CO伴生气混合过程的数值模拟研究

Numerical Simulation of CO Associated Gas Mixing Process

张涛 杨若凡 常文杰 陈斌

ZHANG Tao YANG Ruofan CHANG Wenjie CHEN Bin

西南石油大学石油与天然气工程学院, 四川 成都 610500

Petroleum Engineering School, Southwest Petroleum University, Chengdu, Sichuan 610500, China

低渗油气田CO驱生产后期，采出物是含有大量CO的伴生气，进一步生产过程需要对不同来源的伴生气进行计量及处理。针对这一过程，首先采用CFD建立了CO气质扩散流动的几何模型和数值模型，进而研究了现场工况条件下气质扩散距离，为在线色谱仪的安装位置提供了依据。研究结果表明，来自不同气源的CO伴生气进入混合管后没有立刻充分混合，而是沿着管长方向，两侧的速度逐渐变小，浓度差异也变小，扩散一段距离后发生明显的混合；方案B时，随气体流动速度和压力的增大，气质扩散混合均匀的距离也增大；方案分别为A、B、C时，在40、45及30 m左右CO和CH质量分数达到稳定值，建议在此位置安装气相色谱仪，选择取样点进行测量。

In the late stage of CO flooding production in low permeability oil and gas fields, the produced product is associated gas containing a large amount of CO. In the further production process, the associated gas from different sources needs to be measured and treated. In order to solve this problem, the geometric model and numerical model of CO gas diffusion flow are established by Fluent software, and then we study the mixing distance of gas diffusion under field conditions, which provides a basis for the installation position of on-line Chromatograph. The results show that CO associated gas from different gas sources is not fully mixed immediately after entering the mixing pipe; obvious mixing occurs after diffusion for a certain distance along the length direction of the pipe with the velocity on both sides gradually decreasing, and the concentration difference decreasing. With the increase of gas flow velocity and pressure, the homogeneous mixing distance of gas diffusion increases with the increase of component B. When the component content is A, B and C, the mass fraction of CO and CH reaches a stable value at about 40, 45 and 30 m. It is recommended to install a gas chromatograph at this position and select a sampling point for measurement.

10.11885/j.issn.1674-5086.2021.11.10.01