Multiphase Flow Tomography Using Transit Time and Attenuation
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Solution Overview
Problem
Existing tomographic imaging techniques fail to provide a satisfactory picture of three-phase multiphase flow in conduits, particularly in hydrocarbon production, due to the different fluid properties of water, oil, and gas, which existing methods like filtered back projection algorithms and attenuation approaches have not adequately addressed.
Innovation Solution
A system comprising an array of transmitters and receivers mounted around a conduit, measuring energy travel speed and attenuation between them, and a data processing system forming composite images of the relative presence and position of three fluid phases based on these measurements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If filtered back projection algorithm is used for two-phase flow reconstruction, then imaging capability for two phases is achieved, but imaging capability for three phases is insufficient
Solution Approach 1:
The patent segments the three-phase flow imaging problem into two separate two-phase imaging problems by performing sequential reconstructions. First, oil and water are imaged using the filtered back projection algorithm, then gas and liquid (oil+water) are imaged separately. This segmentation allows the use of established two-phase algorithms to solve the more complex three-phase problem, improving adaptability while maintaining measurement precision through the sequential approach.
2Adaptability or versatility
If attenuation approach is used for liquid-gas flow, then gas-liquid flow measurement is enabled, but satisfactory picture of three-phase flow is not achieved
Solution Approach 1:
The patent merges the advantages of the filtered back projection algorithm (good for oil-water separation) and the attenuation approach (effective for gas-liquid detection) into a unified three-phase reconstruction system. By combining both methods sequentially, the system achieves satisfactory imaging quality for all three phases simultaneously, resolving the contradiction between adaptability and measurement precision.
3Measurement precision
If separate imaging methods are used for different phase combinations, then specific two-phase imaging is optimized, but integrated three-phase imaging is not achieved
Solution Approach 1:
The patent implements continuous sequential imaging where the first reconstruction (oil-water) is immediately followed by the second reconstruction (gas-liquid), with both processes using the same transmitter-receiver array. This continuous action approach integrates multiple imaging methods without requiring separate devices, maintaining measurement precision while managing system complexity through efficient resource utilization.
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
Enables the formation of accurate tomographic images of three-phase flow in conduits, allowing for the evaluation and analysis of the presence and location of oil, water, and gas, thereby improving the understanding of multiphase flow dynamics.
Implementation Method 1
An array of a plurality of transmitters is mounted about the periphery of the conduit emitting ultrasonic energy to travel through the fluid in the conduit, and an array of a plurality of receivers mounted about the periphery of the conduit receiving ultrasonic energy after travel through the fluid in the conduit
Implementation Method 2
The data processor forms measures of the attenuation of the energy between individual ones of the plurality of transmitters and receivers
Implementation Method 3
The data processing system includes a processor which forms measures of the speed of travel of the energy between individual ones of the plurality of transmitters and receivers
Data Source
Figure 1
Figure 2~3
Figure 4A~4B
AI summary
Tomographic reconstruction is performed of cross-sectional images of downhole or surface multiphase flows containing water (brine), oil, and gas phases. Measures are obtained of digital transmission (or analog attenuation) and also of analog transit time to form two views of the same cross sectional flow in a location of interest in a flow conduit. The measures are then merged by synthesizing a composite image of the multiphase flows. Rather than performing a complex tomographic reconstruction requiring a large number of calculations, measures are also obtained directly from the tomographic pattern which can be used to reconstruct an approximation of the cross sectional flow by the superposition of circles of variable position, radius and density representing flow patterns.