Multiphase separation is an important step in the oil - gas gathering and transportation. How to reduce the geometrical sizes while improve their separating performances has always been the research subject. T-junction pipe, as a new kind of pipe - type separator, has been successfully applied in some onshore and offshore oilfields. Compared to those conventional separators, it possesses several advantages including relatively high separating efficiency, compact sizes, lower pressure drop, etc. The phase distribution in a T - junction joint has a great influence on the separating performances and the flow characteristics, which is still far away from been totally understood due to the inherent complexity of multiphase flow. For smooth stratified flow, the PLIC algorithm in VOF model is applied to reconstruct the oil / water interfaces in a T - junction joint. The simulations reconstruct the phenomena of stretching, breaking up and distortion of oil phase and agree well with the experiments. The lower inlet velocity helps to enhance the separating efficiency and the flux ratio is key to the liquid - liquid separation. The present work is valuable for the structural optimization and the field applications of this new kind of multiphase separator.
The produced liquid mainly comprises of crude oil, free water, sand particles and some other mechanical impurities. At the mid-late stage of oilfield development, the volume fraction of water in the produced liquid may be ranged from 70 to 80 percent, and in some cases even higher than 90 percent . The large quantity of free water would reduce the equipment utilization rate, and increase the consumption of the transportation energy and the fuel. Besides, the sulfide, cyanide and other chemicals often contained in the free water would pollute the surrounding environment severely.