水平井气液两相流动压降变化规律实验研究

Experimental study on changing laws of pressure drop of gas liquid two phase flow in horizontal wells

随着水平井技术的完善和规模的不断扩大,水平井气液两相流压降计算对气田生产具有重要意义。现阶段水平井筒内流型判别研究都是将流动参数带入单独管段流型判别公式中进行预测。通过室内模拟水平井实验进行水平井气液两相流流动可视化研究,通过目视法观察水平井水平段、造斜段与垂直段在不同气液流速下流型变化并记录。将实验数据与现阶段常用流行判别式进行比对,为减小误差,对不同井段常用流型判别式进行评价优选。通过模拟实验,优选出不同井段的流型判别方法。在已知气量和液量的情况下,对压降进一步分析发现随着气体流速的逐渐降低,压降会存在骤变的现象,通过单独管段实验发现在压降发生骤变的气体流速下,持液率也会发生突然变化,结合实验观察得到现象得到了水平井临界携液流速的判断方法。通过对Beggs-Brill压降计算公式的修正,得到了准确率有明显提高的新公式,能降低水平井压降预测的误差。

With the improvement of horizontal well technology and the continuous expansion of scale,the calculation of pressure drop of gas-liquid two-phase flow in horizontal wells is of great significance to gas field production.At present,the flow pattern discrimination research in horizontal wellbore is to bring flow parameters into the flow pattern discrimination formulas of individual sections for prediction.The visualization of gas-liquid two-phase flow in horizontal wells was studied through laboratory simulation of horizontal wells.The flow pattern changes of horizontal,inclination and vertical sections of horizontal wells at different gas-liquid flow velocities were observed and recorded by visual method.Comparing the experimental data with the popular discriminants at present,in order to reduce the error,the flow pattern discriminants commonly used in different sections were evaluated and optimized.The flow pattern discrimination method for different well segments was selected by simulation experiments.In the case of known gas and liquid volume,further analysis of pressure drop showed that with the gradual decrease of gas flow rate,pressure drop will have a sudden change.Through separate pipe section experiment,it was found that under the gas flow rate with sudden change of pressure drop,liquid holdup will also change abruptly.Combined with experimental observation,it was found that the phenomenon was approaching the horizontal well.The method of determining the flow rate of carrying liquid.By modifying the Beggs-Brill pressure drop calculation formula,a new formula was obtained,which can obviously improve the accuracy and reduce the error of pressure drop prediction in horizontal wells.