METHOD AND DEVICE FOR STABILIZING AND CONTROLLING LOWERING OR RAISING OF A STRUCTURE BETWEEN THE SURFACE AND THE SEA FLOOR

摘要

The invention concerns the use of a buoyancy fluid having a density lower than that of sea water confined in sealed rigid or flexible envelope (41, 191), to form an immersed buoyancy element (4, 19). The invention is characterized in that said buoyancy fluid is a compound occurring naturally in gaseous state at ambient temperature and pressure and in liquid state at the underwater depth whereat said element is immersed. The invention also concerns a method for setting between the surface and the sea floor a buoyancy element characterized in that said fluid is stored in a tank on a ship (61) at the surface in liquid state compressed or cooled, and it is injected in liquid state into a pipe (23) from the surface (61) where it is stored up to said one envelope (41, 191) immersed at an underwater depth whereat the underwater pressure is not less than the vapour pressure of the gas corresponding to said compound.