Abstract: There is described the processing seawater in a subsea facility on the seabed in various methods and apparatus. In various examples, the facility is coupled to at least one well, is configured to provide the well with water to be injected into at least one formation of the well, and comprises filter elements arranged in housings, the filter elements being configured for ultrafiltration or microfiltration. In such examples, treated seawater in at least one of the housings is filtered using at least one filter element, producing thereby filtered water, and at least one filter element in at least one other of the filter housings is cleaned by backwashing performed using at least some of the produced filtered water.

Abstract: Disclosed is an electrolytic cell having an anode and a cathode, wherein the cathode comprises a surface layer which is repellent towards inorganic material. Such repellent layer may be employed to prevent formation of scale on an electrolytic cell. Also disclosed is an apparatus for cleaning seawater that employs such electrolytic cell, . and a system for injecting cleaned seawater into a hydrocarbon reservoir, wherein the system comprises tubing, an injection pump, and the seawater cleaning apparatus employing the disclosed electrolytic cell.