Patent ID: 6817809
Filing Date: 2004-11-16
Classification: B63B,B65D,E21B

Abstract:
An oil storage and offtake system, comprising:a storage tank attachable to a seabed and adapted to store hydrocarbons therein; at least one fluid channel having a first end positioned inside of the tank proximal a bottom of the tank and a second end in fluid communication with seawater outside of the tank; at least one offload line having a first end coupled to and in fluid communication with the tank proximal a top of the tank and a second end adapted to be fluid coupled to a tanker and accessible from a water surface, wherein the at least one offload line comprises a substantially rigid lower portion coupled to the tank and extending therefrom to a selected depth below the water surface, and a flexible upper portion coupled to and in fluid communication with the lower portion and extending therefrom to proximal the water surface, wherein the lower portion comprises a top-tensioned riser maintained in tension by a subsurface buoyant device coupled to the riser, wherein the flexible upper portion of the at least one offload line is coupled proximal one end to a surface buoyant device for access from the water surface; and at least one hawser having a first end operatively coupled to the tank at a location below the water surface and a second end coupled to the surface buoyant device, wherein the at least one hawser has a length less than a length of the flexible upper portion of the at least one offload line, wherein the second end of the at least one hawser is adapted to be accessible from the water surface and attachable to the tanker to anchor the tanker during offtake operations.