Characterization of crude oil by ultraviolet visible spectroscopy

1. A system for characterizing the API gravity of a sample of crude oil based upon ultraviolet visible spectroscopy data derived from the sample and the weight of the sample, the system comprising:

an ultraviolet visible spectrophotometer;

a non-volatile memory device that stores calculation modules and data;

a processor coupled to the non-volatile memory;

a first calculation module that calculates a crude oil ultraviolet visible index value for the sample from a summation of absorbance values of the spectroscopy data over a predetermined range of wavelengths, divided by the weight of the sample;

and a second calculation module that characterizes the API gravity of the sample based on the crude oil ultraviolet visible index.

2. A system for characterizing the API gravity of a sample of crude oil based upon separately provided ultraviolet visible spectroscopy data of the sample and a separately provided weight of the sample, the system comprising:

an ultraviolet visible spectrophotometer;

a non-volatile memory device that stores calculation modules and data;

a processor coupled to the non-volatile memory;

a first calculation module that calculates a crude oil ultraviolet visible index of the sample from a summation of absorbance values of the spectroscopy data over a predetermined range of wavelengths, divided by the weight of the sample;

a second calculation module that calculates an estimated API gravity of the sample based on the crude oil ultraviolet visible index;

and a third calculation module that calculates a classification value for the sample from the estimated API gravity.

3. A method for operating a computer to characterize the API gravity of a sample of a hydrocarbon oil collected from an oil well, stabilizer, extractor, or distillation tower, the method comprising:

weighing the sample;

preparing the sample for ultraviolet visible spectroscopy analysis by diluting the sample with solvents;

obtaining ultraviolet visible spectroscopy data from an ultraviolet visible spectroscopy analysis in a wavelength range from 220-500 nm;

entering into the computer spectra data obtained by ultraviolet visible spectroscopy analysis of the sample;

calculating an ultraviolet visible index of the sample from a summation of absorbance values of the ultraviolet visible index spectroscopy data, divided by the weight of the sample;

calculating the API gravity of the sample from the ultraviolet visible index;

determining from the API gravity the nature of products that can be manufactured from the crude oil; and

determining an appropriate refining technology to allow the products to be processed most efficiently and effectively.

4. The method of claim 3 , wherein the ultraviolet visible spectroscopy data is obtained from an ultraviolet visible spectroscopy analysis in a wavelength range from 220-400 nm.

5. The method of claim 3 , wherein the solvent used is a mixture of paraffinic and polar solvents.

6. The method of claim 5 , wherein the paraffinic solvent contains carbon from 5-20 atoms.

7. The method of claim 5 , wherein the polar solvent is selected based on its Hildebrand solubility factor or by its two-dimensional solubility parameter.

8. The method of claim 7 , wherein the polar solvent has a Hildebrand solubility rating of at least 19.

9. The method of claim 7 , wherein the two-dimensional solubility factors of the polar solvent are the complexing solubility parameter and the field force solubility parameter.

10. The method of claim 9 , wherein the polar solvent's complexing solubility parameter component describes the hydrogen bonding and electron donor acceptor interactions.

11. The method of claim 9 , wherein the polar solvent's field force solubility parameter is based on the van der Waals and dipole interactions.

12. The method of claim 5 , wherein the paraffinic-to-polar solvent ratio is 70:30 or greater.

13. The method of claim 5 , wherein the paraffinic-to-polar solvent ratio is 90:10 or greater.

14. A method for operating a computer to characterize the API gravity of a sample of oil collected from an oil well, stabilizer, extractor, or distillation tower, the method comprising:

weighing the sample;

preparing the sample for ultraviolet visible spectroscopy analysis by diluting the sample with solvents;

obtaining spectra data for the sample by an ultraviolet visible spectroscopy analysis in a wavelength range from 220-500 nm;

entering into the computer the spectra data for the sample;

calculating an ultraviolet visible index of the sample based on a summation of absorbance values of the spectra data, divided by the weight of the sample;

calculating an estimated API gravity from the ultraviolet visible index;

classifying the sample from the estimated API gravity and determining from the API gravity the nature of products that can be manufactured from the crude oil; and

determining an appropriate refining technology to allow the products to be processed most efficiently and effectively.

15. The method of claim 14 , wherein the ultraviolet visible spectroscopy data is obtained from an ultraviolet visible spectroscopy analysis in a wavelength range from 220-400 nm.

16. A system for characterizing a sample of crude oil based upon ultraviolet visible spectroscopy data for the sample and the weight of the sample, the system comprising:

an ultraviolet visible spectrophotometer;

a non-volatile memory that stores calculation modules and data;

a processor coupled to the non-volatile memory;

a first calculation module that calculates a crude oil ultraviolet visible index of the sample based on a summation of absorbance values of the spectroscopy data over a predetermined range of wavelengths, divided by the weight of the sample;

and a second calculation module that calculates the aromaticity of the sample from the crude oil ultraviolet visible index.

17. A system for characterizing a sample of crude oil based upon ultraviolet visible spectroscopy data for the sample and the weight of the sample, the system comprising:

an ultraviolet visible spectrophotometer;

a non-volatile memory that stores calculation modules and data;

a processor coupled to the non-volatile memory;

a first calculation module that calculates a crude oil ultraviolet visible index of the sample from a summation of absorbance values of the spectroscopy data over a predetermined range of wavelengths, divided by the weight of the sample;

a second calculation module that estimates the API gravity of the sample from the crude oil ultraviolet visible index;

and a third calculation module that calculates the aromaticity of the sample from the crude oil ultraviolet visible index.

18. A method for operating a computer to characterize a sample of crude hydrocarbon oil collected from an oil well, stabilizer, extractor, or distillation tower, the method comprising:

weighing the sample;

preparing the sample for ultraviolet visible spectroscopy analysis by diluting the sample with at least one paraffinic solvent and at least one polar solvent;

obtaining ultraviolet visible spectroscopic spectra data from an ultraviolet visible spectroscopy analysis in a wavelength range from 220-500 nm;

entering into the computer the spectra data obtained for the sample;

calculating an ultraviolet visible index of the sample based on a summation of absorbance values of the spectra data, divided by the weight of the sample;

characterizing the gravity of the sample from the ultraviolet visible index;

calculating the aromaticity of the sample from the ultraviolet visible index;

determining from the gravity and the aromaticity the nature of products that can be manufactured from the crude oil; and

determining an appropriate refining technology to allow the products to be processed most efficiently and effectively.