Aging of water-in-crude oil emulsions: Effect on rheological parameters

The production of crude oil containing emulsified water causes various problems, such as corrosion of transport systems and catalyst poisoning during refining. The ease of separating the produced water from the oil varies with the emulsionʹs age, but is not significantly correlated with water droplet size and size distribution or the emulsionʹs dynamic viscosity. The aim of this work was to assess the relation between aging and the viscoelastic properties of a petroleum emulsion produced in Brazil and five model emulsions prepared from asphaltenes extracted from crude oil and dispersed in different oil phases. The emulsions were evaluated just after preparation and during 60 days at 15-day intervals, in an oscillating rheometer. The emulsions stability is related to their bulk phase elastic behavior. Model emulsions containing higher asphaltenes content exhibit higher elastic modulus, and so they are more stable. The behavior of asphaltenes in the petroleum are closely related to their interactions with other petroleum fractions since that the results from oscillating rheology for petroleum emulsion is quite similar to that for the model system containing different content of asphaltenes.