Impact of Asphaltene Stabilizers on the Elasticity of a Crude Oil-Water Interface and Its Correlation to Demulsification under Desalting Conditions

The use of asphaltene stabilizers, also referred to as crude stabilizers, is a valuable chemical tool available to the refiner to successfully process unstable or incompatible crude oil blends in crude oil desalters. The increasing interest in crude stabilizers has motivated the need to understand their mechanism of action and ways to predict their actual performance in the field from lab-scale experiments. In the present study, commercial crude stabilizers were evaluated as asphaltene inhibitors and as interfacial viscosity modifiers in interfacial dilatational rheology experiments. Moreover, their ability to enhance the activity of a commercial demulsifier to break water-in-crude oil emulsions was evaluated in a lab-scale electrostatic desalter simulator that aims to replicate the conditions of a refinery desalter. The results showed that the improvement in demulsification efficiency did not correlate to the asphaltene inhibition performance, but it correlated better to the reduction in interfacial viscosity (viscous modulus) due to the addition of crude stabilizers. The synergistic interactions between the demulsifier and some crude stabilizers were captured in the interfacial dilatational experiments, which suggests that this technique would be a useful tool for the selection of the best demulsifier/crude stabilizer combination, and quantify the expected performance and benefits in the refinery desalter.

Automated summary

The use of crude stabilizers is an important chemical tool for refining unstable crude oil blends. Research has found that the ability of crude stabilizers to enhance demulsifier activity is mainly related to reducing interfacial viscosity rather than inhibiting asphaltenes. Interfacial dilatational experiments can capture the synergistic interactions between demulsifiers and certain crude stabilizers, making it a useful tool for selecting the best demulsifier/crude stabilizer combination.