Effects of stress and oscillatory frequency on the structural properties of Daqing gelled crude oil at different temperatures

摘要

The structural properties of Daqing gelled waxy crude oil were studied with a controlled-stress rheometer under oscillatory shear mode. Our results demonstrate that the gelled waxy crude oil shows viscoelastic properties. The linear viscoelastic region and yielding of crude oil can be determined not only by the critical linear shear stress (τ_(cl)) and yield stress (τ_y), but also by the critical linear shear strain (γ_(cl)) and yield strain (γ_y) respectively. With the decrease of test temperature, τ_(cl) and τ_y increased greatly while γ_(cl) and γ_y decreased gradually. The crude oil showed more elastic at lower temperatures. The frequency had little effect on the structure of crude oils in the measured range.