Fracture Geometry Mapping Using 3D Diffusive Tortuosity
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Solution Overview
Problem
Existing methods for mapping fracture geometry in subterranean formations are limited in accuracy and efficiency, particularly in determining anisotropic fracture pathways and in situ stresses, and often require destructive sampling or are prone to high noise levels and uncertainty.
Innovation Solution
A method and system using pulsed field gradient nuclear magnetic resonance (PFG NMR) signals to measure diffusive tortuosity in multiple directions, generating fracture network maps that depict anisotropic fracture pathways, and enabling non-destructive, in situ stress determination for improved hydraulic fracturing simulations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If destructive sampling methods are used to map fracture geometry, then measurement precision can be improved, but loss of substance and time are increased
Solution Approach 1:
The patent replaces destructive mechanical sampling with non-destructive PFG NMR measurement technology. The NMR method uses magnetic field gradients to measure diffusive tortuosity without physically damaging the formation samples, thereby maintaining formation integrity while obtaining accurate fracture geometry data.
Solution Approach 2:
The patent introduces PFG NMR signals as an intermediary measurement medium. Instead of directly observing fracture geometry through destructive sampling, the NMR signals interact with fluid molecules in the formation to indirectly measure tortuosity and fracture characteristics through diffusion behavior.
2Measurement precision
If conventional fracture mapping methods are used, then ease of operation is maintained, but measurement precision and reliability are reduced
Solution Approach 1:
The patent changes the measurement parameters from direct geometric observation to diffusive tortuosity measurement. By measuring tortuosity values in multiple directions (first, second, and third directions) and comparing them, the method determines anisotropic fracture pathways through parameter analysis rather than direct geometric mapping.
Solution Approach 2:
The patent creates a virtual model of fracture geometry through PFG NMR measurement. The measured diffusive tortuosity data is used to generate fracture network maps that represent the actual fracture geometry, allowing complex three-dimensional fracture structures to be captured and analyzed without direct physical access.
3Measurement precision
If single-direction tortuosity measurement is used, then ease of operation is improved, but measurement precision is insufficient for accurate fracture mapping
Solution Approach 1:
The patent segments the measurement process into separate directional components. Diffusive tortuosity is measured independently in the first direction, second direction (orthogonal to first), and third direction (orthogonal to both first and second), allowing each directional component to be analyzed separately before integrating results for comprehensive fracture mapping.
Solution Approach 2:
The patent transitions from single-direction measurement to multi-dimensional measurement. By adding orthogonal directions (second direction perpendicular to first, third direction perpendicular to both), the method captures three-dimensional fracture geometry information, enabling accurate representation of complex anisotropic fracture networks.
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
Enhances the accuracy and quality of fracture geometry mapping, allowing for more precise hydraulic fracturing simulations and water influx predictions, while avoiding destructive sampling and reducing uncertainty.
Implementation Method 1
generating a pulsed field gradient nuclear magnetic resonance signal in the first direction, the second direction, and the third direction
Data Source
Figure 1
Figure 2A~2D
Figure 3~4
AI summary
A fracture geometry mapping method includes determining a value of a diffusive tortuosity in a first direction in a first rock sample from a subterranean formation with one or more hardware processors; determining a value of a diffusive tortuosity in a second direction in the first rock sample from the subterranean formation with the one or more hardware processors, the second direction orthogonal to the first direction in the first rock sample; determining a value of a diffusive tortuosity in third direction in the first rock sample from the subterranean formation with the one or more hardware processors, the third direction orthogonal to both the first direction and the second direction in the first rock sample; comparing the values of the diffusive tortuosities in the in the first direction, the second direction, and the third direction; and based on the comparison, generating a first fracture network map of the subterranean formation, the first fracture network map including a first plurality of anisotropic fracture pathways.