Asphaltene Induced W/O Emusilon: False or True?

Abstract

Tight brine-in-oil emulsions and related high viscosities are common oil field problems experienced in mid-to late-life. Emulsions can have a detrimental effect on water separation efficiency, and costs for injection equipment and demulsifier chemicals are high. It is commonly assumed that asphaltenes play a dominant role in emulsion formation, although in some crudes it was found that resins play a role in emulsion formation, especially the carboxylic acids. For the asphaltenes, polarity, and crude oil aromaticity play an important role in their interactions at the oil-water interface, and to a lesser degree the brine pH. For the resins, pH plays an important role, as carboxylic groups are mostly active when de-protonated. In this article, we studied the role of asphaltenes in oil/water emulsions by application of Critical Electrical Field measurements in topped oil and de-asphalted topped oil. The emulsion stability was measured for a range of water cuts (from 2 to 60%), brine pH, temperature, and shear rates.

Model molecules mimicking asphaltenes

“…-asphaltenes 1,11,12,123 -naphthenic acids [124][125][126] . It must be noticed that their properties strongly depends on their ionization degree, i.e.…”

Stability Proxies for Water-in-Oil Emulsions and Implications in Aqueous-based Enhanced Oil Recovery

“…These colloidal "particles" sit at the interface and might act as stabilizing particles. Grutters et al [41] carried out experiments to evaluate the role of asphaltenes in the stabilization of W/O emulsions in a 20 API° crude oil with the viscosity approximately 70 cP at 25 °C. They argue that the observed loss of stability when asphaltenes are precipitated could be related to decreased viscosity of the continuous phase.…”

“…Sztukowski et al [43] indicate that kaolinite has been identified as one of the most common clay minerals in oil-sands reservoirs and Kaolin clays with adsorbed asphaltenes have been identified as emulsion stabilizers. Liu et al [41] used zeta potential distribution measurements to study the interaction between bitumen and clay in aqueous solutions. In the absence of calcium, a mixture of bitumen emulsion and montmorillonite or kaolinite clay suspensions shows a bimodal zeta potential distribution.…”

Determination of Asphaltene Critical Nanoaggregate Concentration Region Using Ultrasound Velocity Measurements

“…In the context of WOE formation and remediation, asphaltenes are significant due to their surface activity and emulsion stabilisation properties 2,38,39 . Thus, asphaltenes are often likened to surfactants 40 and below we outline a number of important properties to compare with asphaltene phase behaviour.…”