Methods and apparatus for offshore power generation from a gas reservoir

An offshore facility comprising:

• an offshore production unit configured for producing a produced gas from a gas reservoir;
• a gas turbine configured to receive the produced gas for producing power and a flue gas;
• a gas separator configured to receive the flue gas for at least partially removing nitrogen from the flue gas and for producing a carbon dioxide-enriched flue gas and a nitrogen-enriched flue gas, wherein the nitrogen-enriched flue gas is reacted with a hydrogen stream to produce ammonia;
• a gas compressor configured to receive the carbon dioxide-enriched flue gas for producing a compressed gas;
• and
• an injection unit configured for injecting the compressed gas from the gas compressor into the gas reservoir.

A method comprising:

• providing an offshore facility comprising a gas turbine, a first gas separator, a reformer, a second gas separator, and an ammonia reactor;
• producing a produced gas from a gas reservoir to the offshore facility;
• combusting the produced gas in a gas turbine to produce power and a flue gas;
• at least partially removing nitrogen from the flue gas in the first gas separator to produce a carbon dioxide-enriched flue gas and a nitrogen-enriched flue gas;
• reforming a portion of the produced gas in the reformer to produce a stream comprising hydrogen and carbon dioxide;
• at least partially separating the carbon dioxide in the second gas separator from the stream to yield a carbon dioxide stream and a hydrogen stream;
• reacting the hydrogen stream and the nitrogen-enriched flue gas in the ammonia reactor to yield ammonia;
• combining and compressing the carbon dioxide stream and the carbon dioxide-enriched flue gas in a gas compressor to produce a compressed gas;
• and
• injecting the compressed gas from the gas compressor into the gas reservoir, wherein 80 mol % or more of hydrocarbon in the produced gas is combusted, reformed, and/or injected into the gas reservoir.

An offshore facility comprising:

• an offshore production unit configured for producing a produced gas from a gas reservoir;
• a gas turbine configured to receive the produced gas for producing power and a flue gas;
• a first gas separator configured to receive the flue gas for at least partially removing nitrogen from the flue gas and for producing a carbon dioxide-enriched flue gas and a nitrogen-enriched flue gas;
• a reformer configured to receive a portion of the produced gas from upstream of the gas turbine for producing a stream comprising carbon dioxide and hydrogen;
• a second gas separator configured to receive the stream for at least partially removing carbon dioxide from the stream and for producing a carbon dioxide stream and a hydrogen stream;
• an ammonia reactor configured to receive the hydrogen stream and the nitrogen-enriched flue gas for producing ammonia;
• a gas compressor configured to receive the carbon dioxide-enriched flue gas and the carbon dioxide stream for producing a compressed gas;
• and
• an injection unit configured for injecting the compressed gas from the gas compressor into the gas reservoir.