Three models of Accuflow metering system are available: The SR series and the LT series. The SR series is our full range model, covering low to high production rates as well as light to heavy crude. The LT version is our compact version of the SR. The relatively small footprint is particularly attractive for locations with limited space such as offshore platforms. The LT design is most suitable for applications with relatively light crude oil and low to medium liquid production rate. Consult the factory to determine which design is more suitable for your application. » Accuflow SR »Accuflow LT » Accuflow JR

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The figure below shows the process flow scheme and major components of the Accuflow Multiphase Metering System (AMMS). This metering system consists of a vertical pipe section and a horizontal pipe section connected together as shown. Multiphase fluid (oil, water and gas) from the production flow line enters the vertical pipe tangentially, creating a cyclonic action in the vertical pipe where a majority of gas is separated and flows upward. The slightly downward inclination of the inlet pipe promotes liquid/gas stratification in the inlet pipe that enhances gas/liquid separation in the vertical separator pipe. The remaining gas, mostly in the form of small bubbles, is carried downward with the liquid stream and enters the horizontal pipe section.

Liquid level in the horizontal separator pipe section is controlled in the middle of the pipe using a control valve located in the gas flow line. As the liquid level in the horizontal pipe rises, a liquid level signal is transmitted to the gas control valve. This causes the control valve to “pinch” or close slightly and creates a slightly higher back pressure in the gas phase. The back pressure then “pushes” the liquid to flow at a higher-than-average flow rate that in turns causes the liquid level in the horizontal pipe to fall and stabilize to the set point. Conversely, when the liquid level falls, the control valve opens slightly to reduce the back pressure in the gas phase. This reduction of back pressure causes the liquid to flow out of the system at a lower-than-average flow rate. Consequently, liquid level rises and stabilizes to the set point.

As the liquid stream flows through the horizontal pipe, gas bubbles rise to the gas/liquid interface and are completely separated as the liquid stream flows toward the outlet end of the horizontal pipe. Large gas/liquid interface area, thin gas-bearing liquid layer, and quiescent flow in the horizontal pipe, all contribute to efficient removal of entrained gas bubbles from the liquid stream.

A Coriolis-type flow meter is typically used to measure liquid flow rate. Water cut in the liquid stream is measured by one of two methods, density differential or conventional water cut meter. The conventional water cut meter is based on microwave frequency shift principle. A net oil transmitter or PLC receives liquid flow rate signal from the Coriolis flow meter to perform net oil calculations and display net oil and water rates and volumes.

After measurement, gas and liquid streams are typically recombined and returned to the multiphase flow line.

The AMMS has the following significant features:

• Suitable for all flow regimes – Because the multiphase stream is completely separated into a liquid and a gas stream prior to measurement, the same metering system can operate in all multiphase flow regimes. In other words, it is applicable for full range of GVF (gas void fraction).
• Low pressure drop - The metering system uses only one control valve in the gas flow line to modulate liquid level in the horizontal separator pipe. Unlike the conventional test separator system, there is no control valve in the liquid line, nor a back pressure regulator in the gas line. Hence the operating system rises and falls with the production line pressure. Pres sure drop across the entire metering system is typically between 10 kPa (1.3 psi) to 23 kPa (3.0 psi).
• Piping system – The entire metering system is made of common steel pipes and fittings, hence it can be designed and maintained in accordance with the recognized piping code (e.g., ANSI/ASME B31.3), rather than the pressure vessel code.
• Low liquid inventory - As compared to conventional test separators, this metering system has significantly lower liquid inventory. Consequently, when the metering system is used in conjunction with multi-well testing header, frequent well testing is obtainable due to significantly reduced purge time.