In our example process the high- and intermediate-stage separators are two-phase, while the low-pressure separator is three-phase. This is calleda “free water knockout” (FWKO) because it is designed to separate the free water from the oil and emulsion, as well as separate gas from liquid. The choice depends on the expected flowing characteristics of the wells. If large amounts of water are expected with the high-pressure wells, it is possible that the size of the other separators could be reduced if the highpressure separator was three-phase. This would not normally be the case for a facility such as that shown in Figure 2-1 where individual wells are expected to flow at different FTPs. In some instances, where all wells are expected to have similar FTPs at all times, it may be advantageous to remove the free water early in the separation scheme.
