be connected to the secondary drilling center 12 using a running tool or another tool of the type shown in fig8 the 20 inch casing may then be run into the 26 inch hole and cemented in place at the times shown in fig4 after the 30 conductor 22 is placed onto the seabed floor sb and jetted in the riser 24 and blowout preventer 26 may be continued to be run into the seabed s in other words in embodiments where it was not possible to get the blowout preventer 26 proximate to the seabed floor at the point in time when drilling operations can begin the downward course of the riser 24 and blowout preventer 26 may be continued thereafter as possible specifically that downward running of the blowout preventer 26 may be continued while the 30 inch conductor is being jetted in the 26 inch hole is being drilled and the 20 inch casing 18 is transferred to the trolley to the secondary drilling center 12 and then run into the seabed and cemented in thus operations in the main drilling center 14 with the blowout preventer 26 continue to the extent necessary and as possible while other operations.