Heavy Oil Plus-Fraction Correction via Elution Ratio
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Solution Overview
Problem
The quantification of heavy oil compositions is challenging due to issues like oxidation, emulsions, impurities, and non-elution in chromatographic analysis, where a significant portion of heavy oil remains behind in the chromatographic column and is not detected.
Innovation Solution
A method is developed to characterize heavy oil by treating it as two portions: components up to a full elution carbon number (C60) and those beyond, using gas chromatography to determine the area fraction of non-eluted components and applying correction formulas to calculate the plus-fraction area, molecular weight, and mole fraction, with an elution ratio (R) to compensate for non-elution.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If gas chromatography is used to analyze heavy oil, then the analysis method is simple and widely applicable, but a significant portion of heavy oil components (non-eluted fraction) remains in the chromatographic column and is not detected
Solution Approach 1:
The method performs preliminary characterization of the heavy oil plus-fraction using distillation curves and empirical correlations before chromatographic analysis. By pre-determining expected component distributions and using these as reference data, the method compensates for non-eluted portions and achieves accurate quantification without modifying the straightforward GC procedure.
Solution Approach 2:
The method uses empirical correlations and distillation curve data as feedback to correct the chromatographic results. The expected component distributions from preliminary characterization are compared with actual GC measurements, and correction factors are applied to account for the non-eluted fraction, thereby improving quantification accuracy.
2Measurement precision
If the chromatographic column temperature is increased to elute heavier components, then more heavy oil components can be detected, but the risk of oxidation and thermal degradation increases
Solution Approach 1:
The method changes the analytical approach by using distillation curve parameters and empirical correlations derived from lower-temperature measurements to characterize the heavy plus-fraction. Instead of directly measuring high-carbon-number components at elevated temperatures, the method uses parameters from controlled-temperature GC analysis combined with empirical models to predict heavy component distribution, avoiding thermal degradation while achieving comprehensive characterization.
3Measurement precision
If iterative estimation and calculation methods are used to determine plus-fraction composition, then the quantification accuracy can be improved, but the complexity of the analysis method increases
Solution Approach 1:
The method uses the chromatographic data itself and readily available distillation curve information to generate correction factors through empirical correlations. The system is self-sufficient, requiring no additional complex instrumentation or external reference materials beyond what is already obtained from standard GC analysis and distillation testing.
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 method provides accurate characterization and quantification of heavy oil by accounting for non-eluted components, improving the accuracy of material properties and composition analysis, which is essential for oil production and refining processes.
Implementation Method 1
Chromatography includes the analysis of a compound to determine the identification and relative amount of the components. A sample of the compound is heated in a chromatographic column and the components detected at a detector.
Implementation Method 2
A sample of the compound is heated in a chromatographic column and the components detected at a detector.
Data Source
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AI summary
A method of determining the plus-fraction correction for a heavy oil sample including analyzing the heavy oil sample using gas chromatography, selecting an elution ratio based on the percentage of plus-fraction elution, applying the elution ratio to provide a maximum carbon number and a plus-fraction correction to compensate for the non-elution of the plus-fraction. An elution ratio as a function of the percentage of C60+ elution is provided. A corrected molecular weight for the C60+ fraction (MWC60+) and the C90+ fraction (MWC90+) as well as the total oil (MW) is provided.