结蜡对内置电缆连续油管流场的影响

Effects of wax deposition on the flow field of coiled tubing with built-in cable

为了研究结蜡分布和结蜡厚度对原油流速、压力的影响规律,解决原油在输送过程中管壁结蜡带来的能量损耗及安全隐患。采用简化结蜡模型,利用Fluent软件对结蜡和无结蜡直井中内置电缆连续油管的流场进行三维数值模拟。结果表明:原油进入结蜡管道后,沿井筒轴线缓变流动,在结蜡起始位置和终止位置附近,原油流束局部会相应地收缩或扩张;由于存在石蜡层,过流断面不再是环形,流速云图也脱离了轴对称分布,流速峰值出现在过流断面未结蜡的部分且明显增大,无论是否结蜡,流速径向分布曲线均为抛物线型;结蜡井筒与无结蜡井筒过流断面处压力相等,且过流断面压力由入口向出口降低;结蜡井筒除了沿程能量损失外,还存在局部能量损失,因此井筒能量损失更大。

In this paper, the effects of the distribution and thickness of wax deposition on the flow velocity and pressure of crude oil were investigated so as to deal with the energy loss and potential safety hazards caused by the wax deposition on pipeline walls in the process of crude oil transportation. The three-dimensional numerical simulation was conducted on the flow field of coiled tubing with built-in cable in a vertical well with/without wax by using the computational fluid dynamics software Fluent in the simplified wax deposition model. It is shown that the crude oil flows slowly along the axial line of the wellbore after it enters the pipeline with wax deposition. The crude oil flow locally shrinks or expands correspondingly in the vicinity of the wax-starting position and the wax-ending position. Due to the paraffin layer, the flow cross section is no longer circular and distribution of the flow velocity cloud chart is also separated from the axial symmetry. The peak flow velocity appears in the flow cross section without wax deposition and increases significantly. The radial velocity profile is parabolic whether wax is deposited or not. The pressure at the flow cross section of the wellbore with wax deposition is equal to that without wax deposition and they decrease from the inlet to the outlet. The wellbore with wax deposition suffers not only the energy loss along the course, but also the local energy loss, so its energy loss is greater. （5 Figures, 20 References）