激光-PDC钻头联合破岩机理及特性研究

Research on the mechanism and characteristic of jointrock-breaking of laser-PDC drill bit

随着我国油气勘探逐步向深层、超深层和复杂难钻岩层转移,现有的机械钻头存在着破岩效率低及作业成本高等问题。因此,提出了一种新型激光-PDC钻头,以实现高效破岩和节能降耗。采用有限元方法,基于岩石HJC(Holmquist-Johnson-Cook)本构模型,建立了激光-PDC(polycrystalline diamond compact,聚晶金刚石复合片)钻头联合破岩非线性动力学模型,开展了激光-PDC钻头联合破岩仿真研究。仿真结果表明:激光的辐射作用使岩石表面受辐射区域产生了较高的温度和较大的预应力,进而在岩石表面形成了相互贯穿的损伤带,降低了岩石强度,更有利于切削齿破碎岩石;与无激光单PDC钻头相比,激光-PDC钻头在破岩过程中受到的反扭矩降低了24.8%,钻头轴向加速度波动幅度降低了10.5%,钻进位移增加了8.67 mm,钻进速度提升了112.79%。搭建了激光-机械联合破岩实验台架,进行了激光-PDC钻头联合破岩实验。实验结果表明,激光-PDC钻头联合破岩有着更好的钻进稳定性和连续性,大大提高了破岩效率。研究结果为激光-机械破岩技术的发展和应用提供了一定的理论支撑和技术支持。

With the gradual shift of oil and gas exploration to deep,ultra-deep and complex rock formations,the existing mechanical drill bits have the problems of low rock breaking efficiency and high operating cost.Therefore,a new type of laser-PDC(polycrystalline diamond compact)drill bit was proposed to achieve efficient rock-breaking and energy-saving and cost-reducing.Using finite element method and based on the HJC(Holmquist-Johnson-Cook)constitutive model of rock,a nonlinear dynamic model of laser-PDC drill bit joint rock-breaking was established,and simulation research on laser-PDC drill bit joint rock-breaking was conducted.The simulation results showed that the radiation effect of laser generated higher temperature and greater prestress in the radiated area of rock surface,which in turn formed interpenetrating damage zones on the rock surface,reduced the strength of the rock,and was more conducive to cutting teeth to break the rock;compared with non-laser single PDC drill bit,laser-PDC drill bit experienced a 24.8%reduction in anti-torque during rock breaking,a 10.5%reduction in axial acceleration fluctuation,an increase in drilling displacement of 8.67 mm,and an increase in drilling speed of 112.79%.A laser-mechanical joint rock-breaking experimental bench was built to conduct laser-PDC drill bit joint rock-breaking experiment.The experimental results showed that laser-PDC drill bit joint rock-breaking had better drilling stability and continuity,greatly improving the rock-breaking efficiency.The research results can provide theoretical and technical support for the development and application of laser-mechanical rock-breaking technology.