is used to cool the cooling medium in the cooling medium plate exchangers. 2322.7 m3/hr of seawater now at 6 barg and 20°C is routed to the fine filters and then to the sulphate removal membrane where reverse osmosis is used to remove sulphate ions from the water. Desulphated water flows to the top of the deaerator column, this operates at a partial vacuum (0.3 bara) sustained by the deaerator vacuum unit. The deaerator internals comprise three packed beds. Deaerated water is taken from the base of the deaerator by transfer pumps which deliver 1632 m3/hr at 3.6 barg to the degasser surge drum. From the surge drum water is transferred to the water injection pumps which deliver water at up to 250,000 BWPD to up to 11 water injection wells. Produced water is also injected into the reservoir at up to 350,000 BWPD. Water injection wells The table shows the number of water injection wells on a selection of offshore installations mainly in the North Sea. Sources and notes "New Billions In Oil" Popular Mechanics, March 1933—i.e. article on invention of water injection for oil recovery Water injection Waterflood Performance Predictive Calculations Petroleum production