Oil and gas production handbook An introduction to oil ... - ABB Group

The desired setting for each well and which of the wells produce at HP and
LP for various production levels are defined by reservoir specialists to
ensure optimum production and recovery rate.
4.2 Separation
As described earlier, the well-stream may consist of crude oil, gas,
condensates, water and various contaminants. The purpose of the
separators is to split the flow into desirable fractions.
4.2.1 Test separators and well test
Test separators are used to separate the well flow from one or more wells for
analysis and detailed flow measurement. In this way, the behavior of each
well under different pressure flow conditions can be defined. This normally
takes place when the well is taken into production and later at regular
intervals (typically 1-2 months), and will measure the total and component
flow rates under different production conditions. Undesirable consequences
such as slugging or sand can also be determined. The separated
components are analyzed in the laboratory to determine hydrocarbon
composition of the gas oil and condensate.
Test separators can also be used to produce fuel gas for power generation
when the main process is not running. Alternatively, a three phase flow
meter can be used to save weight.
4.2.2 Production
separators
The main separators shown
here are gravity types. On
the right, you see the main
components around the first
stage separator. As
mentioned before, the
production choke reduces
well pressure to the HP
manifold and first stage
separator to about 3-5 MPa
(30-50 times atmospheric
pressure). Inlet temperature
is often in the range of 100-
150 ºC. On the example
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