Study On The Start Destructing Characteristic Of GNPOC Crude Oil

In this paper, shear creep tests were conducted with GNPOC Sudan crude oil samples which were gelled at different temperatures. Then several typical viscoelastic / plastic models were compared, and the viscoelastic damage model, which is coupled the Burgers viscoelastic model and continuum damage factor model, was used to match the creep experiments of the gelled crude oil. A new viscoelastic damage model with three parameters was found through some reasonable simplification in the process of matching. This model, with fewer parameters and high accuracy, can describe the viscoelastic properties of gelled crude oil very good. The viscoelastic damage model and the improved viscous model were combined to describe the new equation of the gelled crude oil with non-linear viscoelastic- plastic properties. The results show that this equation can describe the non-linear viscoelastic- plastic shear rheological curves of the gelled crude oil accurately.The time-temperature-stress equivalence principle was introduced to obtain the creep compliance master curve. In addition to taking into account the horizontal displacement, the vertical displacement ( amendment ) factor was also introduced in the process of displacement overlap, and the expression for the relevance of the displacement factor temperature ( stress ) was obtained at the same time.While the vertical displacement amendment was found that, it can be neglected in the process of displacement with the same stress but can not be ignored in the process of displacement with the same temperature, and it played a significant impact on the creep compliance master curve. The viscoelastic damage model was matched with the creep compliance master curve, and results show that the fitting curve was fitted highly with the experimental data.Finally, the constitutive model describing the initial destruction of gelled crude oil process was established, and the model was verified with experiments. It was found that this model has a very good fitting results; The failure process of gelled crude oil could be described by damage parameters.