Numerical study of rock-breaking mechanism in hard rock with full PDC bit model in compound impact drilling
Numerical study of rock-breaking mechanism in hard rock with full PDC bit model in compound impact drilling
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DOI：
10.1016/j.egyr.2023.02.084
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发表时间：
2023
期刊：
影响因子：
5.2
通讯作者：
Jian Huang;Bo-dong Zeng;Yuhang He;Xudong Wang;Liqing Qian;Chengyu Xia;Xianzhong Yi
中科院分区：
文献类型：
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作者：
Jian Huang;Bo-dong Zeng;Yuhang He;Xudong Wang;Liqing Qian;Chengyu Xia;Xianzhong Yi
地热储集岩具有高应力、高硬度、高研磨性的特点，使得钻井速度低、钻井成本高，阻碍了地热能的应用。提高硬岩地层钻进效率是地热能大规模应用的前提。冲击钻井被认为是硬地层中最有效的钻井方法。PDC钻头复合冲击钻进是近年来受到广泛关注的冲击钻进方法之一。为了进一步提高该方法的钻进效率，对PDC钻头复合冲击破岩机理进行了研究。采用Drucker-Prager准则作为岩石本构关系，等效塑性应变作为岩石破坏准则，MSE（机械比能）作为破岩效率的评价方法，建立了全尺寸复合冲击破岩PDC钻头的三维仿真模型。分析了PDC钻头复合破岩过程中的破岩规律以及冲击矢量角和冲击持续时间对破岩效率的影响。结果表明，复合冲击钻削能有效缓解粘滑振动现象，提高钻削效率。在复合冲击模式下，压应力破坏和拉应力破坏同时发生，拉应力破坏是主要的破坏模式。岩石的峰值应力比非冲击模式高5.49%，残余塑性变形比非冲击模式小4.28%。随着冲击角的增大，均方误差先减小后略有增大。最佳冲击矢量角在30° ~ 50 °范围内。随着冲击时间的增加，均方误差呈波浪形减小。在0.2 ms-1.0 ms范围内，最佳冲击时间为0.8 ms-1.0 ms。
Geothermal reservoir rocks have the characteristics of high stress, high hardness and high abrasiveness, which makes the drilling rate low and the drilling cost high, and hinders the application of geothermal energy. Improving drilling efficiency in hard rock strata is the prerequisite for large-scale application of geothermal energy. Impact drilling is considered to be the most effective drilling method in hard formations. PDC (Polycrystalline diamond Compact) bit compound impact drilling is one of the impact drilling methods, which has been widely concerned in recent years. In order to further improve the drilling efficiency of this method, the mechanism of PDC bit compound impact rock breaking is studied. Drucker–Prager criterion was used as rock constitutive relation, equivalent plastic strain was used as rock failure criterion, MSE (mechanical special energy) was used as evaluation method of rock-breaking efficiency, and a three-dimensional simulation model of full-size PDC bit for compound impact rock-breaking was built. The rock breaking law in PDC bit compound rock breaking process and the impact vector angle and impact duration on rock breaking efficiency are analyzed. The results show that the compound impact drilling can effectively alleviate the stick–slip vibration phenomenon, and improve drilling efficiency. In the compound impact mode, compressive stress failure and tensile stress failure occur at the same time, and the tensile stress failure is the main failure mode. The peak stress of the rock is 5.49% larger, and the residual plastic deformation is about 4.28% smaller than that of non-impact mode. With the increase of impact angle, the MSE decreases first and then increases a little. The optimal impact vector angle is in the range of 30°–50°. With the increase of the impact time, the MSE decreases in a wavy manner. In the range of 0.2 ms–1.0 ms, the optimal impact time is 0.8 ms–1.0 ms.