Unique gas void fraction measurement to improve separator performance & accuracy

In Brief
Expro Meters provides client unique gas void fraction (GVF) measurement to improve separator performance and accuracy
Product Line
North and Latin America
  • Industrial Vox Analyzer supplies flow measurement solutions to the oil and gas industry, including gas-liquid cylindrical cyclone (GLCC) separators – a compact two-phase separator which utilises centrifugal and gravitational forces to separate gas and liquid phases
  • Oil and water liquid flow rate is typically measured with turbine or Coriolis meters; the water cut is determined via a density measurement using either a Coriolos or microwave device
  • All measurements (flow, density and water cut) assume complete separation, which is not always achievable, especially over a wide range of flow conditions and process fluid types; incomplete separation and subsequent gas carry under becomes the main source of error given the Coriolis’ sensitivity to the difference in gas and liquid densities
  • In heavy oil applications, separation efficiency is particularly challenging; gas in the separator liquid leg can result in significant net oil measurement errors
  • Gas carry under is recognised as a major source of error however it has been impossible to measure the free gas to correct the liquid measurement in real time 
Expro Excellence
  • Expro’s sonar technology measures entrained GVF and corrects the volumetric rate and fluids density measurement in real time
  • Laboratory and field tests have validated the ability to correct primary phase measurement devices in presence of up to 20% GVF
  • Expro’s PassiveSONAR™ meters:

–  provide an accurate real time

measurement of entrained gas

–  are the only clamp-on sensor available to measure GVF

–  have been installed on many convention and GLCC separators

No field shutdown or flow diversion associated with meter installation, commissioning or testing 

Value to client
  • The GVF measurement is used to correct Coriolis measurements of volumetric flow rate and mixture density
  • PassiveSONAR™ provides quantitative measurement of separator efficiency and enables accurate flow and net oil measurement where there is incomplete gas/liquid separation
  • Enables water cut devices to accurately report net oil in the presence of entrained gas
  • PassiveSONAR™ enables the use of small footprint GLCC technology in lieu of larger three-phase horizontal gravity separators