Floating production system and method

Abstract

A floating production system, comprising a superstructure configured to float on the sea, such that portions of the superstructure are configured to rest above and below the surface of the sea. A mooring system is configured to moor the superstructure to the seabed using neutrally buoyant mooring lines of steel pipes. The mooring system may be arranged in catenary. One or more risers disposed between the seabed and a semi-submersible platform, arranged in a curtain, are configured to facilitate the transport of liquid material from the seabed toward the surface of the sea. Liquid material may be stored in storage tanks disposed in vertically-disposed legs extending downward from the upper portion of the superstructure and/or in horizontally-disposed pontoons extending between at least two of the legs. The horizontally-disposed pontoons may form a square ring providing tanks for oil over water storage and/or dry storage.

What is claimed is: 
     
         1 . A floating production system, comprising:
 a superstructure configured to float on the sea, such that at least a first portion of the superstructure is configured to rest above the surface of the sea;   a mooring system configured to moor the superstructure to the seabed, the mooring system comprising:
 a first end operatively connected to the superstructure configured to secure the mooring system to the superstructure; 
 a second end configured to secure the mooring system to the seabed; and 
 a line between the first end and the second end configured to facilitate the mooring of the superstructure to the seabed; 
 wherein the line between the first end and the second end is arranged in catenary. 
   
     
     
         2 . The floating production system of  claim 1 , wherein the line comprises:
 a first line portion extending from the superstructure through a first upper portion of the neutrally buoyant line;   a second line portion extending from the seabed through a second lower portion of the neutrally buoyant line; and   a pipe portion extending between the first upper portion and the second lower portion of the neutrally buoyant line.   
     
     
         3 . The floating production system of  claim 1 , wherein the line is a neutrally buoyant line. 
     
     
         4 . The floating production system of  claim 1 , wherein the second end of the mooring system further comprises an anchor configured to anchor the mooring system to the seabed. 
     
     
         5 . The floating production system of  claim 1 , wherein the second end of the mooring system further comprises a deadweight. 
     
     
         6 . The floating production system of  claim 1 , wherein the first line portion is a chain. 
     
     
         7 . The floating production system of  claim 1 , wherein the first line portion is a cable. 
     
     
         8 . The floating production system of  claim 1 , wherein the line further comprises floats disposed at intervals along the line to provide buoyancy to the line. 
     
     
         9 . The floating production system of  claim 1  further comprising:
 at least one pontoon; 
 wherein the pontoon is configured to reduce heave and wherein the depth at which the pontoon is disposed is selected to provide a heave response of less than 0.5 of a wave height causing the heave. 
 
     
     
         10 . A system for transporting liquids between the seabed and a semi-submersible platform on the surface of the sea, comprising:
 one or more pipes disposed between the seabed and a semi-submersible platform configured to float on the surface of the sea, wherein the pipe has a first end extending toward the semi-submersible platform and a second end extending toward the seabed, and where the pipe is configured to facilitate the transport of liquid material from the seabed toward the surface of the sea;   a pipe anchor configured to anchor the one or more pipes to the seabed; and   a pipe connector configured to secure the one or more pipes to the semi-submersible platform.   
     
     
         11 . The system of  claim 10 , wherein the one or more pipes comprise at least two pipes arranged in a coplanar curtain. 
     
     
         12 . The system of  claim 11 , wherein the at least two pipes arranged in a coplanar curtain comprise spacers configured to cause the pipes arranged in a coplanar curtain to form an integral unit. 
     
     
         13 . The system of  claim 10 , further comprising a bearing disposed on the semi-submersible platform and configured to secure the two or more pipes to the semi-submersible platform and to minimize the bend moments in the two or more pipes. 
     
     
         14 . The system of  claim 10 , wherein the bearing is a gimbal adapted to facilitate the control of the bend of the radius of the two or more pipes arranged in catenary. 
     
     
         15 . The system of  claim 10 , further comprising a ground riser configured to secure the two or more pipes to the seabed. 
     
     
         16 . The system of  claim 10  further comprising an anchor template configured to secure the two or more pipes to the seabed, and configured to withstand horizontal forces applied on the anchor template by the two or more pipes in catenary. 
     
     
         17 . The system of  claim 10 , wherein the anchor template is configured to facilitate decoupling of the two or more pipes. 
     
     
         18 . A semi-submersible vessel comprising:
 an upper portion configured to provide a platform; and   a lower portion comprising:
 vertically-disposed legs extending downward from the upper portion; and 
 a horizontally-disposed pontoon extending between at least two of the legs; 
 wherein the lower portion is configured to provide sufficient buoyancy to maintain the upper portion substantially above the water, and wherein the lower portion is configured to store liquid mater. 
   
     
     
         19 . The semi-submersible vessel of  claim 18 , wherein the liquid matter stored in the lower portion comprise one or more of sea water, ballast water, and/or crude oil. 
     
     
         20 . The semi-submersible vessel of  claim 18 , wherein the lower portion is comprised of rectangular tubular elements. 
     
     
         21 . The semi-submersible vessel of  claim 18 , wherein the lower portion comprises a plurality of cubic boxes. 
     
     
         22 . The semi-submersible vessel of  claim 18 , wherein the lower portion is configured to receive an amount of crude oil for storage and to eject a corresponding amount of ballast water. 
     
     
         23 . The semi-submersible vessel of  claim 22 , further comprising filtration tanks configured to receive and filter crude oil from the ejected ballast water. 
     
     
         24 . The semi-submersible vessel of  claim 18 , further comprising storage tanks disposed in the pontoons. 
     
     
         25 . The semi-submersible vessel of  claim 24  wherein the storage tanks further comprise externally, disposed strengthening components. 
     
     
         26 . The semi-submersible vessel of  claim 24 , wherein, during operation, the storage tanks are maintained at capacity. 
     
     
         27 . A floating production system comprising:
 a superstructure configured to float on the sea, such that at least a first portion of the superstructure is configured to rest above the surface of the sea;   a mooring system configured to moor the superstructure to the seabed, the mooring system comprising:
 a set of neutrally buoyant lines operatively connected to the superstructure and the sea bed, wherein the set of neutrally buoyant lines are arranged in a catenary curtain to provide horizontal stabilizing forces to the superstructure to facilitate, maintaining the superstructure over an area of the seabed; 
   one or more pipes disposed between the seabed and a superstructure, wherein, the one or more pipes are configured to facilitate the transport of liquid material from the seabed toward the surface of the sea;   legs extending downward from an upper portion of the superstructure to a lower portion of the superstructure; and   at least one horizontally-disposed pontoon extending between at least two of the legs, wherein the pontoon is configured to store the liquid material.