Importance

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Abstract

Diclosed is a connecting assembly for communicating between a first location and a second location lower than the first location, with the two locations separated by a fluid body. A first tube extending between the two locations generally encloses a second tube, and the annular area between adjacent surfaces of the two tubes is sealed toward the second location. The buoyancy of the assembly is selectively controlled by selectively controlling the quantity and density of fluid in the area between the tubes. In an embodiment shown, a marine drilling facility is joined to an underwater well site by a riser with a liner set and sealed therein, and gas-lift pumping is used in controlling buoyancy. In a method, a riser is set between an underwater well site and a marine well operating facility. A first segment of the well may be drilled through the riser. Casing is cemented in the well, and a liner is sealed at its bottom end to the riser. Air and jet lines are positioned in the area between the liner and the riser to control the density and quantity of fluid in that area. Continued drilling may occur through the liner and the casing. The connecting assembly may also be constructed by extending a first tube between two locations and generally enclosing a second which is anchored to the riser toward both ends and held in tension. In a method, a riser is set. Then, a liner is positioned within the riser, and anchored to the riser near the bottom of the liner. The liner is then pulled up on relative to the riser, and anchored at the top to hold the liner in tension and to prevent it from slipping downwardly relative to the riser.

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First Claim