Mixed Interfaces of Asphaltenes and Model Demulsifiers, Part II: Study of Desorption Mechanisms at Liquid/Liquid Interfaces

Abstract

This article is the continuation of a preceding paper (Part I) in which the adsorption and desorption of asphaltenes from the oil/water interface by pure solvent and model demulsifiers was studied. In this second part, the composition of mixed interfaces of asphaltenes and two demulsifiers (Brij®-93 and Pluronic® PE8100) was studied. Desorption of asphaltenes by demulsifiers, and vice versa, was determined. First, the composition of a mixed interface (asphaltenes and demulsifiers) through the use of the Langmuir equation of state (EoS) was determined. Second, an experimental set-up that mimics, to some extent, the chemical demulsification of water-in-crude oil emulsions during the production stages was used.Desorption of already adsorbed asphaltenes at the liquid-liquid interface by the action of two demulsifiers was assessed. It was found that desorption is always initiated by interactions between demulsifiers and asphaltenes. It is followed by the plausible formation of complexlike structures to finally end in the replacement, by displacement from the interface, of asphaltenes by demulsifiers. Third, the assessment of Brij®-93 and PE8100 desorption from the oil/water interface by the action of asphaltenes was also carried out. It was found that asphaltenes can desorb PE8100 at low surface coverage.

Sorption and Interfacial Rheology Study of Model Asphaltene Compounds

“…BisAC11 was purified by contact with silica particles (Aerosil 200) for 24h to remove any surface active impurities. Desorption experiments were performed with a previously used 42,43 accessory to the tensiometer that consists of two concentric capillary tubes (a schematic is shown in performed by duplicate at 22°C and the experimental conditions were set up based on our previous studies 42, 43 . Additional details on the technique can be found elsewhere 44,45 .…”

“…The small portion of C5PeC11 that remains at the interface could explain the prediction differences of the LvdT model. First, asphaltene adsorption is almost irreversible 43 . Secondly, extra stresses inherent to the interface are not accounted for in the LvdT model 54 .…”

“…S2 of the supporting material) accessory to the ADSA instrument. This system has been previously used to study desorption of asphaltenes and model demulsifiers, hence details on how it works can be found elsewhere 42,43 . For comparison purposes, a desorption model based on the Langmuir isotherm is also included (partly obtained from equation (3)).…”

Probing Interfacial Structure and Dynamics of Model and Natural Asphaltenes at Fluid–Fluid Interfaces

“…Enhanced oil recovery of heavy and extra-heavy hydrocarbons , and cost reduction in transportation through pipelines are strongly influenced by these interactions and set the path in the present and future work for the oil industry around the world. Asphaltenes are the most interfacially active fraction of crude oil and play an important role in issues such as conventional and unconventional oil production, flow assurance, and environmental management. − Different studies have been conducted to assess the effect of asphaltenes on these issues, but a comprehensive understanding is still elusive. − Asphaltenes are highly associative and prone to aggregation ,, and precipitation. , These may result in wettability alteration, rock permeability reduction, or crude oil thickening. , Asphaltenes stabilize water-in-oil emulsions, , an undesirable phenomenon for operations. Asphaltenes are defined as a solubility fraction which makes them inherently difficult to study because their properties will change depending on the type of oil and the precipitation procedure. − One possible way to circumvent these issues is through the use of model compounds. − However, a complete description in terms of chemistry and surface/interfacial activity is hard to obtain because a synthesized set of molecules would not be able to capture all aspects of the indigenous components.…”

Improved Oil Recovery in Carbonates by Ultralow Concentration of Functional Molecules in Injection Water through an Increase in Interfacial Viscoelasticity

“…Oil–water rheology has been studied extensively in relation to the effect of asphaltenes strengthening the oil–water interface. The polar components in crude oil may lead to a rigid, highly viscoelastic oil–water interface due to the accumulation and arrangement of heavy oil components at the interface. − The process may lead to stabilization of water-in-oil emulsions at the interface.…”