Switchable Electrode Array for Electrical Impedance Tomography
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Solution Overview
Problem
Monitoring fluid flows in oil and gas production systems is challenging due to the simultaneous flow of liquids, gases, and solids through pipes, leading to difficulties in measuring volume, velocity, and spatial distribution, which affects production control and efficiency.
Innovation Solution
An electrical impedance tomography (EIT) system with a switchable array of electrodes is used to monitor the flow of materials by applying interrogation currents and measuring responses, allowing for the derivation of conductivity and admittivity distributions within the pipe, even in complex flow regimes like those near valves and bends.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a fixed electrode arrangement is used for EIT measurements, then the system is simple to operate, but it cannot accurately measure flow regimes that deviate from assumptions (especially near valves and sharp bends)
Solution Approach 1:
The patent applies the dynamics principle by making the electrode array reconfigurable rather than fixed. The electrode array can be dynamically reconfigured to form different measurement patterns (e.g., complete arrays, arc segments, chords) depending on the specific measurement needs and flow regime conditions. This allows the system to adapt to complex flow patterns near valves and bends while maintaining operational simplicity through automated reconfiguration.
Solution Approach 2:
The patent applies segmentation by dividing the complete electrode array into multiple selectable segments or subsets. Rather than requiring all electrodes to be active simultaneously, the system can selectively activate specific portions of the array (e.g., arc segments for localized measurements, chord configurations for specific flow directions). This reduces the effective complexity for each measurement while maintaining the capability to handle diverse flow regimes.
2Loss of information
If multiple flow regimes are measured simultaneously, then comprehensive flow data is obtained, but measurement difficulty increases due to separation between gases and liquids
Solution Approach 1:
The patent applies the dimensionality change principle by using multiple electrode arrays arranged in different spatial configurations (e.g., axial arrays, circumferential arrays, helical arrays). This multi-dimensional electrode arrangement enables the system to capture flow information from multiple perspectives simultaneously, allowing reconstruction of three-dimensional spatial distributions of gas and liquid phases. The additional spatial dimensions provided by multiple arrays help overcome the measurement difficulties caused by phase separation.
3Measurement precision
If real-time measurements are taken near valves and sharp bends, then accurate local flow data is obtained, but the flow regime deviates from standard assumptions
Solution Approach 1:
The patent applies the local quality principle by enabling the electrode array to be configured specifically for localized measurements near valves and sharp bends. The system can activate only the electrode segments relevant to the region of interest, applying appropriate measurement patterns tailored to the local flow geometry. This allows accurate local flow measurements without requiring the entire array to conform to standard flow regime assumptions, as each local measurement can be optimized for its specific conditions.
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
The EIT system provides accurate real-time measurements of fluid flow characteristics, enabling better control and optimization of production processes by obtaining detailed spatial distributions and flow rates of different materials within the pipes.
Implementation Method 1
electrical impedance tomography (EIT) to map the spatial distribution of materials within the pipe. The principles of EIT are based on the understanding that materials have variations in electrical properties due to different characteristics such as density or chemical composition. These electrical properties, such as electrical conductivity and electric permittivity, determine the behavior of the materials under the influence of electric fields.
Implementation Method 2
Conductive materials have a high electrical conductivity, and both direct and alternating currents flow easily through them. EIT employs a fixed electrode arrangement around the pipe to supply interrogation currents and measure the responses of the material sufficient to derive the desired measurements
Implementation Method 3
For example, dielectric materials have a high electric permittivity, and alternating currents flow easily through them
Data Source
Figure 1
Figure 2A~2B
Figure 3A~3B
AI summary
An electrical impedance tomography based flow monitoring system includes a flow accepting pipe having a cylindrical grid of m x n electrodes, wherein m is an integer greater than 3 representing a number of circumferential grid positions and n is an integer greater than 2 representing a number of axial grid positions. Each combination of adjacent circumferential grid positions and adjacent axial grid positions defines a cell having four electrodes electrically connectable in various combinations by a switch, and the switches are set to connect the electrodes into multiple axially-extending arrays. The system further comprises a controller coupled to the multiple axially-extending arrays to acquire multi-point electrical tomography measurements, wherein the controller processes the measurements to derive a monitored quantity.