Automated NMR Borehole Analysis for Fast Relaxation
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Solution Overview
Problem
Existing low frequency NMR relaxometry methods for oil-bearing earth formations evaluation are inefficient for high throughput automated measurements, particularly at well sites, and fail to effectively combine surface and downhole data, measure fast relaxation components, and handle samples with moisture barriers.
Innovation Solution
An automated NMR measurement apparatus and method that includes a sensing unit with a sample cassette for batch analysis, automatic sample transfer, and adaptive data stacking, enabling two-region NMR measurements in one cycle, and integrates NMR with natural gamma spectroscopy for comprehensive characterization of borehole materials.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If manual loading of samples in a sample holder is used, then measurement accuracy can be maintained, but measurement throughput is low and automation is insufficient
Solution Approach 1:
The sample analysis process is segmented into discrete positions within a sample holder, allowing automated sequential measurement of multiple samples. The sample holder is divided into multiple measurement positions, each capable of being independently analyzed by the NMR sensing unit, thereby enabling batch processing and high throughput automation.
Solution Approach 2:
The NMR sensing unit is designed to universally measure multiple different sample types (drill cuttings, core plugs, sidewall cores, bulk samples) using the same measurement protocol. The system can automatically adapt to different sample configurations and perform various NMR measurements (T1, T2, fast relaxation) without requiring manual reconfiguration, achieving multi-functionality and high automation.
2Measurement precision
If standard NMR pulse sequences are used, then measurement reliability is maintained, but fast relaxation components cannot be captured
Solution Approach 1:
The system employs periodic NMR pulse sequences with varying timing parameters to capture fast relaxation components. By using short repetition times and optimized pulse sequences, the system periodically excites and measures fast-relaxing fluids, accumulating data over multiple cycles to achieve precise measurement of fast relaxation components that would be missed in single-shot measurements.
Solution Approach 2:
The measurement system dynamically changes NMR pulse sequence parameters (repetition time, echo time, flip angles) to optimize detection of fast relaxation components. By adjusting these parameters based on the specific sample characteristics and desired measurement goals, the system can capture fast relaxation signals while maintaining overall measurement efficiency and reliability.
3Measurement precision
If surface NMR measurements are performed separately from downhole measurements, then equipment complexity is reduced, but formation evaluation accuracy is insufficient
Solution Approach 1:
The system merges surface NMR measurement capabilities with downhole NMR data processing and interpretation workflows. By integrating the surface measurement apparatus with existing downhole analysis software and methodologies, the system combines the advantages of both measurement types to achieve enhanced formation evaluation accuracy without requiring completely separate systems.
Solution Approach 2:
The patent introduces an intermediary data processing and interpretation layer that bridges surface and downhole NMR measurements. This intermediary system harmonizes data from both sources, applying consistent processing algorithms and interpretation models to combine the information into a unified formation evaluation framework, thereby improving accuracy while managing system complexity.
4Reliability
If measurements are performed on samples with moisture barriers, then sample preservation is improved, but NMR signal quality deteriorates
Solution Approach 1:
The system extracts or removes the moisture barrier layer during the measurement process to allow direct NMR signal detection from the sample. By taking out the barrier that prevents signal penetration, the system restores full NMR signal quality while maintaining sample integrity through controlled removal rather than permanent destruction of the sample.
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 measurement throughput and accuracy by automating bulk sensitive NMR measurements, combining surface and downhole data, and handling samples with moisture barriers, providing detailed petrophysical properties of borehole materials.
Implementation Method 1
applying a static magnetic field, generating an at least one sequence of pulses of a radio-frequency magnetic field... acquiring a free induction decay signal from the sample of a borehole material, acquiring an at least one spin-echo signal from the sample of a borehole material
Data Source
AI summary
A method (and apparatus) for NMR relaxation measurements on borehole materials (e.g., drill cuttings, sidewall cores and whole cores) is based on combining an FID signal and spin-echo signals to obtain relaxation properties of a sample having fast relaxation components. The method comprises acquiring NMR signals from the sample, acquiring calibration NMR signals and acquiring a background signal (e.g., ringing after an excitation pulse). The background signal may be acquired using an additional static magnetic field to substantially spoil the NMR excitation volume in the sample. The acquired signals are processed to obtain a nuclear magnetic resonance relaxation property of the sample with at least one (first point) on the relaxation data produced from the FID and with the background data eliminated from the relaxation data.