Multi-Nucleus NMR Detection for Fluid Discrimination
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Solution Overview
Problem
Conventional NMR methods using a single resonant nucleus, such as 1H, are insufficient for discriminating fluid phases in certain oil recovery applications, particularly in pre-salt carbonate formations, and fail to access petrophysical parameters like permeability and pore size distribution.
Innovation Solution
The method involves simultaneously detecting multiple resonant nuclei, like 1H and 23Na, using a dual-resonance probe design, allowing for robust fluid-phase discrimination and petrophysical parameter determination without removing the sample from the NMR magnet, enabling dynamic process monitoring and improved imaging of fluid distributions within rock samples.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional single-nucleus NMR (1H) is used for fluid-phase discrimination, then the measurement is consistent with downhole tools and minimizes magnetic susceptibility contrast effects, but it fails to discriminate fluid phases in certain formations like pre-salt carbonate formations
Solution Approach 1:
The patent employs multi-nucleus NMR detection (detecting multiple resonant nuclei such as 1H, 23Na, 19F, 133Cs) to provide universal fluid-phase discrimination capability across different formation types. By simultaneously detecting signals from different nuclei, the system achieves both the magnetic susceptibility benefits of 1H NMR and the enhanced discrimination capability needed for challenging formations like pre-salt carbonates
Solution Approach 2:
The patent changes the detection parameter from single-nucleus to multi-nucleus NMR. By detecting additional nuclear spin resonances beyond 1H, the system introduces new contrast mechanisms that enable fluid-phase discrimination in formations where conventional 1H NMR fails, while maintaining compatibility with downhole tool physics
2Measurement precision
If multiple resonant nuclei are detected simultaneously using dual-resonance probe design, then fluid-phase discrimination and petrophysical parameter determination are improved, but device complexity increases
Solution Approach 1:
The dual-resonance probe is designed with segmented functional components that can independently detect different nuclear spin resonances. The probe includes separate detection channels or frequency-tuned elements that can be selectively activated, allowing complex multi-nucleus detection to be broken down into manageable segments that reduce overall system complexity
Solution Approach 2:
The patent employs dynamic switching between different resonance detection modes in the dual-resonance probe. The system can dynamically adjust detection frequencies and parameters based on which nuclei need to be observed, allowing the complex multi-nucleus capability to be activated only when needed rather than operating continuously in all modes
3Loss of information
If conventional single-nucleus NMR is used, then the measurement process is simple and quick, but it cannot access petrophysical parameters like permeability and pore size distribution
Solution Approach 1:
The multi-nucleus NMR system performs continuous measurements of multiple resonant nuclei without requiring sample removal or interruption of the measurement process. The dual-resonance probe enables simultaneous or rapidly alternating detection of different nuclei, maintaining continuous observation and providing multiple petrophysical parameters in a single integrated measurement sequence
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 quantitative determination of fluid phases, enhanced petrophysical information, and improved interpretation of well-logs, enabling more effective enhanced oil recovery techniques and better understanding of reservoir properties.
Implementation Method 1
nuclear magnetic resonance (NMR)... Low-field 1H (proton) NMR... NMR has a significant advantage over X-ray computed tomography (CT) in these measurements: the ability to discriminate fluid phases (oil, gas, brine) based on inherent properties of the fluids (spin relaxation time, diffusion coefficient)... The NMR signals from multiple resonant nuclei (e.g., 1H, 23Na, 19F, or 1H and 133Cs, etc.) may be acquired sequentially using a dual resonance probe design
Data Source
AI summary
Methods for improved interpretation of NMR data acquired from industrial samples by simultaneously detecting more than one resonant nucleus without removing the sample from the sensitive volume of the NMR magnet or radio frequency probe are disclosed. In other aspects, the present disclosure provides methods for robust imaging/analysis of spatial distribution of different fluids (e.g., 1H, 23Na, 19F) within a core or reservoir rock. NMR data may be interpreted in real-time during dynamic processes to enable rapid screening, e.g. of enhanced oil recovery techniques and products and/or to provide improved interpretation of well-logs. Measurements of resonant nuclei other than 1H may be performed in the laboratory or downhole with a NMR logging tool. In other aspects, the present disclosure describes a novel kernel function to extract values for underlying parameters that define relaxation time behavior of a quadrupolar nucleus.