NMR Logging Interecho Interval Control for Fast-Relaxation Detection
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Nuclear magnetic resonance (NMR) logging tools face limitations in data acquisition speed and measurement accuracy, particularly in capturing short time constants, due to constraints in interecho interval (TE) timing, which hinders the analysis of fast-relaxation components in geological formations.
Innovation Solution
The implementation of controlled interecho interval (TE) methods and systems in NMR logging tools, utilizing a TX/RX controller with a pulse sequence generator and TE calibration module, allows for reduced TE values while ensuring adequate spin echo data recovery, employing asymmetric and symmetric receiver window options to optimize data acquisition and signal-to-noise ratio.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If conventional fixed interecho interval (TE) timing is used in NMR logging tools, then the system operates with fixed timing constraints, but data acquisition speed is limited and measurement of short time constants is inaccurate
Solution Approach 1:
The patent implements dynamic interecho interval control where the TE timing is no longer fixed but adapts based on formation characteristics. The system uses a TE calibration module to determine optimal TE values and a pulse sequence generator to dynamically adjust pulse timing, allowing the NMR tool to optimize data acquisition speed while maintaining measurement accuracy for different formation types.
Solution Approach 2:
The system changes the timing parameters of the pulse sequence dynamically. By using a TE calibration module to determine optimal TE values and adjusting the pulse sequence generator accordingly, the system modifies the interecho interval parameter to match formation relaxation characteristics, thereby improving both acquisition speed and measurement precision.
2Measurement precision
If reduced interecho interval (TE) values are used to capture fast-relaxation components, then measurement of short time constants improves, but signal-to-noise ratio decreases
Solution Approach 1:
The system performs preliminary TE calibration using a TE calibration module before actual data acquisition. This preliminary action determines the optimal TE value that balances the need to capture fast-relaxation components with maintaining adequate signal-to-noise ratio, allowing the pulse sequence generator to be configured with appropriate timing parameters in advance.
Solution Approach 2:
The system incorporates feedback through the TE calibration module that determines optimal TE values based on formation characteristics. This feedback mechanism allows the system to adjust the pulse sequence timing to achieve the best compromise between capturing fast-relaxation components and maintaining signal quality.
3Productivity
If asymmetric receiver window options are used to optimize data acquisition, then acquisition speed improves, but system complexity increases
Solution Approach 1:
The system uses the TE calibration module to automatically determine optimal TE values and configure the pulse sequence generator accordingly. This self-service approach allows the system to optimize data acquisition speed through asymmetric receiver window options without requiring complex manual configuration, as the calibration process automatically adapts the parameters.
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 faster data acquisition and improved measurement of fast-relaxation components, allowing for the analysis of rock formations with very fast relaxation times that are otherwise invisible to conventional tools, with a minimal reduction in signal-to-noise ratio.
Implementation Method 1
NMR logging tools operate by using an imposed static magnetic field, B0, to give nuclei with non-zero nuclear spin (non-zero magnetic moment and angular momentum) split energy levels
Implementation Method 2
The nuclei converge upon their equilibrium alignment with a characteristic exponential relaxation time constant. When this convergence occurs after the nuclei have been placed in a cooperative initial state (discussed below), it is known as recovery. The time constant for recovery is called the 'spin-lattice' or 'longitudinal' relaxation time T1
Implementation Method 3
the tool applies a perturbing field, usually in the form of a radio frequency electromagnetic pulse whose magnetic component, B1, is perpendicular to the static field B0
Implementation Method 4
The polarized nuclei are perturbed simultaneously and, when the perturbation ends, they precess around the static magnetic field gradually re-polarizing to align with the static field once again
Implementation Method 5
The polarized nuclei are perturbed simultaneously and, when the perturbation ends, they precess around the static magnetic field gradually re-polarizing to align with the static field once again while losing coherence in the transverse plane (T2 relaxation)
Data Source
AI summary
A nuclear magnetic resonance (NMR) logging tool includes a pulsed magnetic field source which provides an NMR logging pulse sequence having a reduced interecho interval (TE). A controller in communication with the pulsed magnetic field source provides a pulse sequence designed to substantially align an echo peak with a measurement deadtime boundary, yielding a partial spin echo data recovery which is at least partially compensated by a substantially higher measurement density.