Constant Gradient NMR Analyzer for High-Temperature Rock Core Evaluation
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current NMR instruments face challenges in measuring the diffusion coefficient of crude oil due to the requirement for a large gradient field, which is limited by transient electrical currents, and cannot perform high-temperature and high-pressure tests on rock cores with metal shells, constraining the development of NMR laboratory techniques.
Innovation Solution
A constant gradient field NMR rock sample analyzer is developed, featuring a gradient magnet with a yoke plate, magnetic steel, and polar plate made from specific materials, connected by glue, generating a uniform magnetic field and horizontal gradients, along with a high-temperature high-pressure probe, and a control system for pulse sequence design and data acquisition, enabling two-dimensional NMR spectrum analysis.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a large gradient field is used to measure the diffusion coefficient of crude oil, then the measurement precision is improved, but the device complexity increases due to the limitation of transient electrical current amplification
Solution Approach 1:
The patent replaces the electrical gradient system with a permanent magnetic gradient system. Instead of using transient electrical currents to generate a gradient field, the invention employs permanent magnets arranged in a specific configuration to produce a constant gradient field, thereby eliminating the need for complex current amplification equipment while enabling precise diffusion coefficient measurements.
Solution Approach 2:
The patent changes the fundamental parameter of gradient field generation from transient electrical current to permanent magnetic field. This parameter change allows the system to maintain a stable, constant gradient field without the limitations of electrical current amplification, simplifying the overall system while improving measurement capability.
2Ease of operation
If an electrical gradient system is used to generate a gradient magnetic field, then the ease of operation is improved through electrical current control, but the adaptability deteriorates due to inability to perform high-temperature and high-pressure tests
Solution Approach 1:
The patent replaces the electrical gradient system with a permanent magnetic gradient system that can operate in high-temperature and high-pressure environments. The permanent magnets generate a stable gradient field without requiring electrical connections or complex control systems, enabling the instrument to perform reservoir condition simulations that were previously impossible.
Solution Approach 2:
The permanent gradient magnet system provides universal applicability across different testing conditions including high-temperature and high-pressure environments. The system maintains its gradient field generation capability without modification, making the instrument versatile for various petroleum exploration and development applications.
3Adaptability or versatility
If a constant gradient field is generated using permanent magnets, then the adaptability is improved for high-temperature and high-pressure tests, but the manufacturing precision requirements increase
Solution Approach 1:
The patent employs an asymmetric arrangement of permanent magnets with different configurations (including wedge-shaped and block-shaped magnets) to generate the gradient field. This asymmetric design allows for flexible compensation of manufacturing tolerances and provides a practical solution to achieving the required field uniformity without excessive manufacturing precision requirements.
Solution Approach 2:
The patent applies different magnet shapes and materials in specific locations within the gradient magnet assembly. By optimizing the local properties of individual magnets (such as using wedge-shaped magnets in certain positions and block-shaped magnets in others), the system achieves the required gradient field characteristics while accommodating practical manufacturing constraints.
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
The analyzer effectively measures petrophysical parameters such as diffusion coefficient, porosity, permeability, and fluid saturation, enabling accurate fluid identification and reservoir evaluation, and supports high-temperature and high-pressure testing, enhancing NMR rock sample analysis capabilities.
Implementation Method 1
The gradient magnet (2) generates a magnetic field B0 which is longitudinally uniform and has horizontal gradients to form a sample detection area
Implementation Method 2
a constant gradient field NMR rock sample analyzer capable of measuring a diffusion coefficient and performing a high-temperature and high-pressure test
Implementation Method 3
By obtaining one-dimensional relaxation time T2 spectrum through measurement, the equipment may rapidly give petrophysical parameters
Data Source
Figure 1
Figure 2
Figure 3~4
AI summary
The present invention relates to a constant gradient field nuclear magnetic resonance (NMR) rock sample analysis method and instrument. The method includes: in a constant gradient field generated by a magnet, performing NMR measurement to acquire measurement data; converting the measured NMR data into a two-dimensional NMR spectrum D-T2; performing measurement and inversion on a standard sample of a constant gradient field to obtain a standard sample two-dimensional NMR spectrum D-T2; measuring the rock sample to acquire a two-dimensional NMR spectrum D-T2 of a fluid in the rock sample; identifying fluid types according to the practically measured two-dimensional NMR spectrum D-T2 of the rock sample; computing the fluid property of the rock sample and the petrophysical parameters according to the two-dimensional NMR spectrum D-T2 of the fluid in the rock sample; performing single slice scanning on the rock sample to acquire partial oil and water saturation of the rock sample; performing continuous slice scanning on the rock sample to obtain axial oil and water saturation distribution and movable fluid saturation distribution of the rock sample. The method is very suitable for reservoir evaluation and fluid identification.