Download - C13.Separator Geneal
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Separator Operation
FTC 28 October 2013 P.1
PRINCIPLE OF
OPERATION CAPACITIES AND
RETENTION TIME
LEVEL CONTROL
OIL METERING GAS METERING
SAFETY FEATURES
Separator OperationDRAFT ONLY
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Pump
Oil Burner
Gas Flare
Gauge TankThree PhaseTest Separator
Heateror Steam Exchanger
ChokeManifold
Flowhead
HIGHPRESSURE
ATMOSPHERICPRESSURE
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Test separator
Test separators areversatile pieces ofequipment that allowseparation, metering andsampling of all phases ofthe effluent.
Because test separators areused on exploration wellswhere the effluent isunknown, they must be ableto treat widely varyingeffluents such as gas, gascondensate, light oil, heavyoil and foaming oil, as wellas oil containing water andimpurities such as mud or
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The vessel capacity for eachphase depends on the current
conditions of pressure andtemperature and effluentproperties such as:
Viscosities and densities ofthe liquids, which are afunction of the amount ofdissolved gas vesseloperating
Liquid level
Vessel internals
Required liquid gas separatorefficiency in terms of size ofliquid droplet to be separated
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The vesselcapacityfor oilversusliquid level
and gascapacityversuspressureand liquidlevel.
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PIPING LAYOUT
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Control systemsGas line control: Wizard
One 3 PCV (Pressure ControlValve)
Fail Safe Open to release
vessel pressure if air supply is
lost.
Oil line control: LevelTrol
One 1 and one 2 LCV (Liquid
Control Valve)
Fail Safe Closedto retain oil
(minimize pollution) if air supplyis lost.
Water line control: LevelTrol
One 2 LCV (Liquid Control
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Pressure control
When gas line pressure
drops bourdon tube contracts
closing nozzle, relay switches
allowing pressure build up to
close valve.
As gas line pressure rises
bourdon tube expands
opening relay and releasing
pressure from valve allowingit to open.
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Pressure control
proportionalband.The proportional band
valve reduces the
response time of the valveto act as a damper and
prevent oscillation of the
valve, and therefore,
reducing pressure
oscillation in the Separatorvessel.
Full range is 1500 psi
10 % on the PB ->
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Level controlWith low level flapper nozzle isopen to atmosphere. Pressure
cannot build up and valve remains
closed.
As level increases float rises
closing the nozzle with the float.Pressure builds up and valve
opens.
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Level control
proportionalbandThe proportional band
valve reduces the
response time of thevalve to act as a damper
and prevent oscillation of
the valve.
Full range is 12 inches
10 % on the PB ->
0.6 in before valve open
or close fully above and
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MeteringGas metering: Daniel orifice
Barton chart recorder
Oil metering:
3 Rotron vortex meter, High
flowrate 2 Floco positive displacement
meter,
Low flowrate
Water metering:
2 Floco positive displacement
meter,
3 phase separation
BSW at choke manifold,
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Oil/water metering- Floco
The positive displacement metermeasures the liquid passing through it
by separating the liquid into segments
and counting the segments. Liquid
entering the meter strikes the bridge
and is deflected downward, hitting theblades and turning the rotor in the
right direction. The seals on the
bridge prevent the liquid from
returning to the inlet side. The rotor
movement is transferred to a register
(readout device) with magnetic
coupling.
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Oil/water metering- Floco
It is important to check the Floco gearing is set for the correctunits especially when swapping between conventional and
electronic sensors.
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Oil metering-
RotronThe ball vortex meterconsists of a body with an
offset chamber and a rotor
that are mounted
transversely to the flowstream. When liquid flows
through the meter, a
vortex is created in the
offset chamber. The
rotational velocity of theliquid vortex is
proportional to the rate of
flow. The rotor movement
Meter type and rating in barrels per/day:
Ball bearings Sleeve bearings
2-in. Vortex meter 850 to 6800 1700 to
8500
3-in. Vortex meter 2000 to 17,000 3400 to
22,000
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Gas metering
The Daniel orificemeter:
Orifice plate
generates a
differential pressurewhich when combined
with Static pressure
and gas temperature
allows a gas rate to
be calculated.
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Gas meter
At the beginning of a test, thegas flow rate is unknown.During the test, the gas flowrate may change; therefore,different sizes of orifice platesare used.
It's important to have anapparatus that allows theorifice plate to be changedwithout interrupting the gas
flow. The orifice gas meter isdesigned for this purpose.
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Gas meter
To obtain accuratemeasurements, the flow ofgas must be streamlinedbefore it reaches the meter.
An adequate length ofstraight pipe andstraightening vanes (bundleof straight tubes fitted insidethe pipe) are positionedbefore the meter to reducethe disturbances created by
the elbows in the gas line.
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Gas meteringTo record the differential pressure,
a measuring instrument called a
differential pressure recorder is
used. The high pressure side of
the recorder is connected on the
upstream side of the orifice and thelow pressure side is connected on
the downstream side. The
movement of the recorder is
transferred to a pen that records
the differential pressure on a chart.The same chart is used to record
the static pressure, measured
downstream of the orifice plate. In
addition another en is used to
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Gas metering
Barton chart recorderRecords gas differential pressure
(blue pen).
Records static pressure
downstream
Of orifice (red pen).May also record gas line
temperature (green pen).
Note: colors given are for the
normal situation, check your rigup.
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Gas ScrubbersThe gas used to operate the differential
pressure recorder is provided by the
separator gas line. This gas is first
filtered, on both the high and low
pressure lines, using bottom gas
scrubbers. These gas scrubbers arevertical pots where impurities, oil, and
emulsion settle. Before the gas reaches
the recorder, it is filtered again by the
top gas scrubber. The top scrubbers actas a buffer between the gas and the
recorder. In case the gas contains H2S
or CO2(sour gas), the top scrubbers can
Separator Operation
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Measures oil line shrinkage (Shr)
Necessary for correction of oil and gas
rates (GOR2)
Requires temperature as well as volume
Shrinkage Tester
The shrinkage tester,usually attached to theoil sight glass of theseparator, is used toestimate the shrinkagefactor in the field. The
shrinkage factor is acorrection factor usedin the oil volumecomputations. Itrepresents the amount
of dissolved gas in theoil that will be freedwhen the pressuredrops from theseparator pressure to
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Relief valves
Relief valves areinstalled on allpressurized vesselsto protect thevessel from beingpressurized above
its workingpressure. On theseparator there istwo valves,normally a pilot
operated reliefvalve set to openwhen pressureexceeds workingpressure.
The picture shows a old type relief valve, this
isnt the pilot operated valve. The basic principalcan be understood by looking at this type. If theseparator pressure acting on the piston exceedsthe spring force acting opposite way the valvelifts from the seats and open.
Separator Operation
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Rupture disk.
On old separators arupture disk is installedinstead of one of therelief valves. The rupturedisk has a set pressureto open when pressure
exceeds 110 % of theseparators workingpressure. The problemwith the rupture disk isthat it will not close when
pressure in the vesselgoes below workingpressure.
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Sight Glass, levelindication.
The sight glass is aweak point on theintegrity of theseparator. Becauseof this two safety
valves are installedon the ports to theseparator. Both willshut if the flow pastthem exceeds their
design point.
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DATA QUALITY
When taking separator readings always ensure:
Oil meter readings are taken at the correct time for accurate rate
calculations.
Take readings at regular times, 5 min, 10 min, 15 min etc.
BSW and SGs should be recorded at the time the sample wastaken and not the reading.
Completeness of data, e.g. oil SG and shrinkage are quoted with
temperature.
Only enter actual measurements, e.g do not enter the previous
BSW reading because you forgot to take it this time.
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DATA QUALITY
If the separator is bypassedbefore shutting in the well the
build up data necessary for
interpretation may be
damaged
If the well is shut in
before bypassing the
Separator a clean BHPcurve is obtained for
accurate interpretation.
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PRINCIPLE OF
OPERATION CAPACITIES AND
RETENTION TIME
LEVEL CONTROL
OIL METERING GAS METERING
SAFETY FEATURES
The END