Assessment of Asphaltene and Maltene Interfacial Interactions with Antifoam Additives: A Rheological Approach

Polydimethylsiloxane (PDMS)-based oil antifoams are extensively employed, but still, their impact on oil remains inconclusive due to the intricate nature and diverse composition of the oil. So far, the literature declares asphaltenes as the main contributors to foam stabilization followed by resins, along with short-chain carboxylic acids, solids, and even naphthenic acids. The present work aims to study the influence of antifoam formulations containing silicones of different molar masses on the oil/air interface, as well as evaluate its influence on the fractions separately, that is, on asphaltenes, on the model solution/air interface, and also on resins, examining the maltene/air interface. Hence, the interfacial rheology technique utilizing the Double Wall Ring (DWR) accessory was employed to assess the viscoelastic behavior of oil and its constituents (asphaltenes and maltenes) in the presence of antifoam products. This approach aims to gain insight into how these products interact with the oil-air interface and the various fractions of the oil. The findings from the DWR accessory align with the results of the foam formation tests, indicating that the products demonstrating superior efficacy in reducing the initial foam height also played a role in decreasing the interfacial elastic modulus of the respective systems.