The depth and diameter of the drainage hole greatly rely on he rock - breaking performance of the jetting bit. The law and performance of the multi - orifice nozzle and combined jet nozzle commonly used as jetting bit in radial drilling were compared by experiment. The results show that the influence of impacting time, nozzle pressure, standoff distance and confined pressure on the rock - breaking law of the two nozzles is almost the same,and the optimal standoff distance of multi - orifice nozzle is 5 to 6 times of the nozzle diameter,but there is not optimal standoff distance of combined jet nozzle. The rock breaking efficiency is higher and depth of drainage hole is greater of multi - orifice nozzle, but the drainage hole diameter of the combined jet nozzle is bigger than multi - orifice nozzle. The results of this paper can be guidance for the choice of jetting bit of radial drilling.%射流钻头的破岩性能对井眼深度和大小有重要影响.本文对径向水平井常用的2种射流钻头——多孔喷嘴和混合射流喷嘴采用室内试验的方法对它们的破岩规律和破岩性能进行了分析和对比.结果表明,冲击时间、喷嘴压降、喷距和围压对2种喷嘴破碎效果的规律基本相同,混合射流喷嘴的最优喷距不明显,多孔喷嘴的最优喷距为5～6倍喷嘴当量直径,多孔喷嘴的破岩性能要优于混合射流喷嘴,同时混合射流喷嘴在破碎孔径大小方面优于多孔喷嘴.本文可以为水力喷射径向水平井射流钻头的选择提供试验依据.
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