Investigation on flow patterns and pressure drops of highly viscous crude oil–water flows in a horizontal pipe

• Flow patterns of viscous oil–water horizontal flow is a function of pressure drops.
• Occurrence probability of each flow pattern for the oil–water flow was analyzed.
• Three modified models for the pressure drop prediction was presented.
• Effects of temperature, water cut and flow rate on flow patterns were discussed.

Pressure drops were measured during the co-current flow of a highly viscous oil and water in a horizontal stainless steel pipe with 40 m in total length and 25 mm inner diameter. Measurements were made for the velocities of the oil–water mixtures from 0.3 to 1.5 m/s, water volume fractions from 0.5 to 0.8 and experimental temperatures from 85 to 60 °C. Six flow patterns that most likely occur during the oil–water two-phase flow with high water fractions were found in previous studies, and the occurrence probability of each flow pattern was preliminarily evaluated according to the agreement between the experimental and theoretical values of pressures drops. And then three of the six pressure drop prediction models were well modified and verified. Flow pattern maps were constructed in the water fraction versus mixture velocity at different temperatures, which demonstrates various impacts of temperature, water fraction, and mixture velocity on flow patterns. This work may be the first attempt to investigate highly viscous oil–water flow behavior with flow pattern transitions under different temperatures.

The most probable six kinds of flow patterns in horizontal highly viscous oil–water flow with high water fractions.Figure optionsDownload as PowerPoint slide