Offshore nitrogen production and injection
First Claim
1. Apparatus for injecting gas into an undersea hydrocarbon reservoir that lies under the sea floor of a sea, comprising:
- a seaworthy vessel hull that has a deck and that is moored to the sea floor;
a nitrogen production complex that has an air intake for receiving environmental air, equipment for cooling the air and separating out nitrogen in the air from other components in the air, and equipment for pressurizing the nitrogen to inject it into the reservoir;
most of the volume of said nitrogen production complex being mounted on top of said deck of said vessel hull, with at least 80% of the volume inside the vessel hull being left unoccupied by the separation system to provide buoyancy for the separation system on top of the vessel hull.
1 Assignment
0 Petitions
Accused Products
Abstract
Nitrogen is produced above an offshore hydrocarbon reservoir (12) and injected into the reservoir, by a complex (40) mounted on a previously used vessel hull (16). The vessel weathervanes and the complex includes equipment that takes in ordinary air from a bow end (32) of the vessel, cools the air using sea water pumped into the equipment, and liquefies the oxygen component of air so pure nitrogen remains. The complex also includes injection equipment that heats and pressurizes the pure nitrogen to inject it into the reservoir. The complex is mounted above pipes (24) on the deck (22) of the vessel hull, on spacers (62) so mounting of equipment can be accomplished rapidly and without major alterations to the hull. A riser bundle (150) that extends from the hull to the sea floor, may include both a production riser (152) that carries crude hydrocarbons up to the vessel for storage in hull tanks (20), and an injection riser (160) that carries pressured nitrogen. The lower end of one of the risers is connected to a sea floor pipeline (162) that extends at least 100 meters away from the lower end of the other riser.
7 Citations
11 Claims
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1. Apparatus for injecting gas into an undersea hydrocarbon reservoir that lies under the sea floor of a sea, comprising:
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a seaworthy vessel hull that has a deck and that is moored to the sea floor;
a nitrogen production complex that has an air intake for receiving environmental air, equipment for cooling the air and separating out nitrogen in the air from other components in the air, and equipment for pressurizing the nitrogen to inject it into the reservoir;
most of the volume of said nitrogen production complex being mounted on top of said deck of said vessel hull, with at least 80% of the volume inside the vessel hull being left unoccupied by the separation system to provide buoyancy for the separation system on top of the vessel hull. - View Dependent Claims (2, 3, 4, 5, 6)
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7. Apparatus for injecting gas into an undersea hydrocarbon reservoir to pressurize it, comprising:
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a seaworthy vessel hull that has a bow and stern;
a separation system that has an air intake for receiving environmental air, equipment for cooling the air and separating out nitrogen in the air from other components in the air, and equipment for pressurizing the separated-out nitrogen to pump it into the reservoir;
a mooring system that limits hull drift while allowing the hull to weathervane so its stern points in changing directions away from its bow with changing winds, waves and currents;
said air intake is closer to the bow than to the stern of the hull. - View Dependent Claims (8)
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9. A method for pressurizing an undersea hydrocarbon reservoir comprising;
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mounting a separation system on a deck of a vessel hull and mooring the hull to the sea floor;
drawing ambient air into the separation system and operating the separation system including cooling the drawn-in air using sea water pumped in from the sea as a heat sink and further cooling the air and separating out the nitrogen from the oxygen;
operating the separation system to heat the separated-out nitrogen, and pump the separated-out and heated nitrogen into a first location in the undersea hydrocarbon reservoir. - View Dependent Claims (10, 11)
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Specification