Study on Interface Evolution and Blockage Characteristics in Low-Temperature Transportation of High-Water-Cut Crude Oil

The failure of the temperature threshold and pipeline blockage in the low-temperature gathering and transportation of produced fluids from high-water-cut oil wells can easily lead to safety accidents. The key mechanisms are temperature threshold hysteresis and interface evolution blockage. In the present study, we employ computational fluid dynamics (CFD) to investigate the interface evolution and multifield coupling effects in nonisothermal, non-Newtonian oil/water two-phase flows. The mechanism of temperature threshold hysteresis and failure of traditional measurement methods based on the synergistic effect of the flow field and temperature field is proposed. In addition, based on the distribution characteristics of the oil outlet interface and oil-water interface, the composition of stratified base flow under low-temperature transportation conditions is elucidated. According to linear stability analysis, interface instability and slug formation mechanisms have been further elucidated. The global flow resistance analysis shows that the local resistance in the slug region is the most significant. Analysis of interface forces, energy dissipation, and generation parameters reveals that insufficient shear force can lead to a sustained increase in pressure drop, thereby driving oil phase transport. On the contrary, energy transfer is mainly achieved through the viscoplastic dissipation mechanism of waves and slug regions, promoting oil phase transport. This study systematically clarifies pressure surge dynamics and blockage formation mechanisms by combining field experiments with numerical simulations, uncovering previously unrecognized multiphase flow instabilities in low-temperature transportation.