Effect of Water on Deposition, Aggregate Size, and Viscosity of Asphaltenes

Abstract

The aggregation and structure of polar molecules in nonpolar media may have a profound effect on bulk phase properties and transport. In this study, we investigate the aggregation and deposition of water and asphaltenes, the most polar fraction in petroleum fluids. In flow-line experiments, we vary the concentration of water from 500 up to 175,000 ppm and provide the evidence for clear changes in asphaltene deposition. Differential interference contrast (DIC) microscopy and dynamic light scattering (DLS) are used to measure the size of the aggregates. Rheological measurements are performed to get fixed ideas on the structural changes that water induces at different concentrations. This study demonstrates the significant effect of water on asphaltene aggregation and deposition and explores the molecular basis of water-asphaltene interaction. Our aggregate size measurements show that while asphaltene molecules increase the solubilization of water, there is no increase in the aggregate size. Our aggregation size measurements are different from the reports in the literature.

Controlled releases of asphaltene inhibitors by nanoemulsions

“…Non-polar oils dissolve very small amounts of water depending on the saturation limit of the type of oil. Beyond the saturation limit, water becomes either emulsified when surfactants are added or separated as free water [46,47]. According to Sjöblom et al [46] and Aslan et al [47], water delays the precipitation of asphaltene, which could be due to i) water forms a layer around asphaltene and prevents asphaltene from precipitation or ii) water molecules act as a bridge between asphaltene molecules via hydrogen bonds between water molecules and heteroatoms in asphaltenes.…”

Molecular dynamic simulation of asphaltene co-aggregation with humic acid during oil spill

“…During the last decade, great efforts have been made to interpret the asphaltene aggregation process using experimental techniques and molecular simulation approaches. For instance, the effects of temperature and pressure (Espinat et al, 2004), solvent (Aslan and Firoozabadi, 2014), inhibitors (Safaie and Nazar, 2014), molecular structures (Jian et al, 2013(Jian et al, , 2014 and concentrations (Haji-Akbari et al, 2014) on the asphaltene aggregation were investigated. However, our understanding on the driving force and inhibition factors on the asphaltene aggregation remains limited.…”

Modeling of asphaltene and water associations in petroleum reservoir fluids using cubic‐plus‐association EOS

“…The L 1 phase is calculated to also contain n ‐butane in the presence of asphaltene and water. One way to interpret this calculation result is that the L 1 phase contains water‐in‐oil emulsion. When the pressure is reduced to 3400 kPa, the L 2 phase is split into the V and L 2 phases, while the L 1 and W phases remain nearly unaffected.…”

“…One of the known limitations in cubic EOS is that they are originally not designed to represent complex phase behavior associated with polar components, such as water and asphaltene. These polar components are quite common in oil reservoirs, especially in viscous‐oil reservoirs . Modeling of them is important when they affect oil‐recovery mechanisms and processes; for example, asphaltene precipitation/deposition during CO 2 injection and coinjection of steam and solvent for heavy‐oil/bitumen recovery .…”