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The
following are flowmeter applications in the oil industry.
The applications described here mainly occur in oil production,
transportation, and distribution. These
would also be described as upstream applications.
Custody
Transfer: Custody
transfer applications occur when possession of the oil is transferred from
one party to another. What
distinguishes custody transfer applications is the high degree of accuracy
required, and the fact that the type of flowmeters used are subject to
approval by an organization such as the American Petroleum Institute
(API). Custody transfer
operations occur at a number of points along the way.
These include from an oil production platform to a ship, barge,
railcar, or truck. Custody
transfer also occurs when oil is transferred from a ship, barge, railcar,
or truck to a destination point, such as a refinery.
Allocation
Metering:
One difference between custody transfer and allocation
metering is that in allocation metering, accuracy requirements are
typically not as high. Examples
of allocation metering include measuring oil movements between production
units, measuring separator flows, and metering the movements of oil at
jetty offtake and at loading points for tankers. Allocation also refers to the distribution of production from
a number of wells in a particular field.
Check
Metering:
Check metering is typically used to verify or monitor the
performance of another flowmeter. Clamp-on
ultrasonic flowmeters are sometimes used for his purpose, since they can
easily be mounted inline with the meter whose performance is being
verified, and then easily removed when the verification is complete.
Well
Injection:
Used to measure the inflow of chemicals that are injected
into the well, sometimes for measurement purposes.
Leak
Detection:
Used to determine whether leaks are occurring in a line.
This is often done by measuring the flow at the beginning of a line
and at the end of the line. Ultrasonic
flowmeters are used for this purpose.
Multiphase
Flow Measurement:
Multiphase flow measurement is becoming increasingly
important, and is sometimes replacing the use of separators at the
wellhead. Multiphase flow measurement typically measures the percent of
water, gas, and oil that the fluid coming out of the well contains.
This measurement is typically done at the wellhead.
Fuel
Measurement:
Fuel is typically measured when it is used, e.g., at a
power plant or power station. Fuel is also measured within a refinery, and downstream from
a refinery. Fuels that are
the output of the refining process are metered as they are transferred to
trucks, railcars, and ships, and also as they are delivered.
Process
Measurement:
Process measurement occurs within refineries and other
process plants as part of the refining and manufacturing process.
There are many occasions within a refinery or process plant when
liquids need to be measured so that the right products will be produced.
These applications can be grouped under the title of process
measurement.
Downstream
Applications: Downstream applications include fuel measurement, custody
transfer, and check metering. Once
the refining process is complete, the difference liquids need to be
measured as they are loaded into trucks, railcars, and ships. They are then measured at their destination points, as they
are offloaded either to end-users or to distributors. Coriolis, turbine, and positive displacement flowmeters are
used for this purpose. Coriolis
flowmeters are increasing market share due to their high accuracy and
their ability to measure mass flow.
Types of
Flowmeters: The types of flowmeters used
in oil flow measurement include differential pressure (DP), turbine,
positive displacement, Coriolis, and ultrasonic.
Of these types, Coriolis and ultrasonic are gaining ground on the
other types, but the DP, positive displacement, and turbine flowmeters
have the largest installed base.
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