涡流钻头降压机制及设计原则  

Depressurization mechanism and design principles of vortex drilling-bit

作　　者：朱海燕[1,2] 邓金根[1] 王墨翟 薛亮[1] 闫传梁[1] 

机构地区：[1]中国石油大学油气资源与探测国家重点实验室,北京102249 [2]西南石油大学油气藏地质及开发工程国家重点实验室,四川成都610500 [3]中国石油大学石油工程学院,北京102249

出　　处：《中国石油大学学报（自然科学版）》2014年第1期64-69,共6页Journal of China University of Petroleum(Edition of Natural Science)

基　　金：国家自然科学基金项目(51221003;51134004);国家科技重大专项(2011ZX05024-003-02)

摘　　要：涡流钻头通过反向喷嘴和高速旋转形成负压漩涡,降低井底压差,提高钻井的机械钻速.对涡流钻头降压机制进行研究.采用混合网格计算方法分析反向喷嘴的轴向倾角、径向倾角、上返流量、出口高度和旋转速度等对涡流钻头降压性能的影响,并提出涡流钻头的设计原则.结果表明：反向喷嘴下方井底钻井液回流是影响涡流钻头降压能力的主要因素.涡轮钻头设计的理论原则：轴向倾角为150°～ 180°、径向倾角为60°～75°、上返流量大于30％、反向喷嘴的出口高度为100～140 mm,井壁间隙应小于3 mm,尽可能地提高钻头旋转速度.The drilling practice of oil and gas wells has indicated that reducing the bottom-hole pressure difference can signif-icantly improve the rate of penetration （ROP）. Vortex drilling-bit can reduce the bottom-hole pressure difference via a re-verse nozzle to generate a vortex flow due to the high rotary speed of the drilling-bit. The depressurization mechanism of thevortex bit was analyzed. By using a hybrid mesh method, the key factors that affect the depressurization capacity of the vortexbit were investigated, which include axial angle, radial angle, reverse flow ratio, rotation speed, bit clearance, and distancebetween reverse nozzle outlet and the bottom-hole wall. The results show that backflow below the reverse nozzle outlet is themain reason that can decrease the depressurization effect of the vortex bit. A guideline for the design of the vortex bit is givento maximize the depressurization effect. The optimum axial and radial angles are 150°-180°and 60°-75°respectively, andthe flow ratio of the reverse nozzle is best above 30%. The bit clearance should be kept below 3 mm, and the distance be-tween the reverse nozzle outlet and the bottom-hole surface can be 100-140 mm. The rotation speed of the bit should be aslarge as possible.

关 键 词：钻井 涡流钻头 井底压差 反向喷嘴 数值模拟 

分 类 号：TE21[石油与天然气工程—油气井工程]