Subsea production and processing units need to be compact in order to reduce wall thickness and weight. While huge gravity separators are used for first stage separation topside, it is not feasible to bring such huge equipment down to waterdepths of 3000 meters. Compact separation is thus inevitable in deep water subsea environment. When the equipment becomes compact, there arises a need for advanced control technologies to optimize the operation.

This project will be based on results from the SUBPRO projects “Modelling and multivariable control of subsea systems ” and “Adaptive control of subsea processes”. Focus will be on produced water treatment, where water from first stage separators such as a gravity separator or a pipe separator is further processed by hydro cyclones or compact flotation units. Purified water from this stage can be used for water re-injection to build up pressure in oil wells and enhancing the production or it can on a longer term be discharged to sea, if oil contents can be reduced to the required level. Discharge of produced water to sea is regulated internationally by the OSPAR commission, which has specified the limit as 30 mg of dispersed oil per liter of produced water. Hence it is important to maintain the efficiency of water treatment equipment in all operating environment.

We are also building a compact separator laboratory consisting of hydro cyclones, gas liquid cylindrical cyclones, compact flotation units and an associated pump system, where we will be able to do laboratory experiments and validate the mathematical models, estimators and control algorithms developed by this and other projects in SUBPRO.