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空心抽油杆应用于油井热洗工艺,可有效解决高含蜡油井定期清蜡问题,克服了常规热洗对油层的污染和产量恢复期长的弊端。但是,通常在确定它的下入深度时只考虑了原油的析蜡点,而忽视了井筒温度场和井下单流阀开启压力的影响。以井筒长度微元为单位,依据井筒能量平衡方程建立了井筒流动与传热数学模型,计算出热洗溶蜡拐点温度,确定空心抽油杆下入深度。然后,考虑热洗泵车施加的开启压力,进行了空心抽油杆的轴向应力校核。现场50余口油井应用表明,建立的模型可靠性高,平均节省空心抽油杆120m,且抽油机正常运行最大载荷平均下降18.35%,既满足了油井清蜡需要,又节省了油井开发成本。
The hollow sucker rod is applied to oil well thermal cleaning process, which can effectively solve the problem of regular waxing in high waxy oil wells and overcomes the shortcomings of conventional hot water cleaning on oil layer pollution and long production recovery period. However, it is common to consider only the waxing point of crude oil in determining its depth of penetration, ignoring the effects of wellbore temperature field and downhole single-valve cracking pressure. According to wellbore length micro-unit, the wellbore flow and heat transfer mathematical model was established according to wellbore energy balance equation, and the inflection point temperature of hot wash wax was calculated to determine the depth of hollow sucker rod. Then, considering the opening pressure applied by the hot-wash pump truck, the axial stress checking of hollow sucker rod was carried out. The application of more than 50 wells in the field shows that the established model has high reliability and saves 120m hollow sucker rod on average, and the average maximum load of pumping unit drops by 18.35% on average, which not only meets the need of well de-waxing but also saves oil well development cost .