(75d) An Automated Microfluidic System for High Throughput Mechanistic Study of Asphaltenes Deposition and Dissolution in Porous Media Using in Situ Spectroscopy

Asphaltenes, known as ‘cholesterol in petroleum’, attributed to the viscous properties of the crude oil. The precipitation and deposition of asphaltenes could lead to the fouling and impairment problem in petroleum industry. The motivation to tackle these problems triggered great interests in both academic and industrial research. However, the study of asphaltenes could be laborious and time-consuming due to the broad definition of asphaltenes. Defined as materials that are soluble in aromatic solvents and insoluble in alkane solvents, asphaltenes molecules have a rather complex molecular structure: aromatic core with heteroatoms (e.g., N, O, and S) and metals (e.g., V, Ni, and so on).^1–4 These facts result in requirement for high throughput experimentation in asphaltenes study.

In the present work, we designed and assembled an automated microfluidic system to achieve the high throughput study of asphaltenes deposition and dissolution in porous media. The experimental period was decreased from days and weeks to minutes and hours when compared with our previous version of micro-packed bed reactor. The Peltier module enabled the swift temperature change of the microsystem at the rate of 1.0 K/s. The in-situ characterization window of the microsystem enabled the access to implement the characterization of the micro-packed bed region during the asphaltenes deposition and dissolution process by Raman spectroscopy for the first time. The acquisition of Raman mapping of the 4.5-µL micro-packed bed region took about 21 min to finish. As a result, one would obtain 5 maps during asphaltenes deposition and dissolution process. The result of bed occupancy provided the concentration of asphaltenes onto the porous media, while the sheet size information of asphaltenes provided the molecular level information about asphaltenes. The results will be presented and explanted to provide the insights toward the mechanisms of asphaltenes deposition and dissolution.

Reference:

(1) Mullins, O. C. The Asphaltenes. Annu. Rev. Anal. Chem. 2011, 4 (1), 393–418.

(2) Gray, M. R.; Tykwinski, R. R.; Stryker, J. M.; Tan, X. Supramolecular Assembly Model for Aggregation of Petroleums Asphaltenes. Energy Fuels 2011, 25 (7), 3125–3134.

(3) Hu, C.; Morris, J. E.; Hartman, R. L. Microfluidic Investigation of the Deposition of Asphaltenes in Porous Media. Lab Chip 2014, 14 (12), 2014–2022.

(4) Pinho, B.; Minsariya, K.; Yen, A.; Joshi, N.; Hartman, R. L. Role of HZSM‑5 Aluminosilicates on Asphaltenes Deposition by High-Throughput in Situ Characterizations of a Microreservoir. Energy Fuels 2017, 31, 11640–11650.