Abstract: In order to adapt to the surface gathering requirement of heavy oil cold production, the gathering process based on the reinjection of hot water is adopted in Wellblock Ji-7 of Changji Oilfield. With the continuous expansion of the productivity construction scale, a series of problems occur in Wellblock Ji-7. For example, the temperature and pressure of the blending hot water in the oil wells are lower, and the quantity of the blending hot water is too large. In this paper, the relevant field production data was statistically analyzed. Then, the major factors influencing the quantity of blending hot water were analyzed, and the heat loss in the gathering process of blending hot water was calculated. Finally, the experiment on stopping the reinjection of hot water was carried out in some oil wells. It is shown that the quantity of the blending hot water of oil well is mainly affected by the length of gathering pipeline. The gathering pipeline of blending hot water is poorer in heat preservation effect and its heat loss is more serious. In the process of stopping the reinjection of hot water, there is obvious slug flow in the wellhead produced fluid, which tends to make oil gathering and transportation difficult. The research results can provide theoretical guidance for field management and optimization of heavy oil cold production in Changji Oilfield.