煤层气井有杆排采泵筒煤粉流动特征

Study on the characteristics of coal moving in sucker rod pump for CBM wells

  • 摘要: 煤层气井煤粉颗粒在有杆排采泵筒内固液两相流中的流动特征是埋泵、卡泵和凡尔漏现象的重要因素。基于泵筒中液体携煤粉的运动学和动力学分析,建立了泵筒中液体流动和煤粉运移的计算模型,并依据仿真分析得到不同排液量和煤粉粒径时,煤粉在泵筒内的运移特征。结果表明,泵筒中的煤粉运移与液体流动特征相近,煤粉运移速度正负的分界点随排液量的增大而逐渐扩大,煤粉排出量也随之不断提升。泵筒中液体携煤粉在泵筒入口附近发生湍流,并在固定阀阀孔两侧由于涡流而发生煤粉沉淀,而在泵筒内部固液两相流动则变为层流运动。两相流进泵速度较低或煤粉粒径较大时,泵入口附近开始出现煤粉沉淀,煤粉运移速度损失较小。该研究首次系统分析煤层气井泵筒内煤粉流动特征,为防煤粉有杆泵的设计及其排采作业方法提供了重要依据。

     

    Abstract: The characteristics of coal moving in two-phase (solid+liquid) flow of sucker rod pump is related to analyze the problem of buried and card pumps and its valve leak. Based on the kinematic and dynamic analysis of coal moving with well liquid, the mathematical model of coal moving and well liquid flow was developed. The coal moving characteristics in pump was obtained on simulation analysis for different flow rate and coal diameter. The results show that the characteristics of coal moving is similar to that of well liquid flow. The positive and negative demarcation point of coal moving velocity enhances with the increase of flow rate, which will improve the coal production. The turbulence occurs at the entrance of pump, and coal is deposited in both sides of fixed valve hole due to the eddy. But two-phase (solid+liquid) flow is changed into laminar flow in the pump. The coal is deposited in the entrance of pump while the flow velocity is low or the coal diameter is large, and it results to low speed loss of coal moving. The systematic analysis of coal moving in pump of coalbed methane (CBM) wells is completed for the first time, which will provide the reasonable basis for designing sucker rod pump and operating system.

     

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