Use of hydrate slurry for transport of associated gas

Abstract

A system and method for the transport of the natural gas associated with the production of crude oil from offshore wells includes transforming the associated gas into a solid gas hydrate. The solid gas hydrate is mixed with liquid crude oil to form a pumpable slurry. The conversion of the gas into a solid gas hydrate and the mixing of the pumpable slurry may take place on a floating offshore storage vessel or on a shuttle tanker. The pumpable slurry is transported on a shuttle tanker to an onshore location where the solid gas hydrate may be extracted from the oil and the associated gas transformed from a solid gas hydrate back into a gaseous state.

1 . A method for transporting the associated hydrocarbon gas produced at offshore production platforms to an onshore location, said method comprising the steps of: 
 transferring the associated gas to a floating storage vessel;    transforming the associated gas into a solid gas hydrate onboard said floating storage vessel;    forming a pumpable slurry by mixing said solid gas hydrate with liquid oil onboard said floating storage vessel;    temporarily storing said pumpable slurry on said floating storage vessel;    transferring said pumpable slurry from said floating storage vessel to shuttle tankers;    transporting said pumpable slurry to the onshore location.    
   
   
       2 . The method as defined in  claim 1  further including the step of holding said pumpable slurry in cooled tanks while aboard said shuttle tanker.  
   
   
       3 . The method as defined in  claim 1  wherein a portion of said associated gas is used as an energy source onboard said floating storage vessel before being transformed into a solid gas hydrate.  
   
   
       4 . The method as defined in  claim 1  wherein said pumpable slurry is offloaded from said shuttle tanker at the onshore location.  
   
   
       5 . The method as defined in  claim 1  wherein said solid gas hydrate is separated from said pumpable slurry at the onshore location and then transformed into gaseous hydrocarbons.  
   
   
       6 . A method for transporting the associated hydrocarbon gas produced at offshore production platforms to an onshore location, said method comprising the steps of: 
 transferring the associated gas to a floating storage vessel;    transferring the associated gas from said floating storage vessel to a shuttle tanker;    transforming the associated gas into a solid gas hydrate onboard said shuttle tanker;    forming a pumpable slurry by mixing said solid gas hydrate with liquid oil onboard said shuttle tanker;    transporting said pumpable slurry to the onshore location.    
   
   
       7 . The method as defined in  claim 1  wherein said pumpable slurry is held in cooled tanks while onboard said shuttle tanker.  
   
   
       8 . The method as defined in  claim 1  wherein a portion of said associated gas is used as an energy source onboard said shuttle tanker before being transformed into a solid gas hydrate.  
   
   
       9 . The method as defined in  claim 1  wherein said pumpable slurry is offloaded from said shuttle tanker at the onshore location.  
   
   
       10 . The method as defined in  claim 1  wherein said solid gas hydrate is separated from said pumpable slurry at the onshore location and then transformed into gaseous hydrocarbons.  
   
   
       11 . A system for transporting associated hydrocarbon gas from an offshore production platform to an onshore location, said system comprising: 
 a conduit for transferring gas from the offshore production platform to a floating storage vessel;    a plant for transforming the associated gas into a solid gas hydrate onboard said floating storage vessel;    a device for mixing said solid gas hydrate with liquid crude oil contained on said floating storage vessel to form a pumpable slurry;    a cooled tank on said floating storage vessel for containing said pumpable slurry;    a conduit for transferring said pumpable slurry from said floating storage vessel to a shuttle tanker calling on the onshore location.    
   
   
       12 . The system as defined in  claim 11  further including a cooled tank onboard said shuttle tanker for containing said pumpable slurry.  
   
   
       13 . The system as defined in  claim 11  further including a conduit for diverting a portion of the associated gas away from said plant and into an energy transformation system onboard said floating storage vessel.  
   
   
       14 . The system as defined in  claim 11  further including a conduit to unload said pumpable slurry at the onshore location.  
   
   
       15 . The system as defined in  claim 11  further including a plant to separate the solid gas hydrate from the pumpable slurry at the onshore location.  
   
   
       16 . A system for transporting associated hydrocarbon gas from an offshore production platform to an onshore location, said system comprising: 
 a conduit for transferring the associated gas from the offshore production platform to a floating storage vessel;    a conduit for transferring the associated gas from said offshore production vessel to a shuttle tanker;    a plant for transforming the associated gas into a solid gas hydrate onboard said shuttle tanker;    a device for mixing said solid gas hydrate with liquid crude oil contained on said shuttle tanker to form a pumpable slurry;    a cooled tank on said shuttle tanker for containing said pumpable slurry;    a conduit for transferring said pumpable slurry from said shuttle tanker at the onshore location.    
   
   
       17 . The system as defined in  claim 16  further including a cooled tank onboard said floating storage vessel.  
   
   
       18 . The system as defined in  claim 16  further including a conduit for diverting a portion of the associated gas away from said plant and into an energy transformation system on said shuttle tanker.  
   
   
       19 . The system as defined in  claim 16  further including a plant to separate the solid gas hydrate from the pumpable slurry at the onshore location.