Flow Measurement of Oil-Water Two-Phase Flow at Low Flow Rate Using the Plug-in Conductance Sensor Array

Area of Science:

• Fluid mechanics
• Multiphase flow measurement
• Sensor technology

Background:

• Accurate measurement of oil-water two-phase flow at low flow rates is challenging due to slippage and non-uniform phase distribution.
• Existing methods often struggle with precision in dispersed flow regimes.

Purpose of the Study:

• To develop and validate a plug-in conductance sensor array (PICSA) for enhanced accuracy in measuring water holdup and cross-correlation velocity in low-flow oil-water mixtures.
• To optimize PICSA design using finite element analysis for improved electric field characteristics.

Main Methods:

• Finite element method (FEM) for electric field analysis and sensor optimization.
• Experimental validation using a dynamic oil-water two-phase flow loop with varying water cut (10-98%) and mixture velocity (0.0184-0.2580 m/s).
• Cross-correlation technique with upstream and downstream sensor arrays for velocity measurement.

Main Results:

• PICSA demonstrated good resolution for water holdup measurement across dispersed oil-in-water slug (D OS/W), transition (TF), dispersed oil-in-water bubble (D O/W), and very fine dispersed oil-in-water bubble (VFD O/W) flow patterns.
• Cross-correlation velocity showed sensitivity to flow pattern changes but maintained linearity within the same pattern.
• Kinematic wave theory and drift flux model provided accurate predictions of mixture velocity and individual phase volume fractions, respectively, based on flow pattern identification.

Conclusions:

• The PICSA is effective for accurate water holdup and velocity measurements in low-flow oil-water mixtures.
• Flow pattern identification is crucial for accurate velocity prediction using kinematic wave theory.
• The drift flux model enables high-precision prediction of phase volume fractions, enhancing overall flow characterization.