Viscosity reduction of crude oil through structure determination of asphaltene molecule
Asphaltene may be effectively broken into smaller molecules by first elucidating the structure of the asphaltene and then developing a catalyst system based on the elucidated structure. The structure may be determined based on a series of analytical techniques including NMR, FTIR, Raman spectroscopy, XPS, and LDI. The most probable structure is determined using computational methods based on quantum mechanics and classical molecular dynamics and the catalyst system is developed for the most probable structure.
1. A method of catalytically breaking asphaltene macromolecules comprising:
a. obtaining a sample of a fluid containing the asphaltene macromolecules;
b. identifying a target structure of the aromatic core of the asphaltene macromolecules in the fluid;
c. estimating the free energy of the target structure;
d. identifying aliphatic and functional groups within the asphaltene macromolecules;
e. approximating the probability of a molecular structure of the target structure and estimating the free energy of the molecular structure;
f. developing a catalyst system capable of breaking the bonds of a most probable molecule and
g. breaking down the asphaltene macromolecules into small molecules with the developed catalyst system.
2. The method of claim 1 , wherein the fluid is crude oil.
3. The method of claim 1 , wherein the functional groups are carbonyls, hydroxyls and sulfoxides.
4. The method of claim 3 , wherein the developed catalyst system has a component capable of breaking the bonds of the carbonyl, hydroxyl or sulfoxide functional groups.
5. The method of claim 1 , wherein step (b) further comprises determining the percent carbon, hydrogen, nitrogen, oxygen, sulfur, nickel and vanadium in the asphaltene sample.
6. The method of claim 1 , further comprising determining the architecture of the asphaltene sample, wherein the architecture is either rosary, island or a combination thereof.
7. The method of claim 1 , wherein step (b) further comprises determining the presence and quantity of pyridine, pyrrole, sulfoxide and thiophene in the asphaltene sample.
8. The method of claim 7 , wherein the developed catalyst system has a component capable of breaking the bonds of the pyridine, pyrrole, sulfoxide and thiophene.
9. The method of claim 1 , wherein the functional groups in the asphaltene sample are determined in step (d) by x-ray photoelectron spectroscopy.
10. The method of claim 1 , wherein the aromatic core size of the asphaltene sample is determined in step (b) by Raman spectra.
11. The method of claim 1 , wherein step (b) further comprises identifying a type of linkage of a heteroatom in the asphaltene macromolecule.
12. The method of claim 1 , further comprising subjecting the asphaltene sample to elemental analysis.
13. The method of claim 1 , further comprising assessing the aromatic content, aliphatic content and side chain content of the asphaltene sample.
14. The method of claim 13 , further comprising, in conjunction with 13 C, determining the presence of —CH 3 , —CH 2 and —CH in the asphaltene sample by Distortionless Enhancement by Polarization Transfer.
15. The method of claim 1 , wherein step (b) further comprises determining chains of the asphaltene sample.
16. The method of claim 1 , further comprising determining the molecular weight distribution of the asphaltene sample by Laser Desorption Ionization.
17. A method of catalytically breaking asphaltene macromolecules comprising:
a. obtaining a most probable molecular structure of the asphaltene macromolecules that is based on target structures of an aromatic core of the asphaltene macromolecules, and that are identified by analytical techniques and a geometric optimization based on a free energy calculation;
b. performing computational analysis to select a catalyst system from a catalyst inventory, and that is capable of breaking bonds of the most probable molecular structure; and
c. breaking the bonds of the asphaltene macromolecules with the selected catalyst.
18. A method of breaking bonds in asphaltene macromolecules comprising:
a. determining a molecular structure of the asphaltene macromolecules based on target structures of an aromatic core of the asphaltene macromolecules;
b. estimating bond energies of the target structures within the molecular structure;
c. identifying a catalyst system based on the estimated bond energies; and
d. promoting a reaction of the asphaltene macromolecules with the identified catalyst system that breaks down the asphaltene macromolecules.
19. The method of claim 18 , further comprising approximating the probability of a molecular structure of the target structures and estimating the free energy of the molecular structure.
20. The method of claim 19 , further comprising identifying the most probable structure based on the free energy calculation of the target structure.