Capillary Pressure Curve Correction Using Hyperbolic Tangents
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Solution Overview
Problem
Existing methods for predicting water and hydrocarbon saturation in oilfield reservoirs at the reservoir scale are unreliable due to dependence on unstable models and limited data points, especially when multiple pore throats are involved.
Innovation Solution
A computer-implemented method for correcting and normalizing capillary pressure curves using hyperbolic tangents, which involves adjusting closure correction pressure cutoffs, determining entry pressure, and extrapolating curves to 100% wetting phase saturation, thereby stabilizing the saturation model.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If saturation height function is used for reservoir scale modeling, then saturation prediction is attempted, but the model becomes unstable and unreliable when multiple pore throats are involved
Solution Approach 1:
The patent segments the complex multi-pore throat capillary pressure curve into multiple individual pore throat curves, each represented by a hyperbolic tangent function. This segmentation allows each pore throat system to be modeled separately and then combined, providing both the accuracy needed for saturation prediction and the stability required for reservoir-scale modeling by avoiding the instability of direct multi-pore throat modeling
Solution Approach 2:
The patent transforms the capillary pressure data into hyperbolic tangent parameters (a, b, c) that characterize each pore throat system. By changing the mathematical representation from raw capillary pressure curves to standardized hyperbolic tangent parameters, the model achieves stability while maintaining the ability to accurately predict saturation across different reservoir conditions
2Measurement precision
If capillary pressure data is used directly for saturation modeling, then saturation values are obtained, but the results are inaccurate due to closure correction issues and limited data points
Solution Approach 1:
The patent performs preliminary correction of capillary pressure data by identifying and removing the closure pressure effect before modeling. By applying closure correction and determining the true entry pressure in advance, the model eliminates systematic errors that would otherwise lead to inaccurate saturation calculations, ensuring that the hyperbolic tangent functions are fitted to corrected rather than raw data
Solution Approach 2:
The patent introduces hyperbolic tangent functions as an intermediary between the corrected capillary pressure data and the saturation model. These functions serve as a mathematical mediator that smoothly transitions between different saturation regimes and pore throat systems, providing continuous and accurate saturation predictions even when direct data points are limited
3Device complexity
If traditional saturation models are used, then modeling is simplified, but the models are unstable and dependent on the number of data points and best fit intervals
Solution Approach 1:
The patent creates a universal hyperbolic tangent-based model that can handle both single and multiple pore throat systems with the same mathematical framework. This universal approach eliminates the need for different modeling strategies depending on the number of data points or pore throat complexity, providing stable and consistent results across diverse reservoir conditions while maintaining reasonable modeling complexity
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 a more accurate and stable saturation model by correcting capillary pressure curves and improving the reliability of saturation predictions in multi-pore throat systems, enhancing the precision of water and hydrocarbon saturation calculations.
Implementation Method 1
a saturation height function, where the saturation height function is a function of a capillary pressure
Data Source
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AI summary
A system and method for correcting capillary pressure curves includes creating a capillary pressure curve using multiple linked hyperbolic tangents, determining a closure correction pressure cutoff of the capillary pressure curve, and correcting the capillary pressure curve. The correction may include normalizing the capillary pressure curve and extrapolating the capillary pressure curve.