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现代旋转钻井破碎岩石是以机械破岩为主导方式 ,射流辅助机械破岩的目的是提高机械钻速。文章论述了牙轮钻头与岩石相互作用过程及岩石剪切破坏的内在规律 ;重点研究了射流的水楔作用对岩石裂纹产生、扩展、贯通及破坏的机理。实验结果表明 ,射流辅助钻井的门限压力是岩石抗拉强度的 4 .1倍 ,是抗压强度的2 6 % ;还与井底压差及其它岩石物理力学性质有关。同时指出 ,超高压射流的研究与应用是辅助钻井高效破岩的重要发展趋势
Modern rotary drilling broken rock is dominated by mechanical rock breaking, jet assisted mechanical rock breaking is to improve the ROP. In this paper, the inner law of interaction between rock bit and rock and the shear failure of rock are discussed. The mechanism of jet wedge effect on the generation, propagation, penetration and destruction of rock crack is mainly studied. The experimental results show that the threshold pressure of jet-assisted drilling is 4.1 times of the tensile strength of rock and 26% of the compressive strength, and also relates to the bottom hole pressure difference and other petrophysical and mechanical properties. At the same time, it is pointed out that the research and application of UHP jet flow is an important trend of assisting rock drilling with high efficiency