Study on the unheated gathering boundaries of crude oil during high water content period in cold region

The energy consumption of oil gathering and transportation can be effectively reduced by using an unheated gathering process in oilfields with high water content. However, the phenomenon of "condensate sticking to the wall" may arise due to low temperatures in the cold region, which affects the safe production of this process. In this study, the safe production temperature limit of high water content crude oil in a cold climate without heating is determined by using a combination of a cold finger experiment and a field test. Research using cold finger devices indicates that crude oil's viscous wall temperature typically below the pour point and diminishes as water content and shear stress rise. Through field tests with gradually decreasing oil–water mixture temperatures, the relationship between the oil–water mixture temperature and pipeline pressure drop is established. The temperature at the pressure drop surge point is then chosen as the limit for unheated gathering and transportation. A model for calculating the viscous wall temperature considering the flow state is established, its average calculation error is 1.44%. This study can provide important guidance for the feasibility judgment of the unheated gathering and transportation process and its safe operation in oil fields in cold regions.