煤层气井管壁煤粉清洗弯曲射流影响因素分析

Factors Affecting Curved Jetting in Cleaning Coal Fines on Wellbore Wall in Coalbed Methane Wells

为了解决煤层气排采过程中井筒管壁黏附煤粉和井底沉积煤粉导致的埋泵、卡泵等问题,基于煤层井管壁煤粉黏附特性,建立了煤层气井管壁黏附煤粉清洗临界流速模型,采用理论计算与Fluent软件模拟分析相结合的方法,在垂直射流和斜射流的基础上,研究了旋转喷头弯曲射流流场规律,得到了不同喷嘴偏转角、喷嘴直径、喷头转速对弯曲射流流场的影响变化规律。研究结果表明:随着喷嘴偏转角变小,弯曲射流流线与管壁接触面增大,即弯曲射流冲洗面积增大;喷嘴直径越大,所产生的弯曲射流最大流速相应的减小。清洗时随着喷嘴直径和转速的增加,弯曲射流产生的壁面冲击力减小;当转速为200 r/min、喷嘴直径为2.0 mm时,产生的壁面冲击力为20 MPa;转速由600 r/min增速至800 r/min,弯曲射流产生的最大壁面冲击力减小了29.03%。所得结果可为煤层气井管壁/炮眼黏附煤粉清洗工具现场实施和参数优化提供理论依据。

During coalbed methane production,the adhesion of coal fines to the wellbore wall may cause the issues such as pump burial and pump sticking.Based on the adhesion characteristics of coal fines on wellbores,a critical flow velocity model for cleaning the coal fines on the wellbore wall in coalbed methane wells was established.By combining theoretical calculations with Fluent software simulation analysis,and considering vertical jetting and inclined jetting,flow fields of curved jetting from rotating nozzle were investigated and the influences of nozzle deflection angle,diameter and rotating speed on the flow field of curved jetting were identified.The results show that as the nozzle deflection angle decreases,the contact area of the curved jetting flow with the wellbore wall increases,leading to a larger cleaning area of curved jetting.The larger the nozzle diameter,the slower the maximum flow velocity generated by the curved jetting.During cleaning,increasing the nozzle diameter and rotating speed can reduce the wall impact force generated by the curved jetting.When the rotating speed is 200 r/min and the nozzle diameter is 2.0 mm,the wall impact force generated by the curved jetting is 20 MPa.When the rotating speed is increased from 600 r/min to 800 r/min,the maximum wall impact force generated by the curved jetting is reduced by 29.03%.The research findings provide a theoretical basis for the on-site implementation and parameter optimization of tools used to clean coal fines adhering to the wellbore wall or perforations in coalbed methane wells.