The industrial production of ammonia is carried out using synthesis gas containing hydrogen generated in the Steam Methane Reforming (SMR) in the Haber-Bosch process that fixes nitrogen with hydrogen. The Haber-Bosch process was developed in the early 1900s by Fritz Haber and was later modified to become an industrial process to make fertilizers by Carl Bosch. In this process a high pressure, 100-200 bars, at temperatures of 400-500°C allows to shift equilibrium in the catalytic reaction N2 + 3H2 2NH3 to produce ammonia. Typical catalysts used in the reaction are iron or ruthenium. Depending on the method of producing synthesis gas, the CO:H2 ratio can vary from 1 :1 to 1 :3. The cost of ammonia production is greatly reduced using autothermal reforming, originally commercialized by the Danish company Topsoe established by Haldor Topsoe. The autothermal reforming process combines homogeneous partial oxidation of methane and SMR to produce syngas with a high CO content, resulting in a higher hydrogen yield and reduced coke formation. The so called "blue" ammonia production anticipates capture, separation and sequestration of carbon dioxide formed in the SMR process, resulting in the ammonia cost increase by 20-30%.

This invention relates to the process of producing "blue" ammonia offshore. The facilities required to perform the “blue” ammonia production are placed on floating units or vessels or on the seabed at the site of the natural gas field development. CO and CO ₂ produced in the SMR process will be separated offshore and injected in a shallow reservoir in the area of the gas field, geologically sequestrated, retained in-situ, or injected into a producing oil reservoir in the area to increase oil recovery. Offshore on site “greenhouse” gas sequestration will significantly reduce the cost of decarbonization of ammonia as a product.

In the process of ammonia production, there is an excess of heat and steam at various pressures generated in the production cycle. The excess heat is usually exported and used in related industries. When the process is carried out offshore, steam can be used in turbines to drive rotating machines such as synthesis gas compressors, air compressors and water pumps. Thus, together with gas turbines, it is possible to ensure complete energy autonomy of the "blue" ammonia production cycle offshore.

The process of miscible displacement of oil by gas, in the case of CO ₂ injection in the oilgas field, can give a significant increase of oil recovery. CO ₂ injected in the oil reservoir after its breakthrough into production wells in such a cycle will be captured, separated, and re-injected back in the injection wells without escaping to the atmosphere.

Wells producing natural gas and wells used for injection and geological sequestration of CO ₂ will have subsea completions on the seabed. CO ₂ can be injected in the wells as compressed gas or as carbonated water, with CO ₂ being dissolved in produced water, thereby providing an environmentally closed cycle, without polluting emissions to the sea and atmosphere.

Figure 1 shows schematically “blue” ammonia production offshore facilities at the site of the natural gas field. Production, separation, and injection facilities installed on a floating platform or vessel can be used at different offshore gas fields, stranded or depleted fields, which can have “greenhouse” gases or acid gases in its gas composition. Such mobile floating industrial facilities can be used consecutively in several gas field projects moving from one geographical location to another.

The offshore ammonia production can also be carried out in conjunction with the process of Hydrogen Generation from Hydrocarbons Subterrain (HGHS) described in patents US 8763697, EAPO 021444 and 050009. Air or oxygen injection into the reservoir with oxidation reactions of hydrocarbons allowing to achieve the required temperatures for the conversion of methane to hydrogen when reforming and cracking process catalysts are injected into the reservoir at HGHS process allowing to produce hydrogen in-situ.

Facilities for separation of oxygen and nitrogen from the air, separation of “greenhouse” gases and other unwanted gas components from natural gas and hydrogen can be installed on floating units as well.

Development of the ammonia production technologies achieved a level when industrial processes can be scaled up and implemented in modules with a high level of automation, reducing the required number of maintenance personnel required to work offshore.

The “blue” ammonia produced at the offshore field, which is also one of the most energy efficient liquid carriers of hydrogen, can be easily delivered to the markets for consumption using the existing fleet of commercial ammonia tankers.

Offshore production of “blue” ammonia will allow to protect and preserve the environment, avoid a need to build onshore large-scale production and infrastructure facilities, alienate large land areas, and optimize ammonia transportation and logistic solutions.