Offshore hydrocarbon processing facility and method of operation

Abstract

An offshore hydrocarbon processing facility ( 2 ) comprises an offshore floating structure ( 8 ) and a submerged floating riser deck ( 10 ). The submerged floating riser deck is operatively connected to a subsea hydrocarbon riser ( 12 ). Hydrocarbon processing equipment ( 26 ) is disposed on the submerged floating riser deck. The offshore floating structure ( 8 ) may be connected to the submerged floating riser deck ( 10 ) using a riser ( 16 ) that can be disconnected if there is inclement weather.

1 . An offshore hydrocarbon processing facility comprising:
 an offshore floating structure;   a submerged floating riser deck operatively connected to a subsea hydrocarbon riser; and   hydrocarbon processing equipment disposed on the submerged floating riser deck.   
     
     
         2 . An offshore hydrocarbon processing facility according to  claim 1 , wherein the submerged floating riser deck floats suspended from the offshore floating structure. 
     
     
         3 . An offshore hydrocarbon processing facility according to  claim 1  or  2 , comprising a riser arranged for disconnectable connection between the offshore floating structure and the submerged floating riser deck. 
     
     
         4 . An offshore hydrocarbon processing facility according to  claim 1 ,  2  or  3 , wherein the hydrocarbon processing equipment is entirely disposed on the submerged floating riser deck. 
     
     
         5 . An offshore hydrocarbon processing facility as claimed in any preceding claim, wherein the offshore hydrocarbon processing facility is an unmanned hydrocarbon processing facility, comprising at least one of:
 no permanent personnel;   no provision of facilities for personnel to stay on the offshore hydrocarbon processing facility, for example there may be no shelters for personnel, no toilet facilities, no drinking water, no personnel operated communications equipment and/or no lifeboat; and/or   a requirement that personnel be present for fewer than 10,000 maintenance hours per year.   
     
     
         6 . An offshore hydrocarbon processing facility as claimed in any preceding claim, wherein the offshore floating structure is an unmanned structure and/or an unmanned production structure, comprising at least one of:
 no permanent personnel;   no provision of facilities for personnel to stay on the platform, for example there may be no shelters for personnel, no toilet facilities, no drinking water, no personnel operated communications equipment and/or no lifeboat; and/or   a requirement that personnel be present for fewer than 10,000 maintenance hours per year.   
     
     
         7 . An offshore hydrocarbon processing facility as claimed in  claim 1 , wherein the offshore floating structure further comprises topside processing equipment located on the offshore floating structure, arranged to produce at least one of a hydrocarbon liquid product, a hydrocarbon semi-stable liquid product and a liquefied gas product. 
     
     
         8 . An offshore hydrocarbon processing facility as claimed in  claim 7 , wherein the facility is configured such that a hydrocarbon fluid to be processed is processed first by the subsea equipment and then by the topside equipment. 
     
     
         9 . An offshore hydrocarbon processing facility as claimed in any preceding claim, wherein the offshore floating structure is horizontally offset from the submerged floating riser deck, such that the two are not vertically aligned. 
     
     
         10 . An offshore hydrocarbon processing facility as claimed in any preceding claim, wherein the submerged floating riser deck is arranged to separate liquid hydrocarbons, flash the separated liquid hydrocarbons and store the flashed hydrocarbons at the submerged floating riser deck. 
     
     
         11 . An offshore hydrocarbon processing facility as claimed in any preceding claim further comprising a buoy, wherein the submerged floating riser deck is operatively connected to the buoy for offload of hydrocarbon products to a floating vessel. 
     
     
         12 . A method of operating the offshore hydrocarbon processing facility of any of  claims 1  to  11 , comprising:
 receiving hydrocarbons at the submerged floating riser deck from the subsea hydrocarbon riser; and 
 processing the hydrocarbons using the hydrocarbon processing equipment. 
 
     
     
         13 . A method of operating the offshore hydrocarbon processing facility as claimed in  claim 12 , comprising disconnectably connecting the submerged floating riser deck to the offshore floating platform using a riser for transfer of hydrocarbons between them. 
     
     
         14 . A method of operating the offshore hydrocarbon processing facility as claimed in  claim 12  or  13 , comprising:
 fluidly connecting the submerged floating riser deck to a floating vessel for transfer of hydrocarbons from the submerged floating riser deck to the floating vessel; 
 and/or fluidly connecting the submerged floating riser deck to a pipeline for transfer of hydrocarbons from the submerged floating riser deck via the pipeline. 
 
     
     
         15 . A method of operating the offshore hydrocarbon processing facility as claimed in  claim 12 ,  13  or  14 , comprising:
 fluidly connecting the submerged floating riser deck to a buoy; and 
 transferring hydrocarbons from the buoy to a floating vessel. 
 
     
     
         16 . A method of using the offshore hydrocarbon processing facility as claimed in any of  claims 12  to  15 , comprising:
 separating and flashing liquid hydrocarbons at the submerged floating riser deck; and 
 storing the flashed hydrocarbons in storage tanks at the submerged floating riser deck.