| 摘要 |
A method for controlling the pressure at the base of a gas-lifted riser (10) during casing (66) installation is disclosed. Prior to casing installation, drilling fluid (67) is displaced from the riser (10) and the riser is filled with seawater (68). During casing installation, the riser base pressure is monitored, and the height of seawater (hsw) in the riser is adjusted to compensate for increase 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 (66).
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