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在温度低到一定程度时,含蜡原油存在着屈服应力。介绍了动屈服应力物理意义及概念的引伸,指出动屈服应力是维持物料继续流动所需要的最小剪切应力,由平衡流变曲线外延确定,反映了含蜡原油经过破坏后不能完全恢复的残余结构的强度,不是唯一值。对含蜡原油动屈服应力的测量,通常采用的方法有直接法和间接法,间接法中的应力松弛法被认为是一种较好的测量方法。胜利油田原油动、静屈服应力的测量值与预剪切过程中选用的剪切率有关,由平衡流变曲线外延得到的动、静屈服应力之间存在着很大差别。介绍了动屈服应力在含蜡原油低温输送和含蜡原油停输后再启动过程中的应用。
At low temperatures to a certain extent, waxy crude oil has yield stress. The introduction of the physical meaning and concept extension of yield stress points out that the yield stress is the minimum shear stress needed to maintain the material flow, which is determined by the equilibrium rheological curve epitaxy, which reflects the residual of waxy crude oil that can not be completely recovered after it has been destroyed The strength of the structure, not the only value. For the measurement of yield stress of waxy crude oil, the direct methods and indirect methods are usually used. The stress relaxation method in indirect method is considered as a better measurement method. The measured values of dynamic and static yield stress of crude oil in Shengli Oilfield are related to the shear rates used in the pre-shearing process. There is a great difference between the dynamic and the static yield stress obtained from the equilibrium rheological curve. This paper introduces the application of dynamic yield stress in the process of re-starting after low-temperature delivery of waxy crude oil and waxy crude oil.