多级孔板提高井筒气体携液能力实验研究

An Experimental Study on Improving the Liquid-carrying Capacity of Wellbore Gas by a Multi-stage Orifice

气井生产时,井底积液会影响气井产量,甚至导致气井停产。加入泡沫剂、更换小直径油管或氮气举升等措施排出井底积液是保证气井生产的重要手段,但造成液体回流的井筒结构并没有变化。改变适合于单相流体的均一井筒结构,降低气液两相流中液体在井筒的回流,提高气体携液能力,形成适用于气液两相流的井筒结构,可以改善气井生产。实验设计了安装于管筒内的类似于倒置漏斗形的多级孔板装置,以井底气体为动能,借助"爬楼梯"原理,利用孔板减少或阻止液体回流,使液体通过多级孔板逐级上升;实验利用气体压缩机提供气源,测试了不同气体流速下,加入孔板对于气体和泡沫携液能力的影响。实验表明,在管筒内加入液体回流限制装置,大幅度地提高了管筒的气体携液能力和排液效果,减少了管筒液体回流量,降低了气体排液和泡沫排液的气体流速临界值。多级孔板可用于气井增产,能够提高气体携液能力,提高泡沫携液效果,降低泡沫剂的使用量和井底残液,但在实际生产中气体流量和装置的匹配性,还有待于在现场试验中进一步验证和优化。

Liquid accumulation in the bottom hole of gas wells will affect the production process and lead to production stoppage in severe cases.Measures currently taken to drain bottom liquid include the adding of foaming agent,replacement of smalldiameter tubing,and nitrogen lift.These measures are play an important role in gas well production,but the wellbore structure that causes liquid backflow has not changed.Changing the conventional wellbore structure to suit for single-phase fluids could help reduce the backflow of liquid in a wellbore of gas-liquid two-phase flow and improve the liquid-carrying capacity.We propose a wellbore structure suitable for gas-liquid two-phase flow that has practical significance for improving gas well production.We design a multi-stage orifice device similar to the inverted funnel that is installed in the wellbore tube.Bottom hole gas is used as the kinetic energy.The orifice plate is designed to reduce or prevent liquid backflow so that the liquid passes through the multi-stage orifice plate and rises sequentially.A gas compressor is used to provide a gas source,and the effect of the addition of the orifice on the gas and foam carrying capacity at different gas flow rates is tested.When the multi-stage orifice device is added into the tube,it greatly improves the gas carrying capacity and the liquid discharging effect of the tube.It also reduces the liquid backflow and the critical value of the gas flow rate in the gas and foam drainage.The experiment proves that the method and principle of multi-stage orifice plate for gas well stimulation works well,improving the gas carrying capacity and the liquid-carrying effect of the foam as well as reducing the amount of foaming agent and residual liquid in the bottom hole.