Effect of Emulsified Water on Asphaltene Instability in Crude Oils

Abstract

Understanding asphaltene precipitation and subsequent deposition during oil production is of great importance for the oil industry nowadays because of the potential risk associated with this heavy fraction in plugging wellbores and production equipment. Although water is commonly present in the produced fluids, because of instrument limitations and inadequate techniques, it is usually separated from the oil prior to any experimental analysis. Therefore, the effect of water on asphaltene stability and deposition tendency is not completely understood, and the information available in the literature is scarce. In this work, the effect of emulsified water on asphaltene instability in crude oil systems is investigated. Three crude oils and one bitumen sample were used in this study. The crude oils had American Petroleum Institute (API) gravities ranging from 26°to 40°and asphaltene content between 1.2 and 13 wt %. Model oils were also prepared with asphaltenes extracted from these crude oils. A total of nine systems were investigated with and without the presence of emulsified water. It was found that, for the crude oils from the Middle East and Canada and their corresponding model oils, the addition of water did not have a significant effect on either the detection of asphaltene precipitation or the amount of precipitated asphaltenes. However, the stability of asphaltenes in the crude oil from the Gulf of Mexico and the model oils from the Athabasca bitumen (containing n-C 5 and n-C 7 asphaltenes) was significantly affected by the presence of water. The experimental evidence suggests that some asphaltenes are more prone to interact with water at the oil−water interface. This work provides a simple technique to screen whether water has an effect on asphaltene stability for a given crude oil at ambient pressure and different temperatures. With this study, we aim to contribute to a better understanding of the interaction of water and asphaltenes in crude oil systems, which will eventually lead to the development of cost-effective strategies for the mitigation of this flow assurance problem.

Water versus Asphaltenes; Liquid–Liquid and Solid–Liquid Molecular Interactions Unravel the Mechanisms behind an Improved Oil Recovery Methodology

“…In the past decade, a limited number of controversial research studies have been undertaken to understand the effect of water emulsions on asphaltene precipitation and deposition. From a review of available literature 28–31 , it appears that opinion differs significantly as to which experimental methods should be utilised to determine the asphaltene stability and deposition tendency, which conditions should be applied and how data should be interpreted. Several workers have claimed that the existence of water microemulsions had no remarkable influence on the asphaltene precipitation 28,31 , while others concluded that water increases the solubility of the asphaltenes in the system and delays the asphaltene aggregation and deposition phenomena 29,30 .…”

Combined interfacial shear rheology and microstructure visualization of asphaltenes at air-water and oil-water interfaces

“…Additionally, asphaltenes are known to be surface-active and assemble at oil-water and air-water interfaces, often forming an interfacial film. This leads to flow assurance problems, such as difficulty in transporting highly viscous fluids or separating phases in stabilized water-in-oil emulsions [13,14]. Furthermore, tailings/wastewater containing bitumen and crude oil that are discharged into tailing ponds often deposit and form a film on the pond [15,16].…”

Application of Magnetic and Dielectric Nanofluids for Electromagnetic-Assistance Enhanced Oil Recovery: A Review

“…More studies are anticipated in the future for better clarifications of this mechanism. While investigation of asphaltene-brine interaction is still ongoing, some studies were made with dissimilar opinions, whereby some researchers advocated that the presence of water microemulsions has no significant effect on the precipitation and deposition of the asphaltene [24,25], whereas the others recommended that asphaltene deposition and aggregation were observed to reluctantly act in the presence of water, and also that the asphaltenes solubility was equally found to have increased when water was present [26,27].…”