The invention discloses a double-layer
underwater production supporting floating
barrel and installation and recycling methods thereof. The floating
barrel comprises an outer floating
barrel body and an inner floating barrel body, wherein the inner floating barrel body is nested in the outer floating barrel body. The outer floating barrel body is used for providing tension force of
mooring cables, the inner floating barrel body is used for providing top tension force required by a rigid vertical
pipe, accordingly, the double-layer floating barrel can conveniently and separately provide the top tension force required by the rigid vertical
pipe and the
mooring cables, and by applying the double-layer floating barrel in an ultra-deep ocean oil-gas project development
system, the requirement for practical project application can be met. The perpendicular movement and stress of the rigid vertical
pipe and the outer floating barrel body are decoupled, so that the stress and movement amplitude of the rigid vertical pipe are reduced, and the strength and fatigue performance of the rigid vertical pipe can be improved advantageously. The outer floating barrel body is moored on a
seabed through the four
mooring cables, when any one of the cables breaks off and fails, the other three cables can still maintain stability of the outer floating barrel body, and safety of the oil-gas development
system is ensured.