Breaking of Water-in-Crude-Oil Emulsions. 2. Influence of Asphaltene Concentration and Diluent Nature on Demulsifier Action

Abstract

The stability of water-in-oil emulsions formed during oil slicks or petroleum production operations is ensured by natural surfactant molecules (principally asphaltenes) that are present in the crude oil. These persistent emulsions may be broken by adding a suitable demulsifier at the proper concentration to attain a so-called optimum formulation at which the stability of the emulsion is minimum. In this report, the concentration of asphaltenes is varied by diluting the crude oil with a solvent such as cyclohexane, toluene, or mixtures of them. The experimental evidence shows that there exists some critical asphaltene concentration at which the interfacial zone seems to be saturated. Beyond this threshold, which is typically around 1000 ppm of asphaltenes, the demulsifier concentration necessary to attain the emulsionʼs quickest breaking is constant. Below it, e.g. when the crude is highly diluted with a solvent, the optimum demulsifier concentration is found to be proportional to the asphaltene concentration. The map of emulsion stability versus asphaltene and demulsifier concentrations exhibits a typical pattern for different demulsifiers and diluents, which contributes to improving the interpretation of the demulsifying action.

Evaluating the hydrophilic–lipophilic nature of asphaltenic oils and naphthenic amphiphiles using microemulsion models

“…Aside from predicting the phase behavior given a set of processing conditions, the HLD can also be used to assess processing conditions which promote the destabilization of emulsions in crude oil formulations [5,9,[52][53][54][55][56]. Stable emulsions are produced near the phase transitions Type I-III and Type III-II where jHLDj % 1-5 [5].…”

“…It is well established that reducing the solubility of asphaltenes within the oil phase results in the formation of aggregates that are surface-active compared to their monomeric counterparts [5][6][7][8][9][10]. This surfaceactivity has been linked to the formation of asphaltene skins at the oil-water interface that contribute to the stability of emulsions [11,12].…”

Application of rhamnolipid as a novel biodemulsifier for destabilizing waste crude oil

“…), the proposed added chemical surfactants and the natural solid particles (clay and waxes) (Banat et al, 2000;Jiang et al, 2010;Rondón et al, 2007). Such waste crude oil was normally comprised of 30-90% of oil, 30-70% of water and 2-15% of solids by mass and presented as a complex water-in-oil (W/O) type emulsion (Yang et al, 2005;Zhang et al, 2012).…”

Surface Properties and Thermodynamic Parameters of Some Sugar‐Based Ethoxylated Amine Surfactants: 1—Synthesis, Characterization, and Demulsification Efficiency

“…It has been previously mentioned that the demulsifier destabilizes the emulsion either by replacing part of the asphaltene molecules that are arranged on the interface [29] or by combining with them [30,31]. This process is clearly time-consuming.…”