Oil-Gas-Water Three-Phase Slug Flow Liquid Holdup Model in Horizontal Pipeline

According to experiments and relational documents, slug regime, appeared in this experiment, can be divided into the following flow regimes: oil-based separated slug, oil-based dispersed slug, water-based separated and water-based dispersed slug. Experiments for oil-gas-water three-phase flow in a stainless steel pipe loop (25.7mm inner diameter, 52m long) are conducted. Compressed air, mineral oil and water are used as experiment medium. Mineral oil Viscosity is 64.5mPa.s at 20°C. Gas superficial velocity, liquid superficial velocity and water cut ranges are 0.5∼15 m/s, 0.05∼0.5 m/s and 0∼100% respectively. There are some strange observed in this experiment. At the very low gas superficial velocity less than 1m/s, the average liquid holdup of low liquid superficial velocity was larger than that of higher liquid superficial velocity especially in higher inlet water cut experiments. This is because at very low gas superficial velocity, the regime is separated slug flow which has water film below their liquid film zone, velocity difference between oil film and water film will affect the average liquid holdup greatly. With the increase of gas and liquid superficial velocity, the regime becomes dispersed slug flow which oil and water are homogeneous. It will be more obvious with the increasing of water cut for the thicker water film. A new liquid holdup model of oil-based and water-based separated slug has been developed. Based on statistical analysis, it is observed that the new model gives excellent results against the experimental data.