超高压射流钻头破岩实验研究

Experimental study on rock breaking with ultra-high pressure jet

超高压水射流技术在石油工程中的应用越来越广泛,目前超高压射流联合机械破岩是提高钻井速度最具潜力和最具可行性的方法。通过室内实验和现场试验研究了淹没条件下超高压水射流破碎岩石的主要规律,探寻影响破岩效果的主要因素及其规律,为超高压射流联合机械破岩及超高压PDC钻头的进一步研究奠定了基础。研究发现,影响超高压射流破岩的主要因素有压力、喷距、喷嘴移动速度和喷射角度等,射流压力越高破岩效果越好,最优喷距随着压力的升高而增大,200MPa时最优喷距达到32.5倍喷嘴直径。实验条件下,150MPa时破岩效率最高,喷射角为14°破岩效果最好。根据实验结果,对钻头切削齿和喷嘴布置进行了优化,设计制造了专用设备和工具,现场试验取得了较好的效果,可进一步推广应用。

Ultra-high pressure water technology is widely used in petroleum engineering.At present,ultra-high pressure jet,assisted by mechanical breaking of rock,is considered as the most potential and feasible approach to improving drilling speed.In this paper,the law of rock drilling with ultra high pressure water jet under submerged conditions is studied based on both lab and field experiment.The main factors and relations between these factors that determine the rock breaking effect are discussed as well.This provides a basis for further study on ultra-high pressure jet assisted by mechanical breaking of rock and on PDC bit with ultra-high pressure.The result shows that the main factors affecting the breaking of rock are jet pressure,the standoff distance,the nozzle moving speed,the jet angle.The higher the water jet is,the better the rock breaking effect is.And the optimum standoff distance increases with the rise in pressure.The optimum standoff distance increases to 32.5 times larger than the nozzle diameter when the pressure is 200 MPa.Under laboratory conditions,the highest efficiency of rock breaking is obtained when the pressure equals to 150 MPa,and the optimum jet angle is 14 degrees.According to the experimental results,the configuration of cutters and nozzles is optimized and special equipment and tools are made.Great success is achieved in the field experiment.