基于Fluent的井下油水分离和润滑过程中新型润滑元件设计分析

为解决含水稠油采输时油水分离和降黏减阻的问题，采用Fluent软件对井下油水分离和润滑过程进行数值模拟，并设计出一种新型的润滑元件，使其能就地安装，形成高质量油水环状流，有效控制采出液的含水率，提高含水稠油井采收率，并降低后续原油处理成本。固定入口流速为0.6m/s，分流比为0.5，进行润滑元件结构的单因素分析。结果表明：流体在溢流口处径向速度极小，说明形成的油核几乎不存在偏心现象，轴向速度的存在有利于形成清晰的油水界面，从而利于形成高质量的油水环状流，经过元件的流体分离出部分水后轴向速度也得到了提升，有利于提高原油采收率。进行与仿真模拟相同工况下的室内实验，通过改变流速观察润滑元件的压降值与流型的变化情况。结果表明：合理的入口流速范围内，采用雷诺应力模型（RSM）与混合多相流模型（Mixture）计算模拟润滑元件内部流场情况具有较高的可信度。

Design and analysis of novel lubricating element in downhole oil-water separation and lubrication based on Fluent

In order to solve the problems in oil-water separation and viscosity reduction during the production and transportation of heavy oil with free water, Fluent software was used to simulate the downhole oil-water separation and lubrication process. And a new type of lubricating element was designed to be installed on site to form a high-quality oil-water annular flow, which could effectively control the water cut of well stream, improve the recovery of heavy oil with free water, and reduce the cost of subsequent heavy oil processing. The inlet flow velocity was maintained at 0.6m/s, and the split ratio was maintained at 0.5. A single-factor analysis was carried out on the structure of the lubricating element. The results showed that the radial velocity of the fluid at the overflow was extremely small, indicating that the formed oil core had almost no eccentricity. The existence of axial velocity was conducive to the formation of a clear oil-water interface and high-quality oil-water core-annular flow. The axial velocity of the flow was increased after part of the water was separated by passing through the element, which was conducive to improving the heavy oil recovery. The indoor experiment under the same operating conditions as the simulation was carried out, and the changes of pressure drop and flow pattern of the lubricating element as the flow velocity were observed. The results showed that within a reasonable range of inlet flow velocity, the Reynolds stress model (RSM) and the mixture multiphase model (Mixture) could simulate the internal flow field of the lubricating element with high reliability.