Capacitive Phase Shift Detection for Measuring Water Holdup in Horizontal Oil⁻Water Two-Phase Flow

Area of Science:

• Multiphase flow measurement
• Capacitive sensing technology
• Fluid dynamics

Background:

• Accurate measurement of water holdup in oil-water flows is crucial for process control.
• Traditional methods face challenges with nonuniform phase distributions and complex flow patterns.
• Concave capacitance sensors (CCS) offer a potential solution for improved flow impedance detection.

Purpose of the Study:

• To design and investigate a phase shift detection system for oil-water stratified flow impedance using a CCS.
• To model and analyze the sensor's performance based on equivalent circuit and finite element models.
• To evaluate the CCS's sensitivity and linearity for water holdup measurement across different flow patterns.

Main Methods:

• Design of a phase shift detection system utilizing a concave capacitance sensor (CCS).
• Development of equivalent circuit and finite element models to investigate flow impedance.
• Experimental study of horizontal oil-water two-phase flows, observing stratified (ST), stratified wavy (SW), dual continuous (DC), and dispersed oil-in-water (DO/W&W) patterns.
• Analysis of CCS phase shift responses to water holdup variations.

Main Results:

• The CCS demonstrated satisfied sensitivity for stratified (ST) and stratified wavy (SW) flow patterns.
• Model predictions (equivalent circuit and finite element) aligned with experimental results for ST and SW flows.
• The CCS exhibited good linearity and sensitivity to water holdup variations even in nonuniform DC and DO/W&W flows.
• Capacitive phase shift detection proved advantageous for measuring water holdup in challenging oil-water flow conditions.

Conclusions:

• The designed CCS-based phase shift detection system is effective for measuring water holdup in horizontal oil-water flows.
• The technology shows robustness and accuracy across diverse flow patterns, including those with nonuniform phase distributions.
• Capacitive phase shift detection offers a promising method for real-time monitoring in the oil and gas industry.