煤层气水平井PE筛管完井用泵送工具推进力研究

针对煤层气水平井现场作业工况，为优化设计聚乙烯塑料筛管（PE筛管）完井用泵送工具参数，提高PE筛管的泵送效率，利用CFD数值模拟方法开展了钻井液性能参数、钻杆和泵送工具参数对泵送工具推进力影响的研究。结果表明，泵送工具承压抬肩处的流体压力为正压，引导头表面的流体压力为负压，二者方向相反，合力为泵送工具前行提供动力；泵送工具推进力随钻井液排量、黏度和密度增大呈增大趋势，但钻井液排量和密度对推进力的影响远大于钻井液黏度对推进力的影响；泵送工具的推进力随着泵送工具与钻杆内壁之间环空间隙增大先快速减小后缓慢减小，随泄流孔直径增大呈线性减小的趋势，环空间隙对推进力的影响远大于泄流孔直径对推进力的影响。室内研究与现场应用表明，该泵送工具能产生足够大的推进力，能满足PE筛管完井的现场作业要求。 

Research on the Driving Force of the Pumping Down Tool for a PE Screen Completion in CBM Horizontal Wells

In order to efficiently design the parameters of the pumping down tool and to improve the pumping efficiency of PE screens, a study was conducted to investigate the effects of drilling fluid, drilling pipe and pumping down tool parameters on the driving force of pumping down tools by means of a CFD numerical simulation method based on the on-site operational conditions of CBM horizontal wells.It was shown that the fluid pressure at the pressurized ledge of pumping down tools was positive and the fluid pressure at the guiding surface was negative.In view of the opposite directions of the positive and negative force, their resultant force was the force to drive pumping down tools forward.The driving force on the pumping down tools increased by increasing the flow rate, viscosity and density of drilling fluid, but the effect of drilling fluid viscosity on driving force was much less than that of drilling fluid density and flow rate.The driving force on the pumping down tools decreased quickly at first and then slowly by increasing of the annular clearance between the drilling pipe and the pumping down tool, and decreased lineally by increasing the drainage orifice diameter.The effect of annular clearance on driving force was much more than that of drainage orifice diameter.Indoor investigation and field application indicated that the driving force produced by thispumping down tool was large enough to satisfy the field operation of PE screen completion.