Determination of Hamaker constants for asphaltenes in a mixture of pentane and benzene

Asphaltene deposition during oil production may lead to expensive and frequent clean-up operations. Knowledge of the interaction between asphaltene particles and deposition is vital in order to predict the magnitude of this problem. Surface energies for asphaltenes precipitated at field conditions are determined from measurements of contact angles of several probe liquids. Using the surface tension component model, the energies are found to be dispersive. Hamaker constants of a simple mixture of pentane and benzene are estimated from the application of Lifshitz theory. The effective Hamaker constants of asphaltenes in a pentane/benzene mixture are calculated. It is shown that increasing amounts of benzene lowers the attractive interaction between asphaltenes. This result is consistent with the definition that asphaltenes are soluble in benzene. (C) 2008 Elsevier B.V. All rights reserved.