Hybrid system and method for treating produced water and sea water to be re-injected into a subsea oil reservoir

摘要

The present invention relates to systems for treating process water and sea water for secondary recovery in oil wells. In this situation, the present invention provides a hybrid system for treating produced water and sea water to be re-injected into a subsea oil reservoir, comprising (i) at least one inlet for the water to be treated, (ii) at least two treatment modules (20), each module comprising (ii-a) at least one set of micro/ultrafiltration membranes (20a, 20b, 20c) suitable for removing oils and solids from the water being treated, or (ii-b) at least one set of nanofiltration membranes (20a, 20b, 20c) suitable for removing sulphate ions from the water being treated, and (iii) at least one outlet for the treated water. The volume of water to be treated is led to a treatment module (20) comprising micro/ultrafiltration membranes or to a water treatment module comprising nanofiltration membranes, depending on the quality of the water, with regard to the oil and solid content or to the sulphate ion content. The present invention further provides a hybrid water treatment method associated with the above-mentioned system. Thus, the present invention provides a system and method for treating sea water and produced water, allowing the produced water to be re-injected without requiring an additional treatment system on the platform. Other advantages of the present invention include reduced oil discharge into the sea and reduced mounting, operation and maintenance costs, in comparison with an additional system on the sea installation.