井下节流及其对携液能力的影响研究

井下节流工艺将地面油嘴转移到井筒中,在实现井筒节流降压的同时,充分利用地温对节流后的天然气气流加热,从而达到降低地面管线压力、防止水合物生成、取消地面加热装置、减少注醇量等目的。为准确预测井下节流后气井井筒温度、压力分布,建立了气井井下节流井筒压力和温度动态预测模型。结合油田实例,预测气井节流后温度、压力沿井筒的分布,计算节流后温度、压力条件下井筒内气体流速和临界流速,为气井的生产提供了重要依据。井下节流后,气体由于压力降低而膨胀,气体的内能转变成动能,促使气流速度增大,临界流量减小,从而很大程度上提高了气流的携液能力,延长了气井的自喷生产期,大大的增加了气井的累计产量。对于即将积液或者积液不久的井来说,井下节流工艺可以改善井况,延长生产时间,也可作为一种排水采气工艺。

Research on Downhole Throttling Technology and The Affect of Fluid-carrying Capability

Downhole throttling technology is to adjust downhole pressure through installing the throttle valve on the tube.When decreased the pressure of surface line,the gas flowing through the throttle valve is heated up by the geotherm, so as to prevent hydrate formation,cancel surface heating equipment and reduce the methanol injection.For predicting the distribution of wellborn pressure and temperature,the prediction model of the wellborn pressure and temperature is described.Combined with the fact of field,it predicts the distribution of wellborn pressure and temperature and calculates the flow velocity and critical flow rate of the gas,as to offer the reference for the gas well production.Gas expands due to pressure drops after flowing through the throttle valve and the pressure energy of the gas is converted into kinetic energy,thus the flow velocity of gas increases,the fluid-carrying capability of the gas well is improved,the production period of the gas well is prolonged and the cumulative production of the gas well is increased.For the gas well of liquid loading or liquid loaded recently,the downhole throttling technology can be saw a kind of drainage gas recovery technology,because it could improve the well condition and prolong the production period.