Method of controlling salinity of a low salinity injection water

Abstract

An integrated system includes a desalination plant including a reverse osmosis (RO) array to produce an RO permeate blending stream and a nanofiltration (NF) array to produce an NF permeate blending stream. The integrated system also includes a blending system. Further, the integrated system includes a control unit. Still further, the integrated system includes an injection system for one or more injection wells that penetrate an oil-bearing layer of a reservoir. Moreover, the integrated system includes a production facility to separate fluids produced from one or more production wells that penetrate the oil-bearing layer of the reservoir and to deliver a produced water (PW) stream to the blending system. The blending system is configured to blend the RO permeate and NF permeate blending streams with the PW stream to produce a blended low salinity water stream. The control unit is configured to dynamically alter operation of the blending system to adjust amounts of at least one of the RO permeate blending stream and the NF permeate blending stream to maintain a composition of the blended low salinity water stream within a predetermined operating envelope.