The main topic to be studied in the sequential separation sub-project is the quality of the water and oil phases from several separation stages, with a focus on the water quality. Adding additional subsea oil polishing steps as described in the “All subsea” and “Subsea Factory” visions entails a more complex separation system for both the oil and the water phases. The composition and properties of the well stream will change over the lifetime of the installation, which also affects the water and oil quality at different separation stages.

To predict how inlet conditions will affect the oil and water quality at the different stages of the separation, more knowledge is needed about the compounds that affect the separation. The compounds of interest in this sub-project are the indigenous polar crude oil compounds which display surface active properties, focusing on the resin fraction. This mostly entails acidic molecules like naphthenic acids or basic molecules like pyridines. These compounds partition themselves between the oil and water and affect the emulsion stability by adsorbing at the oil-water interface.

We will study the partitioning kinetics of acids and bases of different sizes, and how parameters like pH and water cut affect the partitioning.