having a BOP bore aligned with the spool bore and the wellhead housing bore; drilling a first hole with a first bit having first cutting diameter by passing the first bit through the BOP and the spool; lowering a casing string carrying a casing hanger through the bores of the BOP and the spool tree and landing the casing hanger in the bore of the wellhead housing; drilling a second hole with a second bit having a second cutting diameter less than the first cutting diameter by passing the second bit through the BOP, the tree spool, and at least a portion of the casing string; positioning a sleeve-shaped subsea tree bore protector within the bore of the spool when drilling one of the first hole and the second hole; and lowering a tubing string carrying a tubing hanger through the bore of the BOP, and landing the tubing hanger in the bore of the spool.