Method for installing a well casing into a subsea well being drilled with a dual density drilling system

摘要

A method for controlling the pressure at the base of a gas-lifted riser during casing installation is disclosed. Prior to casing installation, drilling fluid is displaced from the riser and the riser is filled with seawater. During casing installation, the riser base pressure is monitored, and the height of seawater in the riser is adjusted to compensate for increases in the riser base pressure. The riser base pressure is thereby maintained substantially equal to the seawater pressure at the base of the drilling riser throughout installation of the casing.