| 摘要 |
A coolant gas, eg nitrogen, is liquefied in a land-based plant 12, transported to an off-shore wellhead, supplied to a heat-exchanger 21 to liquefy natural gas 27, and then passed via compressor 23 and heater 24 for use in an enhanced oil recovery (EOR) process. A supplementary refrigeration plant 31 may be provided at the wellhead. The heat-exchanger 21 is mounted on an off-shore platform or a vessel stationed at the wellhead. The same vessel may be used to transport liquified nitrogen and liquified natural gas in opposite directions and the liquified natural gas may be used to liquify the nitrogen in the land-based plant 12. <IMAGE> |
