Flow characteristics of heavy oil-water flow during high water-content cold transportation

As the water content in heavy oil gathering systems increases to 70–90% and large-scale popularization of cold transportation. Understanding the characteristics of heavy oil-water flow during high water-content cold transportation has greatly gained in importance. Here, a comprehensive flow loop experiment and microscopic observation was employed to investigate the flow characteristics of oil-water flow at low temperatures. The flow patterns of cold transportation were studied experimentally. The flow pattern maps were also created in detail, taking into account the temperatures (60–20 °C), mixture velocities (0.1–1.0 m/s), and water contents (70–90%). The relevant influencing factors of the pressure gradient were then investigated. The lubrication coefficient and viscosity models were used to modify the pressure gradient models, and average relative deviations were within ±25%. Moreover, the distinction between the oil-sticking layer and wax deposition formation mechanisms was highlighted. According to microscopic observation, the major elements impacting the strength of the oil-sticking layer were asphaltene aggregation and water droplet distribution. Finally, an evaluation method for predicting the minimum heavy oil-gathering temperature during high water-content cold transportation was presented. The findings of this study greatly contribute to understanding the mechanisms of cold transportation.