Asphaltene Concentration Prediction Using High Boiling Point Precipitants
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Solution Overview
Problem
Existing methods for predicting asphaltene concentration in oil samples, such as those described in U.S. Pat. No. 8,269,961 and International Patent Application Publication WO 2013/126732, are limited by the boiling point of the precipitant used, making it challenging to correlate optical data with wet chemistry data at elevated temperatures due to vaporization issues.
Innovation Solution
Adapting the techniques by using a precipitant with a boiling point higher than the temperature of the oil sample, and correlating the absorbance data obtained with a higher boiling point precipitant to standard wet chemistry measurements using a lower boiling point precipitant like heptane, allowing for the determination of asphaltene content at elevated temperatures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a lower boiling point precipitant (e.g., heptane) is used to correlate optical data with wet chemistry data, then measurement precision is improved, but the method becomes inapplicable at elevated temperatures due to vaporization
Solution Approach 1:
The patent changes the physical parameter (boiling point) of the precipitant by substituting heptane with higher boiling point alkanes such as decane, dodecane, or tetradecane. This allows the optical measurement method to function at elevated temperatures where heptane would vaporize, while maintaining the ability to correlate with standard wet chemistry methods through a calibration relationship between different precipitants
Solution Approach 2:
The patent introduces higher boiling point alkanes as intermediary substances that bridge between the standard heptane-based wet chemistry method and the need for high-temperature optical measurements. These intermediaries allow optical data to be collected at elevated temperatures and then correlated back to standard heptane-based concentration values through established relationships
2Temperature
If a higher boiling point precipitant is used to enable elevated temperature measurements, then temperature range applicability is improved, but direct correlation with standard wet chemistry data becomes impossible
Solution Approach 1:
The patent establishes a feedback relationship where optical measurements taken with higher boiling point precipitants at elevated temperatures are correlated back to standard heptane-based wet chemistry concentration values. This feedback loop allows the system to maintain compatibility with industry standards while operating under extended temperature conditions
Solution Approach 2:
The patent transforms the measurement system by changing the precipitant parameter from heptane to higher boiling point alkanes, and simultaneously establishes a mathematical or empirical relationship that converts the optical data obtained with these alternative precipitants into equivalent heptane-based concentration values, thus restoring correlation capability
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
Enables the prediction of asphaltene concentration at elevated temperatures by establishing a correlation between absorbance data from higher boiling point precipitants and standard wet chemistry measurements, ensuring accurate determination of asphaltene content despite temperature limitations.
Implementation Method 1
The asphaltenes are normally dissolved in the crude oil, but can be precipitated out of solution by titrating the crude oil with an alkane precipitant, such as heptane
Implementation Method 2
the optical spectrum of crude oil is the sum of the optical spectra of its constituent fractions, the asphaltenes and the maltenes
Data Source
AI summary
A method for determining the asphaltene content of oil includes obtaining an oil sample, determining an optical spectrum of the oil sample and removing asphaltenes from the oil sample by precipitating asphaltenes using a first alkane precipitant. The method also includes determining an optical spectrum of maltenes of the oil sample and subtracting the optical spectrum of the maltenes of the oil sample from the optical spectrum of the oil sample to yield an optical spectrum of asphaltenes of the oil sample. The method further includes using the optical spectrum of asphaltenes of the oil sample to determine asphaltene content of the oil sample using a second alkane precipitant.