NMR Fracture Quantification in Unconventional Source Rocks
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Solution Overview
Problem
In unconventional tight reservoirs, such as shale formations, it is challenging to accurately quantify fractures due to their low matrix permeability, as fluid flow is significantly faster through fractures than through pore networks, making it difficult to distinguish between fracture-induced and fracture-free fluid flow without external pressure.
Innovation Solution
The method employs Nuclear Magnetic Resonance (NMR) spectroscopy and imaging to track fluid changes and generate fluid distribution profiles, calculating transverse relaxation time (T2) and quantifying fracture volume by analyzing NMR measurements, allowing for the identification of fracture presence and volume within rock samples.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Difficulty of detecting and measuring
If fluid flow measurement is used to detect fractures in tight reservoirs, then fracture presence can be identified, but it is difficult to distinguish between fracture-induced flow and fracture-free flow due to extremely low matrix permeability
Solution Approach 1:
The patent introduces NMR technology as an intermediary measurement method that indirectly detects fractures through fluid distribution and relaxation time characteristics rather than direct fluid flow measurement. The NMR measurements provide a mediating parameter set that resolves the ambiguity between fracture-induced flow and fracture-free flow in tight reservoirs
Solution Approach 2:
The patent changes the measurement parameters from direct fluid flow rate to NMR relaxation time parameters (T1, T2) and fluid distribution profiles. By measuring the transverse relaxation time and generating fluid distribution profiles, the method detects fractures through characteristic relaxation signatures that differ between fracture and matrix regions, overcoming the precision limitations of direct flow measurement
2Measurement precision
If NMR measurements are used to track fluid changes, then fracture volume can be quantified, but the measurement process requires complex data processing and analysis
Solution Approach 1:
The patent segments the NMR data analysis into distinct processing stages: acquiring raw NMR measurements, calculating transverse relaxation time (T2), generating fluid distribution profiles, and finally quantifying fracture volume. This segmentation of the complex data processing into manageable steps reduces overall system complexity while maintaining measurement precision
Solution Approach 2:
The patent replaces complex mechanical or chemical analysis methods with NMR-based magnetic field measurements and computational data processing. The substitution of physical measurement complexity with magnetic resonance and algorithmic analysis simplifies the overall measurement system while enhancing fracture volume quantification accuracy
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 enables efficient quantification of fracture volume in rock samples, facilitating better understanding of fluid movement and permeability, thereby improving the assessment of unconventional rock reservoirs.
Implementation Method 1
acquiring, by a computer processor, nuclear magnetic resonance (NMR) measurements of the rock sample to track fluid change in the rock sample, calculating transverse relaxation time (T2) based on the NMR measurements
Implementation Method 2
NMR may track the temporal and spatial changes of fluids into the rock samples. generating, by the computer processor and based on a NMR imaging, fluid distribution profiles, the fluid distribution profiles representing a movement of the fluid
Data Source
AI summary
A method for analyzing unconventional rock samples using nuclear magnetic resonance (NMR), tracking fluid change in the rock sample over a time period, calculating transverse relaxation time (T2) generating fluid distribution profiles by the computer processor and based on a NMR imaging, where the fluid distribution profiles representing a movement of the fluid, and obtaining, quantification of fracture volume by the computer processor and based on the NMR imaging.