多孔式射流钻头流场数值模拟研究

Numerical Simulation Study on Flow Field of Multi-hole Jet Bit

多孔式射流钻头是应用于径向水平井技术的一种新型射流钻头。本文建立了多孔式射流钻头流场计算模型,采用RNGk-ε湍流模型进行数值计算,分析了射流钻头内外不同区域的流场分布情况和局部流动特性。模拟计算结果表明:多孔式射流钻头有效扩大了井底冲击区,有利于扩大成孔直径;反向射流冲刷井壁,可以进一步扩大孔径,其反推力平衡了正向射流的反推力,有利于轨迹控制;反向射流的附壁作用,增大了喷嘴局部阻力系数。射流钻头入口及环空的压力和流量的数值模拟结果与试验测试结果一致。

Multi-hole jet bit is a new kind of jet bit which applies to radial drilling technology. On the theory basis of the k -ε double equation of turbulent flow , physical model is established, Flow field of different regions inside and outside jet bit and complex global flow characteristic was analyzed. The results showed that multi-hole jet bit enlarged bottom-hole impact zone which is beneficial to enlarge hole diameter; reverse jets can further enlarge hole diameter and its reverse thrust offsets the reverse thrust of forwards jets, which is beneficial to trajectory control ; action of jet wall-attachment increases local resistance coefficient. Inlet pressure, annulus pressure and flow rate was proved by experimental method.