Auxiliary subsurface compensator

摘要

Force-dampening arrangement (100) for dampening forces between two interconnectable parts in a tube string, of which interconnectable parts a lower part (101) is connected to the upper end of a string element (105, 3a) extending into a subsea well (5) and an upper part (103) is suspended from a floating surface installation (1) through at least one suspension element (3b) extending up to said surface installation. The force-dampening arrangement (100) is connected to the tube string above a string-portion (3a) extending into said subsea well, and below at least a portion of said suspension element (3b). The force dampening arrangement (100) exhibits an upper and lower section (109, 111) that are vertically movable in relation to each other, thereby yielding for impact forces between said interconnectable upper and lower parts (103, 101) resulting from vertical heave movement of said portion of suspension elements (3b) moving vertically in respect of the string element (3a).

主权项

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.