Abstract Gas well stimulation based on a ball-drop fracturing system is a widely adopted operation in the oil & gas industry. The flow resistance of a multistage fracturing pipe string increases as the number of stages grows, which is a major problem for the traditional graduated ball-drop multistage fracturing system, as it can increase the load of the pump and may ultimately result in a high-cost operation. A new openhole multistage hydraulic fracturing system, which has unlimited multistages, activated by ball plugs is proposed to improve the operation efficiency. In this system, all the downhole sliding sleeves are a single size, and a group of ball plugs activate them to achieve full-inner-diameter pipe access. As a key part of the fracturing system, the approximate cylinder-shaped ball plugs would suffer from a larger resistive force in the horizontal pipe than that of the sphere-shaped fracturing ball. Therefore, a simplified miniature indoor experiment setup is built to investigate the motion of the ball plug. The physical dimensions of the cylinder models and the velocities of the pumping flow vary in the experiment. In addition, the motion in the cylinder models are observed with a high-speed camera. Finally, the experimental data are analysed by a combination of dimensional analysis and the empirical equation method, and the results can help to determine the pumping rate during operations.

中文翻译：

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新型裸眼多级水力压裂系统与水平管球塞运动

摘要 基于球滴压裂系统的气井增产是油气行业广泛采用的作业方式。多级压裂管柱的流阻随着级数的增加而增加，这是传统的分级球落多级压裂系统的主要问题，因为它会增加泵的负载，最终可能导致高成本操作。提出了一种新的裸眼多级水力压裂系统，该系统具有无限多级，由球塞激活，以提高作业效率。在该系统中，所有的井下滑套都是单一尺寸，由一组球塞激活，实现全内径管道接入。作为压裂系统的关键部分，近似圆柱形的球塞在水平管中比球形压裂球承受更大的阻力。因此，建立了一个简化的微型室内实验装置来研究球塞的运动。气缸模型的物理尺寸和泵流速度在实验中有所不同。此外，使用高速相机观察圆柱模型中的运动。最后，结合量纲分析和经验方程法对实验数据进行分析，其结果有助于确定作业过程中的抽速。气缸模型的物理尺寸和泵流速度在实验中有所不同。此外，使用高速相机观察圆柱模型中的运动。最后，结合量纲分析和经验方程法对实验数据进行分析，其结果有助于确定作业过程中的抽速。气缸模型的物理尺寸和泵流速度在实验中有所不同。此外，使用高速相机观察圆柱模型中的运动。最后，结合量纲分析和经验方程法对实验数据进行分析，其结果有助于确定作业过程中的抽速。