Properties of Crude Oil-in-Water and Water-in-Crude Oil Emulsions: A Critical Review

Abstract

Water and crude oil emulsions can be produced during oilfield operations. Since most oilfields are in the secondary or tertiary recovery stages, the amount of produced water is not negligible. Furthermore, enhanced oil recovery makes use of surfactants injection (chemical substances that lower the surface tension of the liquid) and polymer flooding (polymers are large molecules, composed of repeating blocks bounded together, which are injected to decrease the water–oil mobility ratio), leading to increased emulsion problems. Knowledge of fluid petrochemical properties and behavior is fundamental for designing the production system, transport infrastructures, and refinery layout. Depending on the fluid composition, the flow rate, and the PVT conditions, different physical behaviors and flow patterns will occur. Even though significant effort has been carried out to take a broader view of liquid–liquid models, there is a wide range of correlations to consider with different crude oil compositions and diverse field conditions. In this work, a critical review was carried out to assess the main principles that affect an emulsion, how the flow patterns are influenced by the water fraction, which equations can be used to estimate the main physical properties, and last what are the methods or techniques for identifying or characterizing an emulsion. As a result, a strong background in this matter is offered, and future research directions are synthesized.

Chemical Enhanced Oil Recovery from Carbonate Reservoirs by Coherent Surfactant and Surfactant–Alkali (SA) Slug Injection Using a Green Cationic Surfactant Synthesized from Avocado Oil

“…This ratio can determine the type of emulsion formed. In general, as the water content increases, the emulsion tends to change from a water-in-oil (W/O) emulsion to an oil-in-water (O/W) emulsion . The type of emulsion formed can affect its stability and behavior.…”

“…In general, as the water content increases, the emulsion tends to change from a water-in-oil (W/O) emulsion to an oil-in-water (O/W) emulsion. 56 The type of emulsion formed can affect its stability and behavior. Different types of emulsions are effective in EOR process; however, a system that includes both water-in-oil and oil-in-water emulsions is known to be the most effective.…”

Adsorption and Aggregation Behavior in Aqueous Solution of Tetrasiloxane‐based Carboxylate Surfactants via “Thiol‐ene” Photochemical Reaction

“…These anionic carboxylate silicone surfactants with excellent performance have the ability to replace traditional hydrocarbon surfactants used in cosmetics, emulsifiers, and crude oil extraction. [57,58] In addition, owing to their non-toxic and negatively charged properties, they are good candidates to replace cationic silicone surfactants in textile dyeing, biomaterials, and drug carriers.…”

Solubility of Asphaltenes in Maltenes under Different Conditions

“…Despite the important information obtained and the possibility of proposing interaction mechanisms, these analytic techniques do not directly investigate the colloidal properties of the asphaltenes . Recent studies have been carried out to isolate and characterize the chemical structures of interfacially active molecules with the aim of correlating this characteristic with the respective degrees of interfacial activity, having identified interfacially active molecules in both the asphaltenes and maltenes fractions. − The molecules present in crude oil, such as resins, naphthenic acids, and asphaltenes, play a fundamental role in the stabilization of water-in-oil emulsions, due to their amphiphilic characteristics. , …”

“…11−13 The molecules present in crude oil, such as resins, naphthenic acids, and asphaltenes, play a fundamental role in the stabilization of water-in-oil emulsions, due to their amphiphilic characteristics. 14,15 The precipitation of asphaltenes is a problem in the petroleum industry, due to their deposition in reservoirs, storage tanks, pipelines, and refinery equipment. Therefore, understanding the solubility of asphaltenes is important to minimize or prevent their precipitation during the production and refining stages, thus mitigating the flow reduction of crude oil and refined products and reducing the need for shutdowns for cleaning and maintenance, which cause additional costs.…”