Experimental investigation of a novel multifunctional chemical solution on preventing asphaltene precipitation using two crude oil samples with different molecular properties

Abstract

Asphaltene deposition in the reservoir and the pipelines reduce production and increases costs. There are two strategies for dealing with this problem using dispersant or inhibitor to prevent asphaltene precipitation, or in case of deposition, solvents are used. In this study, a solvent called AUT Force 110 was constructed, and its properties were investigated. This solvent is also called multifunction (MS) because of its molecular geometry for asphaltene inhibition and dispersion as well as dissolving asphaltene. Its performance was examined on two crude oil samples with different molecular properties. The Fourier-transform infrared spectroscopy (FTIR) showed the MS solvent comprised of polar functional groups including hydroxyl, thiol, carbonyl, and carboxylic acid. The presence of these functional groups enables the MS molecule to form hydrogen bonds with adjacent molecules. Also, aliphatic compounds in MS molecule observed with a low carbon number that causes its compatibility within the crude oil. In the next stage, the dynamic light scattering (DLS) was used to measure the hydrodynamic diameter of asphaltene in the presence of precipitant. If asphaltene contains a high concentration of acidic functional groups such as thiol and hydroxyl, MS will reduce about six times the particles diameter. However, increasing the length of aliphatic chains and reduction in the tendency of asphaltene to form hydrogen bonds, the performance of MS in asphaltene dispersion rises. The MS has excellent potential in asphaltene inhibition regardless the type of crude oil and asphaltene molecular structure. The addition of 100 ppm MS to crude oil and n-heptane solution improved the rheological properties of the solution, and viscosity also reduced. Calculating the solubility number index, MS was classified in the category of solvents with moderate to good solvation power. MS is known as a hydrogen bonding acceptor and donor due to containing hydroxyl, thiol and carbonyl functional groups, and can establish strong interactions with deposited asphaltene. Since, MS has long aliphatic chains in its structure, creating steric hindrance prevents re-aggregation of asphaltene particles and makes a stable solution.