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

oil level. When this condition
is triggered, there is a risk of
blow-by, which means gas
leaks out of the oil output and
causes high pressure in the
next separation stage or
other following process
equipment, such as a
desalter. Transmitters are
preferred over switches
because of better diagnostic
capabilities.
Emergency shutdown actions
are defined in a cause-andeffect
chart based on a
HAZOP of the process. This
study identifies possible
malfunctions and how they should be handled. On the left of the chart, we
have possible emergency scenarios. On top, we find possible shutdown
actions. At an oil and gas facility, the primary response is to isolate and
depressurize. In this case, the typical action would be to close the inlet and
outlet sectioning valves (EV 0153 20, EV 0108 20 and EV 0102 20 in the
diagram), and open the blowdown valve (EV 0114 20). This will isolate the
malfunctioning unit and reduce pressure by flaring of the gas.
Events are classified on a
scale, e.g., 0 to 5, where a
full abandon platform/facility
shutdown (APS – ESD 0)
as the highest level means
a complete shutdown and
evacuation of the facility.
The next levels (ESD1,
ESD2), define emergency
complete shutdown. The
lower levels (e.g., PSD 3,
PSD 4 and PSD 5)
represent single equipment
or process section
shutdowns. A split between
APS/ESD and PSD is done
in large installations
because most signals are
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