APPARATUS AND METHOD FOR MANAGED PRESSURE DRILLING

摘要

There is disclosed herein a method for changing the density of a drilling fluid comprising, injecting a fluid of a first density through a drill pipe; injecting a fluid of a second density through an annular space between a riser and a concentric riser; mixing the two fluids below the concentric riser; and returning the mixed density fluid toward the top of the riser in the annular space between the drill pipe and concentric riser.