摘要
为了解决长庆气田多级滑套压裂工艺中压裂球无法排出而影响后期生产及作业的问题，通过分析压裂球在水平段和直井段的受力情况，分别建立了压裂球在水平段和直井段的运动模型。从模型可知，压裂球能否返排成功的关键是直井段的启动流速。对启动流速影响因素进行了分析和现场验证，结果表明：在水平段，其他条件相同时，不同密度、尺寸的压裂球的移动情况差别很小；而在直井段，随着压裂球密度或者尺寸增加，压裂球启动流速增加明显。通过与现场5口井压裂球返排统计数据进行验证，模型预测精度为85.77%。计算公式及方法可用来优选压裂球材质及尺寸，预测压裂球返排时间及液量，也可用于采油井或注水井中同类球形物体返排条件分析及水平井冲砂规律研究。
Abstract
In order to solve the problem caused by fracturing balls that still stay in the tubing after completing the fracturing operation in Changqing gas field, which has a bad effect on the production or later work operation. Analyzing its force when fracturing ball moves in horizontal section and vertical section, two moving mathematical models have been established respectively. One is horizontal section model, and the other is vertical section model. According to model analysis, it is obvious that the critical returning velocity in the vertical section determines if the fracturing ball can be moved up to the ground or not. To prove this important result, a series of procedures have been carried out, including affecting factor analysis, example calculation and field verification. The result shows that the ball′s returning velocity is almost irrelevant to the its density, and diameter when moving in the horizontal section, but when it comes to the vertical section, the ball′s critical returning velocity is increased obviously as its density or diameter increases. The returning ball data from 5 horizontal gas wells in the field test proves that the model′s accuracy is about 85.77%. Therefore, this model can be used to optimize the ball′s material, size and forecast the returning time and flowback volume, and it also can be used to analyze the critical recovering condition of similar sphere object in the production well or injection well, the moving trace of sand when washing bore in horizontal well.
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