硬地层复合钻头破岩特性与提速机理研究

发布时间：2018-11-24 17:17

【摘要】：PDC-牙轮复合钻头是一种综合了PDC钻头与牙轮钻头结构特点和工作原理的新型钻头,能更高效地钻进硬地层。但由于对其破岩机理认识不足,使得PDC-牙轮复合钻头的研发具有盲目性,推广受限。基于弹塑性力学和岩石破碎学,采用Drucker-Prager准则描述岩石本构关系,塑形应变作为破岩判据,通过有限元法建立全尺寸复合钻头和PDC钻头动态破岩的非线性动力学模型,分析了复合钻头作用下硬地层岩石的破坏机制,对比了硬地层中两种钻头的动态破岩过程。结果表明:复合钻头钻井能满足井壁稳定性的要求,然而一旦井壁失稳,井壁岩石将大块脱落;以拉应力破岩为主是复合钻头在硬地层中大幅提高机械钻速的原因之一;硬地层中复合钻头扭转振动低于PDC钻头,破岩效率更高;由于牙轮滚动的多边形效应,复合钻头沿钻进方向对岩石的冲击较PDC钻头更大,能更快钻进硬地层。
[Abstract]:PDC- cone compound bit is a new type of bit which integrates the structure and working principle of PDC bit and cone bit, and can be used to drill into hard formation more efficiently. However, due to the lack of understanding of the rock breaking mechanism, the research and development of PDC- cone composite bit is blind and limited. Based on elastic-plastic mechanics and rock fragmentation, the constitutive relation of rock is described by Drucker-Prager criterion, and the plastic strain is used as the criterion of rock breaking. The nonlinear dynamic model of dynamic rock breaking of full-size composite bit and PDC bit is established by finite element method. The failure mechanism of hard formation rock under the action of composite bit is analyzed, and the dynamic rock breaking process of two kinds of bit in hard stratum is compared. The results show that the compound bit drilling can meet the requirements of wellbore stability, but once the shaft wall is unstable, the wall rock will fall off, and the tensile stress rock breaking is one of the reasons for greatly increasing the mechanical drilling speed of the composite bit in the hard formation. The torsional vibration of composite bit in hard formation is lower than that of PDC bit, and the rock breaking efficiency is higher. Because of polygon effect of roller rolling, the impact of compound bit along drilling direction on rock is greater than that of PDC bit, and it can drill into hard formation faster.
【作者单位】：西南石油大学机电工程学院;长城钻探工程有限公司钻井二公司;
【基金】：国家科技重大专项课题项目(2008ZX05022-006)资助
【分类号】：TE921.1

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