Experimental Investigation On Phase Inversion Point And Flow Characteristics Of Heavy Crude Oil-Water Flow

The phase inversion point is of great significance for drag reduction in the flow of heavy crude oil. In this study, we used 25-mm inner diameter (ID) stainless steel pipes to investigate the oil-water flow characteristics of four heavy oils at five temperatures (90, 85, 80, 75 and 70 degrees C). The effects of temperature, velocity, and oil viscosity on the phase inversion point of heavy oil-water flow were studied. The viscosity of the experimental oil ranges from 358 to 4995 mPa.s. The phase inversion model of Yao and Gong (2006) was modified to fit high-viscosity oils. The proposed model was verified with pipe flow experimental data from various heavy oilfields. This study found that the effect of temperature on the phase inversion point of heavy crude oil is almost negligible. The flow pattern with the largest pressure drop during heavy oil-water flow is Int, and the flow patterns with a smaller pressure drop include semi-Anw, Anw, and DAnw. The water content at the inversion point of heavy oil-water flow is mostly between 45% and 70%. As the viscosity increases, the water fraction at the inversion point decreases. A high velocity helps the water maintain a continuous phase. The occurrence of phase inversion requires the mixture velocity to be maintained above a specific value, which should be high enough for the flow pattern to transition to semi-annular flow.