# Study on Flow Characteristics of Venturi Accelerated Vortex Drainage Tool in Horizontal Gas Well
## 5 Conclusions  
1. The vortex tool can effectively perform gas-liquid separation in the horizontal tube. This effect is achieved by transforming the turbulent gas-liquid mixture into laminar spiral flow of the liquid near the wall and the gas in the center of the tube. The venturi accelerated vortex tool can significantly improve drainage efficiency, resulting in a longer and more stable spiral flow.
2. The venturi accelerated vortex tool produced the highest negative pressure in the horizontal tube, followed by the vortex tool alone, and the negative pressure of the tube drainage was the smallest. When the venturi accelerated vortex tool was adopted, only half of the gas flow rate was needed to generate the same negative pressure. This effect was caused by a strong spiral flow, which, in turn, results in the decrease in the total pressure drop in the horizontal and vertical tube.
3. The increase in the gas flow rate leads to the increase in the length of the spiral flow. As a result, the liquid-carrying capacity is enhanced and the negative pressure in the horizontal tube is exponentially increased. These effects yield a reduction in the total pressure drop in the horizontal and vertical tubes. Especially the venturi accelerated vortex tool exhibits better liquid-carrying performance under these conditions. Under the utilization of a suitable gas flow rate, the length of the spiral flow produced by the venturi vortex tool was longer by about 20% with respect to that formed by the  
Figure 17: The average pressure drop for the venturi accelerated vortex tool with liquid flow rate of 1-15 L/min and gas flow rates of 100-600 m\({}^{3}\)/h.  
vortex tool. Its length of the spiral flow and pressure drop with different gas and liquid flow rates was derived, which can provide valuable insights for determining the liquid-carrying applicability of the tool under different production conditions.
* When the liquid flow rate increased, the intensity of the spiral flow was initially raised. Subsequently, the unstable flow coupling of spiral and turbulent flows occurs, and the instability of the pressure fluctuations is enhanced. The total pressure drop across the horizontal and vertical tubes also increased. Despite these changes, the drainage performance of the venturi accelerated vortex tool remained superior to that of the vortex tool and the tube drainage.  
The following supporting information can be downloaded at: [[https://www.mdpi.com/article/10.3390/app14072944/s1](https://www.mdpi.com/article/10.3390/app14072944/s1)]([https://www.mdpi.com/article/10.3390/app14072944/s1](https://www.mdpi.com/article/10.3390/app14072944/s1)), Figure S1: Instantaneous pressure drop of different tools in the horizontal tube with liquid flow rate of 3 L/min and gas flow rates of 100-600 m\({}^{3}\)/h; Figure S2: Instantaneous pressure drop of venturi and vortex tool in the horizontal tube with different liquid flow rates (1, 3, 5, 10, 15 L/min) and the gas flow rate of 300 m\({}^{3}\)/h.  
Conceptualization, overall planning, investigation, H.Z.; methodology, formal analysis, writing--original draft preparation, Y.X.; writing--review and editing, M.C. and J.L.; validation, data curation, M.F.; visualization, X.Z. All authors have read and agreed to the published version of the manuscript.  
This research was funded by National Natural Science Foundation of China (Grant No. 11402051), Natural Science Foundation of Heilongjiang (Grant No. LH2022A004), Natural Science Foundation of Heilongjiang (Grant No. LH2022E016).  
Not applicable.  
The data presented in this study are available on request from the corresponding author.  
The authors declare no conflicts of interest.