Fluid Blob Tracking for Multiphase Flow Simulation Accuracy
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Solution Overview
Problem
Current methods for determining the permeability of fluid phases in porous media, especially at residual oil saturation, are inaccurate due to numerical integration effects and spurious velocities, which interfere with the measurement of small average velocities, impacting the prediction of relative permeability and residual oil saturation.
Innovation Solution
The method involves identifying and tracking connected fluid phase regions, or 'blobs,' using a computer system to calculate their center of gravity and velocity, allowing for a weighted average permeability assignment, which is more accurate than traditional volume integration methods, especially when average velocities are small.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If traditional volume integration methods are used to determine average fluid phase velocity, then the measurement process is simple, but the measurement precision deteriorates when average velocities are very small due to numerical integration effects and spurious velocities
Solution Approach 1:
The patent segments the continuous fluid phase into discrete connected regions called 'blobs'. Instead of integrating velocity over the entire fluid volume, the method identifies and tracks individual blobs, calculating their velocities separately. This segmentation approach eliminates numerical integration effects and spurious velocities that plague traditional methods when measuring small average velocities, as each blob's velocity can be determined more accurately through center-of-gravity tracking.
Solution Approach 2:
The patent changes the measurement parameter from volume-integrated average velocity to center-of-gravity-based velocity. By tracking the movement of the center of gravity of each blob between timeframes and calculating velocity from this displacement, the method avoids the numerical integration problems that occur when computing small average velocities over large volumes. This parameter change fundamentally resolves the precision issue at residual oil saturation.
2Measurement precision
If connected fluid phase region tracking is implemented, then the determination of fluid phase velocities and permeabilities becomes highly accurate even at low velocities, but the computational complexity increases
Solution Approach 1:
The patent segments the fluid phase into discrete connected blobs and processes each blob independently. This allows for precise velocity and permeability determination for each blob, which can then be aggregated. The segmentation enables accurate tracking of individual blob movements and contributions to overall permeability, resolving the precision issue while maintaining computational tractability through localized processing.
Solution Approach 2:
The patent extracts and processes only the connected fluid phase regions (blobs) that are relevant to permeability determination, rather than processing the entire simulation domain. By identifying and isolating these connected regions, the method focuses computational resources on the critical elements that contribute to fluid flow and permeability, improving both accuracy and efficiency by eliminating unnecessary computations in regions without fluid presence.
3Reliability
If blob tracking and center of gravity calculation are used, then spurious velocities and numerical integration effects are eliminated, but the device complexity and processing requirements increase
Solution Approach 1:
The patent changes the velocity determination parameter from volume-integrated average to center-of-gravity displacement. By calculating the center of gravity of each blob at different timeframes and determining velocity from the displacement between these centers, the method eliminates spurious velocities and numerical integration effects. This parameter change fundamentally improves reliability while the computational complexity is managed through efficient blob identification and tracking algorithms.
Data Source
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AI summary
Methods, systems, and apparatus, including computer programs encoded on computer storage media, for fluid blob tracking. One of the methods includes identifying, by a computer system, a connected fluid phase region in a flow simulation. The method includes tracking, by the computer system, the connected fluid phase region over a first timeframe and a second timeframe. The method also includes determining, by the computer system, movement of the connected fluid phase region from the first timeframe to the second timeframe based on the tracking.