反向水眼磨鞋数值模拟研究及结构设计

Numerical Simulation and Structural Design of Reverse Nozzle Milling Shoe

页岩气藏勘探开发过程中,完成压裂施工作业后需要进行通井钻磨作业,钻磨过程中常常发生磨鞋被卡住或连续管下入困难的情况,因此磨鞋的设计与优化研究对改善磨鞋卡钻问题、保证页岩气的高效增产开发具有重要意义。鉴于此,基于传统磨鞋结构研发了一种能够额外向井底方向提供推力的反向水眼磨鞋工具,并结合流体动力学基本理论,建立了工具流场计算域的几何模型;在此基础上进行了不同孔眼直径、不同孔眼数目、不同孔眼与工具中轴线角度下的流场分析,完成了该磨鞋结构的推力计算,并对工具结构进行了优选。研究结果发现:反向水眼磨鞋推力主要由管柱内外节流压差产生;改变孔眼直径是调整节流压力及调整工具推力最直观有效的方法;反向水眼磨鞋结构优选孔眼直径为5.61 mm,孔眼角度为17°,孔眼数目为5;优选的反向水眼磨鞋结构能够帮助连续管顺利下入,产生的推力可以多拖动长达430 m的连续管管柱。研究结果对于现场通井钻磨作业过程中所需磨鞋的设计与优化具有一定的指导意义。

During shale gas exploration and development,milling operations will be carried out after pressure operation.In the process of milling,the milling shoe is often stuck or it is difficult to run in hole via coiled tubing.Therefore,the design and optimization of milling shoe is of great significance to solve the problem of milling shoe stuck and ensure the efficient production and development of shale gas.Based on the structure of traditional milling shoes,a reverse nozzle milling shoe was developed,which can provide an additional thrust.Combined with the basic theory of fluid dynamics,the geometric model of the milling shoe flow field calculation domain was established.By using this model,the flow fields with different nozzle diameters,different nozzle numbers,different angles between nozzle and the milling shoe axis were analyzed.The thrust of the milling shoe was calculated and the milling shoe structure was optimized.The results show that the thrust of the reverse nozzle milling shoe is mainly caused by the throttling pressure difference between inside and outside of pipe string;changing nozzle diameter is the most direct and effective way to adjust throttle pressure and milling shoe thrust.The structure of reverse nozzle milling shoe is optimized with the nozzle diameter of 5.61 mm,the nozzle angle of 17°and the nozzle number of 5.The optimized reverse nozzle milling shoe structure helps to RIH via coiled tubing smoothly and the thrust can drag an additional 430 m length of the coiled tubing.The research results provide a guidance for the design and optimization of milling shoes in the drilling and milling process of on-site drifting operations.