含蜡原油胶凝过程特性研究

利用RS75流变仪在小振幅振荡剪切的模式下分别研究了3种不同历史条件下含蜡原油的胶凝过程, 同时通过偏光显微镜观察了不同降温速率条件下原油中的蜡晶形貌. 结果表明, 在静态降温条件下, 降温速率越大, 原油胶凝的温度越低, 原油形成的胶凝结构越弱; 并且降温速率越大, 原油在恒温静止过程中, 结构随时间恢复的速率越大, 恢复至平衡所需时间越长, 但最终的平衡结构却越弱; 在同样的降温速率下, 原油低温胶凝结构随着降温过程中剪切作用的增强而减弱, 但当历史剪切速率超过一定数值时, 原油的胶凝结构将基本不再继续变化; 在同样的历史剪切速率下, 降温速率越大, 原油在低温(31 ℃)静止初始的储能模量越小, 但最终的平衡结构却越强.

Research on the Properties of Gelling Process of Waxy Crude Oil

The gelling processes of waxy crude oil under three different historical conditions were studied in detail. The RS75 rheometer was used in a small amplitude oscillatory shear mode in the study. Meanwhile, the morphology of wax crystals in the waxy crude oil at different cooling rates was investigated through a polarized light microscope. The results show that the gel point of the waxy crude oil becomes lower and the strength of the gel structure reduces with the increase of the cooling rate under quiescent conditions. As the crude oil is kept static under isothermal conditions, with the increase of cooling rate, the recovery rate of the structure increases and the time needed for recovering to balance extends, but the strength of the final balance structure is weaker .At the same cooling rate, the strength of the gel structure for waxy crude oil at a low temperature reduces with the increase of historical shear rate. However,when the historical shear rate exceeds a critical value, the strength of the gel structure keeps nearly unchanged. At the same historical shear rate, the higher the cooling rate is, the smaller the initial storage modulus at low temperature(31 ℃) is and the stronger the strength of final balance structure is.