Patent ID: 6474422
Filing Date: 2002-11-05
Classification: E21B

Abstract:
A method for controlling a subsea well, the method comprising:shutting at least one blowout preventer; opening at least one isolation line; circulating a formation fluid influx out of a well while an inlet pressure of a subsea mudlift pump is adjusted to maintain a drill pipe pressure at a substantially constant initial circulating pressure; pumping drilling mud with a kill mud weight from a water surface into the well; reducing the drill pipe pressure according to a preselected drill pipe pressure decline schedule until the kill mud weight drilling mud reaches a bottom of the well; maintaining the drill pipe pressure at a substantially constant final circulating pressure after the kill mud weight drilling mud reaches the bottom of the well by adjusting the inlet pressure of the subsea mudlift pump; and circulating the kill mud weight drilling mud from the bottom of the well to the water surface while maintaining the substantially constant final circulating pressure.