Fractured Porous Media Generation

This program generates 2D & 3D fractured porous media with both matrix porosity and fracture networks.

Overview

This MATLAB program generates 3D fractured porous media with both matrix porosity and fracture networks. It extends the original pore network generation code to include realistic fracture systems.

Features

1. Pore Network Generation

• Spherical pore generation with controlled size distribution
• Target porosity control
• Average pore size control

2. Fracture Network Generation

• Multiple fracture planes with random orientations
• Controllable fracture parameters:
• Length and width
• Aperture (thickness)
• Dip angle (inclination)
• Strike angle (azimuth)
• Realistic 3D fracture geometry

3. Analysis Capabilities

• Topological analysis (vertices, edges, faces, cells)
• Connectivity analysis (connected components)
• Pore size distribution
• Surface area calculation
• Skeletonization

4. Visualization

• 5 comprehensive figures showing different aspects
• Isosurface rendering
• Skeleton visualization
• Pore size histogram
• Cylindrical sample extraction

5. Export Options

• STL files for 3D printing or CFD simulations
• MAT file workspace
• Fracture data text file

Key Parameters

Domain Size

matlab

nx = 100; % X dimension

ny = 100; % Y dimension

nz = 100; % Z dimension

Pore Network Parameters

matlab

targetPorosity = 0.35; % Matrix porosity (0-1)

targetPoreSize = 8; % Average pore radius (voxels)

Fracture Parameters

matlab

numFractures = 15; % Number of fractures

minFractureLength = 20; % Minimum fracture length (voxels)

maxFractureLength = 60; % Maximum fracture length (voxels)

fractureAperture = 2; % Fracture thickness (voxels)

Usage Instructions

Basic Usage

1. Open MATLAB
2. Navigate to the directory containing the script
3. Run: fractured_porous_media_generation
4. Wait for generation and analysis to complete
5. Examine the 5 generated figures
6. Check exported files in the working directory

Customization

Edit the parameters in Sections 1-3 of the script:

• Adjust domain size for larger/smaller samples
• Modify porosity for different rock types
• Change fracture parameters for different fracture densities
• Adjust random seed (rng) for different realizations

Output Files

1. STL Files:

• fractured_porous_media_pores.stl - Pore space geometry
• fractured_porous_media_solid.stl - Solid matrix geometry
• fractured_porous_media_cylindrical.stl - Cylindrical sample

1. Data Files:

• fractured_porous_media_workspace.mat - Complete workspace
• fracture_data.txt - Fracture properties

Visualization Guide

Figure 1: Pore Space and Solid Phase

• Cyan: Pore space (including fractures)
• Red: Solid matrix
• Shows the complete 3D structure

Figure 2: Pore Network Skeleton

• Blue transparent surface: Pore space
• Red dots: Skeleton points
• Useful for connectivity analysis

Figure 3: Pore Size Distribution

• Logarithmic x-axis
• Shows frequency distribution of pore diameters
• Helps characterize pore structure

Figure 4: Cylindrical Sample Extraction

• Green: Pore space in cylindrical sample
• Yellow: Solid phase in cylindrical sample
• Simulates core sample extraction

Figure 5: Fracture Network Centers

• Shows fracture center locations
• Red markers indicate fracture positions

Technical Details

Fracture Generation Algorithm

The program generates fractures using a planar approach:

1. Define fracture center point
2. Specify length, width, and aperture
3. Apply dip angle (0-30°) and strike angle (0-360°)
4. Create rotation matrices for 3D orientation
5. Voxelize the fracture plane

Connectivity Analysis

• Uses MATLAB's bwconncomp function
• Identifies isolated pore clusters
• Reports size of largest connected component

Performance Considerations

• Typical runtime: 1-5 minutes for 100³ domain
• Memory usage: ~100 MB for 100³ domain
• Larger domains (200³) may require 10-30 minutes

Applications

1. Geothermal Reservoir Modeling

• Simulate fractured reservoir rocks
• Analyze permeability pathways

1. Oil & Gas Engineering

• Characterize fractured carbonate reservoirs
• Model enhanced oil recovery

1. Groundwater Hydrology

• Study contaminant transport
• Analyze fracture-matrix interaction

1. CO2 Sequestration

• Model storage in fractured formations
• Assess sealing capacity

1. CFD Simulations

• Use exported STL files in flow simulators
• Study fluid dynamics in fractures

Troubleshooting

Issue: Out of Memory

Solution: Reduce domain size (nx, ny, nz) or increase MATLAB memory

Issue: Too Few Fractures Visible

Solution: Increase numFractures or fractureAperture

Issue: No Connected Pore Network

Solution: Increase targetPorosity or add more fractures

Issue: Generation Takes Too Long

Solution: Reduce domain size or target porosity

Extension Ideas

1. Realistic Fracture Networks

• Implement fractal fracture patterns
• Add fracture clustering

1. Anisotropic Pore Structure

• Preferred orientation for pores
• Layered heterogeneity

1. Multi-scale Porosity

• Add micro-porosity within matrix
• Nested pore systems

1. Flow Simulation Integration

• Export to OpenFOAM
• Permeability tensor calculation

References

Based on:

• Jimmy Li (2024). Pore Network Generation and Analysis
• MATLAB Central File Exchange
• https://au.mathworks.com/matlabcentral/fileexchange/170286

License

MIT License - See script header for full license text