Patent ID: 8931563
Filing Date: 2015-01-13
Classification: E21B

Abstract:
1. A tube string assembly extending into a subsea well through a wellhead at a sea floor, said tube string assembly comprising: a lower interconnectable part connected to an upper end of a string element extending into the subsea well through the wellhead at the sea floor; an upper interconnectable part suspended from a floating surface installation from a suspension pipe, the string element and the suspension pipe being components of the tube string assembly, in a connected mode the lower interconnectable part is connected to the upper interconnectable part at a subsurface position and in a disconnected mode the upper and lower interconnectable parts are disconnected at the subsurface position; a hang-off tool connected to the string element, when in the disconnected mode the string element is suspended in the subsea well by the hang-off tool arranged in the wellhead; a force-dampening arrangement connected to the tube string assembly above the string element and below the floating surface installation in a position closer to the sea floor than to the floating surface installation when the string element is in a position or situation to be hung off in the subsea well from the hang-off tool; the force dampening arrangement exhibits a first section and a second section that are vertically movable in relation to each other both in the connected mode and in the disconnected mode, thereby yielding for impact forces between the upper and lower interconnectable parts during connection or disconnection of the string element and the suspension pipe at a subsea position resulting from vertical heave movement of the suspension pipe moving vertically with respect to the string element; and wherein when in the connected mode, the tube string assembly is adapted to be lifted upwards towards the floating surface installation.