Laboratory evaluation of a novel multifunctional chemical solution for asphaltene precipitation and aggregation problem: Comparison with an industrial chemical solution

Abstract

Asphaltene deposition in the near-wellbore area and within the pipelines reduces productivity and is costly. There are usually 2 methods to remedy this hardship that are using dispersants or inhibitors to preventing asphaltene deposition or using solvents when asphaltene deposits on inner surface of pipes or in the porous media. In this study, additive called AUT Force 110 has been developed and its properties have been inspected. This solvent has multifunctional efficiencies (MS) such that can be used as asphaltene inhibition and dispersion and dissolve asphaltene deposits. Furthermore, its performance is compared to an industrial solvent called PL5001 (CS). Analyzing the fourier-transform infrared spectroscopy (FTIR) of the two additives were found to have polar functional groups of hydroxyl, thiol, carbonyl and carboxylic acid in their molecule. The existence of various functional groups gives the MS molecule the ability to interact with adjacent molecules through hydrogen bonding. In addition, aliphatic compounds were observed in the MS molecule with a low carbon number, which leads to its compatibility with crude oil. In contrast, the CS consists mainly of aromatic rings. Two carbonyl and ether functional groups were also observed in its molecular structure, which are very low in concentration compared to polar compounds of MS. Then, the confocal microscopy imaging was used to observe asphaltene aggregates with precipitant. The crude oil and n-heptane were combined in a ratio of 1–30 volumes. The addition of 100 ppm MS reduced about 87% of the mean diameter of asphaltene aggregates; while this reduction was less than 70% by adding CS. Also, adding MS narrowed the dispersion range of the asphaltene particles diameter to 2–16 μm. The carboxylic acid and thiol functional groups play important roles in asphaltene dispersion in MS system. Both MS and CS delayed the onset of asphaltene precipitation, however MS has greater asphaltene inhibition power as well as improving the rheological properties of crude oil and n-heptane solution due to the reduction in the size of asphaltene aggregates, the interaction of MS with asphaltene, and the reduction of the interaction between the asphaltene-asphaltene molecule besides the polar nature of MS. Turbiscan test was also used to measure the solvation power of two additives. The solubility number of MS was lower than that of CS and was reported to be a good solvent, indicating that it has better solvation power than CS. Because MS has the ability to hydrogen bond with asphaltene molecules as both donor and acceptor. Secondly, its aliphatic chains cause steric hindrance, which contributes to the stability of asphaltenes within MS.