Process Solutions Guide
Rosemount Key Benefits
g
g
maintenance free flowmeter technologies not only reduce cost, but also provide advanced diagnostic capabilities to
Rosemount 8800 has no moving parts and a non clog design which does not require any routine replacement or
Separator Water Measurement Using Rosemount Vortex
• Reduced maintenance and operations cost
• Reduced risk of lost revenue due to gas blow by
• Reduced environmental risk of gas venting
• Improved reliability of separator water
measurement for reservoir modelin
• Improve well availability
Overview
Many oil and gas producers are looking for opportunities to decrease maintenance costs and maximize production.
Eliminating the utilization of older technology, such as mechanical meters, to measure flow provides an opportun ity
to reduce maintenance and operating costs and ensure the reliability of field data to maximize production. Modern
reduce disruption should the meter or well require attention.
Producing wells flow into either a production or test separato r to separate gas from liquids and further separate the
oil from water. This document will focus on water measurement on the separator outlet. Typically on the water leg
of the separator, flow rates are being measured by turbine meters. Due to debris in flow lines and gas blow by,
turbine meters often require extensive maintenance to replace or clean the rotating internals. Many oil and gas
producers report that replacement or cleaning of the internal parts is needed at least once per year. Also, when the
meters fail, the water flow rate is not measured and must be inferred. This failure can be very costly, especially
when the well experiences high water production and well intervention is needed. Also, not having accurate water
production data decreases the reliability of the reservoir model. Some operators also monitor the trends in water
production. A sudden increase in the flow rate or daily volume may indicate a stuck dump valve, and gas is being
vented through the water leg of the separator resulting in lost revenue and environmental hazards.
The Rosemount 8800 vortex flowmeter can significantly reduce flowmeter related maintenance and failures. The
cleaning to maintain performance. The Rosemount 8800 vortex flowmeter ensures an accurate and reliable
measurement providing data to the reservoir model, and can be configured for multi-fluid measurement using the
adaptive digital signal processing to detect a sudden increase in flow rate caused by gas discharge from the water
leg. By setting flow limits in the RTU, this diagnostic tool can be used to shut in the well until corrective action can
be taken reducing lost revenue and decreasing the environmental impact of venting gas to the environment.
© Emerson Process Management, Inc. All Rights Reserved
Rev. B
Separator Water Measurement Using Rosemount Vortex
0.5 (15)
1.0
(25)
65.4
974.1
diameters upstream and 5 straight pipe diameters downstream is required for best measurement results. Vertical
Vertica
g
etca ou t g
Hori
Flowmeter Sizing Guide
Process Solutions Guide
Meter Size in Inches
(mm)
1.0 (25) 1.5 (40) 142 2770.7
1.5 (40) 2.0 (50) 240.6 6526.7
2.0 (50) 3.0 (80) 378.2 10757.8
Reducer Meter Size
in inches (mm)
Min Instantaneous Flow
Rate (barrels per day)
Table 1
Max Instantaneous Flow
Rate (barrels per day)
Sizing Considerations
The key to correctly sizing a vortex flowmeter on the water outlet of a separator is understanding what the
instantaneous flow rate is. The instantaneous flow rate is often much higher than the average daily rate and it should
be used to ensure that meter is correctly sized for the application. A snap acting dump valve should be used to
provide the highest flow rate to ensure the flow remains above the low flow cutoff of the meter. The trim size of the
dump valve can often be used to aid in determining the expected flow rate. If configuring the meter for multi-fluid
measurement to detect gas blow-by, it is important not to oversize the meter and select a smaller meter that does
not exceed the maximum flow rate. See the multi-fluid configuration section on the next page for more details. The
sizing chart in Table 1 references water flow rates that can be measured by each meter type and size. For detailed
analysis for your application consult an Emerson representative or the Instrument Toolkit®
be downloaded from www.rosemount.com
.
sizing software which can
Many vortex meter installations require a line size reduction in
order to take advantage of the optimal flow range of the meter.
Rosemount also offers a Reducer vortex meter which has built in
reducers integral to the flanges eliminating the need to modify
piping. The reducer meter has the same lay length as the
standard vortex meter allowing for a drop in replacement should
the flow rates change during the life of the field. Reducer Meter Standard Flanged
Installation Recommendations
The design of the process piping should ensure that the meter body will remain full, with no entrapped air. For best
results the meter should be installed upstream of a snap acting dump valve. A minimum of ten straight pipe
mounting with flow up for liquids is the best orientation, but horizon tal mountin g is also acceptabl e. When mounting
horizontally with fluids with small solids content such as sand, it is recommended to have the flowmeter installed with
the electronics to the side. This will minimize potential measurement errors by allowing solids to flow under the
shedder bar without interrupting the vortex shedding. The Rosemount 8800 vortex meter design is less susceptible
to error and abrasive wear due to sand content than turbine or differential pressure meters, but in applications with
very high sand content it may be necessary to delay installation of the meter until the well stabilizes and sand
production is reduced.
l Mountin
zontal Mounting
Preferred
© Emerson Process Management, Inc. All Rights Reserved
Flow up
Rev. B
Okay
Separator Water Measurement Using Rosemount Vortex
Up to three outputs are available on the Vortex 8800 transmitter to represent flow, 4
20mA analog, pulse output
1.Select gas/steam as the process fluid in the meter configuration
Process Solutions Guide
Configuration for Multi-Fluid Measurement
In order to detect if the dump valve on the separator has become stuck in the open position, the vortex meter must
be configured for multi-fluid measurement. Multi-fluid measurement is defined as the ability of a single meter to
measure more than one separate homogeneous fluid (liquids and/or gases) without chang ing the meter
configuration, while multi-phase measurement is defined as a liquid and gas mixture. Multi-phase fluids will result in
inaccurate measurements using vortex technology and is beyond the scope of this document. As in all vortex
applications, the selected flowmeter size must be able to measure both fluids over the desired flow ranges and a
sizing analysis should be performed. Since each size meter has flow limitations, some compromises may be
necessary for the liquid or gas measurement. In order to best optimize the adaptive digital signal processing, it is
best to select a smaller meter size provided the liquid flow rates do not exceed the maximum value in Table 1.
-
,
and HART (digital) communications. When measuring liquid and gas with a single configura tion the approp riat e
output must be selected. The flow velocity for liquids can be as much as 1/10th the flow velocity of gas. As can be
seen in the Figure 1 below, the span of the liquid output is limited when trying to measure both liquid and gas using
the 4-20mA scale. This can result in a significant measurement error for the liquid measurement. In order to ensure
the best possible measurement, the pulse output or HART output should be used with a multi-fluid configuration.
The pulse output resolution remains constant over the entire span and the digital HART output is unaffected by the
span of the vortex meter providing a more accurate measurement. Alternatively, the vortex meter can also be
configured so that the 4-20mA output is used for liquid measurement and the pulse output is used for gas
measurement.
Figure 1
In order to measure both liquids and gases, the adaptive digital signal processing must be configure d correctly
using a HART field communicator or AMS® Suite: Intelligent Device Manager.
.
2. Set the adaptive digital signal processing filter settings using the density of the gas to be measured. This is the
“optimize flow range” selection in AMS or HART field communica t o r.
3. Decrease the low flow cutoff to half the maximum expected water flow rate. The low flow cutoff should not be
set to a value lower than minimum flow rate value for the meter size listed in Table 1. It may be necessary to
adjust the low flow cutoff value if vibration or noise is present and the meter registers flow when no flow is
present.
4. Set the trigger level to 4.
Using the above configuration, the vortex meter will measure both gas flow and liquid flow rates. Since the gas will
flow at a much higher velocity than the liquid flow rate, flow limits and alarms setup in the RTU can be used as an
indication that gas blow by is occurring on the separator water outlet. Table 1 can be used as a guideline for the
maximum measurable liquid flow rate limits to be set in the RTU.
© Emerson Process Management, Inc. All Rights Reserved
Rev. B
Separator Water Measurement Using Rosemount Vortex
FOUNDATION Fieldbus
Process Solutions Guide
Additional Specifications
Performance Specifications
Liquids – Reynolds number over 20000
Digital and pulse output: ±0.65% of rate
Min Upstream / Downstream Piping Length
The Rosemount 8800D Flowmeter may be installed
with a minimum of ten straight pipe diameters (D)
upstream and five straight pipe diameters (D)
downstream by following the K-factor corrections as
described in the 8800 Installation Effects Technical
Gas and Steam – Reynolds number over 15000
Digital and pulse output ±1.0% of rate
Data Sheet (00816-0100-3250). No K-factor
correction is required if 35 straight pipe diameters
upstream (35D) and 10 straight pipe diameters
Output Signals
downstream (10D) are available.
4-20 mA Digital HART signal Power Supply
Superimposed on 4-20mA signal
Scalable pulse output
0-10000 Hz; transistor switch closure with
adjustable scaling via HART communications;
capable of switching up to 30Vdc, 120mA max
HART Analog
External power supply required. Flowmeter operates
on 10.8 to 42 Vdc terminal voltage with 250-ohm
minimum load required for HART communications ,
16.8 Vdc power supply is required.
Power Consumption
One watt maximum
Consult the 8800 Product Datasheet for additional product specifications
Flanged Wafer Reducer Weld End Multi-Variable Critical Process NPT Threaded
© Emerson Process Management, Inc. All Rights Reserved
Rosemount 8800 Vortex Offering
Rev. B
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