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Tests were carried out to investigate the potential of new Zeta Dynamics internals for the optimisation of the water handling capacity of the Draugen primary separators. To this end these new internals were installed in the Draugen test separator and an assessment was made of its separation performance before as well as after the installation. Since the production at Draugen is still practically dry, the advent of water production was simulated by flowing heated seawater through the separator. The tests were carried out on the wellstream of one of the horizontal platform wells, and water was injected upstream of the choke valve using the high mixing intensity in the valve to disperse the water in the crude. The tests consisted of varying the crude and water flow, and measuring the distribution of water and oil upstream, inside and downstream of the separator, via sampling and radiological techniques. It could be concluded that the modification of the separator internals has not led to an obvious breakthrough in separation performance. The new internals improve the flow distribution, as claimed by the vendor. This appears from the sharper interfaces in the tests after the modification, and from the reduced spread in the residence time distributions. However, the new inlet internal has a negative effect on the phase distribution of the incoming feed. This appears from the increasing mixing of gas, crude and water in the separator with increasing flowrate, this despite the simultaneously decreasing stability of the crude/water dispersion and the existing gas/liquid stratification at the inlet. It can be conjectured that the originally installed Shell 'Schoepentoeter' inlet gives less resistance to the flow and may even favour coalescence and preseparation due to centrifugal acceleration. The test results show that the size of the water droplets at the inlet is correlated with the water concentration and the pressure drop over the choke valve. However, the correlation is different from the one established from laboratory experiments, which is probably due to the different degree of premixing in both cases. The density profiles in the separator give evidence for the presence of a dispersion band, varying in size with process conditions. The predictions of separation efficiency as a function of flow rate and feed droplet size according to the SRTCA dispersion band expansion model (ref. SPE 38816) are in agreement with the test results. Finally the future dehydration capacity of the Draugen installation was estimated by combining the validated separation efficiency correlations with calculations of the droplet size expected at the prevailing operating conditions. P. 121