井下涡流工具有效作用距离研究

Study on Effective Operating Distance of Downhole Vortex Tool

井下涡流工具在国内气井上的使用效果不佳,原因在于对于涡流工具的使用条件缺乏较明确的认识、选井不合适以及工具结构参数有待进一步优化。为此,对井下涡流工具的有效作用距离进行了研究。通过涡流工具数值模拟分析,发现切向速度和轴向速度的变化不是影响涡流工具有效作用距离的关键因素;利用压降模型计算未安装和安装涡流工具时井筒内压降,发现涡流工具可有效降低气液两相在井筒内的压力损失;利用携液模型计算实际流速和临界流速,发现涡流工具使临界流速降低了13.5%~16.1%,揭示了涡流工具排水采气的本质在于切向速度和轴向速度的变化引起液相流动形态的改变,使分散液滴流变成了环状流。结合现场使用涡流工具的6口生产井数据进行临界流速计算,结果表明涡流工具可使临界流速最多降低40%。当一口未使用涡流工具井的实际流速为临界流速的0.6~1.0倍时,使用涡流工具可以有效排液,其有效作用距离超过1100 m。研究结果对于提高井下涡流工具的现场使用效果具有一定的参考意义。

The inferior application performance of downhole vortex tools on domestic gas wells are due to the unclear understanding of the application conditions of vortex tools,improper well selection,and the tool structure that needs to be further optimized.To address the problem,the effective distance of downhole vortex tool was studied.Through numerical simulation analysis of the vortex tool,it was found that the tangential velocity and axial velocity were not the key factors affecting the effective distance.The pressure drop model was used to calculate the pressure drop in the wellbore with/without vortex tool,and it was found that the vortex tool was effective in reducing the pressure loss of the gas-liquid two-phase in the wellbore.The liquid-carrying model was used to calculate the actual flow rate and the critical flow rate.The vortex tool reduced the critical flow rate by 13.5%~16.1%.The liquid removal principle of the vortex tool is that the change of tangential and axial velocity causes the change of liquid phase flow,making the dispersed droplet flow into an annular flow.Based on the data of 6 production wells using vortex tools,the critical flow rate was calculated.The results show that the vortex tool can reduce the critical flow rate by up to 40%.When the actual flow rate of a well without vortex tool is 0.6~1.0 times the critical flow rate,the vortex tool can effectively remove the fluid,and its effective distance exceeds 1100 m.The study results have certain reference significance for improving the application of downhole vortex tools.