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Viscoelastic models for Mexican heavy crude oil and comparison with a mixture of heptadecane and eicosane. Part II

Abstract:

The viscoelastic properties of crude oils, at a fixed temperature, can be interpreted in terms of a distribution of relaxation times. A square relaxation spectrum applied to the Maxwell model is in accordance with experimental results obtained for a crude oil specimen from the Cantarell reservoir in south-east Mexico. As a continuation of a previous paper, the Weissenberg number formerly proposed for steady viscosity, is also proposed to scale G′ and G″ at different temperatures. Although, the mixture of n-heptadecane and n-eicosane provided good results in the description of viscous properties of the considered crude oil - as reported in the previous paper - the viscoelastic properties of the mixture of n-heptadecane and n-eicosane are very poor in comparison to those of crude oil. In general, aging of crude oil causes an increment of tan δ quicker with temperature increment. Moreover, two years of aging cause a huge increment of G′. The main objective of this paper is providing a suitable and complete model to describe the viscoelastic properties of the considered crude oil. © 2007 Elsevier Ltd. All rights reserved.