领眼与扩眼双级PDC钻头井底流场数值模拟

Numerical simulation on the downhole flow field of the pilot and reaming two-stage PDC bit

闫炎 管志川 杨才 阎卫军 耿潇

YAN Yan GUAN Zhichuan YANG Cai YAN Weijun GENG Xiao

中国石油大学(华东)石油工程学院 山东省深地钻井过程控制工程技术研究中心 中国石油长城钻探工程有限公司国际测井公司 中国石油长城钻探工程有限公司钻井一公司

College of Petroleum Engineering, China University of Petroleum (East China), Qingdao 266580, Shandong, China Shandong Research Center of Deep-Seated Drilling Process Control Engineering and Technology, Qingdao 266580, Shandong, China International Logging Company, CNPC Greatwall Drilling Company, Panjin 124010, Liaoning, China No.1 Drilling Company, CNPC Greatwall Drilling Company, Panjin 124010, Liaoning, China

针对领眼与扩眼双级PDC钻头，利用FLUENT有限元软件进行了井底流场数值模拟，得到了四刀翼双级PDC钻头与六刀翼双级PDC钻头井底的速度场、压力场特征。仿真结果表明，领眼钻头刀翼上的内侧切削齿由于低速滞留区的存在导致表面钻井液流速较低，清洗效果较差；从领眼钻头井底上返的钻井液流过阶梯状环空井眼台阶处时出现压力波动。对比两种双级PDC钻头仿真结果，四刀翼双级PDC钻头领眼体与扩眼体井底水力能量分配更加均衡，同时领眼空间与扩眼空间均形成了较大的轴向压差，更加利于钻井液携岩上返。领眼钻头的井眼尺寸、领眼钻头与扩眼钻头喷嘴的过流面积配比对于双级PDC钻头的井底流场有着较为明显的影响。

The downhole flow field of the pilot and reaming two-stage PDC bit was numerically simulated by using the finite element software FLUENT. And the characteristics of downhole velocity fields and pressure fields of four-blade two-stage PDC bit and six-blade two-stage PDC bit were figured out. The simulation results show that due to the existence of low-velocity retention zone at the inner cogging in the blade of pilot bit, the superficial flow velocity of drilling fluid is lower and the cleaning effect is poorer. In addition, the pressure fluctuates when the drilling fluid returning from the downhole of pilot bit flows through the step of step-type annulus hole. Finally, the simulation results of two kinds of two-stage PDC bits were compared. It is indicated that the downhole hydraulic energy of pilot body and reaming body of four-blade two-stage PDC bit is distributed more evenly and larger axial pressure difference is formed in the pilot space and the reaming space, which is more favorable for the cuttings carrying and returning of drilling fluid. The match between the hole size of pilot bit, the pilot bit and the open area of the reaming bit nozzle has a significant effect on the downhole flow field of two-stage PDC bit.

10.13639/j.odpt.2019.01.006