Abstract: A method of sanitising seawater at a subsea location comprises: exposing flow of seawater in a treatment reactor to UV radiation that sanitises the seawater without the addition of sanitising chemicals; and outputting the sanitised seawater from the reactor into a subsea structure such as a pipeline or a wellhead. The flow of seawater may be exposed to successive emitters of UV radiation such as pressure-compensated LEDs. The efficacy of sanitisation may be determined by: injecting a tracer fluid into the flow of seawater upstream of the reactor; and, downstream of the reactor, sensing transformation of the tracer fluid due to exposure of the tracer fluid to the UV radiation in the reactor.

Abstract: A method of sanitising seawater at a subsea location comprises: exposing flow of seawater in a treatment reactor to UV radiation that sanitises the seawater without the addition of sanitising chemicals; and outputting the sanitised seawater from the reactor into a subsea structure such as a pipeline or a wellhead. The flow of seawater may be exposed to successive emitters of UV radiation such as pressure-compensated LEDs. The efficacy of sanitisation may be determined by: injecting a tracer fluid into the flow of seawater upstream of the reactor; and, downstream of the reactor, sensing transformation of the tracer fluid due to exposure of the tracer fluid to the UV radiation in the reactor.