基于FLUENT的黏稠油垂直上升水环输送数值模拟

Numerical simulation of vertical upward water annulurs transportation of heavy oil based on FLUENT

海洋稠油资源是未来原油产量增长的重要来源,但相对于陆上油田,海洋稠油集输因涉及低温环境与立管输送而更具挑战性。采用水环举升稠油可以极大地减小输送摩阻,是一种非常有潜力的稠油"冷输"方法。基于油水两相流及计算流体动力学理论,利用FLUENT 6.3.26及GAMBIT2.3.16软件,建立了垂直上升稠油-水中心环状流(CAF)的几何模型与数学模型,评价了模型的有效性,模拟分析了垂直上升CAF的流态及特点,探讨了不同水环生成器环隙宽度及油水流速对垂直上升CAF的影响。结果表明:当油水流速比在一定范围内时,所建模型对垂直上升CAF的模拟结果与实验结果一致性较好;垂直上升CAF在入口端能保持理想的中心环状流,具有光滑的油水界面,但随着油水协同向上流动,油水界面开始波动;水环生成器的环隙宽度对垂直上升CAF的影响较大,环隙过小,水环稳定性较差,流动摩阻较大,而环隙过大则输油量较小;同时兼顾能耗与输油量,在模拟条件下,水环生成器环隙宽度为1.8 mm时输油效率最高。(图7,表1,参13)

Offshore heavy oil is an important source for the increase of crude oil production in the future, but compared with land oilfields, the gathering of offshore heavy oil is more challenging due to low temperature environment and riser transportation. Lifting heavy oil with water annulurs can significantly reduce the transporting friction, so it is a very promising way for the cold-transportation of heavy oil. Based on the theory of oil-water two-phase flow and computational fluid dynamics, the geometrical and mathematical models of the vertical upward heavy oil-water central annular flow （CAF） are built by using FLUENT 6.3.26 and GAMBIT 2.3.16 software, and the validity of this model is discussed. The flow regime and features of vertical upward CAF are simulated and analyzed, and the influences of the width of annular gap in different water annulurs generators and flow velocity of oil-water on the vertical upward CAF are discussed. The results show that when the ratio of flow velocity of oil to water is in a certain range, the simulation result of vertical upward CAF by this model is in good agreement with the experiment result. Vertical upward CAF can maintain ideal central annular flow at the entrance and has a smooth oil-water interface, but the oil-water interface begins to fluctuate as the oil and water rise up together. The width of annular gap in water annulurs generators has a great impact on the vertical upward CAF and if the width is too small, the stability of water annulurs will be poor and the flowing friction will be high, while on the other hand, if the width of annular gap is too big, oil output will be too small. Considering the both of energy consumption and oil output, the efficiency ofoil transportation is the highest when the width of annular gap in water ring generator is 1.8 mm under the simulation conditions. （7 Figures, 1 Table, 13 References）