Figure 2-7 is an enlargement of the FWKO of Figure 2-1 to show the amount of detail that would be expected on a process flowsheet. A flash calculation is needed to determine the amount of gas and liquid that each separator must handle. In the example process of Figure 2-1, the treater is not considered […]
Read More…Category: Separation
Two Phase vs Three Phase Separator
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 […]
Read More…Separator Operating Pressure
The choice of separator operating pressures in a multistage system is large. For large facilities many options should be investigated before a final choice is made. For facilities handling less than 50,000 bpd, there are practical constraints that help limit the options. A minimum pressure for the lowest pressure stage would be in the 25 […]
Read More…Fields With Different Flowing Tubing Pressures
The discussion to this point has focused on a situation where all the wells in a field produce at roughly the same flowing tubing pressure, and stage separation is used to maximize liquid production and minimize compressor horsepower. Often, as in our example flowsheet, stage separation is used because different wells producing to the facility […]
Read More…Selection of Stages
As more stages are added to the process there is less and less incremental liquid recovery. The diminishing income for adding a stage must more than offset the cost of the additional separator, piping, controls, space, and compressor complexities. It is clear that for each facility there is an optimum number of stages. In most […]
Read More…Stage Separation
Figure 2-5 deals with a simple single-stage process. That is, the fluids are flashed in an initial separator and then the liquids from that separator are flashed again at the stock tank. Traditionally, the stock tank is not normally considered a separate stage of separation, though it most assuredly is. Figure 2-6 shows a three-stage […]
Read More…Initial Separator Pressure
Because of the multicomponent nature of the produced fluid, the higher the pressure at which the initial separation occurs, the more liquid will be obtained in the separator. This liquid contains some light components that vaporize in the stock tank downstream of the separator. If the pressure for initial separation is too high, too many […]
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