Water Cut Meter Technologies

Water cut meters measure BS&W or the content of water in crude oil. They operate using multiple technologies, including capacitance, optical, density and microwave. Capacitance probes rely on the difference in the dielectric constant of oil and water. As the percentage of water (water cut) increases, so to does the dielectric property of the fluid. Optical meters generally emit a signal in the IR spectrum and measure the absorption, reflection and scattering of the signal due to the oil phase.

Density can be used to measure water cut in light oil flows by measuring the combined density of water and oil and comparing that against the known density of the individual phases. Finally, microwave meters measure multiple electronic properties (complex permittivity) of the fluid to determine water cut.

Applications for water cut meters

Understanding water cut is vital to operations and optimization at many points in production, storage, and refining. Water cut meters can be used for:

• Monitoring well heads and well tests – generally after a 2-phase separator
• Monitoring production fields and automating/optimizing production management
• 3-phase separator performance
• Custody transfer, including marine and truck unloading as well as LACT units
• Automatic tank dewatering
• Oil skimming
• Tank interface
• Refinery feedstock
• Desalter optimization
• Theft prevention

Considerations in purchasing a water cut meter

All water cut meters are not alike. In addition to the different technologies, options for water cut meters vary in the type of installation, accuracy and accuracy across a full range (0-100%), requirements for flow conditions, and requirements for ambient conditions.

Operators should consider the following in making their decision:

• Water cut range
• Installation (inserted into a pipe or tank vs. on a flow loop)
• Flow conditions including gas fraction, temperature, flow rate, salinity and density
• Ambient conditions
• Communications and power requirements