METHOD, SYSTEM, AND PRODUCTION AND STORAGE FACILITY FOR OFFSHORE LPG and LNG PROCESSING OF ASSOCIATED GASES

Abstract

A method, system and production and storage facility is disclosed for offshore LPG and LNG processing of associated gases. The system includes a first production facility and a second production and storage facility. The first facility receives and processes produced fluids to produce crude oil, water and rich associated gases. The second facility includes a gas treatment unit for processing the rich associated gases to remove contaminants and produce a treated gas stream of hydrocarbons. The second facility also has at least one LPG and/or LNG production unit for producing one of LPG and/or LNG from the treated gas stream. At least one storage tank on the second facility stores at least one of the LPG and/or LNG. The second production facility may be a retrofit LNG or LPG carrier. The treatment unit, LPG and/or LNG production and needed offloading facilities and equipment can be added to the LNG/LPG carrier. Existing storage tanks can be modified as needed or else new storage tanks can also be added.

What is claimed is: 
     
         1 . A method for separating produced fluids containing hydrocarbons received from an offshore subterranean reservoir, the method comprising:
 (a) receiving a rich associated gas stream on an offshore production and storage facility and removing at least one of acid gases, water vapor and mercury from the rich associated gases to produce a treated gas;   (b) producing at least one of liquefied petroleum gas (LPG) and liquefied natural gas (LNG) from at least a portion of the treated gas; and   (c) storing the at least one of LPG and LNG in at least one of a liquefied petroleum gas (LPG) storage tank and a liquefied natural gas (LNG) storage tank on the production and storage facility.   
     
     
         2 . The method of  claim 1  wherein:
 LPG is produced in step (b); and 
 LPG is stored in step (c) in at least one LPG storage tank located on the production and storage facility. 
 
     
     
         3 . The method of  claim 1  wherein:
 LNG is produced in step (b); and 
 LNG is stored in step (c) in at least one LNG storage tank located on the production and storage facility. 
 
     
     
         4 . The method of  claim 1  wherein:
 LPG and LNG are both produced on the production and storage facility in step (b). 
 
     
     
         5 . The method of  claim 4  wherein:
 LNG is stored in at least one LNG storage tank and LPG is stored in at least one LPG storage tank. 
 
     
     
         6 . The method of  claim 1  wherein:
 acid gases are removed from the rich associated gases in step (a). 
 
     
     
         7 . The method of  claim 1  wherein:
 the production and storage facility is one of an LPG carrier or an LNG carrier which is retrofit to include a gas treatment unit for removing at least one of acid gases, water vapor and mercury from the rich associated gases and which includes at least one of an LPG and LNG production unit to produce one of LPG and LNG. 
 
     
     
         8 . An offshore production and storage facility comprising:
 a support structure;   a gas treatment unit which is adapted to receive rich associated gases, the gas treatment unit mounted on the support structure and being capable of removing at least one of acid gases, water vapor and mercury from associated gases to produce a treated gas stream;   at least one of an LPG production unit and an LNG production unit mounting on the support structure and being capable of producing at least one of LPG and LNG from at least a portion of the treated gas stream; and   at least one storage tank on the support structure to store at least one of the LPG and LNG.   
     
     
         9 . The offshore production and storage facility of  claim 8  wherein:
 the at least one of an LPG production unit and an LNG production unit is a LPG production unit; and 
 the at least one storage tank includes at least on one storage tank for storing LPG. 
 
     
     
         10 . The offshore production and storage facility of  claim 9  wherein:
 the at least one of an LPG production unit and LNG production unit is an LNG production unit; and 
 the at least one storage tank includes at least on one storage tank for storing LNG. 
 
     
     
         11 . The offshore production and storage facility of  claim 9  wherein:
 the at least one of an LPG production unit and LNG production unit includes both an LPG production unit and an LNG production unit. 
 
     
     
         12 . The offshore production and storage facility of  claim 11  wherein:
 at least one storage tank includes at least on one storage tank for storing LNG and at least one storage tank for storing LPG. 
 
     
     
         13 . The offshore production and storage facility of  claim 9  wherein:
 the supporting structure is a floating vessel. 
 
     
     
         14 . The offshore production and storage facility of  claim 13  wherein:
 the floating vessel is one of a retrofit LNG carrier and a retrofit LPG carrier. 
 
     
     
         15 . A system for separating produced fluids containing hydrocarbons received from an offshore subterranean reservoir, the system comprising:
 a first offshore production facility and a second offshore production and storage facility and a first conduit fluidly connecting the first and second facilities;   the first offshore production facility being adapted to receive produced fluids from at least one subterranean reservoir and having facilities for separating the produced fluids into crude oil, water and rich associated gases;   the second offshore production facility including:   a gas treatment unit in fluid communication with the first conduit to receive the rich associated gases from the first production facility and capable of removing at least one of acid gases, water vapor and mercury from the rich associated gases to produce a treated gas stream;   at least one an LPG production unit capable of producing LPG from a portion of the treated gas stream and one of an LNG production unit capable of producing LNG from a portion of the treated gas stream; and   at least one storage tank for storing at least one of LPG or LNG on the second production and storage facility.   
     
     
         16 . The system of  claim 15  wherein:
 the one an LPG production unit capable of producing LPG from a portion of the treated gas stream and one of an LNG production unit capable of producing LNG from a portion of the treated gas stream includes an LPG production unit. 
 
     
     
         17 . The system of  claim 15  wherein:
 the one an LPG production unit capable of producing LPG from a portion of the treated gas stream and one of an LNG production unit capable of producing LNG from a portion of the treated gas stream includes an LNG production unit. 
 
     
     
         18 . The system of  claim 15  wherein:
 the at least one an LPG production unit capable of producing LPG from a portion of the treated gas stream and an LNG production unit capable of producing LNG from a portion of the treat gas stream includes both an LPG production unit and an LNG production unit. 
 
     
     
         19 . The system of  claim 18  wherein:
 the at one storage tank for storing at least one of LPG or LNG includes at least one storage tank for storing LPG and at least one storage tank for storing LNG located on the second production and storage facility.