Multiphase Fluid Water Cut Detection via Dielectric Spectroscopy
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Solution Overview
Problem
Current methods for measuring water content in multiphase production fluids, such as hydrocarbon production fluids, are inaccurate due to variations in permittivity and density of crude oils, leading to high error levels, especially in multiphase flows where hydrates are present, and require prior knowledge of fluid properties.
Innovation Solution
The method involves measuring the real and imaginary parts of the complex permittivity of production fluids using dielectric spectroscopy at multiple frequencies, specifically dielectrically non-dispersive and dispersive frequencies, to accurately determine the water cut and hydrate concentration without relying on dry oil properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If permittivity measurement is used to determine water cut, then measurement can be performed, but high error levels result due to variations in crude oil permittivity and density
Solution Approach 1:
The patent changes the measurement parameter from single-frequency permittivity to complex permittivity at multiple frequencies. By measuring at both dispersive and non-dispersive frequencies, the system captures frequency-dependent behavior that characterizes water specifically, eliminating errors caused by variations in crude oil properties. The complex permittivity (real and imaginary parts) provides additional discriminatory power to distinguish water from hydrocarbons reliably.
2Measurement precision
If single frequency permittivity measurement is used, then measurement is simple, but accuracy is insufficient due to inability to distinguish water from hydrocarbons
Solution Approach 1:
The patent segments the frequency measurement into two distinct components: dispersive frequency measurement and non-dispersive frequency measurement. Each frequency serves a specific purpose - the dispersive frequency captures water's frequency-dependent permittivity behavior while the non-dispersive frequency provides a reference. This segmentation allows accurate water detection without requiring complex multi-parameter analysis, maintaining system simplicity while improving precision.
3Adaptability or versatility
If indirect thermodynamic calculation is used to detect water, then measurement can be performed in hydrate conditions, but significant error remains due to chemical additives affecting calculations
Solution Approach 1:
The patent replaces indirect thermodynamic calculation methods with direct dielectric spectroscopy measurement. Instead of calculating water content from temperature and pressure data (which are affected by chemical additives like methanol and glycol), the system directly measures the complex permittivity of the fluid. Water's unique dielectric properties at dispersive frequencies provide a direct measurement that is insensitive to the presence of chemical additives, maintaining both adaptability to hydrate conditions and measurement precision.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach provides improved accuracy and reliability in measuring water cut and hydrate detection, reducing errors and enabling precise measurements in dynamic environments without prior knowledge of fluid properties, suitable for industrial and commercial applications.
Implementation Method 1
measuring the real and imaginary parts of the complex permittivity of production fluids using dielectric spectroscopy at multiple frequencies
Data Source
AI summary
An apparatus and method for measuring the concentrations of oil, water and/or hydrates in a multiphase production fluid flow comprises measuring the complex permitivities, both real and imaginary parts, of the flow at at least two frequencies. One dispersive and one non-dispersive frequency are used. In one embodiment at least three frequencies may be selected, one of which is below about 1 MHz while the other two are within the dispersive and non-dispersive ranges for water. In this embodiment water may be distinguished from hydrates and both measured simultaneously.