Discrete Fracture Network Permeability Robustness
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Solution Overview
Problem
Current methods for determining the permeability of discrete fracture networks in earth formations are computationally intensive and often neglect connectivity, making them inefficient and inaccurate, especially for less connected networks.
Innovation Solution
A computer-implemented method and system that assesses the robustness of discrete fracture network permeability estimates using a processing system with modules for receiving and analyzing DFN data, determining directional equivalent permeability through numerical upscaling and Oda's method, and comparing results to quantify robustness, thereby reducing computational resources and improving efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If numerical methods are used to calculate permeability, then measurement precision is improved, but computation time increases
Solution Approach 1:
The patent performs preliminary classification of DFN connectivity using topological analysis before conducting full permeability calculations. By pre-identifying connected vs. unconnected fracture networks through graph theory methods, the system avoids unnecessary computational work and directs numerical methods only where needed, thus improving precision where required while reducing overall computation time.
Solution Approach 2:
The patent segments the permeability calculation process into distinct stages: (1) topological connectivity assessment using graph theory, (2) classification of DFN connectivity status, and (3) selective application of numerical methods only to connected networks. This segmentation allows the system to achieve high precision for permeability estimation in connected networks while avoiding wasted computation on unconnected networks.
2Productivity
If Oda's analytical method is used, then computation time is reduced, but reliability deteriorates due to neglecting connectivity
Solution Approach 1:
The patent applies preliminary topological analysis using graph theory to assess fracture connectivity before applying Oda's analytical method. By pre-classifying DFNs as connected or unconnected, the system ensures Oda's method is only applied to connected networks where it remains valid, thus maintaining reliability while preserving the computational efficiency of the analytical approach.
Solution Approach 2:
The patent applies different calculation methods to different local cases: Oda's analytical method is applied specifically to connected DFNs where it provides accurate results, while numerical methods are reserved for unconnected or complex cases. This localized application of methods optimizes both computational efficiency and reliability for each specific DFN type.
3Device complexity
If connectivity is neglected for simplicity, then device complexity is reduced, but measurement precision worsens
Solution Approach 1:
The patent segments the analysis into two distinct parts: a simple topological connectivity assessment using graph theory, and a subsequent permeability calculation method selection. This segmentation allows the system to maintain low complexity for the connectivity assessment while improving precision by using appropriate methods for each case, avoiding the need for complex unified approaches.
Solution Approach 2:
The patent performs preliminary connectivity assessment using simple graph theory methods before proceeding to permeability calculations. This preliminary action maintains low complexity for the connectivity determination while enabling subsequent precision improvements through method selection, avoiding the need for complex integrated approaches that would increase overall system complexity.
Data Source
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AI summary
Examples of techniques for determining robustness of a discrete fracture network (DFN) permeability estimate are disclosed. In one example implementation according to aspects of the present disclosure, a method may include: receiving a DFN of an earth formation of interest, the DFN comprising a plurality of connected fractures; determining a directional equivalent permeability of the plurality of connected fractures of the DFN using a numerical upscaling method; and determining the robustness of the directional equivalent permeability.