Critical Review of Underlying Mechanisms of Interactions of Asphaltenes with Oil and Aqueous Phases in the Presence of Ions

Abstract

Asphaltene studies have been a prime focus topic for many decades. However, the underlying interaction mechanisms between water, oil, and asphaltenes requires more attention. Water is involved in all production parts (reservoir, tubing, surface facilities, and refinery), posing comprehensive research about the issues and operating conditions. According to the available literature, there are contradictory opinions regarding the effect of salinity on the aqueous phase and the oil phase interfacial characteristics. This review provides a critical summary of asphaltene’s role in the stability of the aqueous phase emulsions in an oil phase. We reviewed the effect of temperature, pressure, asphaltene concentration, bulk phase components, different salinity, types of ions, and pH on emulsion stability regarding the low salinity water injection aspects. Moreover, the studied cases investigating emulsion stability in the presence of asphaltenes and other species were collected, compared, and categorized. Furthermore, the interfacial and rheological characteristics of the brine–oil interface composed of asphaltenes and other species were compared. We found that the effect of some parameters requires an in-depth study as there are not many related works. For example, the effect of pressure on the rheological characteristics of emulsions and, at the same time, on the aggregation, precipitation, and deposition using visual devices (high pressure–high temperature microfluidic) is missing from the literature. Therefore, we recommend a specific study of each crude oil’s combined effects of temperature, pressure, and salinity. Low salinity water injection is a newly developed enhanced oil recovery method that employs the results of emulsion studies in the presence of different ions and reservoir conditions (high pressure and high temperature).

Impact of the Temperature, Homogenization Condition, and Oil Property on the Formation and Stability of Crude Oil Emulsion

“…Undesirable emulsification has become a critical issue in the petroleum industry. − Crude oil emulsions are encountered during the initial stages of the oil recovery process . Even in low-salinity water flooding (LSWF), a popular method for enhanced oil recovery (EOR) in recent years, emulsion formation can pose challenges as a result of aqueous-phase injection. , Emulsification occurs during oil transportation, processing, and storage as well. , Emulsions, with their larger particle sizes compared to oil or water, can obstruct porous media in reservoirs, leading to inefficient displacement and reduced oil recovery. , The increase in viscosity induced by added water in emulsions can result in elevated pressure drops . The consequences of emulsification in the petroleum industry are far-reaching, including a decrease in oil quality, higher transportation costs, catalyst poisoning in refineries downstream, and corrosion of facilities, pipelines, and tanks. ,, This not only escalates production costs but also reduces the yield of valuable crude oil .…”

“…Various types of crude oil emulsions, including water-in-oil (W/O), oil-in-water (O/W), water-in-oil-in-water (W/O/W), and oil-in-water-in-oil (O/W/O) emulsions, can be found in oilfields . Among them, the W/O emulsion, often referred to as “chocolate mousse”, poses the most common and challenging issue in the petroleum industry. − The primary reason for the formation of crude oil emulsions is typically attributed to increased energy resulting from turbulence, mixing, or agitation. ,,, Studies by Chen and Tao investigated the effects of stirring intensity and mixing time on emulsion stability, using commercial diesel as the oil phase and sorbitan monooleate as the emulsifier . They found that more stable emulsions were obtained with increasing stirring speed or extended mixing time.…”

Molecular dynamics simulations of aggregation and viscosity properties of model asphaltene molecules containing a polycyclic hydrocarbon nucleus with toluene additive under shear interactions

“…1–3 Therefore, studying the viscosity reduction of asphaltene can help improve the utilization efficiency of crude oil. 4–7…”

Mini-Review on Water–Oil Emulsions through Vibrational Sum Frequency Generation

“…Surfactants are divided into categories such as anionic (e.g., carboxylate or sulfonate), cationic (e.g., quaternary ammonium salt), Zwitterionic (contain both charges simultaneously), and nonionic (e.g., polyoxyethylenated alcohol), in which each type has its own utilization and functionality . Natural surfactants can be also present in different forms, such as those in crude oil, in which natural carboxylic acids, − or macro-molecules (e.g., asphaltenes), − and solid particles (inorganic and organic particles), − can be present.…”