Characterization of an API gravity value of crude oil by ultraviolet visible spectroscopy

1. A system for characterizing an API gravity value of an oil sample based upon ultraviolet visible spectroscopy data derived from the sample, the system comprising:

a non-volatile memory device that stores calculation modules and data, the data including ultraviolet visible spectroscopy data indicative of absorbance values over a range of wavelengths;

a processor coupled to the memory;

a first calculation module that calculates and assigns an index value for the oil sample as a summation of the absorbance values over the range of wavelengths, divided by the weight of the sample;

and a second calculation module that calculates and assigns the API gravity value of the oil sample based upon the assigned index value.

2. The system of claim 1 wherein the ultraviolet visible spectroscopy data is obtained by ultraviolet visible spectroscopy analysis is in a wavelength range from 220-500 nm.

3. The system of claim 2 , wherein the ultraviolet visible spectroscopy data is obtained from an ultraviolet visible spectroscopy analysis in a wavelength range from 220-400 nm.

4. The system of claim 1 , further comprising a third calculation module that calculates and assigns a classification to the oil sample based upon the assigned API gravity value.

5. The system of claim 1 , further comprising a third calculation module that calculates and assigns an aromaticity value to the oil sample based upon the index value.

6. The system of claim 1 , wherein the first calculation module calculates and assigns the index value based upon the ultraviolet visible spectroscopy data and a mass of the oil sample.

7. The system of claim 6 , further comprising a third calculation module that calculates and assigns a classification to the oil sample based upon the assigned API gravity value.

8. The system of claim 6 , further comprising a third calculation module that calculates and assigns an aromaticity value to the oil sample based upon the index value.

9. A system for characterizing an API gravity value of an oil sample comprising:

an ultraviolet visible spectrometer that outputs ultraviolet visible spectroscopy data derived from the oil sample,

a non-volatile memory device that stores calculation modules and data, the data including outputted ultraviolet visible spectroscopy data indicative of absorbance values over a range of wavelengths;

a processor coupled to the memory;

a first calculation module that calculates and assigns an index value for the oil sample as a summation of the absorbance values over the range of wavelengths, divided by the weight of the sample;

and a second calculation module that calculates and assigns the API gravity value of the oil sample based upon the assigned index value.

10. The system of claim 9 wherein the ultraviolet visible spectroscopy data is obtained by ultraviolet visible spectroscopy analysis is in a wavelength range from 220-500 nm.

11. The system of claim 10 , wherein the ultraviolet visible spectroscopy data is obtained from an ultraviolet visible spectroscopy analysis in a wavelength range from 220-400 nm.

12. The system of claim 9 , further comprising a third calculation module that calculates and assigns a classification to the oil sample based upon the assigned API gravity value.

13. The system of claim 9 , further comprising a third calculation module that calculates and assigns an aromaticity value to the oil sample based upon the index value.

14. The system of claim 9 , wherein the first calculation module calculates and assigns the index value based upon the ultraviolet visible spectroscopy data and a mass of the oil sample.

15. The system of claim 14 , further comprising a third calculation module that calculates and assigns a classification to the oil sample based upon the assigned API gravity value.

16. The system of claim 14 , further comprising a third calculation module that calculates and assigns an aromaticity value to the oil sample based upon the index value.

17. A method for operating a computer to characterize an API gravity value of an oil sample based upon ultraviolet visible spectroscopy data, the method comprising:

entering into the computer ultraviolet visible spectroscopy data indicative of absorbance values over a range of wavelengths;

calculating and assigning an index value of the oil sample as a summation of the absorbance values over the range of wavelengths, divided by the weight of the sample; and

calculating and assigning an API gravity value of the sample from the assigned index value.

18. The method of claim 17 , wherein the ultraviolet visible spectroscopy data is obtained by ultraviolet visible spectroscopy analysis is in a wavelength range from 220-500 nm.

19. The method of claim 18 , wherein the ultraviolet visible spectroscopy data is obtained from an ultraviolet visible spectroscopy analysis in a wavelength range from 220-400 nm.

20. The method of claim 17 , further comprising calculating and assigning a classification to the oil sample from the assigned API gravity value.

21. The method of claim 17 , further comprising calculating and assigning an aromaticity value to the oil sample based upon the index value.

22. The method of claim 17 , further comprising weighing the sample to obtain a mass, and wherein calculating and assigning the index value is based upon the ultraviolet visible spectroscopy data and the mass of the oil sample.

23. The method of claim 22 , further comprising calculating and assigning a classification to the oil sample from the assigned API gravity value.

24. The method of claim 22 , further comprising calculating and assigning an aromaticity value to the oil sample based upon the index value.

25. A method for operating a computer to characterize an API gravity value of an oil sample comprising:

operating an ultraviolet visible spectrometer that to obtain ultraviolet visible spectroscopy data derived from the oil sample;

entering into the computer the ultraviolet visible spectroscopy data, the data indicative of absorbance values over a range of wavelengths;

calculating and assigning an index value of the oil sample as a summation of the absorbance values over the range of wavelengths, divided by the weight of the sample; and

calculating and assigning the API gravity value of the sample from the assigned index value.

26. The method of claim 25 , wherein the ultraviolet visible spectroscopy data is obtained by ultraviolet visible spectroscopy analysis is in a wavelength range from 220-500 nm.

27. The method of claim 26 , wherein the ultraviolet visible spectroscopy data is obtained from an ultraviolet visible spectroscopy analysis in a wavelength range from 220-400 nm.

28. The method of claim 25 , further comprising calculating and assigning a classification to the oil sample from the assigned API gravity value.

29. The method of claim 25 , further comprising calculating and assigning an aromaticity value to the oil sample based upon the index value.

30. The method of claim 25 , further comprising weighing the sample to obtain a mass, and wherein calculating and assigning the index value is based upon the ultraviolet visible spectroscopy data and the mass of the oil sample.

31. The method of claim 30 , further comprising calculating and assigning a classification to the oil sample from the assigned API gravity value.

32. The method of claim 30 , further comprising calculating and assigning an aromaticity value to the oil sample based upon the index value.

33. The method of claim 25 , further comprising

preparing the sample for ultraviolet visible spectroscopy analysis by diluting the sample with solvent.

34. The method of claim 33 , wherein the solvent used is a mixture of paraffinic and polar solvents.

35. The method of claim 34 , wherein the paraffinic solvent contains carbon from 5-20 atoms.

36. The method of claim 34 , wherein the polar solvent is selected based on its Hildebrand solubility factor or by its two-dimensional solubility parameter.

37. The method of claim 36 , wherein the polar solvent has a Hildebrand solubility rating of at least 19.

38. The method of claim 36 , wherein the two-dimensional solubility factors of the polar solvent are the complexing solubility parameter and the field force solubility parameter.

39. The method of claim 38 , wherein the polar solvent's complexing solubility parameter component describes the hydrogen bonding and electron donor acceptor interactions.

40. The method of claim 38 , wherein the polar solvent's field force solubility parameter is based on the van der Waals and dipole interactions.

41. The method of claim 34 , wherein the paraffinic-to-polar solvent ratio is 70:30 or greater.

42. The method of claim 34 , wherein the paraffinic-to-polar solvent ratio is 90:10 or greater.