Oil and gas production handbook - Process Control and ...

point, means a transfer of responsibility or title from the producer to a customer,
shuttle tanker operator or pipeline operator.
Fig. 1 Metering System
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Although some small installations are still operated with dipstick and manual
records, larger installations have analysis and metering equipment. To make sure
readings are accurate, a fixed or movable prover loop for calibration is also installed.
The figure shows a full liquid hydrocarbon (oil and condensate) metering system.
The analyzer instruments on the left provides product data such as density, viscosity
and water content. Pressure and temperature compensation is also included.
For liquid, turbine meters with dual pulse outputs are most common. Alternatives are
positive displacement meters (passes a fixed volume per rotation or stroke) and
coriolis massflow meters. These instruments can not cover the full range with
sufficient accuracy. Therefore the metering is split into several runs, and the number
of runs in use depends on the flow. Each run employs one meter and several
instruments to provide temperature and pressure correction. Open/Close valves allow
runs to be selected and control valves can balance the flow between runs. The
instruments and actuators are monitored and controlled by a flow computer. If the
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