Assessment of solute partitioning in crude oils (Exxonmobil)

CATEGORY: CRUDE OIL ANALYSIS
PATENT
Assessment of solute partitioning in crude oils (Exxonmobil)
Publication number US20130317793 A1
Publication type Application
Application number US 13/895,635
Publication date Nov 28, 2013
Also published as WO2013176971A2
Inventors
Narasimhan Sundaram, Bryan M. Knickerbocker, Steven Wong
Original Assignee
Exxonmobil Research And Engineering Company
Abstract
Partition coefficients for solutes in solvent-water systems are estimated based on corresponding values for the octanol-water system. The estimation of the partition coefficient includes correction factors based on the nature of the solute and the solvent. Petroleum fractions are an example of a suitable solvent for which a partition coefficient can be estimated, although other types of solvents can be used in developing a model for use in the estimation.
FIELD OF THE INVENTION
This invention provides methods for assessing the partitioning of solutes between oil fractions and water.
BACKGROUND OF THE INVENTION
Petroleum processing and extraction typically results in the interaction of various chemicals with a crude oil, crude oil fraction, pipelineable fraction, or refinery stream. Due to the large number of crude oil compositions and further variations introduced by processing of crude oils, a vast number of combinations of petroleum fraction plus additive are possible. Performing a detailed analysis of each possible combination is impractical for a variety of reasons. As a result, it is desirable to have methods which can allow for prediction of the properties and/or outcomes when a substance is added to a petroleum fraction or refinery stream.
Previous journal articles describes prediction of partition coefficients of organic solutes between water and immiscible solvents. (See Leo et al., Chem. Rev., Vol. 71, pg 525 (1971) or Journal of Organic Chemistry, Vol. 36, pg 1539 (1970).) The article describes efforts to develop a linear correlation between partition coefficients for the octanol-water system and partition coefficients for various organic solvents with water. The organic solvents in the journal article are solvents having ten carbons or less.
SUMMARY OF THE INVENTION
In one aspect, a method is provided for predicting a partition coefficient for a solute between a petroleum fraction and water. The method includes selecting a solute class for a solute; determining a solubility constant of water in a petroleum fraction; calculating a solute activity factor based on the solubility constant of water in the petroleum fraction, a solubility constant of the solute in water, a partition coefficient for the solute in octanol and water, and the solute class; and predicting a partition coefficient for the solute in the petroleum fraction and water based on the partition coefficient for the solute in octanol and water, the solute activity factor, and a scaling factor based on the solubility constant of water in the petroleum fraction.
In another aspect, a method is provided for predicting a partition coefficient for a solute between a solvent and water. The method includes identifying a plurality of solute classes; fitting parameters for determining a slope in a linear or quasi-linear relationship between a partition coefficient in a solvent and water and a corresponding partition coefficient in octanol and water, the parameters for determining the slope corresponding to coefficients in a polynomial expression, the fitting of parameters being based on a plurality of solvent-water systems; selecting a solute class for a solute;
determining a solubility constant of water in a solvent, the solvent being different from solvents in the plurality of solvent-water systems; calculating a solute activity factor based on the solubility constant of water in the solvent, a solubility constant of the solute in water, a partition coefficient for the solute in octanol and water, and the solute class; and predicting a partition coefficient for the solute in the solvent and water based on the partition coefficient for the solute in octanol and water, the solute activity factor, and a scaling factor based on the solubility constant of water in the solvent
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