Abstract Plunger lift is an economical method to solve the liquid loading problem in wells. Following our previous research (Zhao et al., 2018), which focused on the steady-state process of liquid leakage during lifting, the transient variations of plunger velocity, liquid leakage and stress conditions during plunger lifting process are investigated theoretically and experimentally in this paper. Based on the force analysis and finite difference method, the transient physical model for the mass and gas volume fraction of gas-liquid column above plunger is proposed. Combining the similarity experiments and infrared measuring technology, the proposed transient model is verified quantitatively with the relative deviation less than ±10%. The results show that both the liquid leakage and the gas volume fraction of gas-liquid column above plunger cannot be neglected during plunger lifting. The transient change rules of lifting differential pressure, plunger velocity, gas volume fraction of gas-liquid column and liquid leakage flow rate during lifting process are obtained. The influences of liquid loading condition and gas production rate on transient plunger lifting process are discussed. Through the dimensionless analysis, a dimensionless correlation for transient gas volume fraction of gas-liquid column is developed.

中文翻译：

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气井柱塞提升过程中的瞬态漏液

摘要 柱塞举升是解决井内装液问题的一种经济的方法。继我们之前的研究 (Zhao et al., 2018) 专注于提升过程中液体泄漏的稳态过程之后，本文从理论和实验上研究了柱塞提升过程中柱塞速度、液体泄漏和应力条件的瞬态变化。纸。基于受力分析和有限差分法，建立了柱塞上方气液柱质量和气体体积分数的瞬态物理模型。结合相似性实验和红外测量技术，对所提出的瞬态模型进行了定量验证，相对偏差小于±10%。结果表明，柱塞提升过程中，柱塞上方气液柱的漏液量和气体体积分数均不可忽视。得到了提升过程中提升压差、柱塞速度、气液柱气体体积分数和液体泄漏流量的瞬态变化规律。讨论了液体加载条件和产气率对瞬态柱塞提升过程的影响。通过无量纲分析，建立了气液柱瞬态气体体积分数的无量纲关系式。讨论了液体加载条件和产气率对瞬态柱塞提升过程的影响。通过无量纲分析，建立了气液柱瞬态气体体积分数的无量纲关系式。讨论了液体加载条件和产气率对瞬态柱塞提升过程的影响。通过无量纲分析，建立了气液柱瞬态气体体积分数的无量纲关系式。