| 摘要: |
| 复合冲击钻井技术是继扭转冲击钻井技术之后发展起来的新的针对硬地层的提速技术,但其破岩提速机制及其相对于扭转冲击技术的区别还不够清晰,使在实际钻井中对于这两种钻井技术的选择没有依据。针对此问题,在室内试验的基础上基于有限元方法建立单齿复合冲击切削岩石(硬岩和软岩)的拟三维数值仿真模型,研究复合冲击作用下钻齿切削岩石过程中岩屑形成及破岩比功等,并与扭转冲击切削做相应对比分析。结果表明:针对硬岩(雅安花岗岩),当切削深度较小(小于0.6 mm)时,复合冲击切削破岩效率最高;当切削深度适中(0.6～1.2 mm)时,扭转冲击切削破岩效率最高;当切削深度较大(大于1.2 mm)时,扭转冲击和复合冲击相对于常规切削破岩几乎没有提速效果;在软地层(南充砂岩)中复合冲击和扭转冲击切削几乎没有提速效果。 |
| 关键词: 钻井 复合冲击 扭转破岩 破岩机制 破岩比功 |
| DOI：10.3969/j.issn.1673-5005.2020.03.008 |
| 分类号::TE 242 |
| 文献标识码:A |
| 基金项目:页岩油气富集机理与有效开发国家重点实验室开放基金项目(10010099-18-ZC0607-0025)；国家自然科学基金项目(51674214) |
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| Mechanism of rock breaking under composite and torsional impact cutting |
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LIU Weiji1,2, ZENG Yijin1, ZHU Xiaohua2, DING Shidong1
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(1.State Key Laboratory of Shale Oil and Gas Enrichment Mechanisms and Effective Development, Beijing 100083, China;2.School of Mechatronic Engineering, Southwest Petroleum University, Chengdu 610500, China)
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| Abstract: |
| The composite impact drilling method is developed after the widely used torsional impact drilling technique for improving the rate of penetration in hard rock formations in oil gas well drilling. However, its rock breaking mechanism and advantages over the torsional impact drilling were not fully studied, which can cause a confusion in selecting these two drilling methods. In this paper, a quasi-3D numerical simulation for composite impact cutting was conducted in order to investigate the rock breaking mechanism and in comparison with torsional impact for evaluating the applicability of these two methods in different rock formations. The simulation results show that the rock breaking efficiency of the composite impact cutting with a small single tooth cut depth (<0.6 mm) is higher than that of the torsional impact cutting, while the torsional impact cutting has a higher efficiency than that of the composite impact cutting when a medium tooth cut depth (0.6-1.2 mm) is used, and for large tooth cut depth (>1.2 mm), the performance of the two methods is similar. The axial impact amplitude has less influence on rock breaking efficiency, but the influence of the impact frequency can be more significant. Both of these two drilling methods are not applicable to soft rock formations. |
| Key words: drilling composite impact cutting torsional impact cutting rock breaking mechanism mechanical specific energy |
