Hybrid NMR and BET Core Sample Surface Roughness Analysis
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Solution Overview
Problem
Current methods for determining surface roughness of core samples, such as atomic force microscopy and scanning electron microscopy, provide limited and potentially damaging representations of the sample's surface, failing to accurately represent the entire core sample and are limited by optical properties, leading to inaccurate formation analysis.
Innovation Solution
A hybrid surface roughness determination technique combining nuclear magnetic resonance (NMR) diffusion-relaxation and Brunauer-Emmett-Teller (BET) gas-adsorption methods, which utilize different length-scales to calculate surface roughness without damaging the sample, providing a more representative measurement of the formation's surface properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If atomic force microscopy or scanning electron microscopy is used to measure surface roughness, then surface roughness can be determined, but the measurement is limited to the outer surface and may damage the core sample
Solution Approach 1:
The patent replaces mechanical contact methods (AFM stylus scanning the surface) with nuclear magnetic resonance (NMR) technology that uses magnetic fields and radio waves to probe the core sample internally. This substitution enables bulk measurement throughout the entire core sample volume rather than仅限于 the outer surface, eliminating mechanical damage while obtaining representative surface roughness data from the formation.
Solution Approach 2:
The NMR method serves multiple functions: it measures surface roughness, characterizes pore structure, and evaluates formation properties throughout the entire core sample. By using a single technique that provides comprehensive bulk information, the patent eliminates the need for separate surface-only measurements and achieves both non-destructive testing and representative data collection.
2Object-affected harmful factors
If optical methods are used to measure surface roughness, then non-invasive measurement is achieved, but measurements are limited by optical properties of the core sample
Solution Approach 1:
The patent replaces optical measurement methods with nuclear magnetic resonance (NMR) technology that uses magnetic fields and radio frequency pulses. This substitution eliminates limitations imposed by optical properties such as transparency, color, and surface reflectivity, allowing accurate surface roughness measurement regardless of the core sample's optical characteristics.
Solution Approach 2:
The patent changes the physical measurement parameters from optical properties (light interaction) to magnetic resonance properties (nuclear spin response to magnetic fields). By measuring the relaxation times and diffusion coefficients of protons in the core sample, the method obtains surface roughness information independent of optical properties, achieving both non-invasive measurement and high precision.
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 allows for a non-invasive, bulk measurement of surface roughness across multiple scales, improving the accuracy of formation analysis and providing essential data for drilling and hydrocarbon production parameters like wettability, permeability, and saturation profiles.
Implementation Method 1
performing pulsed nuclear magnetic resonance measurements of a core sample to determine a first relaxation measurement
Implementation Method 2
exposing a subsample of the core sample to a volume of an inert gas and measuring a relative pressure and weight of gas adsorbed on the subsample
Data Source
AI summary
Measurements of a core sample at scales of measurement that differ by multiple orders of magnitude can be used to calculate a value that fairly represents surface roughness of the core sample. This surface roughness value can be used to determine petrophysical properties of the subsurface formation from which the core sample was obtained. The measurements can be nuclear magnetic resonance (NMR) diffusion-relaxation and gas-adsorption measurements. Surface relaxivities at the different scales are determined from the measurements and a ratio those surface relaxivities can be used to calculate the surface roughness value.